Guide to rocks and minerals of Florida ( FGS : Special Publication 8 rev. )

Florida Geological Survey
STATE OF FLORIDA Library
DEPARTMENT OF NATURAL ftGSORfBiennessee Street
Elton J. Gissendanner, ExecuefE,~~I Florida 32304

DIVISION OF RESOURCE MANAGEMENT
Art Wilde, Director

BUREAU OF GEOLOGY
FLORIDA GEOLOGICAL SURVEY
Walter Schmidt, Chief

Tallahassee
1987

LETTER OF TRANSMITTAL

Florida Bureau of Geology
903 West Tennessee Street
Tallahassee, Florida 32304

1987

Governor Bob Martinez, Chairman
Florida Department of Natural Resources
Tallahassee, Florida 32301

Dear Governor Martinez:

The Bureau of Geology, Division of Resource Management, Depart-
ment of Natural Resources, is republishing its Special Publication No. 8,
"Guide to Rocks and Minerals of Florida". This revised edition presents
geological information regarding part of Florida's natural resources.
This publication will be useful as an educational resource for scientists,
teachers, public officials, tourists, and the general public.

Sincerely,

Walter Schmidt, Chief
Bureau of Geology

Printed for the
Florida Geological Survey

Tallahassee
1987

ISSN No. 0085-0640

iv

STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Elton J. Gissendanner, Executive Director

DIVISION OF RESOURCE MANAGEMENT
Art Wilde, Director

BUREAU OF GEOLOGY
FLORIDA GEOLOGICAL SURVEY
Walter Schmidt, Chief

Tallahassee
1987

DEPARTMENT
OF
NATURAL RESOURCES

BOB MARTINEZ
Governor

GEORGE FIRESTONE
Secretary of State

BILL GUNTER
State Treasurer

BETTY CASTOR
Commissioner of Education

BOB BUTTERWORTH
Attorney General

GERALD LEWIS
State Comptroller

DOYLE CONNER
Commissioner of Agriculture

ELTON J. GISSENDANNER
Executive Director

TABLE OF CONTENTS
Page

Collecting rock and minerals ............................... 1
Equipment .............................................. 1

Rocks.................................................... 2
Igneous rocks ......................................... 2
Metamorphic Rocks ............................. ............... 3
Sedimentary rocks.......... .. ............... .... ........ 3
Clastics ........... ......................... ......... 3
Sandstone.................................... ... 3
Clays .............................................. 4
Common clay ................. ................... 4
Fuller's earth ....... .............................. 6
Montmorillonite ................................. 6
Kaolin................................... .... 6
Chemical precipitates ........................ ..... 6
Limestone ............................................ 8
Dolomite .................................... ......... 12
Phosphate.......................................... 12
Organic Accumulations ............................. 12

Other rocks, minerals, and related materials.................. 15
Diatomaceous earth .................................... 15
Fossils .................... .......... ... .............. 15

Distribution of rocks in FLorida.............................. 20

Minerals............................... ..................... 20
Physical properties ..................... ............ 20-22

Mineral descriptions ............. .......... .................. 23
Anhydrite ............................................ 25
Aragonite ............................................... 26
Calcite ..................... .......... ............... 26
Dolomite ............................................. 30
Gypsum .................................. ....... ........ 30
Heavy Minerals ............... ............. ........... 31
Lim onite ............ .................................... 34
M ica ..... ............................................. 36
Pyrite ................................................... 36
Quartz ........... ... ...... ............................. 37
Vivianite .............................................. 39
Wavellite ...................................... .. 41

Selected References .................................. ..... 44

Selected Definitions ............................. ............... 46

Appendix: Maps showing distribution of rocks in Florida........ 48

FIGURES

1 Common clay

2 Fuller's earth

3 Fossil corals

4 Coquina

5 Ooitic limestone

6 Hard rock phosphate

7 Peat

8 Diatoms

9 Petrified Wood

10 Fossil shark teeth

11 Fossil sea shells

12 Agatized coral

13 The crystal form of quartz

14 Anhydrite

15 Calcite crystals

16 Massive rhombohedral form of calcite

17 Stalactites, variety of calcite

18 Heavy minerals

19 Limonite

20 Chert

21 Vivianite

22 Vivianite

23 Wavellite
TABLE
Mineral Identification Table

FOREWORD

This completely revised and illustrated edition is the result of continu-
ing efforts of the staff of the Florida Geological Survey in exploring,
studying, and collecting the rocks and minerals of the State. Since the
first edition in 1961, the Survey staff has discovered and acquired many
new, splendid, and sometimes rare, specimens of native rocks and
minerals. Most of the specimens shown and many more can be seen at
the Survey offices, located on the campus of Florida State University,
Tallahassee.

