FLORIDA GEOLOGICAL SURVEY BULLETIN TWENTY-FOUR--FRON
Aerial photograph of the Dunnellon Phosphate Mining Company's hard rock phosphate mine, near Herna, rus County. In the lower left corner are piles of washed phosphate in wet storage preparatory to shipment to
dma for drying and exportation. The waste overflow is shown in the left center and the quarry in the cer which have been built long ramps that extend to two dre dges. These dredges dig rock with a 1 V2 yard sh maximum depth of 35 feet.
Photo furnished by the Dunnellon Phosphate Mining Company.
STATE OF FLORIDA DEPARTMENT OF CONSERVATION
Florida Geological Survey S. E. RICE, Supervisor of Conservation HERMAN GUNTEB, Director, Geological Survey 'S
GEOLOGICAL BULLETIN NO. 24
FLORIDA MINERAL INDUSTRY WITH SUMMARIES OF PRODUCTION FOR 1940 AND 1941
ROBERT 0. VERNON, Ph.D.
Assistant Geologist Florida Geological Survcy I; ___________________________________________________________
Published August 1, 194:1
LETTER OF TRANSMITTAL
Honorable S. E. Rice, Supervisor
Florida State Board of Conservation
I have the honor to transmit a report entitled "Florida Mineral Industry, with Summaries of Production for 1940 and 1941" by Dr. Robert 0. Vernon, Assistant Geologist, Florida Geological Survey, and recommend that it be published as Geological Bulletin No. 24.
This report contains a discussion of the most important mineral resources of the State, including phosphate, limestone, dolomite, marl, clays and other nonmetallic resources of Florida, also briefly the socalled rare earth minerals. It contains many statistical tables showing the output *and value of the various mineral products of the State as a whole and by counties. The principal features of each variety of minioral deposit are appropriately described. The distribution of the leading resources is shown on a generalized map.
It is felt that this report; will prove of considerable interest and value to property owners, to those actively engaged in mining in Florida, to the teachers in the schools of the State and especially to all interested in the development of our mineral resources.
Herman Gunter, Director
Florida Geological Survey
May 28, 1943
The Florida Geological Survey receives many inquiries concerning the State's mineral resources, names of producers, and mining methods. This paper has been prepared with the view of placing such information in available form. The report provides a general library of reference for the use of the mineral industry and others interested, and serves as a forecast of the trends of the industries for future investment. For those specifically interested a broad bibliography is appended for each mineral substance. It is hoped that this paper and the bibliography will stimulate research toward the improvement and refinement of Florida mineral products resuiting in the establishment of special plants to the end that an industrial network utilizing the State's raw products to a fuller exploitation will be built in Florida. R. 0. V., 1943
Florida Geological Survey
The Florida Geological Survey cooperates with the United States Bureau of Mines in obtaining statistics on the mineral production output and value in Florida. The writer has used the Bureau of Mines data freely and has supplemented them with data obtained through the generous help of Florida producers in response to requests for information.
Many producers and interested persons have kindly submitted photographs, and where these have been used as illustrat ions in this report the use is gratefully acknowledged.
1x'itro duc tion **~.*.......*..*... .... a a a...... ..a. c.p.a me mmeamam a...... m.mm - em. mm a me a a - - mae ma. C- - 15
E~r4,dI.1cti()11 ),s7 substances ... . *.... * ** ~ ....... ... - .. *.*. .. a a *.. - .~..*.. - :1.6
~ b3r counties ............... ma.S.*m..m*ama*....a. ecm.mminm*mm .memm*a.e.mmmm..cm 18
Total mineral production for Florida since 1900 ..................... 20
Land forms and geology m ma. ....... emaaamam.. memam.e.ca m mm. a pea.. ... *Smmememc~ a. a am-c a...a.a am.. 23
S t1~I14t11l~ ..a..a.... acm..... mm.... macmama. mmmc .me. ma.. a mmmm..mmm c .me... mc. mm. am ememame. ememmep. -ma cc acm am ma mm 28
Oil and gas .me...... am...... a .mme.mm.a.mm.mmemamamm mae.... mm. cmemamm.amaamamma -mamma.-..-. ..a.aaa.e macam.. ama 31
Florida mineral products in agriculture *maamemae.mae..mamaemamaaamea.a.mm.ammm..mmm 34
.Aims and practices of soil conservation .a.aac.emma.aaaaaamcm.mm.amma.maem.c..mm 35
Soil building allowance a amaaca.e.aaam. m .me...... em. a emmmaaeemm. .me...... meeeaaam.a a mae...... 35
Florida mineral resources .me... mamma... mm a .... amemmasmam mama.... mm...... m - sin.. macmamme .... ma.... 3'?'
]~I[irieral pigTrlelltS mm.aaaa mmmcm... a.m.amaa .. mmmc...... ma am ac.mmcem me-me..., emma am..... amammamaCmamc 3'?'
~ cci.irrence in F'lOllda, mma...... mm...... amine..... ma ma a.... mamma mm...... ma a.m.a...... a a 38
N(inirig mamma..... em..... ammmma.aamm.m. mac-S.c. cinema mmmmc..a em... mSammamae me...... amme.Smmmm am.....
em...... eminmacain .................. m ae.amammeae ...... ma..... 4:1.
cJiay and 01a3' plodUCtS mm. mine mmmmme. macaaa..... .... macmammamm. cmacmaaa..... mm ama...... eec.. a 43
'JI' yp e s of ci~~ mama... a m c a a a m m a m m m m c .... m a a a m a mamamme a. mmmcm cam m a a cm ma.. ............... a a ij 4
Kaolin a. ............... am .Sammm.mea ama. ema ammamams. maemam.ac. a ........... mee.mam..... mama.. 45
Blea~hii'1g Cla.3' am.emaaaaammmaeam.ammammme.ema.maammmmmamecmaemmaeeamammmaac.amacccm&a 46 4~t11~I7 Cl8,31' m.amm.am.e.a.a ecin.ammc.mmammmmammmamm..aaa.caaammcammm.em..m emamm.mmaam.aaaa am 50
E~J7t3ductior1 arid rrxai'ket mc.... emammae.e mammaa...ae maca.m.a c.m.a.mu. ma.mae..me.em. mac m 52
~erxient S.caaa.a.eam.mmaa.e.mmaameaaammaaem..mmaammmamammmmamaamaaamea.aaaaammeamaammaaam.m mmmaminmmmammamee 54
Diatomite ... ......*... mmmcm .cmaaam mmmc em mc maca eaSe me 58
lID esci.iption cmamemmcmmmaeacammm.aS..ca.mamacaamamm.aacmc.amincaaammmmcm.c.mamm.aaama.m.maeemama. 58
Mining and processing memammmmm*mamammmtceaamaccSm.mmmam.mcmaaammamammm.am.a.cc*mm.e 59
~~ccur~'z.ezice mmmc. maacm *a mmaaea..mac..aamc.amaa e.mmaam.ma.aaeSaamcmmcmeammaam.cam.mmmmmmc emammaa
1JJses .5mm-mS mma a-cm...,.. mmcm.. 0 ..... mm.- maa m mama aaaa mmamm mama ma. mmcm mc...... ma mmmmam mm.cmma. camam 60
M marketing mm.... acm.mmmc. am ....Sm-mama-mama. ............. mamma ma mmmcc.... ma mmcc. m a amine a ameca a mm 62
F' 12'~3 dUCt.ILO n ............. a am ma.... mm mm c mm a.... a.... am am me cm. mm am. m mm a me e cm, a mm a m a am a m a mm a mm m 62
E'eat and muck mm...... mm mmmmae mmmcm em...... mc.. ama.,... mm...... ama... me... mmcm mama..., a ameam. em. 62
E1~ e scrip tiO fl cm ammmmeinammam m a a a a c a a .......... a a m ma a ma. ammmmmaeemm.mamaammama.incSa.mcmam c c a e ma a a m 6 2
Distribution am..... a. ama.. mm cam...... mm. ma m mecca ca-mesa a mmma ammaamam.mm mammamm. ma. ma.. am mac.. 63
Origin a emmam..... emma me. ma. em.. a camacac mm*a.mm ama-a.m.a...... a a macma... mm.aa.ammmm amammammam. ama... 64
Chemical changes in the fonnation of peat amaaam.ccamcaeaaammmmaamma 64
Uses ammmaa.m. mmacmcamaaaaam. ma.emaccma* maaaammemamma.mammaa.mSe.e.ammmmmm.cmam.emaSm.m.mm mmmecam 65
Minixi~ and pro~~~ tion 5mm ammacaca. m macmac.. a..... macmama.. mamma mcemacam. ama...... am. 66
ci~iushed StOfle mc aCm.CinSaammmCm mc.*aae.ammmaaamaeama.aacmcmm.c.*amaa.amamceceaaememacaemcaa* 68
Introduction .maaamamamaac.mmeamemammaeaaaaammmmmmmaa.maecm.aamammm.mmmmammemmaammac.a.acinammaa 68
11 3?p es of crushed stOne lxx FlOrida. .amce acme macam.. acam a-a.m.a...... a.m.a.. a. 69
Expansion and opening new quarries emma.. came mmmcm emmm.ma mc.mmcam mm.... 70
Uses a. a am mc mamma mmcm... mmccc... acm a.m.a.....- macemma m cmaa maa..a.m mmmc. maca main am mmma.c mmcm ma ammama mm. 'TI.
Concrete agg~i'egate a m.ameScaamSmaae.amaema a inca... am maca mama maca. m mm maw m cc. m mm 72 Road base material aemmemmemaa.ma.ammaaamSaam.mmcacmmmm.a..aamaemmmaa a.m.a.. ma 7'?' Railroad ballast acm-am. em.memmamm e cm-mr.. m. ....... acm.. mm amma.maacmc.ammmec .ee..ma 79
jl'lorjda East Coast Railway a a macma, mama, a minmmc a mmcm mamacaaa ma 81 Atlantic Coast Line Railroad Company aecamaammmamacam 82 Seaboard at4..i1.~ I.aaifle ltaIliMTa,37 mm.... a.m.a. caam mc.ma a.... ma. me mm... 82
Riprap *acmaamm.macbaammac.eaaecm.maamama.eSemac.mac.m.mmmmmmm.mmaem.eammama.m*amammmmmcma 83 c~t1ier USeB .acammma.mSccamm.mmemamammSemmmmecm..aammm.C.amacam*mmammcUaeeSmmaaaaflmaaam 83
Florida mineral resources- (continued) Page
Introduction **........... .. .... .. *.......a.. cc.... *e.e*ce ee..*.*.eec..C*a~.. a. ..c 89
[Cinds arid origin ****~***~** ***................... .. .. ......... ............... 90
0 oil tic limestone .................. . ......... .......... ... .* ... ** ... * .... 91
Dolomite or niagneBium limestone .................. .. ........ 91
c a~re 1 lxii e stone deposits ---- - .... ............ *. ........ ...... .... . ... 92
I.ioose, granular limestone ............... ........ . ..... .... ............ 93
I.~imestone processing .............. -- C C *eC C Ce-ccCCC -cCCCCCcC CCCC.c..* -Sceec C C C C C C 98
Pfrlar'1cets and pi':d~.i~t.icn s..... .cce ccc...... .... s.c.... -. -. c ce e -. ....e 104
F) ol omit e and do 1 orril ti c ii ni e stone .... ~5 .... . ........ .... ... . . ...... ... ... 1.0 6
Description and occurrence c*.e.**e...e e...... ccc.g* ...... cC...... aa..e 106
J~1irkix.kg aiid t.-aris~:rt.aticri .. ....... s... *. .*....~.... .c -. cc.. CSC. ***... 1.07'
Uses . . . - - - - . - . - - . . . a...... cc...-- e ---a.. - - * .. a C C C~* - - - a * a 108
Production and m arkeUng ........... *........ .......... .....----------------- - 110
c~ oquixia -. . - ..... - - - *. . - - C ~* - c .............. . .. ... . . .. - ....... *. 111
Shells, produced from oyster bars, Indian mounds and freshwater lakes ...cSc.eC .e.... - c.c~ee~ - c e.e.c...... a a*e.c.c. C a Ca....-. aece..... .....-c 117
.a eec.. .a..cc.c....ec c...cCCcccC.c...c. c.cee. -c..... ..~.* c....c.cae cc-c.. cecacec. ec.. cce........e. 119
Uses cec a CCCCCCC*C * cccc ac.ce. c* - cc.c.c ~ccc.cc*~ ccc..... .ce... e cc........ ... 120
S an d and g r a it e 1 ............ ............................. ........... ...... - ........ Ca...... .... 1. 2 1
Definition ...... CCCC.c. cccce..... -ecccc.c .ccc.cc c.CcC.C.cc -..cc...e ---a--Ce...... 121
Co iii y o si t.I on c a a c C - c a e - - C C c C C C * C c - C C C C - c c - a - e a a c - - - 1 22.
~~1assificatlori and origin e - ... - .ec..c c cc .c - c .e ccc c...e - a .Cc..c.C 122
ecC.Cc.--------------------e...ccee.cccc-c. ----------------a.................ceCcC.ccC *CCCCCCCC--------------.c.e~~c.cce. 123
Building aggregate ... *~ - - CC *-* *~ .. . - ~c*~*~ ~ce - .. - .... 123
Grouting sand .................... .ec. ccc.c.*. CcCCCcCCC. c-.e.... c.ca CCCSCC.. 124
P a it In g a g gre gate ...... * C ........ ... .... - .... . . ..... ... ...... C C C *~ I. 2 4
DvlolIing sand Cccc. - C Ccece a - C C C SC C C Ceac .5cc.. eeC ece.c.. CCC C CCC CCcCC a. - 125
Glass sand ............. cC ---- ccccc c a c ......... c~ C-------------- a c c C C C - -------- - - 125
E ii gi n e san d - C C S C C S - ---- ccc. C c ... .... C C C c C C -- ....... C C C C .... ..... ------- ...... 1 2 5
Abrasive sand ....... ----- ---- C C C C C C c c C C C C ---- C C C C a c a e e e c e a c a C ... C C 125
Blast sand cc.-...- seas c-cc.. CCC- cc-c-Cc-, ac-Ca.---.. ccc..... ~ Cc--C-Cc... 126
Li' i 1 t e r san ci and gi a it e 1 ................. C ... c c --- C C C C C C C C C C C C C c * a ----- 1. 2 6
F'lre or furnace sand cccCecccccS.ccCaccCCCCCccCC...Cee.cCcC.CS.cccCe 126 (J e r~ a. xxii c q U & r t.Z cc. ....... a ........ C C C a a c ..... C C ------ C C C C a - c c C C C C 126
F~1 11 111 8. t ~ ri 8.1 .......... C C C CC c a C C C C C C ... C C S C ... e cc - C C ............ a a C C C C C ~. C 1. 2 7
El 'iller sand a a C ...... C C ............ ................. C .... C C a c ------------- C C 5 C S C 127
Railroad ballast C C C CCCc SC C C CCC.CccCC Ci *CCccCCCCS CC- C CC CCcCCCC C cee CCC CC-C C--CCC CCC
Other and special uses ~ CSc C C C C C CS-CC-CCCCCCCc.CC...CccccCCC C C C C C C 127
Mining and preparation A.. .. c*CCCCCCSC. a *cccecc.c - C C C - C C C C e C C C C C C CC 127
J1'ests and properties SccCccCc ccCcCCCccc Cc CCCCCC CSSc C C CCCCCC C C ccc cccccc.c, ac--CC-CC 133 Uses In florida -------------------C C C C C C C C C C C C C c C c C C C C C C C C C CC--------- .... --- C C a c 135
M marketing and prices C C C C C CCC CC* cc. a C C C C C C cc ~ce ccc. C cCC ....... C C C 135
Florida mineral resources- (continued) Page
E~hosi~hate ...... .*........*.***..*. ..... .... ... .... **...*. ..... . .... ... . *0* a.... ..**a. *...*.. 148
[nticclticticii ~ 1.'18
Iryj3es and clesciiptiorts ... ....... .. .. .. ... ..... ...... .*.. ....***. ***.. -. .... 149
IL~ai'ic1 ebIle phosphate - * ~ a. a a a a.. a a a a a. a a a--. aaaa*a*caa. a a a a a . a. 1.49
II a i ci r 0 C 1i p lC s ph ate ... . ... ...... .. .... .. ... - . .. .. . ... --- ... - 1 51.
Distribution and occiirrerice ... .~. ............ .... .*... .. . a... * - 153
~3 rigiri ... ....a.......g... ......a..a...a.. a.... a .aaa*e.aa aaea*aa .a.. *a.*aa.ea. a ..ta. ..aa aa a *.a :154
011 flotation recovery ............. aa.... . a . a - a a a a a a a a a a a a - a. a . a a a. a a a a 166
Marketing a..... .. ... a **. .. a * . ... a a. a a. a ......... - . . ... .. . . .*. ... a ... 169
Uses . *.... ........ a. a... aaaa-.*. a-. a - a a a----------------a---------------------. a.. a---------------------a-aa-a-...a a a-a... 171
~ du~ Hon .... a a a a a. a .... a a. ..... a .....*.. - . ..... a.. a...... a. .aaa..a aaa.aa. 1. '12
Billiogi.aliy - a *. - . .~.- .. -a-a..,. a... * a * a *. a....., a .. .a.. a a a a a . aaaaa.aaa 1'?''?'
Appendix-Directory of Mineral producers for 1941-1942 ..... ...... 185
lndex a.... a.aa.a.aaaaa.a. a.. aaa--------------a...-- aaa a.a..a.aa.a aaa a a. a...a..a aca.. a... a aa..aaa.. a.aaa. a..... a. 201.
Frontispiece-Aerial photograph of the Dunnellon Phosphate Mining Company's hard rock phosphate mine, near Hernando,
Figure Figures Page
1 Graph of total mineral production of Florida for period
1900-1941 a a. a. ate-a..-... a at a. a a a a a a a a.. a, a a a a a a a a a. a a a. a. a.aa.... a a a. a a a aa., a a.. a a a a.., a a-a, a a-a-a 21
2 Key map to the mineral resources of Florida a.aaaaaaanaaaaaaaaa.aaa2&25
3 Kaolin pit of the United Clay Mines Corporation at Crossle)', 121.itriarr1 ~Joi.int3r a,. as.. a.. s-ac-a.... aa aaaa aaaa aaaa.a.aaa.aaaa .aaaa aaaa. aa aa. a *.aaaa p.... 46
4 Aerial view of the fuller's earth plant of the Floridin Cornp an 3T, ii e a r ~ ti Inc 3T, ~ Bd s d e TI Co i.i ii t3' a a a a a ..... a - - a -. --- ..... a a a a a a a a a a a - 4 7'
5 Fuller's earth mine of the Floridin Company, near Quincy,
c1~adsden ~~olxnt3r a .a.saa .aas.a. a a.. -s.. aa.a aaa. aaa a aaa. a *aaa.a a *a a. a. aaaa.aa-.. a.aaa.,a a a.... a 48
6 Clay pit of the Taylor Brick Company, Molino, Escambia
County .. a a. aaa.a a aaa.a.a -a. a a a a a a..aa.a a Ca...... a. a a a ~ a-a.t, a a a.. a a a a a..... ~ a.., a a a a a. 50
7 Clay pit of the Florida Portland Cement Company, Citrus
County, about 60 miles north of Tampa a a aa aaa.., a a.., a a a... a a-aa. a a a a a
8 Air view of the Florida Portland Cement Company plant at
IY8P1II~?a Ca....aa.ataa.a..aaa.a..a...,.a......a.aaa...a..a.aa.....aa.aa...aa..a..a... 56
9 Loaded cars of materials used in the production of cement,
Florida Portland Cement Company, Tampa taaa..aaaC.aaaaa.aaaaa.aa.. 57 10 Diatoms from a deposit 15 miles south of Clennont, Lake
County. 1. Surirefla oblonga Ehrenberg. x 929; 2. General view of strewn material, x 100; 3. Pinnularia major (Ktitzing). x 488; 4. Pinnularia gibba Erhenberg. x 592 (from McLeod Basin, Santa Rosa County); 5. Pinnularict
'niridto (N4t~anh~ v 19Afl 11
Figure Figures Page
14 Limestone Formation in the Florida Caverns State Park,
I~Taria.xina, Ja.Clsorl c1~Oliiit3T .....e.......t..a.............at...ss.........s........b.. 92
15 Cable pulled dump car commonly used in the limestone pits
16 Pit of The McDonald Corporation, near Brookaville, Hernando county *...e*e..e.e...c*......e*...a...e.....e..*.*....*......e....s..........be.... 97'
17 Building block quarry of Richard Hartafleld in the Marla nri a limestone, Jackson County .... .. .. ............. .a . .. ........... - .... 99
18 Building blocks sawed from the Marlanna limestone at
Marianna, Jackson County, by Umestone and Lumber Corn19 Limestone pit of the Miami Lime and Chemical Company,
20 Operating equipment of the Florida Dolomite Company,
near Sarasota, Sarasota. County ....... .. ............ ...... .... .............. 109
21 The Castillo de San Marcos National Monument (Old Fort
Marion), St. Augustilie, St. Johns County . . - . - . . - .. .. -.. 112
22 Fort Matanzas Monument, 14 miles south of St. Augustine,
St. Joluis County ........y... .** -. ... ..... ... - . -. .. . ... .. ... . . ... 113
23 Indurated, cross-bedded coquina in an abandoned beach
ridge, F lagler Beach, F'Iagler County' ~ ....~........ 114
24 Shelter and band shell built of coquina at Daytona Beach .... 115
25 Dry sand filled valley of the intermittent Allapaha River,
north of Jasper, Harriilton County ... ..... .. -. ..*..~* . - ....... ..... .. - 124
26 The Ruth Jeannett, a tug used by the Florida Gravel Company, Chattahoochee, Gadsden County .... ..... ......... ... ..... ... .. ..... 129
27 Dredge, washer, and screens complete on one barge of the
Florida Gravel Company, Chattahoochee, Gadaden County 129 28 The Mammoth Sand Company pit and washer, 3 miles
nortlieast of IZake Wales, Polk ~2oi.irxty .... ...... ............ .. .. - 130
29 Sand pit of the Tallahassee Sand Company, Inc., near Tallahassee, Jaeon County .*.... .. ...*... ...... ..... ..... . -. ... .... - - .. - .. . * * - 131
30 Sand at the United Clay Mines Corporation, Crossley, Putx~iarri c~oliiit3r ... . ... .. *. ** *. . .. .*.*. .. a.. a. eta.... ..a ** ce *... ***** .. a. a. a.. :1.32
31 Soft phosphate prepared for drying at Soil Builders', Inc.,
plant, Hem ando, c3itri.is County ....... .......... ................. -S ... ... - 159
32 Typical flow Bheet of Florida hard rock washer .....~............ 160
33 Typical quarry operation in the land pebble phosphate field,
by Swift and Company Fertilizer Works, near Agricola,
Polk ~Jour1t3r *...a..a..aa....aa.....aa..a..aa...a........aaa.....a............a..... 1.62
34 Washer of the land pebble phosphate field, Swift and Company Fertilizer Works, Agricola, Polk County ...........~. 163
35 Log washers of the type used in the land pebble phosphate
field, Swift and Company Fertilizer Works, Agricola, Polk
36 TypIcal flow sheet of Florida land pebble phosphate washer 165
37 Rotary drier recently installed by the International Minerals and Chemical Corporation, Mulberry, Polk County ... 167 38 Part of the table feed section at International Minerals and
Chemical Corporation flotation Plant No. 6, near Pembroke Iii ['eace Ri~rer ~Talle 3 ..... ............. .. -. -........ .e. .. .. .e .... ... 168
39 Graph of the production of phosphate for the period 1900
tlirc ugh 1941. ...................... .................. ...................... ....... . ........... 125
1 Mineral production in Florida for 1940 and 1941 ~ 17
2 Mineral production, by counties, during 1940 and 1941 ..~. 18
3 ApproxImate tonnage distribution for shipments of Florida
mineral products during 1940 and 1941 ~ 20
5 Analyses of ocher and lhnonitic sands of Florida ..~. 39
7 Value of clay and clay products produced in Florida since
8 Characteristics of Florida diaton-iite ~ 58
9 Production of peat, muck, and diatomite for 1940 and 1941 67
10 Abrasion and accelerated soundness tests made by the Division of Tests, State Road Department of Florida ~ 75 11. Unit weights of coarse aggregates made by the Division of
Tests, State Road Department of Florida .....~.------------------------------------------------76
12 Chemical analyses of limestone for use as road base courses 79
13 Comparative values of different materials used as ballast
14 10~~a ~ Railway ~.------------------. 1~~'*~ ..... -. .. ... .~.. 80
15 Production of limestone by use in 1940 and 1941 ...~. 105
16 Production of dolonxitic limestone for 1940 and 1941 ~. 110
17 Production of coquina for 1940 and 1941 ~ 116
18 Figures for shell, produced from oyster bars and Indian
1.9 ~~rade terrx~ s of (31 as tic iai tide s ------- .. .... . - .. .. - ... - - .... ... -. . :1.22
20 Apparent specific gravities, unit weights, and absorption
percentages of various concrete aggregates produced in the
S t a t e of ~' 10 il d a ... . ........ . . - ..... .... -. - .------------------. - . ................ 1 3 6
21 Average sales prices of various sands and gravels sold in
1 9 4 ~ a xi ci 1 94 1 * ... * *---------------------- - ... .... - .---------------------. ......... .------------------. . ... .... 1 3 7
22 Production of sand and gravel in 1940 and 1941 ~ 139
23 Production of water in 1940 and 1941 ~ 148
24 Production of phosphate in 1940 and 1941 .............~. 174
FLORIDA MINERAL INDUSTRY,
1940 and 1941
Robert 0. Vernon
Although Florida is not generally considered a mining state it has produced in excess of 461,000,000 dollars worth of mineral products since 1900. The total value from mineral output during 1941 was $21,112,277, being an increase of $4,980,584 over that of 1940, which was $16,131,693. This increase is due to greater domestic demands principally from military uses. Nineteen mineral substances were produced in Florida in 1940 and 1941, including the various usages of the different clays, and 45 counties of 67 contributed to the State's totals.
The mineral resources of Florida are largely non-metallics the exception being the heavy minerals, ilmenite, rutile and zircon, recovered from beach sands along the East Coast by the Riz Mineral Company. These sands have been worked irregularly since 1916 and substantial deposits have recently been ptospected in western Florida and in Duval County, the latter is expected to be in production within a reasonable time. Ilmenite, rutile and zircon have been classified as either strategic or critical minerals by the War Production Board, and this added interest has stimulated prospecting for concentrations of these minerals in Florida beach sands. Phosphate has been mined in Florida since its discovery in 1888, and leads the State in the value of output of minerals, being 48.0 per cent of the total value of mineral production for 1940 and 48.5 per cent of the total value of production for 1941. The quantity of all phosphate increased from 2,678,784 long tons in 1939 to 2,847,481 long tons in 1940 and 3,367,797 long tons in 1941. The value of this phosphate decreased from
~ a a - a a a ~ '' - ~ '- '- -~ -~ i a
16 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
Limestone ranks second in value of output, its sale realizing $6,862,966 in 1941 as compared to $5,093,677 in 1940, the increase being due almost entirely to the use of crushed limestone in the construction of military bases throughout the State. Sand and gravel were likewise used more extensively in 1941 than 1940, selling for $1,161,675 as compared to $743,928. With clay, coquina, dolomitic limestone, diatomite, muck, peat, sand, gravel, shells, and water all showing increases, the total production for 1941 was $21,112,277, the second highest yearly output in the history of the mineral industry. This compares with the output of $23,435,804 in 1920 and $20,724,487 in 1926, both of which were post-warboom years.
Production of Substances
The following table shows the quantity and value of mineral substances produced in Florida during 1940 and 1941, as compiled from the United States Bureau of Mines mineral statistics, and from a survey of the Florida mineral industry by the Florida Geological Survey. The approximate total of both part-time and full-time employees is given for each industry in the extreme right column. Figures on production and value are those reported by the operator and include estimates made by such operator where book records were not kept or were not available.
Table 1-Mineral Production in Florida for 1940 and 1941
Amount Value Amount Value
c~lay $ 1,666,120 ----- ---------- $ 1,825,570
.... ......... ..... . ..... .................
Brick and tile' e nn ~. 37,683,157 unitS 430,669 32,027,668 units 336,227
Cement,2 fuller's earth,
kaolin, and pottery 1 -- -. - 117,508 short tons 1,235,501 111,579 short tons 1,489,343
Coquina' - ~. -. -. .~. -- .. ~. 19,888 cubic yds. 24,264 27,073 cubic yds. 30,083
Dolomite (agricultural) 68,777 short tons 222,904 86,453 short tons 279,650
Flint rock *..*~. 80,814 short tons 174,709 48,600 short tons 113,385
I-' Limestone' 3 4 .. -- ~. ~. 3,726,218 short tons 5,093,677 5,266,148 short tons 6,862,966 .4
Diatomite, muck 1 and peat 34,622 cubic yds. 98,052 56,156 cubic yds. 125,548
Phosphate ***.*.*~~*. 2,847,481 long tons 7,747,395 3,367,797 long tons 10,239,778
Sand 1 and gravel ~ 1,040,365 short tons 743,928 1,613,346 short tons 1,161,675
Shells' - .. .-.. - ..... .. -. - -- 230,050 cubic yds. 198,821 308,217 cubic yds. 304,592
Water 1 ........ .~. -. .. .. -. - -e 1,729,942 gallons 161,773 1,824,498 gallons 169,030
Totals $16,131,693 *..**.................. $21, 112,277
C ~-**- *- ~ .e-C.a* ~....eeen....e.w..... ...* *..- --.e.-.e
1 Contains a few values that were estimated by the produced', where no books were kept.
2 Estimated from the number of barrels of cement.
3 Contains an estimate of the limestone used in cement, b ased on the number of barrels, and includes the stone that was sold as concrete aggregate and building stone.
4 Tonnage includes an estimate of tIie tonnage of art and dimensional stone, reported in cubic feet.
18 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
Production by Counties
Table 2-Comparative Values of Mineral ProductB, by Counties1 During 1940 and 1941:
County Mineral Products
1940 J 1941
Alachua $ 386,406 $ 428,172 Flint rock, limestone,
phosphate clay, water.
Bay 9,341 50,400 Peat, sand, gravel.
Bradford and Bre- 5,764 65,183* Coquina, muck, sand,
Broward 96,172 129,608 Limestone, water.
Calhoun and Clay 156,569 53,577 Brick clay, water.
Citrus 910,977 1,194,659 Clay, dolomite, limestone, hard rock
phosphate, p h o sphatic clay.
Dade 1,148,929 1,391,535 Limestone, sand, water.
Duval 130,560 204,509 Coquina, sand, shells,
Escambia 204,200 208,954 Brick clay, pottery
clay, sand, gravel.
Flagler, Hamilton 1,566 265,617 Coquina, limestone,
and Hendry sand, brick clay.
Gadsden 444,300 806,050 Brick clay, fuller's
earth, sand, gravel.
Hernando 2,570,853 3,141,289 Limestone.
Hullsborough 867,428 1,589,442 Land pebble phosphate, sand, shells,
Indian River and 16,250 133,702 Sand1 limestone.
Jackson 8,249 6,616 LImestone, sand,
gravel, brick clay.
Lake 55,012 59,650 Diatomite, sand,
Lee and Leon 85,197 128,179 Limestone, sand,
LeVY 410,601 480,201 Dolomite, limestone.
Manatee 41.274 39.644 Dnlnniite 1hnestnn~~
FLORIDA MINERAL INDUSTRY 19
Table 2- (continued)
County Mineral Products
1940 I 1941
Orange 99,712 107,674 Peat, sand.
Palm Beach, Pasco 71,795 16,024 Limestone, water.
Pinellas 34,412 60,235 Coquina, sand, water.
Polk 6,869,869 8,596,425 Land pebble phosphate, sand, phosphatic clay.
Putnam 330,277 421,918 Kaolin, peat, sand,
Saint Johns 6,398 10,388 Coquina, sand, water.
Santa Rosa, Semi- 82,145 230,198 Flint rock, limestone,
nole, Sumter pottery clay, water.
Sarasota 613,884 103,885 Coquina, dolomite,
Suwannee, Taylor, 39,856 29,502 Brick clay, sand, WaWashington ten
Volusia 32,737 46,437 Coquina, sand, shells,
TJnapportioned 45,080* 130,901 Limestone, sand.
Total values $16,131,693 $21,112,277
Summary: Polk County led in value of output for both years, being almost three times the value for Hernando County, the next highest. These counties are followed in order of production value by Dade,
9 Hilisborough, Marion, Gadsden, Levy, Alachua, and Putnam counties for 1940, and this order is the same for 1941, with the exception that Hilisborough moved up to third place.
Includes the heavy minerals produced from beach sands.
t County totals are grouped, where the number of producers total less than three, to avoid revealing production figures of the Individual
The mineral substances that were produced in Florida during 1940 and 1941 were shipped largely by railA th~ tail)roads handling 57.8 per cent of the total tonnage in 1940,
43 fl fl 97 a .... n n n a A
-~ 'a A 4- -
20. FLORIDA GEOLOGICAL SURVEY4#BULLETIN TWENTY-FOUR
to refining plant, or frdm mine td expert depots. The approximate tonnage distribution. for 1940 and 1941.: shown in the' following chart:
Table 3-Approxhtat&Ponnage Disfrflnition Mineral Products
-- 1940 and 1941
Total Shipments I I I I
*' Short tons Railroad I Truck:~ tj Waterway j tinapportioned 1940 8,602,012 4,973,552 I 1,593,144 I 938,057 I 1,097,259 1941 11,422,337 1 IAOO,44S I 2,620,920 I 1,083,751 I 548,236'
Includes estimates of tonnages for water, shells, peat, muck, diatomit& and dimension stone, but does not include the tonnages for bribk and tile.
Total Mineral Production for Florida Since 1900
The following graph gives the total value of mineral production of Florida by years since 1900. The vaihe of limestone and phosphate, the two most important mineral products, also are graphed. From a value of $128,381 in 1900, limestone production increased slowly until 1922 when the industry rapidly *expanded during the post-war period, reaching the all-time high of $7,277,806 in 1926. The limestone industry was very sensitive to the depression, the output dropping as early as 1927, when building and road construction sharply declined.
The production of phosphate during the period 1900 to 1931 increased steadily up to the first years of World War I when exports were almost stopped, and production depended largely on domestic demands. Following 1918, foreign buyers rushed to replenish their stocks and the abnormal post-war boom sky-rocketed sales, reaching the peak for phosphate pro~1u&ion'in 1920 at $19,464,362, after which the production returned to normall. Phosphate sales increased steadily through the early ~years of the depression and not until 1931 did sales sharply decline.
The output of all the mineral industry increased from 1 Q~9 1-n 1 Q2R whA 1impqtnnc~ fnrannszt th~ oc~wzinnn1 rlanrsJQ..
.* I it
'an I. ** .. .* S .~ .- I
.' .- .4 * .4
... *- . *
ANNUAL ~IIAILLSJE p .*f I
- - - - - - a -
V .-1-2! OF *. .. ,.* :gi,112,27
MINERAL PRODUCTION -~ -- ;u: ii
19 FLORIDA 1900-1941
---- ---- - - - - - -
-- - a -- - - ---C -_____415
0* - - - - -. - a -- -
U) --- --
o I ________411 10,646,628 10,790,30
2 -- - -- - - ---- 9,563,084 I
I- I S .*\
w - \vI - Ia
4 _____ ______ ____________ ________ I 6,862,966
22 FLORIDA CEO LOGICAL SURVEY-BULLETIN TWENTY-FOUR
The degree to which a mineral is commercial depends upon the market demand, which in turn is partly controlled by the availability and ultimate cost of the product and the degree of its competition with related materials. Thus some of the fine beach sands along the East Coast sell for concrete aggregate, when coarser sharper sands are discarded as waste in the Lake Wales district. The availability of the product has increased the sale of muck in Brevard County and lowered the value of peat in Orange County. The Hernando County limestone competes in the production area of the Miami oolitic limestone only through the absorption of heavy freight charges, and the Birmingham slag competition has decreased the margin of profit of each.
Population centers and mineral industries are related insofar as the location of mineral producing areas develop centers of population, as the phosphate industry has in Polk County, or where the growth of towns has locally stimulated mineral development as Miami has the Miami oolitic limestone.
The mineral industry in Florida is exceeded in value only by the tourist trade and by agriculture, and the geologist, industrialist, and farmer are agreed that a better balance between the industries will benefit each. In achieving this balance the rOle of mineral resources in industry far exceeds the annual value of output, and the future of agriculture and the tourist trade depends to a large extent upon the future of the mineral industry. For illustration, the limestone used to build better roads to stimulate travel in Florida will result in greater trade for the farmer. Materials for industrial housing and military construction; peat, limestone, and dolomite for soil conditioning; phosphate for chemicals, fertilizer and explosives; and white-burning clays for pottery are available in large quantities in the State. One pinnacle of Florida's future lies in assembling these raw products with those produced outside the State to build in Florida a diversified
;nAi~~fn;n1 rtn+nvnrl7 4-ha nnt--n,4- ,S nrln4nh n~nn1A ha 1nn4-nA anlus'
FLORIDA MINERAL INDUSTRY 23
unimproved roads,1 and by 19 different railroads operating in Florida with a combined track mileage, exclusive of yard tracks, of 5,371 miles.2
LAND FORMS AND GEOLOGY
The surface of Florida is largely made up of a series of flat surfaces that ascend in a step-like pattern from the coast toward the interior. These step-like surfaces, or terraces, have been produced directly by changes in the elevation of the sea level. These changes were very active during the Pleistocene epoch, or ice age, and were world-wide in effect, as terraces have been reported and described from coastal regions of scattered portions of the world. (see Cooke, 1939 and Vernon, 1942a and 1942b). Terraces are so closely related to many of our deposits of minerals that it would be well to consider these features in some detail.
Five such terraces have been described by Vernon (1942a, pp. 5-28) in western Florida and reconnaissance work indicates that these terraces are present over the whole State. Each terrace is represented by a deposition stage composed of two parts, a coastwise terrace and its contemporaneous alluvial extensions up stream valleys. The coastwise portions are possibly of marine origin as they have seaward facing escarpments, parallel the present coast, and have beach ridges resting upon them in the position of the present Recent beach ridge. However, marine shells have not been found in any of these deposits except the lowest so that their marine origin has been questioned. Extensions up stream valleys are discontinuous patches of alluvium marked by flat surfaces and present on both sides of the streams. Alluviation features such as natural Levees and rim swamp streams are present on the lower alluvial surfaces and were probably present on all.
The oldest of these terraces is believed to be the landward remnant of a delta that formerly covered most of Florida,
26 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
large part of the sediment underlying later terraces. The youngest depositional stage is represented by the present flood plains along streams and by the Recent beaches and sand dunes along coast lines. Each deposit making up a terrace is delimited by erosional escarpments, one rising above and one descending from the surface of the terrace.
These terrace levels and deposits would not be separable today had sea level changes always been of the same magnitude. Fortunately the sum of sea level changes throughout the Pleistocene has been a successive lowering of sea level, so that today older terraces are higher and descend to lower and younger terraces in steps. The progressive lowering of sea level is most easily explained by a continuous uplift of Florida, probably resulting from compensation to overloading of the Mississippi Delta by sediment, although Cooke (Vernon, 1942a, p. 28) believed that the progressively lowered sea level was due to the formation of oceanic deeps combined with progressively smaller deglaciations of the land.
While Vernon (1942) has described five terraces in western Florida, Cooke (1939) has described at least eight for the whole State. The problem to be considered in this paper is not whether there are five or eight surfaces in Florida but rather to understand their relationship to the origin of Florida mineral resources. If then these terrace features are largely depositional, as interpreted by Vernon (1942a, 1942b), and not partly depositional and partly erosional, as interpreted by Cooke (1939, the deposit that underlies and forms each terrace is the same age as the surface, and is more properly Pleistocene than Pliocene as previously considered. Thus, large commercial deposits of peat, muck, sand and gravel, diatomite, flint boulders, kaolin, limestone, marl, pottery clays, and phosphate would be closely associated with the origin of these terraces and are possibly of the same age. For this reason a more detailed state-wide study of these terraces would be advisable as a knowledge of their
nrirnn can,1 rnM-hn1 n-F fnrmfll-lnn ixrniilel fnoilitata thn dnu~1nn-
FLORIDA MINERAL INDUSTRY 27
central lakes are the source of Florida's commercial peat, muck, diatomite, and they have been locally instrumental in concentrating sand to commercial quality, as at Lake Louise in Lake County.
While these sinks of Florida are the result of the localized solution by natural acids of the limestone that underlies most of the Florida surface, the depth to which this solution was effective was certainly increased by the fluctuations of the ground-water table throughout the Pleistocene epoch. Thus, decreasing of sea level lowered the ground-water levels so that deep sinks were formed. The Recent and latest rise in sea level elevated the ground-water surface to its present position, so that today the large part of these sinks are in effect drowned sink holes.
The oldest rock that outcrops in Florida is the Eocene Ocala limestone and the youngest is the Recent floodplain and beach deposit. Older rocks are known to be present beneath the surface rock from cuttings taken from wells. These older rocks are not important economically except for possible sources of oil, gas, and water, so that they are not considered fully in this report. The large part of Florida commercial production is derived from Pleistocene or Pliocene rocks which are distinguished at the surface by terraces, mentioned above. In these rocks are included the Melbourne bone bed, Fort Thompson formation, Anastasia formation, Miami polite, Key Largo limestone, Chariton formation, Citronelle formation, Caloosahatchee marl, Alachua formation, and Bone Valley gravel, and the terrace sand and gravel of western Florida. These beds contain commercial deposits of phosphate, flint boulders, sand and gravel, pottery clay, brick clay, kaolin, coquina, marl, limestone, dolomite, muck, peat, diatomite, oyster shells and sandstone.
Florida's commercial limestone comes from the Ocala limestone, the Suwannee limestone, the Marianna limestone, the Tampa formation, the Key Largo limestone, and the Miami oolitic limestone. Fuller's earth is mined from beds
28 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
Its age is unknown but could be Pleistocene. Shells from oyster bars, and peat, muck, and diatolnite from lake deposits are all produced partially from Recent accumulations, although the lower portions of these. deposits are probably Pleistocene in age.
The following chart of geological formations is that generally accepted by the Florida Geological Survey, but the writer considers all of the beds younger than Miocene as equivalents of the sand and gravel deposits of western Florida as all are distinguished by terrace features, and therefore they are more properly Pleistocene in age with the possibility of only the oldest being Pliocene, as has been interpreted by the writer (1942a).
In all studies dealing with water supplies, especially from artesian aquifer, and with the possibilities of the production of oil and gas both minor and major structures must be considered. Major structures are those large upwarpings or anticlines, and large clcssvnwarpings or synclines. Minor structures are of more limited extent usually with steeper dips, and more readily serve as traps for commercial pools of oil and as local recharge areas for artesian water. These minor structures are sought by the oil geologist, and include salt domes, wedges of porosity, faults, discordant dips, overlapping of sediment over unconformities and old buried land masses, small folds in the rock, and many others. Some of these have been discussed by Campbell (194Th).
The regional structure of Florida is that of a south dipping monocline modified by the large "Ocala uplift" in the northwest Peninsula, and the smaller "Chipley-Marianna uplift" in northwest Florida giving, in a structural section along the axis of the Peninsula, the appearance of an arrested anticline. The regional structure is further complicated by
Table 4-Geological Formations of florida Series Formation or Group Mineral Resources
Recent Bay, beach, floodplain and lake deposits, unnamed. Clay diatomite, gravel, muck, 03
___________________________________________________ shell, peat, phosphate and san' Pleistocene Melbourne bone bed Vertebrate remains.
or Pliocene Fort Thompson formation Limestone, marl.
Anastasia formation Coquina, sand.
Miami oolitic limestone Relative stratigraphic Limestone. Key Largo limestone positions are not fully Limestone.
Chariton formation known. Limestone?
Citronelle formation Clay, gravel, sand, kaolin.
Alachua formation Phosphate.
Bone Valley gravel Phosphate.
Caloosahatchee marl Marl, limestone.
Terrace deposits, possibly contemporaneous with Coquina, clay, diatonaite, dolor the Pleistocene-Pliocene formations listed above. flint, gravel, kaolin, limestone, (see Vernon, 1942 a) oyster and mound shell, sand,
~ Miocene Choctawbatchee formation Buckingham marl Clay, marl.
Alum Bluff group Hawthorn formation Clay, fuller's earth, limestone,
__________________ Tampa formation Clay, limestone.
Suwannee limestone Vicksburg group in part Limestone.
Oligocene Marianna limestone VICKsBUnG group Limestone.
Ocala limestone Jackson ~roup Limestone, flint, dolomitic limest
Eocene Claiborne group
______________ Midway group
Cretaceous ______________________________________________________ Undifferentiated deposits report
Paleozoic? _____________ -
30 FLORIDA GEOLOGICAL SURVEY-BULLEtIN TWENTY-FOUR
tilting westward, Florida being a somewhat remote limb of the active geosyncline about the Mississippi Delta. The obvious structures present in the State may be tabulated as follows:
Southward monoclonal dip
Syndilnal flexures associated with the Ocala
and Marianna-Chipley uplifts
Buried land masses
In a structural section plotted along the center of the Florida Peninsula from the Georgia line to the keys, the beds would be almost horizontal to the vicinity of Bartow, Polk County, from which point they dip south about 9 feet per mile. However, the flat portion of this section in the northern Peninsula is along the local strike of the beds and does not represent the dip. The regional dip here has been modified by elongate parallel folds made up of the Ocala uplift in the western portion and a more or less paralleling synclinal flexure in the eastern portion. The axis of the Ocala uplift trends northwest-southeast and the folding is present from Madison County south to Hardee County. The synclinal flexure is evident as far south as Seminole County where the trend of its axis parallels the Ocala uplift. However, the trend of the axis is northeast-southwest in northeastern Florida, where the gentle pitch of the syncline abruptly increases south of Jacksonville and then flattens north of the city. The dip of the strata on the limbs of the folds probably does not exceed 15 feet per mile and 10 feet per mile is nearer the average.
In western Florida the original regional dip was probably the same as that of the Peninsula, a gentle south dip with the
FLORIDA MINERAL INDUSTRY 31
plicate the regional structure. Only the nose of the anticline is present in Florida, this portion being known as the ChipleyMarianna uplift. It is evident in Holmes, Jackson, Walton, and Washington counties. The axis of both anticline and syncline trend northeast-southwest into Georgia, and the strata on the limbs dip as much as 20 feet per mile. The syncline lies to the east of the Chipley-Marianna uplift and pitches gently southwest across Madison, Jefferson, and Wakulla counties.
Minor structures of possible significance are the known unconformities present in the rocks of Florida. An unconformity can be defined as a buried surface of erosion, although rare types of other origins are known. Regional unconformities are known to be present at the base of the Upper Cretaceous, and at the top of the Ocala in Florida. The unconformity at the base of the Upper Cretaceous is important because it hides the geology of older rock; that of the Ocala is important as this bed is the common structural data plane and the top of the Ocala limestone as encountered in wells may or may not be the true top, and structures are merely reflected by this bed and are not actual. In addition to unconformities, Campbell (1939a, 1940) and Gunter (1923, 1928), have described old land masses, now covered by younger rocks, and oil geologists view such structure with confident hopefulness.
OIL AND GAS
Florida has never had a commercial oil or gas well. Various attempts at discovery have been made, considerable impetus having been received recently by the discovery of a new oil field near Jackson, Mississippi, and from encouragement by the Florida Legislature with the appropriation of a $50,000 fee to be paid for the first commercial well discovered in Florida.4 The possibility of production of petroleum in Florida has been discussed and well logs described in various publications to which reference can be made.5 Levorsen
32 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
(1941, pp. I-?) picked Florida as a possible future oil producing State not on any positive evidence but rather because the meager knowledge of the petroleum geology of the State does not oppose its ~resence. He likewise knew that the* State is underlain by thick sediments that could provide both source beds and oil reservoirs; that oil and gas shows haves been reported; that favorable petroleum geology could be' present, though hidden under regional unconforznities known to be present in the State; and that differing porosities in the form of wedges possibly hidden in the rocks may provide oil reservoir traps.
Florida's importance as a potential producer has increased with new demands on oil tankers, formerly supplying the East Coast and now engaged in military duties, causing a gas shortage. Many oil companies are leasing land and several wildcat wells are now being drilled in the State, arising out of respect of the possibility of new markets and a greater opportunity for higher priced oil. During November, 1942, the following wildcat test wells were being drilled in Florida.
Consumer's Gas and Fuel Company, State No. 1, 39 miles ~vest of Miami, Dade County. (Located but not
Brown and Ravlin Trustees, V. C. Philips No. 1, 2 miles south of Wakulla Station, Wakulla County.
Florida Oil Development Company, Putnam Lumber Company No. 1, 6 miles southeast of Cross City, Dixie
H. H. Givan, Marion Corporation No. 1, near Portland,
Sanford and Arrington, et al., Walton Land and Timber Company No. 1, approximately 10 miles southeast
of DeFuniak Springs, Walton County.
William C. Blanchard, et al., Everglades No. 1, 44
miles west of Miami, Dade County.
In addition the following had located and were drilling in
FLORIDA MINERAL INDUSTRY 33
Hunt Oil Company, sec. 16, T26S, R32E, Osceola
Thompson and Pollard Associates, sec. 16, T13S, R16E,
Prospecting is being actively conducted by several geophysical crews, employed by both oil companies and mdiS
viduals, with the use of magnetic, electrical, gravity, and seismographic methccTs~ In the past both prospecting and drilling locations ha~t teen made rather. haphazard, even by the larger companies, but now greater care is exercised and detailed prospecting is carried on before locations are determined. There are many factors that should be considered besides those of a geological nature, but evidence elsewhere indicates that all oil fields of size are governed by structures.
The outlining of structures and prospecting should precede any well organized venture in drilling. To locate structures in Florida, where surficial Pleistocene sediment masks the underlying rock, the safest method is the drilling of prospective test holes to an easily identifiable key bed, possibly a zone in the Ocala limestone, the most distinctive bed outcropping in Florida. The top of the Ocala, being erosional, is not a good structural datum but a definite key zone would be extremely helpful. Such a program would require a careful study of geological conditions and a large expenditure, and would be time consuming as well. In its favor, however, many points of control would be established, and a potential structure could be condemned or approved for drilling, resulting in a large saving on lease holding expenses. The ultimate test for any prospect is the penetrating of the potential bed, but the use of geological knowledge and the interpretation of rock structures will have been an important factor in locating the hole to the best advantage, and lowering the possibility of the dry hole.
Cheaper, but less reliable, ways of locating rock structures are available through geophysical methods. These have been
34 FLORIDA GEOLOGICAL SURVEY-BUL~ETW TWENTY-FOUR
FLORIDA MINERAL PRODUCTS IN AGRICULTURE
Accurate production figures for the utilization of mineral products in agriculture are not available as production figures are not traced to the ultimate consumer, and many small pits are operated by the farmer for his own use, where no records are kept. Peat, phosphatic clay, phosphate, limestone, dolomitic limestone and oyster shells are being used extensively in agriculture as chicken and stock feed, soil conditioners and fertilizer in Florida, and in 1941 fertilizer tags for 87,550 tons of mineral products to be used on soils were sold by the State Department of Agriculture. 6 From the figures available it is estimated on a tonnage basis that more than 37 per cent of all mineral products in Florida are used in agriculture.
The use of dolomitic limestone, high calcium limestone, and phosphate has been greatly stimulated though the Grantin-Aid Program, administered by the Agricultural Adjusta
ment Administration, which allows the farmer to receive these products in place of payment for his participation in the program. The farmer is supplied with these soil conserving materials at the time when they are needed and their costs are deducted later from the payments due him for adhering to the soil conservation program. The granted thereby has the advantage of applying these materials throughout the growing season, and he saves the interest that he would have paid had he purchased his fertilizers directly from producers with arrangements to make payments after harvest.
Owner operators have a greater stimulus to cooperate in conservation of soils than do the tenant operator and share cropper. This tendency has been overcome to a certain degree, however, by providing a division of the allotments to the landholder, tenant, and share cropper in proportion to which they share in the harvest and profits of the season. Both the tenant and share cropper thereby find it to their interest, in both greater yield and soil conservation, to par-
FLORIDA MINERAL INDUSTRY 35
larly acid. Some counties, especially in the central Peninsula where the underlying rock is limestone, are not particularly deficient in limestone and dolomite. The application of limestone, dolomite, and phosphates are especially recommended when used with legumes, cover crops, and pasturage. There is a recent provision in the government conservation program for the application of humus, peat, and muck, and their usefulness is becoming widely recognized and has increased each year.
Aims and Practices of Soil Conservaflon
The practices selected differ by county and generally are those most needed and not usually employed by the farmer. The aim of the soil conservation program is not to employ normal farming practices, but to particularize in conserving and improving soil fertility, preventing soil erosion, and encouraging the economic use of the land. The program allows for payment to the farmer for part of the costs of carrying on such a program, and these allotments are especially helpful in Florida where the farmer's yearly cash income is very low.
Soil Building Allowance
The soil building allowance is the maximum payment made for adherence to the practices of the soil conservation program.
"This allowance for each farm shall be the sum of the following:
(1) 70 cents per acre of cropland in excess of the
sum of the cotton, peanut, tobacco, and potato allotments for which payments are computed, cropland in commercial orchards, and sugar cane
(2) $2.00 per acre for commercial orchards on the
farm in 1941;
36 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
(4) $1.00 per acre of commercial vegetables grown
on the farm in 1941 where the acreage Is 3 acres
"In addition to the soil-building allowance computed for the farm as outlined above, a forestry allowance of $15 may be
earned only by planting forest trees." I
Soil building practices include the application of approved fertilizers, limestone, dolomitic limestone, phosphate, and muck, in connection with the full seeding of legumes, cover crops, Natal grass, permanent pasture, or green manure crops in orchards.
Any mineral substance to be applied for soil building purpose must be ground sufficiently fine to be easily available, and payments are based on the amount available in the soil the first year in the case of phosphate, and on the per cent of calcium in the case of limestone.
The application of 16 percent superphosphate will earn $10 per ton and other grades will pay in proportion. Raw rock phosphate or colloidal phosphate clay containing not less than 28 per cent of phosphorus pentoxide (P205) earns $4.80 per ton, and that containing not less than 18 per cent phosphorus pentoxide earns $4.20 per ton. The application of dolomitic limestone will earn $4.00 per ton; high calcium limestone $3.00 per ton ; and muck or peat will earn $1.50 per acre when 2 or more tons are applied to the acre.8
Participation in the 1940 Grant-in-Aid Program included 2,273 farms out of a total of 48,443 farms in the State signed up in the Agricultural Conservation Program. The 1941 participation included 2,680 farms out of a total of 50,640 farms cooperating in soil conservation.
The following counties have participated in the program :~ 1940
Brevard Highlands Orange St. Lucie
DeSoto Hillsborough Osceola Sarasota
Gadsden Jackson Pasco Seminole
Hardee Lake Pinellas Volusia
FLORIDA MINERAL INDUSTRY 37
Alachua Gadsden Indian River Orange Putnam
Bay Hardee Jackson Osceola St. Lucle
Brevard Hernando Lake Pasco Sarasota
Calhoun Highlands Madison Pinellas Seminole
DeSoto Hilisborough Marion Polk Volusia
FLORIDA MINERAL RESOURCES MINERAL PIGMENTS ~0
A mineral pigment is any mineral that may be used, with or without treatment, as a color when mixed with drying oils and fillers to form paint. It is much the same as a mineral filler with the difference that the filler imparts little to no color to the paint and is used as an inert extender. A good commercial pigment is insoluble in the paint or stain vehicle or in chemical or other mineral pigments. It is stable and resistant to decomposition by atmospheric conditions and should be bright and clear, or dull and opaque' as the case requires. The texture of a good pigment is granular and fine' and when the pigment is ground into the vehicle or medium the paint should be capable of easy and even appli* cation.
Mineral pigments are especially important to the war effort and the government is anxious to locate all the mineral deposits which could possibly be commercialized under war necessity. Throughout the present war large quantities of brown, tan, green, and gray colors will be required for camouflage of military and civilian areas which might be subjected to attack. Because of transportation difficulties local pigments are desired and the quantity and covering power may be below present commercial standards if the colors are uniform. The pigments should be granular and should have a fine body or texture. Thus some of the Florida clays would require firing to fusion and then grinding before the required texture and color is developed. Brown and dark colored
tin ~ rrnn.,al a v.A R4n4- nniilA ha rrrnuinA ini+hniif +rnnl-vnan+
38 FLORIDA GEOLOGICAL SURVEY-BULL~IN TWENTY-FOUR
green color can be used under war conditions, but the War Department tries to use the colors which most closely correspond to their standard color chart, which can be secured from any local Army or Navy office.
In addition to the emphasized use in camouflaging, mineral pigments
"find their main outlet in low-priced paints, both alone and mixed with chemical pigments. Iron oxide pigments are used extensively in the preparation of paints for the protection of iron and steel work from rust, competing with graphite and red lead for this purpose. Iron oxide paints are also used on freight cars, barns, etc. Other uses for iron oxide pigments are as coloring agents and fillers in the manufacture of imitation leather, shade cloth, shingle stain, and paper and cardboard filler. . Ocher, in addition to its use in paints, is also used as a pigment (toned up with dyes) for linoleum and oilcloth, as a pigment in wood stains and wood fillers, and in coloring
cement, stuccos, and mortars.11
Occurrence in florida
There is no commercial production of mineral pigments in Florida, but during the 'last World War a chemical plant was operated at Inglis, Levy County, and considerable pyrite was imported for use in this plant. The refuse dumps have a high content of iron oxide which was formerly sold locally for pigments. Some of this refuse is still present and is sufficiently high in iron oxide to make a suitable pigment.
Yellow and yellow-brown pigments may be produced from ocher, iron oxide mixed with clay, by grinding the material as it comes from the ground and eliminating the sand impurity by screening. Red and reddish-brown pigments with slight variations in color can be produced by calcining the raw ocher in kilns before grinding. The higher the iron-oxide content the darker the brown color, and the deepest shade of brown in Florida is found in Levy County where limited beds of limonitic ores analyze high in iron oxide.
Ochers and limonitic clays and sands (bog iron ore) are known to occur along the canal on the road from Fort Myers
i-n flar~44-n Qnr~naci in T an flrvnnl-r7 T an~r flnuin4-urr 9 rvl4lnes
FLORIDA MINERAL INDUSTRY 39
near Jacksonville, Duval County, 12 miles east of Seville, Volusia County, Estero Bay, Lee County (see Wilson, 1933 pp. 89-90), and in terrace sands of northern Escambia County. The Levy County limonite has the best commercial possibilities, the deposit covering approximately 40 acres and being high in iron-oxide content. Iron was produced from this deposit in small quantities for the Confederacy. Another deposit of possible commercial development is at Bunnell, Flagler County, where Mr. J. B. High produced a small amount of pigment in 1938, but the problem of production and marketing should be thoroughly studied before attempting commercial production. A small pilot plant might give favorable results.
The following analyses are by the State Chemist and are more or less typical of the ocher and limonitic sands of Florida.
Table 5-Analyses of Ocher and Limonitic Sands of florida
Bunnell, Flagler County County County
J. B. High near near
Red Yellow LimoniPigment Pigment tic Ore
Iron Oxide as Fe203 ~. 37.88% 55.22% 34.24% 14.63% 71.80% Aluminum Oxide as Al203 2.57 3.03 0.64 8.34 Manganese Oxide as MnO 0.05 0.05 0.01
l~4oisture ......... -- - . . . - . .... 5.39 1.66 0.44 13.48 14.88
Water of Combination ~. 18.02 12.82 6.54 6.23 Insoluble Matter (largely
8102) ......................... 3 '1.04 26.39 58.:12 56.09
~angI~ie ......... .... .. ... ............ -. ..... ... ........ ....... 13.32
Brown pigments for war camouflage can be provided by crushing the dolomitic limestone occurring in scattered denosits alona the western coast from Taylor County to Char-
40 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
deposits in western Florida contain brown- and tan-colored
* gravel and coarse sand which can be crushed for brown pig- ment. Likewise, the fuller's earth of Gadsden and Manatee
- i~ounties might, after treatment, be very serviceable for a light earth color. The earth would have to be vitrified and then ground, otherwise it would be rather unstable in paint
* vehicles, having a tendency to react with the oils. Some of this fuller's earth has a greenish tint which possibly could be retained, or, if vitrified, would be some shade of red.
There are a number of brick companies in western and northern Florida which burn clay from local deposits, and with the single exception of the Hall Brick Company at Chipley, Washington County, whose brick is a buff color, the resulting brick is some shade of red. This brick could be ground for mineral pigments, and the clay for its manufacture is common along the present flood plain of western Florida streams and in terrace deposits associated with them.
Green colors are less common in Florida, but the high content of glauconite in some of the mans and clays of western Florida will give dull green colors when ground. These mans are common in Holmes, Washington (Vernon, 1942a), Walton and Okaloosa cQunties (Cooke and Mossom, 1929), and thicknesses of 80 feet exposed in bluffs and steepheads are common in these counties. Except for marl, existing producers of possible pigments may ~be found listed under the individual topic in the directory (Appendix).
All the basic colors necessary for camouflage in Florida will be available in Florida, the production depending upon the tools and machinery necessary for mining and processing. If a mineral pigment industry were started in Florida emphasis should also be placed on the production of extenders or fillers. High-calcium limestone, silica sand, and diatomite could ~ll be used, and in many cases the pigment and filler can be produced from the same area, if not from the same pit.
FLORIDA MINERAL INDUSTRY 41
* hammer mills and jaw crushers would have to be employed. Overburden would not be a great problem as it is generally ~very thin. The big problem will be the lack of a sufficient
- cheap power for processing, and fuel for drying the pigment where a wet process is necessary.
Sand and gravel could be mined by dredge; limestone, clay and coquina by dragline excavator or mechanical shovel, crushed and pulverized, and sized by screen or by air currents. Where burning is necessary the material may be burned in vertical shaft kilns as well as in rotary furnaces, the first being cheaper and requiring less material under priority.
Of special but related interest to mineral pigments is the hard brown sandstone, to which the name hardpan has been applied, underlying nearly all low flat lands of Florida and embedded in some of the high terrace deposits. Hardpan is composed largely of ~ilica sand that has been cemented by humus and iron oxide. It is a zone of concentration resulting from the deposition of iron oxide and humic acid, leached U overlying sands, the iron salts probably reacting with 'the humic acid to cause precipitation.
Ground-water surfaces appear to control the position of deposition, and, as hardpan is impervious, the formation of
one hardpan may create a new ground-water surface which results in a second and higher hardpan. Where the cementing material of hardpan contains a high content of nitrogen it has been used for making Vandyke brown and sap brown, two of the azine dyes.
For a short period during the last World War sap brown was produced by a plant near Fort Walton, operated by J. D. Haseman. Prior to the first World War, Germany supplied all of the sap-brown dye used in this country and after the end of hostilities this supply was reopened and the Florida plant closed. The use then, as now, was primarily as a dye
42 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
vats and then dried in ovens where controlled heat would keep volatilization of the organic matter at a minimum. The dried material is known as Vandyke, a rather general term, and is the raw source of sap brown. Watered Vandyke brown is dissolved in a cheap sodium alkali to form an organic sodium salt, which was given the commercial name, sap brown, by Haseman.
Before World War H, Germany supplied the United States with 95 per cent of the imports of Vandyke brown and Czechoslovakia supplied the remainder. Approximately 900,000 pounds valued at $30,000 were imported annually during 1935 to 1939, but this import dropped sharply with the start of the war, and in 1940 only 14,362 pounds valued at $722 were received in the United States.'2 The cessation of these imports may stimulate a renewed production of sap-brown dye in Florida.
Domestic production of these dyes has recently started with the National Aluminate Corporation, 6225 W. 66th Place, Chicago, illinois, and the New York Color and Chemical Company, Belleview, New Jersey, and the Calco-Chemical Company, Bound Brook, New Jersey, manufacturing sapbrown dye. The source of the Vandyke brown used in this manufacturing is not definitely known, but is believed to have come from North Dakota.'3 A survey of the mineral industry by the Florida Geological Survey has discovered no production of Vandyke brown in Florida.
The U. S. Bureau of Mines has investigated these dyes and has found that the domestic varieties of Vandyke brown
.... though usually of a fine, rich hue, is likely to be fugitive, especially in water color. It may be treated in two ways to increase its commercial value: The simplest method is to roast the raw material gently, making the color darker and more permanent. The result is known as Cologne earth. By another method a water-soluble stain, sap-brown, may be extracted. While precise details have been guarded carefully by the German manufacturers, the general procedure, according
FLORIDA MINERAL INDUSTRY 43
brown and soda ash in the ratio of 100 pounds of pigment to 10 or 15 pounds of alkali are mixed with about 460 pounds of water in a vat fitted with an agitator. During the first halfhour of mixing carbon dioxide is given off. The reaction apparently involves the conversion of the 'humic acid' into sodium humanee'. Experiments with production of the material in edgerunner mills have proved unsatisfactory owing to this effervescence, while attempts to replace the soda ash with caustic soda have been abandoned owing to the inferiority of the stain produced. If the stain is desired in the form of scales, the mix is run over steam-heated roller dryers. Control of temperature is very important. If a granular form is desired the mix is dried in steam-heated ovens at about 7000.
Sap-brown stains are used mostly in paper and cardboard manufacture, but small amounts are also used for staining
CLAY AND CLAY PRODUCTS '5
A precise definition of clay is hard to formulate, although everyone understands what is meant by the term. However, clay is a finely divided mineral substance, possessing the property of plasticity when wet and originally derived from the weathering of aluminous crystalline rocks, chiefly granites and gneisses. With the application of heat clay looses most of its water of combination and its mineral particles coalesce to form a hard stony mass upon cooling, the degree of hardness depending largely upon the chemical composition of the clay and the intensity of heat. The clays of Florida are a mixture of several minerals, but the fundamental composition is some form of hydrous aluminum silicate closely corresponding to the minerals kaolinite, halloysite, montmorillonite, or bentonite. Various minerals, such as quartz, mica, limonite, calcite, gypsum, garnet, zircon, ilmenite, rutile, are commonly embedded in the fundamental matrix.
The following chemical analyses are typical of the types of Florida clays:
44 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
Table 6-Analyses of Florida Clays
1 2 3
Sb---------------------62.83 46.95 45.69
A1203--------... .. -.---------------... 10.35 36.75 34.00
FeO ..... ........ .... ......---------------. . 2.45 0.80 3.40
GaO--------....------------------------ - -- 2.43 0.15 2.95
MgO-------------- . - -. 3.12 0.20 0.21
K00--------. -----------------. .--------------. 0.74 0.24 0.29
Loss on Ignition ----------------------------------------14.13 14.95 12.20
Total-----.. -. ------------------------------- 96.25 100.04 99.64
1. Analysis of fuller's earth from Gadsden County, Florida. U. S.
Geol. Survey, 17th Annual Report, p. 880, part 3, 1896.
2. Kaolin sample from Edgar Plastic Kaolin Company mine, Edgar,
Florida. Analysis from "A little book on clays and clay :minersJ
Edgar Plastic Clay Company, Metuchen, New Jersey.
3. Brick clay from the Taylor Brick Company, Molino, Florida mine.
Analysis by State Chemist.
Types of Clay
The types of clay in Florida may be divided according to their uses, thus there are pottery, brick, and cement clays,
fuller's earth or bleaching clay, and. white firing clay or kaolin. These clays fall into two general groups: transported and residual, depending upon the place of their accumulation. Both groups are secondary and sedimentary, having been derived from previously existing rock. The most common and all of the commercial, clay in Florida has been transported into the State and deposited in thin beds between, or as a matrix of, other sedimentary rock. These beds are either of alluvial or marine origin, having been deposited by streams along their flood plains and in older alluvial terrace denosits. or havizw been transported and reworked by marine
FLORIDA MINERAL INDUSTRY 45
transported by water, so that ultimately all of the State's clay is transported.
Kaolin is almost pure hydrous aluminum silicate and quartz, white in color and white-firing. It is used in the manufacturing of paper, china ware, tile, glazes, pottery, and in any clay product where whiteness is a desirable factor. Two companies produced kaolin in Florida during 1940 and 1941: The United Clay Mines at Crossley, and the Edgar Plastic Kaolin Company at Edgar, both in Putnam County. Edgar Plastic Kaolin Company formerly operated a mine at Okahumpka, Lake County, but now maintains only the one operation. Kaolin is known to occur over a wide area in peninsular Florida generally being correlated with the physiographic type known as the Lake Region, and smaller thin beds are present in the high alluvial deposits in western Florida.
The kaolin now being mined in Florida composes the matrix of some of the coastwise terrace deposits of the northcentral Peninsula. Water-worn quartz gravel and sand are embedded in this matrix and must be removed before the kaolin can be marketed. The minable bed is generally between 20 and 55 feet in thickness and the recoverable kaolin
* content averages generally from 12 to 15 per cent. This bed underlies a variable thickness of red stained, leached, and oxidized sand which is removed as overburden by dragline excavators and loaded to railroad cars, the Atlantic Coast Line using most of it as sand ballast. This overburden may be as thick as 100 feet, but the present mines have to remove less than 20 feet of this sand.
The kaolin-bearing sand is mined by hydraulic-suction pumps, mounted on dredges as the bottom of the pit lies 20-30 feet below the ground-water table. The sludge is pumped over screens and the clay balls (eliminated because of the sand and gravel embedded in them), together with the coarse sand and gravel are removed. Finer sand is removed by oumPinE the s1ud~e over a series of cone-tanks, the sand
46 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
finest sand are allowed to settle out of the sludge as it moves slowly down troughs that are equipped with baffles, or this finer material is screened out of the kaolin by 100 mesh screens.
LA .1 .
.' a a
Figure 3. Kaolin pit of the United Clay Mines Corporation at Crossley, Putnam County, in the center SW'!4, Sec. 27, TiOS, R23E,
the method of the removal of the overburden by dragline exshowing
cavator in the background, and the method of mining by suction pumps on dredges in the foreground.
The kaolin is dc-watered in large settling vats, the water being slowly drained or pumped off in pipes that can be lowered as the clay settles, so that the pipe intake is always near the surface of the sludge in clear water. Thus, the sludge below the pipe intake is not agitated and the kaolin settles more rapidly. The clay is further dc-watered in hydraulic filter presses or on large suction rolls, the water being pressed out or sucked out through fine mesh cloth. Drying is completed in rotary driers or by stacking the moist filterpress blocks of kaolin on shelves of pipe through which steam is forced. The kaolin is pulverized, crushed to inch di-
FLORIDA MINERAL INDUSTRY 47
oils, cleaning fluids and gasoline. Any clay that is naturally adsorptive is a fuller's earth, a loosely used term that got its name from the original use by fullers to remove grease from woolen cloth during the process of falling. Where the adFigure 4. Aerial view of the fuller's earth plant of the IPloridin Company, near Quincy, Gadsden County. The photograph was taken facing southeast and the pit lies approximately one mile to the east.
Printed by courtesy of the Ploridin Company.
sorptive capacity of the clay can be improved or increased by leaching with mineral acids it is known as an activable clay. The basic composition of both groups is that of bentonite which is largely made up of the mineral montmorillonite with the kaolinite mineral group being almost absent. Mansfield (1940a, p. 9) believed that naturally leached decomposed volcanic ash (bentonitic?) is fuller's earth and differs from activable clay only in being naturally leached.
Fuller's earth was discovered in Florida in 1893 at Quincy, Gadsden County, where it is still produced by The Floridin Company. Two companies produced fuller's earth in Florida during 1940 and 1941: The Floridin Company at Quincy and Jamieson, Gadsden County, and The Superior Earth Company
48 FLORIDA GEOLOGICAL S~VEY-BULLETIN TWENTY-FOUR
The fuller's earth of Florida is Miocene in age and is equivalent to the Mum Bluff group (see p. 29). It is interbedded with sand and phosphatic limestone that contain the remains of marine organisms, and is believed to have accumulated under marine conditions. The earth now being mined underlies a Pleistocene sand overburden up to 45 feet in thickness, and in both mining areas there are two beds of fuller's earth which are separated by a thin bed of bentonitic phosphatic sand as in Gadsden County or a thin phosphatic limestone as in Marion County. The earth is therefore mined in benches, a steam shovel or dragline usually operating on each bench, one each removing overburden, mining and loading the upper fuller's earth, and removing the intermediate bed and mining the lower fuller's earth, (figure 5).
The material is hauled to the processing plant by dinkey engines in Gadsden County and by trucks in Marion. It is allowed to air dry in storage sheds and is further dried in oil fired rotary driers. The fuller's earth is ready to market
Figure 5. Fuller's earth mine of the Floridin Company located
FLORIDA MINERAL INDUSTRY 49
after being'crushed or pulverized, and bolted or sized. Eight different grades, from grit to as fine as that which will pass & 300 mesh; screen, are sold in sacks or in bulk, the larger part now being freighted bulk.
The fuller's earth at Ellenton, Manatee County,
formerly mined, but this mine was closed in 1925. A plant built by McCloskey and Company for the United States Maritime Commission to fire this material for use as a lightweight concrete aggregate in the construction of cargo vessels at Tampa has recently been put in operation. While the use of fused argillaceous aggregate in concrete is new to Florida it has been practiced in the United States for at least 30 years.
Fuller's earth is the best material available for this use in Florida, although it requires grinding and mixing to produce a thick paste. This paste is forced through meshes in the form of rods that are cut to form the raw aggregate. This paste must be dry enough that the aggregate-pellets do not adhere, and should contain some organic matter, which must be added in this case. The clay aggregate is run through oil fired rotary kilns at temperatures high enough to cause quick incipient fusion and a seal to prevent the escape of gases formed by the volatilization of the organic matter. This gas then causes the expansion of the clay, leaving gas pockets that increase the lightness of the aggregate. The temperature used in the kiln depends on the fusion point of the clay, and is regulated to heat the clay to the point that it just begins to fuse. Higher temperatures result in the formation of a clinker, which has strength but not lightness.
This plant should find a steady market for its product after the war in pre-cast lightweight concrete units, aggregate for pavement, and in heat and water insulation as it is more resistant to both heat and water penetration than ore diary concrete. Furthermore, concrete made only with this aggregate can be sawed and nails can be driven into it, so
II t~ *~ p i A ~I I p
50 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
of concrete made with limestone or sand and gravel aggregate.
Activable clays are not commercially produced in Florida, but Bay and Munyan (1940) discovered large deposits of these clays outcropping principally in Holmes, Jackson, and Washington counties but also present in Leon and Jefferson. This clay is a new asset to the State and if prospecting of these areas shows an extensive deposit, it should support a large industry. The significance of the discovery is that the better grades of these clays, when properly treated, are from two to five times as efficient in bleaching action as the commercial grades of fuller's earth. Activable clay contains decomposed volcanic ash, and is commonly called bentonite, and must be chemically leached before it can be used as an adsorptive. Naturally active clays (fuller's earth) are likewise bentonitic but have been leached by natural acids. Generally the activity of fuller's earth as a bleaching agent is not improved by artificial leaching and in most tests the activity was decreased (Bay and Munyan, 1940).
Other Clay: Clays having no special properties are often called "common clay" and are composed largely of kaolinite,
FLORIDA MINERAL INDUSTRY 51.
containing one or more of the following impurities: quartz, limonite, feldspar, mica, vegetable matter, and water. These clays are used in Florida for the manufacture of brick, tile, pottery, and cement, and their most important property is their burning quality, in particular as to color, shrinkage, and porosity after firing. Almost every county has a deposit of common clay but good structural and pottery clays are rare, being present only in the north Peninsula and in western Florida. Silt, sand, and vegetable matter are high in some of these deposits, but in the manufacture of tile, brick, and pottery the vegetable matter burns out, and sand and silt are of little importance if the plasticity is high. Iron oxides are disadvantageous where whiteness is desired as they give the fired product a red color.
Alluvial clays, either in the flood plains or in terrace deposits, are used by eight companies to manufacture brick and tile. These brick are red with the exception of the cream colored brick of the Hall Brick Company of Chipley, Washington County, and compare favorably with those of Georgia and Alabama in structural qualities. Brick production is seasonable 'in Florida, no kilns being burned where there is danger of freezing the green-formed brick while drying in open-air drying sheds. Most brick producers try to fire their kilns in the summer and stock their brick for the winter trade. There are four companies that fire permanent downdraft kilns and four that fire temporary updraft or scove kilns. The permanent kilns are constructed of brick and have the advantage of a more uniform product. They likewise reuse the heat in a closed circulation. The kilns are fired largely with wood but some companies are now using oil.
The ease of starting a brick kiln has resulted in the abandonment of many enterprises which met unforeseen economic difficulties, and Florida has several of these. Most of these failures resulted from the lack of a thorough investigation of the raw product, especially as to the extent, uniformity, mining and burning qualities of the clay. This, combined
52 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
There are five kilns that are being fired in Florida to produce pottery, but only two companies mine their own clay. The Santa Rosa Pottery Company operates a pit at Gonzalez, Escambia County, and combines this clay with other clays from the State, and from out of State, to manufacture glazed pottery and art ware. The Johnson Pottery mines and fires a clay at Jay, Santa Rosa County, to produce unglazed and salt glazed pottery. Both of these clays are alluvial, being interbedded in terrace sand and gravel, and are mined by pick and shovel. The Crary Brothers, Bluff Springs, Escambia County; The Floramics Company, Tampa, Hilisborough County; and the Merritt Island Potters, Cocoa, Brevard County, manufactured pottery and art ware in 1941 but mine no clay. Crary Brothers produce salt glazed pottery while the other companies produce glazed pottery and art ware.
Clay is mined near Floral City, Citrus County, by the Florida Portland Cement Company and is freighted to Tampa where it is calcined with a limestone mined in Hernando County to make cement. This clay is a greenish light gray, blocky, slightly sandy and silty clay, containing white phosphatic limestone boulders at the bottom. There is a weathered zone from 3-15 feet in thickness which is removed as overburden. The clay is approximately 40 feet thick and is loaded directly into gondola railroad cars from the quarry by a dragline excavator, (figure 7). This clay is thought to be Alum Bluff group, Miocene in age, and was deposited in marine water.
Production and Market
Accurate production tonnages are not available for the clay used in the manufacture of brick, tile, pottery, and cement, as these materials are not marketed as clay and records are not available to this extent. The quantity of clay used in pottery and cement have been estimated in tons from the number of pieces shipped in the case of pottery and from the number of barrds of cement shined from the niant in the
FLORIPA MINERAL INDUSTRY 53
Almost all of the brick and tile is used locally in the construction of buildings, but in 1940-41 an increasing percentage has been used in military bases. Pottery production is small in Florida in spite of the large deposits of kaolin,
Figure 7. Clay, a basic ingredient of cement, is obtained by the Florida Portland Cement Company from a pit in Citrus County, about 60 miles north of Tampa in the NW'4, Sec. 2, T21S, R19E.
Photo furnished by the Florida Portland Cement Company through
the H. E. McCarthy Advertising Agency.
ball clay, and silica that are available in the State. All of the pottery is sold locally to tourists, merchants, or large producers of honey, marmalade, jellies and such products, for containers. The kiln is frequently operated under contract to sell all of a particular pot to one merchant or the potter may execute a design for a hotel or individual. However, these contracts are small and irregular and the production will vary with the tourist season.
* Both of the markets of kaolin and fuller's earth center outside of the State. Most of the kaolin shipments are made to the New York, Ohio, and New Jersey areas, the center of the pottery and chinaware industry, while almost the entire
. n -. C. a. . Ut .. n a
54 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
absorb a freight rate from the mine to the export depot, an ocean rate, and an import duty, but American producers have to combat a prejudice in favor of the English clays. Today no imported fuller's earth is used in the petroleum industry, but some producers of edible oils still prefer the English clay.
The war has greatly aided domestic clay producers as the scarcity of bottoms prevent large imports and producers are looking to domestic producers for suitable clays. Refinement of processing and mining methods produce a kaolin that wi'1 compare favorably with any, and this refinement is rapidly erasing the prejudice for English clays that arose out of the former domestic production of low grade kaolin.
Fuller's earth has strong and increasing competition from activable clay and other bleaching agents, and largely due to this competition and to the increased usage of colored gasoline the production of Florida fuller's earth in 1941 had decreased to almost one half of its tonnage and one third of its value of ten years ago. The production of kaolin and of clay used in cement during 1941 show slight increases over 1939 and 1940. Production figures for kaolin, fuller's earth, cement clay, and pottery clay are tabulated together in table 7 so that individual figures will not be divulged.
Table 7-Value of Clay and Clay Products
Produced in Florida Since 1937
1937 1938 1939 1940 1941
Brick and tile $ 148,366* $127,606* $ 193,110* $ 430,669 $ 336,227 Cement, t fulIer 's earth, kaolin, and
pottery -------------------1,359,604 828,963 1,106,350 1,235,501 1,489,343
Total ~.~$1,5O7,970 $956,569 $1,299,460 $1,666,170 $1,825,570
U. S. Bureau of census of 1939, probalAy represents only the sales value of the clay that was produced during those years.
t Estimated on the basis of the number of barrels of cement sold.
The history of cement in Florida began in 1898 when an
FLORIDA MINERAL INDUSTRY 55
rels of natural hydraulic cement from the Tampa formation at Chattahoochee, Florida.17 The deposit is extensive, and the cement was said to be of high quality, but no further production is reported. No cement of any kind was manufactured in Florida from 1899 until 1927, when the Florida Portland Cement Company's large and modern plant burned its first clinker. The first shipment of cement was made from this plant October 13, 1927.
Florida portland cement is made by calcining to incipient fusion a finely powdered mixture of limestone from Hernando County, and clay from Citrus County. The limestone and clay are ground with water to produce a slurry, which is burned in kilns (figure 8) with powdered coal to make a clinker. The clinker is then ground with gypsum or other materials to control the setting time and to give the cement special properties. The final product is tested by mixing with sand to make pats, from which the setting time and character are determined, and to make bricquettes, from which the tensile strength is determined under a series of standard conditions.
Production figures cannot be given for the one producer of cement in Florida, but the approximate limestone and clay tonnages and value are included in the figures for those substances. However, the Florida industry has enormously increased its production in the past years, and throughout 1940 and 1941 its activity has accelerated to meet the large demands of military construction in Florida. The number of barrels of cement produced in 1940 and 1941 shows increases of 22 and 30 per cent respectively, as compared with 1939. Florida cement is marketed almost entirely within the State, and the price of the local cement determines the competition from plants outside the State which must absorb the freight rate differences. The national average factory price in bulk per barrel in 1941 was $1.47, an increase of 1 cent compared with 1940. Florida cement sold slightly higher due to larger production and transportation costs.
Figure 8. Air view of the Portland Cement Company plant at Tampa. The three large rotary kilns in
smokestack are each 11 feet in diameter, 175 feet long, and inclined '/2 inch in 12 inches of length. Text
high as 2,700 degrees Fahrenheit are developed in producing a clinker clay and limestone.
FLORIDA MINERAL INDUSTRY 57
imports nor the stock on hand at warehouses, distributors, and contractors. Florida used 2,442,623 barrels or 1.29 barrels per capital in 1940, and 3,172,179 or 1.67 barrels per capital during 1941. 18
Figure 9. Thirty cars of limestone and eight cars of clay are required for a single day's operation at the Florida Portland Cement Company plant at Tampa. The limestone is quarried near Brooksville, Hernando County, and the clay near Floral City, Citrus County.
Photo is printed through the courtesy of the Company, and was
furnished by the H. E. Mccarthy Advertising Agcncv.
The use of cement has been greatly stimulated by a thorough sales promotion of the use of prepared or precast cement products in construction. These products are made by mixing sand, coquina, limestone, or a combination of the three aggregates with cement and either pouring or pressing blocks or ornamental pieces from the concrete. It is estimated that, where the producers mined their own aggregate, ornamental pieces and concrete blocks sold for more than $2,500,000 in 1941. This represents only a fraction of the total sales value of concrete products in Florida, as the number of producers that buy their a~27reEate far exceeds those
58 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
Diatomaceous earth, or diatomite, occurs in Florida associated with peat, and the basic composition is a hydrated amorphous silica. Diatomite is of vegetable origin and consists almost entirely of microscopic silica shells that were secreted by small plants called diatoms. Each shell is composed of two valves which fit one upon the other, much the same as a small pill box. These shells are made up of many designs and shapes, some of which are confined to one locality, and all grew in either fresh or brackish water but rarely both. When these small plants die the organic matter decays and the shells which they had secreted about them build up a deposit on the bottom of the pond in which they lived. This deposit is diatomite.
The diatom shell is so small that it can not be seen with the naked eye, and it can be identified only by the aid of a high-powered microscope. It has been estimated that it requires between 40 and 70 million diatoms to make up a cubic inch. The sharp edges of the diatom make it an excellent polishing and cleaning agent which can not scratch any surface because of the minuteness of the particles. The prepared dry diatomite will absorb from 25 to 40 per cent of moisture which makes it an excellent chemical and medicinal carrier and filler. The Florida diatomite is especially clean and pure. Organic impurities are burned out, and the little sand that is present is eliminated by air currents. The salient features of the refined diatomite as advertised by the American Diatomite Company, the only producer in Florida, are shown in table 8.
Table 8-Characteristics of florida Diatomite
Silica (5102) ~ per cent Specific gravity ...------------------n...--------------1.75
Iron Oxide (IE"e9c~3 ) .41 pfi Alumina (A1203) .~... .48 Bulking value: 11.50 per solid galLime (GaO) .30 ion
Magnesia (Mg) ... .20 Packages -----------------.~25 and 50 pounds
Phn~nhRtA (P fl ~ AS Pnrtinln s~irn 195 250 225 mid
FLORIDA MINERAL INDUSTRY 59
The Florida diatomite is unique in that it is one of the few fresh-water diatomites that is commercial. The fresh-water diatomite has a higher silica analysis and a more porous physical structure than the marine diatomite. A loose packed cubic foot of fresh-water diatomite weighs approximately 8 pounds, whereas the marine diatomite weighs 20 pounds for the same measure. The light weight, chemical purity, angularity, and absorptiveness makes the Florida product indispensable in some industries.20 Mining and Processing
The American Diatomite Corporation operates the only diatomite plant and mine in Florida. They have a preliminary processing plant at the mine 18 miles south of Clermont, Lake County, and a finishing plant at Clermont. In this vicinity the corporation owns and has leases on several bogs, which have been thoroughly prospected by bore holes. The present deposit is from 3 to 6 feet in thickness, and overlies a thick peat bed. There is no overburden in the sense that miners use the term, but the shallow water that covers the bog is pumped over a dam so that the mining area is kept dry. The raw diatomite is cut by hand shovels and loaded to dump trucks, which dump into bins at the preliminary processing plant. The material is fed into a hydraulic press from the bin, where it is pressed into thin sheets, thereby eliminating most of the mechanically held water. These sheets are cut into small square cakes and placed on open drying racks where they are sun-dried. The initially processed cakes are then hauled by truck 18 miles to the finishing plant where the remaining volatile material, peat and water largely, is burned out in wood-fired kilns. The residual silica is shredded in a revolving drum, lined with baffles. A constant temperature of approximately 150 degrees Fahrenheit is maintained in the drum to keep the diatomite dry. A suction fan pulls the shredded diatomite across a sand trap, allowing the sand and diatomite clusters to settle out into a cone from which it is removed periodically. The diatomite is blown into silos from
60 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
All of the reported deposits of diatomite of Florida are composed of fresh-water diatoms and are intimately mixed with peat. Peat and water, in fact, compose the large part of the material that is mined, the recovery being approximately 10 per cent after the organic matter and moisture have been volatilized. All of the present production comes from Lake County, where the diatomite occurs in shallow bogs and ponds ~vhich must be drained before mining is feasible. The adjacent counties, especially Polk County, are reported to have deposits, but the large peat and muck area of the Everglades apparently has no commercial deposits of diatomite. The western Florida counties are a potential producing area, and the deposits of diatomite along Blackwater River have been described by Gunter and Ponton (1933).
In Florida the diatomite occurs as a brownish gray, porous. light, peaty aggregate interbedded with peat, and usually under a variable depth of water. The following section, a bore hole at the American Diatomite Corporation pit. 18 miles south of Clermont, Lake County, is typical:
4. Water 5 feet in depth.
3. Diatomaceous earth, 6 feet in thickness.
2. Peat, 10 to 20 feet in thickness.
1. Diatomaceous earth, thin hyer with siliceous
spicuks. This bed is not mined.
Approximately two-thirds of the production of Florida diatomite is used in the filtering of wine, liquor, milk and naphtha. The diatomite has numerous specialized usages among which are: filler in paint, varnish, cosmetics, plastics; insulation, especially against heat; coating paper; hardening and increasing the life of rubber and leather; abrasive in fine polishes; carrier for pharmaceuticals and insecticides; and as a light aggregate in concrete to increase its density and strength.
Th~ nhvqipnl ~triirtiir~ nnd th~ rh~minn1 ~nrnnnsdfinn nV a
. -- - - -. .-.- - -.
o ~ ~ --~
Cd -d N
-. 0,. -~ 2 K ~ *~* '%.,, jk.
rr~0 0-plo2 wZo
-- -, *
- -. COO
I~UWY\\YWAW 4)t/j/ll/fl1WV1\\\\\ $1 S -:
. - - .- -. - ----,.. - - - .~-* -. -- --
62 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
The chief physical properties that make the Florida diatomite marketable are its high porosity and the relative inertness of the material. The high silica content is its most valuable chemical property. Filtration and heat insulation demand a high porosity and the chemical inertness of Florida diatomite is valuable when used as a filler of paints and as a carrier of drugs and insecticides.
The Florida diatomite is sold to specification, and a buyer can be sure of a uniform product. Four grades, the particles varying from 125 to 500 mesh in diameter, are sold and all are high in silica content and contain no grit. The largest market for this material is in filtration, and as the light weight and great bulk of the diatomite carries a high freight rate most of it is sold locally. Because of the necessity for selling the product nearby, the market area is limited and the chances of successful competition are low. Likewise competition from foreign sources is improbable as diatomite is not a desirable water cargo, and bottoms are scarce at present.
The relative inaccessibility of the deposit, its being small and 18 miles from a railroad, has held the price of the Florida diatomite high, but its special properties, as compared to that of other diatomites, allow a higher sales price.
No yearly production figures can be given for Lhe diatomite industry in Florida. The 1940 and 1941 figures have been included with those of peat and muck because of the close association of these materials. Although the United States leads the world in the production of diatomite, Florida's contribution to this total is small. Pit and Quarry (No. 6, 1941, p. 49) reported the American Diatomite Company had a capacity of 4 tons of finished diatomite per day. Since the Company opened its pit in 1936 it has marketed 1,044 short tons of finished diatomite at a value of $99,790.
PEAT AND MuCK 21
FLORIDA MINERAL INDUSTRY 63
mutations. Peat is the partly decomposed and more or less disintegrated remnant of organic matter produced from the arrested decomposition of vegetation covered or saturated with water. It is fibrous and retains the plant structures, to which small droplets of wax adhere. Arrested decomposition has enriched the carbon content by releasing a large part of the oxygen and hydrogen as gases, a large portion of the original carbon remaining. The peat is acid in reaction and contains much less inorganic matter than organic. Muck is an approximately equal mixture of inorganic and organic matter, formed much the same as peat, but as peat and muck are gradational the names are used interchangeably for deposits of either. Generally, if the deposit ignites freely when dry it is peat, but the common use of the terms in Florida is to call all highly organic lands under cultivation muck lands. The deposit applied to land deficient in organic content is labeled peat if it has been dried and sacked, and compost or muck if it is applied in bulk directly to the land. The third term, "humus," differs from peat and muck in that it is the decayed and oxidized organic matter accumulated in soils that have been exposed to the air most of the time. It composes the "top-soil" of the farmer and is a fine organic powder intimately mixed with the soil. Humus is properly of more interest to the agriculturist than to the geologist and is included here in comparison to peat and muck.
Nearly every county in Florida has deposits of muck and peat suitable for local application to soils or use as a filler in fertilizers. These deposits occur along the floodplain margins of streams, in shallow lakes, lagoons, the Everglades and on marshes of the coast. Some of the large shallow lakes have little to no organic content at the centers, muck at the margins, and peat in between. Soper and Osbon (1922, pp. 199-200) believed that Florida probably contained more peat than any other State except Minnesota and Wisconsin, and
4-k at- 4-in a C14-~ 4-a n~n n n a ~ a tin at -naa a.. a:....e.. '1 0011 1011 non
64 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
Conditions in Florida are almost ideal for the accumulation of peat. Lakes are plentiful and generally Florida lakes have no surface streams emptying into them so that a highgrade peat with little impurity has been formed. Peat occurs, also in the mangrove swamps, along the streams of the State, and extends seaward into the salt marshes. The overflow of the streams into these back swamps, and the action of the waves on the marsh flats, has mixed the peat with silt and mud so that the marsh and floodplain peat is high in inorganic matter and approaches a muck.
Peat requires for its formation a relatively quiet body of water which receives or carries little sediment, and which is not so deep as to prevent plant growth. The plants making the peat deposit require both sunlight and water and a fairly permanent water level, one that does not fluctuate to extremes, alternately drowning the plants and then drying to the extent that the roots and decaying vegetation are exposed to aeration. Deep bodies of water have little vegetation and their margins are so disturbed that the peat is contaminated with mineral matter. Small shallow bodies of water dry up and allow the vegetation which has accumulated in the basin to oxidize, preventing peat formation. Small lakes, spring heads, back swamps along streams, and marshes and lagoons are ideal for plant accumulation.
In addition to a place of accumulation, peat requires a climate that is wet enough to provide permanent bodies of water, warm enough for vigorous vegetation, and one in which rainfall and evaporation are balanced so that there are no large fluctuations in water levels. Also, the large accumulations from the annual plants are desirable in peat formation over the smaller volume produced by biennial and evergreen plants. The most common peat-forming plants, which usually predominate over other types of vegetation (see Harper, 1910), are trees, heath shrubs, weeds and grasses, lilies, reeds, ont-tni1~ nnd fawnsz
FLORIDA MINERAL INDUSTRY 65
a combination of carbon, oxygen, and hydrogen. Because of its complex structure and chemical composition cellulose is easily decomposed when attacked by bacteria and oxygen so that new combinations of its chemical elements are rapidly formed and the plant decays if it f ails on aerated soil. Where the plant is covered or saturated by water the rate of decay is slow as atmospheric oxygen is largely excluded and the disintegration by organisms depends on the amount of oxygen present and necessary for their existence. In fact the disintegration is usually so slow that the chemically active elements, such as nitrogen, oxygen, and hydrogen, are released so much more rapidly than carbon, the least active element in cellulose, that most of the carbon remains. In the formation of peat (C02H72024) from cellulose (072H120060) oxygen and hydrogen are released as water (H20) and carbon, hydrogen, and oxygen are combined in various gases such as carbon dioxide (002) and methane or marsh gas (OH4) (see Soper and Osbon, 1922). The following simplified chemical reaction in peat formation is typical:
72 120 60 02 72 24 + Boo 002 NH
OH 0 *40H0 4
(Cellulose) (Peat) (Water) (Gases)
Both the uses and problems of production of peat have been discussed fully by Davis (1911) and Haanel (1926), and the following comments concern Florida specifically. In countries deficient in coal and oil, the principal use of peat is as a fuel. There is no commercial production of peat as a fuel in Florida because it would have to compete with Alabama coal and with fuel oil from the Gulf Coast oil fields, both of which have the advantages of higher heating capacity and lower production costs. However, during the present transportation difficulties arising out of the war a small plant could possibly operate at a profit in Florida should the shortage of coal and fuel oil become more acute. After the war this plant would have possibilities in the production of charcoal and coke, and in the refining of the resultant tars and
n 4 . 4 *1 I -
66 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
use of both muck and peat in Florida is in agriculture either as a fertilizer filler, direct application to soils deficient in humus, or used directly as a soil. When used for soil the land is called hammock or muck land and utilized for pasturage and cultivation of sugar cane, vegetables, grain crops, celery and sunflower seed. Where the deposit is applied directly to th~ soil without drying or treating, care should be taken to test the soil and, when applied to acid soils, lime or dolomite should be used with it. Peat and muck are used to some extent in Florida to retain moisture in lawns, as a stable litter, for compounding stock feed, and when mixed with manure, for compost. Kimbrel's Florida Humus Company, Panama City, has recently experimented with the manufacture of peat fiber pads to be used as a building insulation and has reported considerable success.
Mining and Production
Mining of peat and muck is comparatively simple as theru is no overburden other than water and green plants. Where it is possible the peat and muck pits are drained, although one company finds it less expensive to mine under water. Where the pit is drained and the material is applied to soils, the green vegetation is found to be detrimental because of a tendency of the undecayed material to "burn" the crop, and it is removed with great care by some producers. Other producers have not found this green plant material detrimental to their product, and it is mined with the peat or muck.
The drained peat and muck are mined by hand shovels and by cable-bucket diggers, while that covered by water is mined by a dragline excavator. The material may be allowed to dry and then be shredded, or it may be loaded directly into trucks for delivery. The larger companies have concrete drying platforms (fig. 11) and drying sheds in which the moisture content of the peat is reduced to a minimum. After drying the material is shredded and cooked, or mixed with fertilizer to make compost. All muck companies sell their
I II I at a I
FLORIDA MINERAL INDUSTRY 67
the pits adjacent to large cities have an economic advantage over those more distantly located. In counties which have no commercial production the farmer may supply his own needs from local swamps and bogs. No record is kept of this
Figure 11. Concrete drying area of the Florida Humus Company, Zeliwood, Orange County, showing method of drying. Plant as it was in July 19, 1932.
material, and the production figures do not represent the full volume of humus that is mined and used in Florida.
Six companies were producing peat and four were producing muck in Florida in 1941. Two each were located in Orange, Brevard, Bay, and Putnam counties, and one each in Volusia and Sarasota Counties. The larger part of this production went into agriculture as fertilizer filler and soil conditioner, but no attempt is made to separate the production according to its uses. The production of peat and muck with that of diatomite, included here because of its association and as there is only one producer of diatomite in Florida, is shown in table 9.
Table 9-Production of Peat, Muck, and DiatonPte for 1940 and 1941
68 FLORIDA GEOLOGICAL SURVEY-BULL~IN TWENTY-FOUR
CRUSHED STONE 23
The crushed stone industry has expanded greatly during the last few years, the approximate volume of production increasing from 1,359,350 short tons in 1939 to 3,460,609 short tons in 1940 and to 5,014,753 short tons in 1941. The value of this stone was $1,257,115 in 1939, $3,035,483 in 1940, and $4,533,478 in 1941. This increase has been due to a greater use of concrete in the building industry and to construction of military projects in Florida.
Crushed stone is produced from limestone, dolomite, and flint rock in Florida, and the large part of this material is used as concrete aggregate, road base courses, and for road surfacing. Each industry has problems of production, transportation, and marketing that are peculiar to itself, and crushed stone is no exception. The industry has to compete with the Birmingham slag, a by-product of the iron industry, which can be marketed at a low price. In fact, the price of crushed stone in Florida is so low that the freight charge is a large part of the market price, and transportation is therefore important and may be the difference between success and failure of an enterprise. For this reason many contractors temporarily lease pits in the vicinity of the job, and abandon them when their purpose has been served. Sometimes mining is continued in such pits to supply a small local demand, but rarely is there an attempt to supply a broader market. However, the demand for the product of the permanent plant may also fluctuate greatly. The construction of a highway or building in the marketing area may create a large demand, for a time, which will drop as the project is completed.
The centralization of the industry near Ocala and Miami has simplified marketing, but at the same time the large number of plants grouped so closely has reduced the proportional market of each plant. The crushed rock of the Miami area competes with that of the Tamna-Ocala area and
FLORIDA MINERAL INDUSTRY 69
rock are conditions that are not desirable. Flint layers and boulders occurring in the soft limestone in the Ocala area are bothersome because they are numerous, break machinery, and increase the labor and production costs by the necessity of their removal. This flint might become an asset if it were sold to local flint crushers or if a flint crusher were operated by the limestone company. There is no such arrangement, in spite of the fact that local flint crushers often do not run at capacity because of the lack of material, generally supplied by farmers from boulders in their fields. Another difficulty in mining the soft Ocala limestone is the large number of clay filled holes and solution channels which penetrate the limestone. The inclusion of too much of the clay lowers the value of the limestone as a binder in road bases, its chief use. Its removal is at a righ cost, as most of the clay must be removed by hand, and an excessive amount entails mining around the objectionable area, a waste in labor, time and material.
These difficulties in mining, marketing, and location of quarries and crushers differ with the locality but must be overcome for the enterprise to be successful, and with careful study methods may be devised to solve them. The solution of a difficult problem gives the producer economic advantage of his competitor who has failed to solve the problem. Where production and marketing problems are excessive the cost of the product is proportionately higher and decreases as problems are overcome.
Types of Crushed Stone in florida
Limestone, flint rock, and dolomite are crushed in Florida. This crushed stone includes rock either with a high crushing strength used as aggregate in concrete and road surfacing, or with a high calcium carbonate content used in road base courses. High crushing strength is characteristic of the hard crystalline limestone of the Brooksville-Tampa area, the flint rock of Alachua, Marion, and Sumter counties, the
nrITaFollinn Anlnm+n nf Poaon hffonn+citi smnA ~ornanfo nniintioa
70 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
for road bases and for surfacing county roads and which is known as "Ocala Road Base Material" or "Ocala Lime Rock,"~ and the harder and more sandy limestone known as Miami oolitic lime rock. The "Ocala Lime Rock" is mined in the mid-Peninsula counties and the "Miami Oolitic Lime Rock" in Broward and Dade counties.
Expansion and Opening New Quarries
In Florida, where surficial sands generally hide the outcrop, a prospective operator should consult established operators about the problems of mining, marketing, and transportation. Before an expensive plant is erected or money is invested in expansion the producer and the prospect should be sure of an adequate deposit suitable for the purpose. The general aspects of the area can be obtained from the Florida Geological Survey, but in areas where there are few mines and outcrops the proposed quarry should be thoroughly prospected before any money is invested; all problems should be anticipated and the amount of material available should be estimated. Where the deposit is to be used for road base courses and a high calcium carbonate content is desired, a churn drill may be used to obtain samples for chemical analyses, provided the samples are collected free from savings of the overlying sand and clay. However, where the rock to be mined is to be used in concrete, strength and abrasion tests are necessary and core drills must be used to obtain a sample of sufficient size. The State Road Department has estimated its operating cost of core drilling to be between $0.22 and $1.61 per foot and an average of $0.51 per foot for a period of years.24 This cost includes the cost of relocating the drill in changing from one project to another, and is based on holes of varying depths up to 400 feet. The costs of operating a churn drill are considerably less and the churn drill should be employed where possible because of the saving in production costs.
Once the extent of a deposit is known the approximate
FLORIDA MINERAL INDUSTRY 71
tons present in the deposit. However,; care should be taken to estimate the tonnage of unusable material, such as flint rock and clay and sand filled cavities in limestone, and to subtract this from the total.
The thickness of the overburden can be determined by the drill holes, or by trenching the overburden to the top of the rock. Trenching has the advantage in mining Florida calcareous rock in that an estimate of the volume of clay-sand filled cavities can be more easily determined. Some of the commercial rock has very little of this cavity fill and the overburden of nearly all is less than 25 feet. Once the overburden has been removed, the depth to which the rock can be mined governs the amount of profit. In Florida, the depth of mining corresponds closely to the proximity of the groundwater surface, and the mines on high elevations generally have economic advantage over those at lower elevations. In the limestone mining the overburden is generally less on hills than in valleys, but the amount of quarry waste generally runs higher because of the presence of a large number of clay-filled caves and fissures.
The Florida State Road Department has in past years used the greater part of the production of crushed rock of all
types, but the increases in production during 1940 and 1941 have been largely absorbed by military construction. Soft limestone was used principally in 1941 in road bases, airport runways, binding agent in fills the harder limestone, flint, and dolomite in concrete aggregate and road surfacing. The Federal and State specifications for rock are approximately the same, and to compete a producer must know what test his product must pass to qualify for a contract. The emS
phases, for road base materials and binding agents, is on a high content of calcium and magnesium carbonate, whereas the important characteristic of concrete aggregate is a high
- --------- 1... - .1 - - .3 - - - - TTh 1 A.. - I.. -
72 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
that each issues covering crushed rock. State and federal specifications are practically the same, and for completeness the State Road Department and various railroad specifications are included in the discussions of the specific uses that follow:
Figure 12. The Ocala Lime Rock Corporation's limestone pit, near Kendrick, Marion County, in the 8E SWVj, Sec. 23, T14S, R21E. The massive occurrence of the Ocala limestone, mining and transportation methods, and machine for drilling shot holes are shown. The ramp leading to the crusher is in the lower right corner.
Concrete aggregate: Local stone has to compete with slags from the Birmingham iron district and the Florida superphosphate industry as a concrete aggregate, and specifications for each aggregate differ. In general, specifications include limits on the per cent of loss due to abrasion, the degree of soundness or the presence of incipient cracks, and the breaking strength of a concrete made with the aggregate. Abrasion is tested in the State Road Department Testing Laboratory, Gainesville, Florida, by rotating approximately 54) rough cubes of the aggregate.. weighing annrnximstelv
FLORIDA MINERAL INDUSTRY 73
the Miami polite, whose thin-bedded, cavernous angularity gives an excessive abrasion loss. The Miami oolite, when crushed for aggregate, dislocates nearly all of the friable material, and abrasion tests made on the aggregate at the size to be used will compare favorably with any limestone aggregate.
Soundness is a measure of the incipient cracks which might result in the disintegration of concrete. No regular test is made for soundness by the State Road Department the Deval abrasion test replacing it, and generally no specifications for soundness are issued. There is no need for a test of soundness by alternating freezing and thawing, as freezes in Florida are rarely severe enough to cause the cracking of concrete. When other tests indicate that an aggregate may be weak, the material is then tested for soundness. The aggregate is soaked in sodium-sulphate solution and dried, the solution in the pores and cracks crystallizing, thereby causing great internal stress. The amount of disintegration and the number of treatments necessary for complete disintegration determines the degree of soundness.
While some estimate of the the strength of materials is gained from the abrasion test, the best and final test of concrete aggregate is to test a block of concrete made from the aggregate. This test is made under standard conditions and if the tested block has a strength equal to, or higher than, a similar concrete block made with the same amounts of cement and water, but with a standard aggregate, it is passed.
For limestone, flint, and dolomite to qualify for the concrete aggregate in the State roads the type A aggregate when subjected to the Deval abrasion test for stone shall show a loss not exceeding 9 per cent, and Type B aggregate shall show a loss not exceeding 6 per cent. The dry prodded weight per cubic foot, when tested by standard methods, shall be not less than 90 pounds for concrete aggregate or 85 pounds
74 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
substances (see State Road Department specifications). The dry prodded weight per cubic foot shall be not less than 70 pounds for use in bituminous mixtures and surface treatments, and not less than 75 pounds for use in Portland cement concrete. The slag shall show a loss not greater than 12 per cent when subjected to the Deval abrasion test.
The following charts (table 10 and 11) are averages of State Road Department tests made on limestone and flint rock that have been used in concrete aggregate. Florida round gravel and the Birmingham slag have been included for comparison.
Concrete aggregate should be hard, strong, durable, and free from disintegrated pieces, salt, alkali, vegetable matter, and adherent coatings. The following is taken from the specifications of the Florida State Road Department.25
"The weight of extraneous substance shall not exceed the following percentages:
Coal and lignite *.. ..... .. .. ....... ..... ...... .... ............ ...... .... - . 1.00
Clay lumps ......... .......... ............ .... .... ....... ......... .... ......... 0.05
S oft f r a gin en t s ... . ... ...... ................ . ... ...... .... ... .......... ...... - . 1 0. 0 0
Cinders arid clinkers ..... ...... - ... - . ..... . ...... ....... - ....... .. ... ... ... 0.50
]L~oss by decantation ... ..... ..... .... ........ ..... -.......... ....----------------. - 1.25
"The sum of the percentages of all materials noted in above table
shall not exceed 10."
The State Road Department has made an extended study of the sizes and density of rock necessary to make the best concrete. The denser the concrete, or the less voids it has after setting, the greater the strength of the concrete. The State Road Department recommends that the greatest density can be obtained from a mix of a fine with a large aggregate. This works a hardship on some producers as they have to stock the intermediate sizes or sell them at a low price, thus lowering their margin of profit. This disadvantage has been overcome by a few producers who sell the intermediate
Table 10-Abrasion and Accelerated Soundness Tests made by the Division of Tests, State Road Department of Florida.
Producer Material Source Per cent wear Accelerated sound
Deval test affected by sodium
Florida Crushed Stone Co.,
Brooksville Limestone Quarry 5.2 29
Limestone Camp, quarry 4.1 6
________________________ Limestone Camp, stock pile 6.1 19
M. M. Thomas, Ocala Flint Zuber, stock pile 2.0 18
Standard Rock Co., Standard Flint Standard, stock pile 2.2 14
Alachua County Stone Co.,
High Springs Flint High Springs 6.2 32
_________________________ Flint High Springs 4.8 18
Central Rock Co., Linden Flint I. Berner siding 3.9 Passes
Fernald and Gray Quarries, Limestone New Port Richey 4.0 48
Inc., Tarpon Springs _________ _____________________ ___________________ _______________Limestone New Port Richey 7.3 44
____________________ (average of 7 s:
Composite Limestone Miami 'averageof6samples) ________-
I I 12.5
Composite I Slag Birmingham, Alabama 'average of 4 samples) _______________-- -
Table 11-Unit Weights of Coarse Aggregates made by the Division of Tests, State Road Department of Florida June 23, 1939
-- ---- ----------Weight in Brooksville Thomas Newsom Griffin Miami
Grade pounds limestone Birmingham flint rock flint rock flint rock oolitic
no."' per (Tampa slag Ocala Williston High lime rock
Cubic foot formation) Springs ________2 Dry prodded (30) 94.0 (30) 88.0 -.. -. .-. ....... .... .... ......... -. ( 3) 87.2
5 Dr3r prodded C 2) 92.0 .... *. ..**... ......... .. ** ** .******* *** ***** *
9 Dr3r prodded (15) 94.0 .... ...... ..... ( 4) 73.0 ...... .... ... .. ........... ... .................
11 Dry prodded (23) 85.7 (24) 79.2 ( 9) 77.8 ( 1) 75.5 ( 5) 76.8 ( 4) 75.0
12 Dz3r prodded ( 1) 83.0 (34) 83.3 --.--~.-.- ..- .....---....-. C 1) 71.0 - ..........
13 Damp loose (11) 83.2 (18) 72.6 (11) 63.5 - -- ( 2) 64.7 ..~...
14 Dry prodded (11) 93.0 ......... *******-..***.. ...------------..........
15 Dry prodded (23) 85.7 C 1) 80.0 68.4 C 2) 63.2 C 2) 63.7
Danip loose (21) 81.9 (10) 74.1 -. .. . .. -.
Note: The above are unit weight averages of samples or the ore from which the slag comes, varies submitted to the Division of Tests over a period of years and limits of gradation permissible for the above g are compiled to give a fairly accurate indication of the unit aggregate are such that the unit weight of an weights of these materials for use in estimates and rough same source may vary appreciably for the calculations. They do not cover all conditions and circum- period. Figures shown in parentheses repress stances since the coarse aggregate from any source may vary of tests used in determining the unit weight. from time to time as the character of the stratum of rock,
See Standard specifications for road and bridge construction. Florida State Road Department. 19'
FLORIDA MINERAL INDUSTRY Ti'
It has been found that flint has the disadvantage of smooth glassy sides which lower the cementing quality, and that crushed limestone has a coating of fine dust that acts in a similar manner. The sharp edges of flint likewise require a greater use of sand. Slag has the best cementing quality, but local production of slag is small and imported slags are expensive in peninsular Florida, and local products are preferred over those out of State.
Road base material: Almost all road base courses are constructed of limestone in peninsular Florida but in western Florida sand-clay fillers are sometimes more available and cheaper, and substitute for limestone. The road base limestone production is centered about Ocala and Miami. In western Florida the largest potential producing area of road base limestone is in Holmes, Washington, and Jackson counties, where most of the roads have sand-clay road base courses. If this limestone were developed Florida would have three strategically located areas from which road base
78 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
limestone could be supplied to all of Florida at a minimum of transportation costs.
Because of the nature of its occurrence, the specifications for road base course material vary for each limestone. The State Road Department has specifications for two limestone, "The Ocala Lime Rock" and the Miami Oolite Lime Rock." The "Ocala Lime Rock" is a general term originally applied to the limestone near Ocala and it formerly included only the Ocala formation but now applies to soft limestone beds of the younger Suwannee limestone and Tampa formation. The limestone outcropping in western Florida qualifies as "Ocala Lime Rock." The "Miami Oolite Lime Rock" outcrops in Broward, Dade and Monroe counties, and it is generally lower in calcium-magnesium carbonate than the "Ocala Lime Rock,~~ the exception being in the vicinity of Miami. Where transportation costs and availability make it feasible the State Road Department has mined the Caloosahatchee marl and the coquina of the Anatasia formation for road base courses, especially in Collier County. Several cities and counties of the East Coast have found coquina very serviceable for this purpose, but the material is not crushed generally. The hiah per cent of impurities in both of these formations make them a poor binder when. compared to. other limestones used for this purpose.
To qualify for road base courses under State specifications a limestone must show no tendency to air-slake or undergo chemical change under exposure to weather. The material should be graded uniformly from 3 inches down to dust and all fine materials shall consist entirely of dust of fracture. To meet specifications, the "Miami Lime Rock" has to be mined from its pits from which all overburden has been removed prior to blasting, and must contain a minimum of 85 per cent calcium-magnesium carbonate (CaMg (003)2) for number one rock, and a minimum of 70 per cent for the number two. Oxides of iron and aluminum shall not exceed 2 per cent; and any other mineral constituents shall be silica.
FLORIDA MINERAL INDUSTRY 79
surface. It must be at least 97 per cent carbonates of calcium and magnesium by weight, and the remaining 3 per cent shall be almost free from organic matter. The limestone from the Tampa formation, sold under the trade name of "Brooksville stone," is generally too high in insolubles to qualify for use in road base courses (see table 12), and can be sold at a higher price for use as concrete aggregate.
Table 12-Chemical Analyses of Limestone for Use as Road CourseB.
The first seven analyses were made by the Testing Division of the State Road Department, the eighth is the average of
five analyses as reported by Mossom. (1925).
Rock insolubles carbonates Remarks
and oxides of Ca
Ocala Lime Rock, Levy County
Average of 4 samples 0.62 99.38 Passes
Ocala Lime Rock, Alachua County
Average of 5 samples 2.08 97.92 Passes
Tampa formation, Pasco County
Average of 4 samples 17.40 82.60 Rejected
Ocala Lime Rock, Marion County
Average of 6 samples 0.80 99.20 Passes
Miami Oolite Lime Rock, Broward
County, 3 samples 14.40 85.60 Passes
Miami Oolite Lime Rock, Dade
County, average of 6 samples 10.80 89.20 Passes
Jackson County limestone
One sample 0.33 99.98 Passes
Washington County limestone
Average of 5 samples 2.99 97.11 Reported
Railroad ballast: The tendency in Florida is to use the best material that is available on the line of the railroad for ballast, and there is a considerable elasticity in the specifications of each railroad. Gravel is scarce, other than in western Florida and here the railroads are near enough to the Birmingham district to use slag for ballast, so that it is seldom used, the gravel producer preferring to sell his product for concrete aggregate at a higher price.
Table 13-Comparative Values of Different Materials Used as Ballast on the Florida East Coast Ral Method: American Railway Engineering Association stE railroad ballast rock
1 2 3 4
Apparent specific gravity
Weight in pounds per cubic foot 145.00 131.00 167.00 167.50
Absorption at 96 hours 3.09% 5.56% 2.70% 1.12%
Compression (lbs. per sq. inch) 389.00 197.00 3,270.00 18,460.00
cc Hardness-Loss in weight-grams 15.25 19.35 14.17 10.70
French coefficient of wear 3.46 3.06 16.90 14.10
Cementing value 800.00 753.00 74.20 56.00
Toughness (blows to fracture) 3.66 4.33 4.66 15.50
Per cent of wear 11.52 11.09 2.36 2.84
Sample 1: From E. P. Maule Rock Company, Ojus, Dade County.
2: From Naranja Rock Company, Naranja, Dade County.
3: Brooksville limestone, Brooksville, Hernando County.
4: Camoa rock, Jamaica, Cuba.
5: Key Largo limestone, Windleys Island, Monroe County.
A compilation of two charts, from L. C. Froham, Chief Engineer.
FLORIDA MINERAL INDUSTRY 81
Engineering Association specifications, but the Brooksville, Hernando County : (Tampa formation) limestone approaches it. The Miami polite at Ojus and Naranja, Dade County is used if the harder portions are selected, and the Florida East Coast Railroad Company has tested the Key Largo limestone on Windley Key as a possible ballast on their former Key West extension. In general, the specifications for limestone ballast require only size and a degree of hardness. The softer varieties of limestone are objected to as they have a high cementing value, and upon exposure to weather they harden and consolidate so that maintenance of the track is made difficult.
Specifications for limestone ballast for each railroad differ, and those of the three most important railroads operating in Florida are quoted on the following pages.
Florida East Coast Railway Company28
"Florida East Coast Railway uses for ballast purposes that rock which is available on its line and is securing rock for ballast from a quarry at Ojus and from a quarry at Naranja, both points being located on the lower East Coast . This rock cannot be classified as a good ballast rock . However, it is the material available in Florida on the line of this railway and, therefore, it is used and its deficiencies accepted. Under the conditions on this railway the deficiencies of the material are not serious as they would be in the northern latitudes and
under railway track of a much greater traffic density.
dl* * We accept the quality of rock as it comes from the quarry
and specify It to be crushed to a size which will pass a 2
inch ring and be retained on a 1/2 inch ring...
"In the past we have used a rock from the Camoa quarries located at Jamaica, (Cuba) ... and have also used crushed slag from the Birmingham district. Each of these materials was used in very large quantities some years ago, the Cuban rock being used on the south end of the line and the slag on the
The Cuban rock (Sample 4 in Table 13) is the best quality for ballast and approximates very closely the specifications
82 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
Atlantic Coast Line Railroad Company 27
"The ballast to be furnished shall be prepared after the following manner; to wit: The ledges of stone from which the ballast shall be taken are to be hard ledges in the quarry. The hard ledges are defined as those ledges which when struck with a sledge hammer shall cause the sledge hammer to ring.
"The broken stone ballast shall be manufactured to conform to the specifications of the American Railway Engineering Association for stone ballast, with proviso that the maximum size of broken stone ballast shall be 2 inches and the minimum shall be inch. The contractor may, at his option, remove the 94 inch stone by passing the same over a screen with one inch perforation. The ~, inch stone so removed will
not be loaded into ballast cars.
"The material which will conform strictly to these specifications
is satisfactory for ballast. The softer rock compacts, and partially consolidates and hardens under the ties upon continued exposure to air and is not satisfactory as material for ballast. . We have not attempted to draw any strict specifications for hardness and durability other than as provided in
the accompanying above specifications.~~
Seaboard Air Line Railway 28
we are using the crushed limestone from the Brooksville
territory and Ojus rock from the Miami territory . our specifications, covering ballast, are only applicable to the limestone and Ojus rock for size, since these specifications were primarily made for stone, slag and gravel ballast.
"Specifications for stone ballast are as follows:
"Stone for use in the manufacture of ballast shall break into angular fragments which range with fair uniformity between the maximum and minimum size specified; it shall test high in weight, toughness, wear, and soundness, but low in cementing
qualities and will be free from dirt, dust, loam or rubbish.
"Tests may be made from time to time at the option of the purchaser and shall be made at a testing laboratory selected by the purchaser, but visual inspection and other tests shall be made at quarry prior to shipments as often as considered necessary. Tests for weight, toughness, wear and soundness shall be in accordance with A. R. S. A. Specifications for Stone
FLORIDA MINERAL INDUSTRY 83
"Class 'B' Ballast will range between the size which will in any position pass through a one and one-half (1%) inch ring, and the size which will not pass
through a three quarters (% ) inch ring."
Riprap: Riprap is a general term applying to large irregular stones which are used in construction to buttress land from waves, currents, and tides. Its chief use is along breakwaters, jetties, spillways for dams, or for shore protection. Almost any hard, durable stone will serve as riprap and ship ballast is often used in Florida. Coquina blocks from the Anastasia formation and the harder limestones about Tampa make suitable riprap. The nearest deposit of hard rock is usually used because transportation is such a large part of the delivered cost, riprap bringing a very low market price, and the flint from the soft Ocala limestone cannot compete in the riprap market for this reason. Riprap quarries are usually opened near the construction project and closed at its termination. Only occasionally are established producers able to sell their by-product as riprap.
Other Uses: Under this head are included the by-products resulting from the production of crushed stone for use in concrete aggregate and as road base materials. Large tonnages of limestone are used in the manufacture of cement and lime but these are not part of the crushed stone business and are not included here, but under separate headings. The alert producer of crushed stone is anxious to market his entire production at a profit. His entire output may be utilized in concrete aggregate, road base materials or riprap, but where there is a tendency to over stock certain sizes, or where unsuitable rock has to be moved in mining, outlet in by-products should be sought. The flint rock in the soft limestone road base mines could be crushed for concrete aggregate and a variety of other uses, outlined in the chapter on flint rock. The concrete aggregate producer usually has an accumulated stock of fines which can find an output as agricultural lime for soil conditioning or as stock feed and chicken grit. The fines and some of the larger aggregate could be used in concrete blocks and tile, and some companies have realized this possibility and operate a concrete products plant in conjunction with their mine and -crusher. Some have found this cement concrete by-product so suc-
84 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
cessful that the large part of their income now comes from it.
Competitive Conditions and Markets
The markets for the Florida crushed stone are entirely local and vary as business conditions and construction varies. Almost the entire output has been used by the State Road Department and by county and city road utility crews in past years, but military construction in Florida has more than doubled the output since 1938. As has been shown, the Florida crushed limestone does not meet rigid specifications for railroad ballast yet it is used because of the low cost of its delivered price, in competition with better out-of-State materials which must include freight charges in their delivery price. The general procedure of the railroad is to use the materials that are located on the line regardless of its suitability, the low cost of the material more than offsetting the increase in maintenance costs. Crushed flint is not used for ballast as its quantity is limited and flint producers prefer to sell their product for specialized uses, thereby bringing a higher price per ton.
The hard variety of limestone and dolomite used for concrete compete with slag from the Birmingham district and the degree of success of such competition increases in ratio to the distance from Birmingham. Thus hard limestone producers are more successful in the Peninsula than in western Florida. However, the potentially successful production of limestone road base course material from Holmes, Washington, and Jackson counties of western Florida again must be emphasized.
Flint, or chert, is a cryptocrystalline form of silica or quartz which occurs in limestone in the form of boulders and as replacements of fossil shells and skeletons. Complete weathering of limestones has left this flint as residual boulders, in some instances, which have been incorporated in younger sands, clays, and gravels. The color of flint is generally some shade of brown or gray, and while the texture of the rock usually is compact a small amount has a high porosity. Crushed flint generally has sharp edges, either splintering or breaking into rounded cusps. The sharp edges increase the need of sand when flint aggregate is used in concrete and
FLORIDA MINERAL INDUSTRY 85
the general opinion is that flint is hard on tires when used in surfacing roads.
For the use of the purchaser:desiring to know the characteristics of Florida flint the following salient features have been determined by the Testing Division of the State Road Department at Gainesville, Florida, over a period of years.29 Due to the extreme variability of this flint these figures should not be used where strict values are necessary. The apparent specific gravity of flint is from 2.25 to 2.34, its dryrodded weight ranges from 72 to 84 pounds per cubic foot, and the per cent absorption, of the aggregate is from 3.0 to 7.0. These figures may be compared with those for crushed limestone and slag in the charts on pages 71, 72, and 75.
Occurrence and Distribution
Flint boulders and layers are common in the soft limestones of Florida, and their removal constitutes a mining difficulty of the road base material industry. No commercial use has been made of these boulders mined from the limestone pits as all of the present production is from boulders of the flint embedded in the sand and clay terrace deposits outcropping' principally in Alachua, Marion, and Sumter counties. These boulders have been reworked into the terrace deposits from their original positions in limestone, and their occurrence is very irregular.
The largest potential area lies in Holmes and Washington counties (Vernon, 1942a, pp. 130-133) where boulders occurring in alluvial deposits are particularly abundant. With present mining conditions a small crusher could be operated here at considerable 'profit, being assured of a substantial deposit. The writer estimates that enough boulders have been accumulated by farmers from their fields to produce 50,000 short tons or approximately 5 years production at present methods. This area is one of the few in Florida which offers possibilities of shallow mining at places where the boulders have been concentrated, and such mining should uncover a large reserve.
The flint producer depends entirely upon buying the raw product from local farmers and woodsmen. The small flint
20 Letter dated Sept. 22, 1939, from H. C. Weathers, Testing Division Engineer.
86 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
boulders are turned up in plowing and accumulate at the field edges. Large boulders are dug out by hand or dynamited, and in some sections a considerable part of the cash income for a season may come from digging these boulders from fields and flatwoods. The boulders are hauled by truck and wagon to the crusher by the farmer who is paid on a tonnage basis. The large boulders are hand broken and the flint is crushed in a jaw-typed crusher, screened to specification, washed, and loaded on either gondolas or trucks.
All of the flint produced in Florida is used locally, and all may be classified as crushed stone. Its use in Florida is as a concrete aggregate or for surfacing small secondary roads and walks. Generally there is a preference for a noncalcareous aggregate where concrete is to be used adjacent to sea water or where resistance to abrasion is a desirable factor, as on concrete steps or walkways.
The fines from flint crushers are overstocked as there is little demand for fine crushed stone aggregate in Florida. Some of this material could be used in the manufacture of abrasives; especially is there a need for abrasive paper and cloth in Florida, and a plant in peninsular Florida should find a ready market.
While the lack of a dependable source of flint would not support the expense of erecting a permanent kiln, the possibility of producing ceramic flint should be investigated. Flint for use in pottery is calcined in a kiln much the same as limestone to produce lime, and then ground to pass a 140 mesh screen. With further pulverizing to pass a 200 or 300 mesh screen the flint can be used for an inert extender in paints and varnishes and as a filler in wood paste.
Nodules of flint are used in tube and pebble mills for grinding various minerals because of its hardness and resistance to abrasion and the lack of iron stain which results with the use of steel balls. Formerly all of this flint was imported, being brought over as ballast, and whether an enterprise making these nodules succeeds in Florida will depend largely upon the price of the material and the distance to the industrial centers where it is used. These nodules could be produced in Florida by roughly crushing the
FLORIDA MINERAL INDUSTRY 87
flint to the size desired and then rounding in abrading machines.
Because of the limited supply and difficult mining conditions the future of the flint industry in Florida is in the specialization of the use of flint, and not in competition with other crushed stone aggregate which can be produced in volume from bedded deposits of known extent at a price so low as to reduce the flint producer's margin of profit below successful competition.
Flint or chalcedony replacements of fossil shells and corals in the Tampa formation and Alum Bluff beds are particularly abundant in the vicinity of Tampa and in the vicinity of White Springs along the Suwannee River. Hookers point and Ballast Point in Hillsborough Bay were formerly the classic collection localities for both replaced shells and corals but war industries and reservations have nearly obliterated these. However, excellent silicified coral heads are abundant along the Hillsborough River in Hillsborough County, and near White Springs in Hamilton County.
These animal shells and coral skeletons were composed of calcium carbonate when the animal secreted them, but this material has been replaced by chalcedony in such a manner that even the finest detail of the original is preserved. Exact replacements of shells by chalcedony are rare and the abundance and preservation of these are unexcelled. They are, therefore, valued for student study sets and collectors items, and good collections are in the possession of the Florida Geological Survey, Tallahassee, Florida, through the generous gift of James G. Manchester (1941) who also maintains a collection, and Ernest Weidhaas of New York City.
Some of these replacements of coral heads are not complete and are in the form of closed cavities or geodes, the insides of which are lined with crystals of quartz or with round, mammillary, and irregular growths of chalcedony. These are likewise valued as collectors items, and lately there has been developed a trade in cutting and polishing the chalcedony, from both geodes and full replacements, as semiprecious stones.
88 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
Production and Market
Flint production in Florida is limited by the availability of the flint which occurs as irreglar boulders in sand and clay deposits, and which is produced only through the accident-of its discovery. Most plants do not work to capacity, partly because of lack of material, and partly due to a low market. This irregularity does not establish confidence in the industry and a strong effort should be made to stabilize the production. The failure of several producers is directly due to the overestimation of their potential supply. Production on a large scale is not feasible and only the small inexpensive plant, where the margin between cost and selling price is high enough to insure a profit, is successful. The low selling price and high transportation costs do not allow competition in distant markets. Instead production should be based upon local and specialized uses. Such a limited market area in itself creates an irregular production in that building projects within the area cause- a large demand that ceases with its completion.
The location of flint crushers have been influenced by the centralization of purchases of concrete aggregate in the vicinity of Ocala and Tampa. While centralization aids the consumer in his purchases, the market area of each producer is thereby decreased, but this centralization offers the possibility of a coalition of the flint production where large contracts can not be supplied by an individual producer.
In the area of present production it is doubtful that the flint market would support another crusher, but there is the possibility of expansion by developing a new market in western Florida with production of the flint boulders in Holmes and Washington counties. Such a market would compete with the Birmingham slag, but a small crusher should be successful in supplying a limited area where transportation costs give it an economic advantage.
Five producers crushed flint in 1941, The Alachua County Stone, Inc., and Coy Thomas in Alachua County, M. M. Thomas Flint Rock Corp., and Standard Rock Co., in Marion County, and the Central Rock Co., in Sumter County. Their combined production, sold as road metal and concrete aggregate, showed a considerable drop in 1941 as compared to
FLORIDA MINERAL INDUSTRY 89
1940. The production of flint in Florida since 1935 is given in table 14.
Table 14-Flint Production Since 1935
1935 .......................................................... 7,500 short tons $ 17,475
1936 .......................................................... 44,490 short tons 93,444
1937 .......................................................... 43,327 short tons 93,328
1938 .......................................................... 43,820 short tons 100,033
1939 .......................................................... 59,290 short tons 130,980
1940 .......................................................... 80,814 short tons 174,709
1941 .......................................................... 48,600 short tons 113,385
Flint is the only mineral product in Florida which dropped in the amount and value of its production in 1941. All other products show gains for this year, and the decrease of flint production came at a time of increased use of concrete and a strong constructional program.
Limestone is the calcareous end member of a calciummagnesium carbonate group of sedimentary rock, the other end being the magnesium portion or dolomite. The series ranges from pure dolomite, which is a mixture of 45.7 per cent MgCO3 and 54.3 per cent CaC03, to pure limestone, or CaCO,. Limestones with less than 5 per cent MgCO3 are called high-calcium limestones, those with less than 40 per cent MgCO3 are dolomitic limestones. The separation of these carbonate rocks is purely arbitrary as all gradations between the extremes exist, and in Florida the rock that is more than 40 per cent MgCO3 is called dolomite. All of this calcareous series may contain impurities of clay and sand, being a sedimentary rock, and as these increase in percentage they qualify the limestone or dolomite, with the predominant impurity making part of the name, as sandy limestone or argillaceous dolomite. Where these impurities approximately equal the per cent of carbonate and the rock is soft and earthy it is called a marl (see pages 119-121). Marls
so Problems of mining, marketing, utilization, and the occurrence of limestone in Florida are discussed in these publications listed in the bibliography: Bowles (1918, 1919, 1923a, 1923b, 1923c, 1942), Bowles and Banks (1936), Bowles and Jensen (1941), Bowles and Myers (1927), Burchard and Emley (1914), Lamar and Willman (1938), Mossom (1925), Myers (1924).
90 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
contain impurities, such as glauconite which contains potash, that make the marl commercially important, although none is mined in Florida. Sometimes the shells and marine organisms are preserved and commonly the limestone is largely composed of these remains, as are the coquina (see pages 111-116) and coraline rocks of Florida.
Florida is underlain by limestone and outcrops are common. The oldest rock outcropping in Florida, the Ocala, is a high-calcium limestone that generally analyzes less than 3 per cent impurities. In fact limestone, dolomite, and marl compose the large part of every formation known in Florida, with the exception of the surficial sand and clay terrace deposits.
Kinds and Origin
Carbonates, though practically insoluble in pure water, are slightly soluble in water containing natural acids, notably humic and carbonic. Thus the waters of all Florida streams, lakes, and adjoining oceans contain small amounts. of dissolved carbonates in the form of bicarbonates. When this material is precipitated as a carbonate by the release of carbon dioxide as a gas it accumulates as deposits of limestone. Carbonate rocks are precipitated by chemical reactions, changes in physical state of the solution such as changes in temperature and pressure, agitation of the water, or by the use of the carbonate in the metabolic processes of organisms whether in their tissues or whether secreted as shells which are deposited as the organisms die.
Such precipitates may form beds of great thickness, which upon consolidation make the rocks of the calcareous series. Some of these still contain the fossil shells indicating their original source, while others contain no evidence of life, its having never been present or having been destroyed in deposition or by later solution and replacement.
Limestone is a sedimentary rock and includes many and varying types, different in origin, structure, texture, composition, and color. However, all have their mineral composition in common, being composed of the mineral calcite (CaCO.), -the mineral dolomite (Ca (Mg,Fe) (CO)2) or a combination of the two. No limestones in Florida are chemically pure carbonates but contain varying percentage of impurities, the more common of which are iron oxides, clay,
FLORIDA MINERAL INDUSTRY 91
silica, alumina, vegetable matter, and sand. The color of limestone is white and that of dolomite pink, when pure. White limestone is common in the Peninsula, but even more common are yellow, brown, and gray colors in both limestone and dolomite. These colors are due to the impurities in the rock, iron oxide making most of the colors, and vegetation causing some of the gray.
Some of the special varieties of limestone occurring in Florida are described below. It must be borne in mind that these varieties grade into each other and some rock may be made of several of the varieties either combined or interbedded.
Coquina (see pages 111-116) is a lagoonal and beach accumulation of whole and broken animal shells and sand that is thin-bedded and has been locally and irregularly indurated. It outcrops on the East Coast from Duval County south to Palm Beach County, and on the West Coast in Pinellas, Manatee, and Sarasota counties. This material is suitable for road base courses, building and ornamental stone, and chicken feed.
Oolitic limestone is a granular limestone composed of small round concretionary grains cemented together. The name oolite was given for the resemblance of the rock to fish roe and means egg-like. The grains are thought to have been formed by the successive accretion of calcium carbonate about a nucleus. Many students believe some oolites are precipitated, and Thorp (1939, p. 292.) reported that artificial oolites have been precipitated by passing air free of carbon dioxide through sea water. The Miami oolitic limestone outcrops in Dade, Broward, and Monroe counties and is the source for a large part of the commercial limestone of the southern Peninsula.
Marl (see pages 119-121) is a loose, earthy mixture of calcium-magnesium carbonates and clay in approximately equal proportions. It is being deposited from Florida sea waters and is present in many of the older formations.
Dolomite or magnesium limestone (see pages 106-111) in Florida consists of a mixture of calcium and magnesium carbonates in a brown, porous, friable to hard, crystalline rock. The magnesium carbonate content averages better
92 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
than 36 per cent, and the material is used almost exclusively as a soil conditioner, with only small amounts of the harder crystalline dolomite being used as concrete aggregate. Commercial deposits outcrop intermittently on the western Peninsula coast between Taylor and Sarasota counties.
Travertine is often called calcareous tufa and is deposited by water along stream and spring courses. There is a gray to brown, laminated, hard dense rock that occurs in the dolomitic limestone of Florida which has been advertised as travertine. The upper portion of this limestone has been secondarily hardened and changed through partial crystallization, and it has some of the structural appearances of travertine and will take a polish. It has been used as polished ornamental and building blocks, and is present along the west coast of Florida from Pasco County south to Sarasota County.
Cave limestone deposits (figure 14) are of commercial interest only where admission is charged for entrance to the cave. Stalactites are the icicle-shaped forms hanging from the roof of caverns, stalagmites are similar forms rising from the floor, and columns are formed where the two join. Cave
deposits are formed by calcium carbonates being deposited
Figure 14. Limestone Formation in the Florida Caverns State Park, Marianna, Jackson County.
FLORIDA MINERAL INDUSTRY 93
from dripping water in caverns. Calcium carbonate charged water is partially evaporated by air currents in caves, and the pressure is less than in the rock from which it seeps, so that carbon dioxide is given off as a gas. Both decreased pressure and loss of carbon dioxide tend to precipitate calcium carbonate, some of which is deposited on the roof and some upon the floor from fallen drops of water. The chemical reaction resulting in the precipitation of calcium carbonate is as follows:
Ca(HCO3)2 > CO2 + H20 + CaCO3
Calcium bicarbonate Carbon dioxide Water Calcium carbonate (dissolved in water)
Loose, granular limestone is best known under the trade name "Ocala Lime Rock" and includes limestone of several geologic formations, the Ocala limestone, the Marianna limestone, and the Suwannee limestone. Generally it is high in calcium carbonate and will analyze as much as 99 per cent CaCO3. Its commercial development centers in Alachua, Marion, and Levy counties with a potential area of development in Washington, Holmes, and Jackson counties. It is known as a high-calcium limestone as compared with the dolomitic or magnesium limestones and is principally used for the manufacture of lime and for road base courses.
Crystalline limestone is largely derived from the Tampa formation and is hard brown limestone, which may have enough clay impurity to be known as argillaceous limestone, or enough sand or silica to be an arenaceous or siliceous limestone. The hard rock character is probably due to recrystallization of the calcite after its deposition so that the material was firmly indurated. The production is centered in Hernando County near Brooksville, and it has the trade name of "Brooksville stone." A rock, similar in texture but approaching a dolomite in composition, outcrops in Pasco, Manatee, and Sarasota counties. Both rocks are largely used as concrete aggregate.
Of the several types of limestones in the preceding discussion this chapter is concerned with oolitic, loose granular, and crystalline limestone, the others are either noncommercial or have been discussed on other pages as noted. All of Florida is underlain by limestone, shell marl, and dolomite,
94 FLORIDA GEOLOGICAL SURVEY-BULLETIN TWENTY-FOUR
but these deposits are covered, for the most part, by younger terrace sand and clay deposits which either prevent mining or must be removed as overburden in the process of mining. There are limestone production centers in Alachua, Brevard, Citrus, Dade, Hernando, Levy, and Marion counties and a potential production center in Washington and Jackson counties. The areas of actual and possible production are shown on figure 2. In general, western Florida, the midPeninsula, and the East Coast have outcrops of limestone suitable for road base course material, while Hernando County, Dade and Brevard counties to a less extent, produces concrete aggregate and railroad ballast.
The rock of all the keys of Florida is limestone and most of the beaches of the Peninsula are formed of coral and shell sand. The key limestones are porous and white and fracture with difficulty, having a spongy tenacity. This rock is believed to be of the same age as the Miami oolite.
All limestone is mined from open pits and either the dry or wet process may be used. The quarrying method used depends upon the use to which the rock is to be put, and upon the specifications made for that use. Where a high purity is desired as in lime manufacture, road base course material, and in chemical and refining uses, care must be taken that all overburden and impurities are kept at a minimum, but impurities are of less importance where the use is of a physical nature.
Whatever the use, there is usually an overburden present, the removal of which increases both the mining costs and the value of the rock. The cost of removal of the overburden decreases in ratio to its thinness, the depth of mining, and to the increase in value of the final product. Where high purity is desired the overburden should be kept stripped well back from the face of the quarry as the sand and clay topping the limestone wash into the pit, over the pit face as well as the broken stone on the pit floor, thereby contaminating and discoloring the stone. This is especially bad where the limestone is to be burned for lime and a high-quality, white lime is desired.
The overburden is removed almost universally in Florida by piling the material back from the quarry face by means
FLORIDA MINERAL INDUSTRY 95
of a dragline excavator, and occasionally by a bulldozer tractor. Where an old pit adjoins the quarry the overburden is piled into it unless it is being used as a water sump, otherwise it is piled over waste land. In areas where the overburden is sand it is sold as fill sand or washed and sold for aggregate. This is especially true where good structural sand is scarce and the demand is great, as in the vicinity of Miami. Where the product is to be concrete aggregate an occasional producer mines the overburden and rock together and eliminates the overburden in washing and screening the aggregate. Small producers of building blocks and agricultural limestone remove the overburden by hand, using wheelbarrows and shovels.
After removal of overburden, care should be taken to clean out all clay filled fissures, caves and other solution ]its to prevent this material from washing and falling into the pit after the face is shattered in mining. This cavity filling is very objectionable because the irregular occurrence forces its removal by hand labor and results in a high quarry waste and increased production costs. These caves and openings, originally formed by circulating water and later filled with sediment, are very irregular in plan, and the quarryman can not avoid them but must take them as they come. Where the product is a high-calcium limestone for use as road base courses, up to 3 per cent of this material can be absorbed, but in lime manufacture a high content of this material in the quarry forces the producer to hand pick the rock.
It is generally preferable and more economical to work as thick a bed of limestone as possible, see figure 12. In Florida where the limestone is very homogeneous a high quarry face can be maintained and the depth of the quarry is controlled almost entirely by the permanent ground-water table, the producer mining to this table and then following the bed horizontally. The efficiency of some quarries could be increased by changing from a dry to a wet process of mining and using dredges where the rock extends below ground water.
Where crushed stone is to be produced, the face of the quarry is usually shattered by dynamite placed in holes drilled by a churn drill. After the material has been shot, however, the handling differs with the company and with
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quarry conditions. The material is commonly loaded by dragline excavator or mechanical shovel into cable-pulled tramcars (figure 15) or dump trucks or a combination of the two, (figure 16) in which the material is carried to the processing plant. Some companies pile the shattered rock with a bulldozer tractor before loading, thus keeping the necessity of moving the heavy dragline excavator or shovel and the loading tracks at a minimum. In the Miami area where some of the quarry bottoms extend below the ground water surface the rock is mined from dredges. In one such quarry a mechanical shovel loads into a sump on the barge from which the mined material is pumped to the crusher. In another, a rotary disk is mounted on the intake of a suction pump which can be elevated to the desired height, where the disk cuts the rock and the pump forces the cuttings to the plant on the shore. Maule Industries, Incorporated, at Ojus have one pit where both shovel and the processing plant are mounted on barges, the material thus being mined, crushed, screened, and loaded on barges for transportation to the stock pile. This company also is operating a recovery barge in the same pit by pumping from refuse dumps into settling vats on the barge, where the fines are washed over the top, and the coarser particles are pulled out by cable drags. The Mills Rock Company of Miami, has found a rotary ditchdigger serviceable in digging the soft Miami oolite. This method has the advantage of digging and loading the rock onto trucks in one operation.
For the manufacture of lime, Florida limestone is hand picked, not only for a high chemical purity, but for size of pieces as well. In mining, large pieces are generally broken and then loaded by and into dump trucks for transportation to the kiln. Pieces too small for mining are sold for road base courses and soil conditioning. Limestone for use in cement is mined the same as that for use in road bases, but less trouble is taken to clean out clay filled cavities as this material is objectionable only insofar as the clay affects the uniformity of the cement mix. The limestone with its impurities is loaded directly into gondola cars for transportation to Tampa where it is mixed with more clay in the manufacturing of cement (see pages 54-57).
Figure 15. Cable pulled dump car of the type commonly used in the limestone pits of Florida.
Photo by the Cummer Lime and Manufacturing Company in their
limestone pit at Kendrick, Marion County.
Figure 16. The pit of The McDonald Corporation near Brooksville, Hernando County, in the N SW 4, Sec. 19, T22S, R20E. This pit is greatly extended and the limestone is loaded into trucks by shovels and reloaded to cable pulled dump cars for final transit. The truck dump ramp is shown in the upper center.
Photo by the company.
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Limestone for road base courses is used as it comes from the mines, or is crushed to sizes ranging uniformly between the fine and coarse particles and then applied. Hard crystalline limestone, as the Brooksville stone and some layers in the Miami oolite, which are to be used as aggregate are crushed in large jaw type crushers, washed, screened, and stored in stock piles for drying. The Camp Concrete Rock Company and the McDonald Corporation load from their stock piles by means of a power operated belt running in a tunnel beneath the stock piles. Individual sizes are loaded onto the belt through trap doors opening into the tunnel.
Blocks, locally called chimney rock, are cut from the Marianna limestone in Jackson County by numerous individuals using crosscut saws (figure 17). Only the Limestone and Lumber Company of Marianna uses a power-driven saw, the mechanism of which is shown in figure 18. The blocks, as cut, are soft and friable but with weathering they caseharden and are very serviceable for construction of small buildings and homes. However, they have a low crushing strength and are not readily transported. The white appearance of stone makes an attractive design when used with red brick, and many good examples occur in the vicinity of Cottondale and Marianna, Jackson County. Limestone building blocks have never become an important industry in Florida because of excessive quarry waste, due to the variable character of the rock, making it difficult to produce a uniform product in competition with other less expensive building products. The Marianna limestone is the most extensively used rock because of its soft, dense character and ease of mining.
Three companies, Mizner Products, Inc., Keystone Art Company, and John B. Orr, Inc., mine the Key Largo limestone on Windleys Key. The method of mining consists of cutting the stone with compressed air and sand or by channeling machines and outlining a block weighing approximately 10 tons and which is approximately 4 feet thick and 6 feet square. This block is jerked out and loaded onto trucks by means of a guy derrick and transported to Miami and West Palm Beach, where it is shaped into ornamental, art, and dimensional stones. The stone is very porous and
Figure 17. Building block quarry of Richard Hartsfield in the Marianna limestone, in NW1!4, Sec. 30, T5S, R9W, 2% miles north of the junction of Florida Highway 90 with Florida Highway 1, Jackson County. Method of cutting slabs and blocks by crosscut saws is shown.
Figure 18. Building blocks sawed from the Marianna limestone at Marianna, Jackson County, by a power-driven disk, shown in left foreground. This pit is operated by the Limestone and Lumber Company of Marianna and is in the NW%4 SEI, Sec. 3, T4N, R10W, just north of Florida Road 1. The limestone is white, soft, granular, and massive.
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absorptive so that it is easily colored, and where density is desired it is impregnated with cement. The stone is polished both in its natural state and after filling with cement. In the natural state it resembles a tufa. Stucco and false marble, both colored and natural, are prepared from a small aggregate developed in shaping the large stone. This fine aggregate was formerly discarded.
Lime is calcium oxide (CaO) that has been formed by firing limestone (CaCO3) to a temperature at which most of its carbon dioxide (CO2) is removed. Only high-calcium lime is manufactuerd in Florida, the limestone from which it is manufactured analyzing close to 99 per cent calcium carbonate. Refractory limes or dolomitic limes are manufactured in the United States, and Florida has deposits of dolomitic limestone which could be used, but at the present there is no production.
All Florida lime kilns are vertical shaft, continuous feed type kilns, usually constructed of brick, with open hoppers at the top and a fire box, which is fired by wood, at the bottom. The height of the kiln is limited, and is usually less than 20 feet, because the Florida limestone is soft and friable and tends to compact and clog the kilns at greater heights. The kilns are kept filled, and this requires a constant supply of limestone from the quarry. For this reason a stock pile is usually maintained to cover delays in quarrying. Limestone lumps between 4 and 8 inches in diameter are carried up a small ramp in cable cars and dumped into the kilns. The kilns are fired to approximately 1700 degrees Fahrenheit and are drawn once each 8 hours. In general, the more porous, granular structure of the Ocala limestone requires both larger pieces for support in the kiln while firing, and higher temperatures for release of its CO2, in comparison with the Miami oolitic limestone. If the pressure of the carbon dioxide is allowed to build up in the kiln during firing, recarbonation may result, so the prompt removal of the gas is necessary for complete calcination. This is accomplished in most kilns by forced drafts through open chimneys. No attempt is made to utilize the carbon dioxide produced in the firing of limestone in Florida, either in the manufacture of