GUIDE TO
ROCKS AND MINERALS OF FLORIDA

by
Ed Lane

COLLECTING ROCKS AND MINERALS
This book has been written to provide basic geological knowledge of
rocks and minerals that occur in Florida. This knowledge will serve as a
guide in the search for rocks and minerals, and as a basis for a better
appreciation of Florida's natural environment.
Collecting rocks and minerals can be a rewarding hobby from an
educational standpoint and from the satisfaction of having a personal
collection of nature's beautiful creations. Many rocks and mineral spec-
imens can be jewel-like, in every esthetic sense, especially after clean-
ing, cutting, or polishing, and mounting for display.
As with any hobby, much of the pleasure of collecting is in the
hunting-and-finding, and the discovery of particularly fine specimens.
However, the observance of a few common-sense rules can add to the
pleasure of the search. The pursuit of collecting can lead one to quar-
ries, road cuts, ditch banks, spoil piles, and similar locations-all poten-
tially dangerous. The collector must always remember the two "P's":
Permission and Personal safety. Remember, anywhere you go, the
property belongs to someone else, and you must obtain prior permis-
sion before trespassing. Quarries and construction sites are especially
hazardous due to falling rocks, blasting, and heavy equipment, and it is
illegal to enter without written permission orwithout an escort. For the
more serious collector, or for someone wishing to pursue more techni-
cal aspects of geology and mineralogy, a list of references has been
provided.

EQUIPMENT

The collecting and identification of rocks and minerals requires only
readily obtainable and inexpensive equipment. These basic supplies, in
conjunction with easily applied tests, will enable one to identify the
common rocks and minerals of Florida. A rockhound'ss" kit should
include the following items. Don't try to carry too much-but don't
forget water and lunch.
SHOES: A pair of sturdy, ankle-high shoes or "boondockers" will pro-
vide support for hiking to outcrops, as well as protection from sharp
rocks.
FIELD BAG: A knapsack, preferably with a shoulder strap, or a back-
pack, to carry equipment and specimens.
WRAPPING MATERIAL: Newspapers are good. A few turns of news-
paper around each specimen will protect it against damage from other
specimens and equipment in your field bag.

NOTEBOOK AND PENCIL: For recording field notes and labelling
specimens.
HAMMER: A geologist's or bricklayers hammer is a necessity. Be care-
ful of flying splinters when hammering on rocks; safety glasses or
goggles are recommended.
CHISEL: Some rocks and minerals occur as hard, massive bodies, and a
chisel can help to obtain more easily manageable specimens. Also, it is
less destructive than a hammer when dealing with fragile specimens,
such as crystals.
MAGNIFYING GLASS: Small, folding types, 5xto 10x, are best. A length
of string around the neck or belt loop will keep it handy.
GLOVES: Cotton or leather work gloves afford protection when dealing
with sharp-edged specimens.
ACID: Hydrochloric acid (10% concentration) is a standard reagent to
test for carbonate rocks and minerals, which are abundant in Florida. It
should be kept in a plastic container, preferably with an eyedropper top.
The test procedure is to place a small drop of acid on a clean surface of
the specimen and observe whether or not it effervesces. Be careful, the
acid will burn your skin.
STREAK PLATE: A small pieceof white, unglazed porcelain (about 2" x
2"); the back of glazed tile can be used. The specimen is rubbed against
the plate and the color of the streak is noted.
OTHER ITEMS: You may want to include a pocket knife, camera, com-
pass, small plastic vials for protecting delicate specimens such as crys-
tals or fossils, and other identification guides to rocks and minerals.

ROCKS

Rocks are aggregates of minerals that comprise the earth's crust. The
earth's crust is not homogeneous. Its surface and interior are made of an
almost infinite variety of rocks, each having its own distinctive charac-
teristics, such as color, density, porosity, and hardness. The great range
in appearance and physical properties that they exhibit depends on the
kinds and amounts of minerals they contain, and upon the ways in which
their mineral grains are held together. Geologists use a genetic classifi-
cation of rocks, according to their origin: igneous, metamorphic, or
sedimentary.

IGNEOUS ROCKS

Igneous rocks (from the Latin word ignis, meaning fire) are formed
deep within the earth's molten interior. Sometimes they are brought to
the surface during volcanic eruptions; these are called extrusives.
Examples of extrusive rocks are basalts, obsidian (volcanic glass), and
pumice (the porous, bubble-filled lava that floats on water). Igneous
rocks that are migrating upward from the earth's interior sometimes do
not reach the surface to be extruded. These rocks are classified as
intrusives or plutonic rocks. They may be squeezed between layers of

rocks, forming tabular sills; they may cut across or through layers of
rocks at angles, forming dikes; or they may form large bodies of rocks at
depth when the magma becomes consolidated. The best-known exam-
ples of intrusive igneous rocks are granites. There are no igneous rocks
exposed at the surface in Florida, although some have been found at
depths of several thousand or more feet in wells throughout the state
(Lloyd, 1985).
METAMORPHIC ROCKS

Metamorphic rocks (from the Greek words meta morphos for
"changed form") form deep beneath the surface of the earth by the
transformation of rocks, such as igneous or sedimentary rocks, as well
as other metamorphic rocks, by the heat, pressure, and chemically
active fluids to which they are subjected after burial in the earth. Exam-
pies of metamorphic rocks are slate (metamorphosed shale), marble
(metamorphosed limestone), and quartzite (metamorphosed quartz
sandstone). There are no metamorphic rocks exposed at the surface in
Florida, although some have been encountered at depths of several
thousand feet or more in wells (Lloyd, 1985).

SEDIMENTARY ROCKS

All rocks exposed in Florida are of sedimentary origin. Sedimentary
rocks are those that were formed at the earth's surface under normal
temperatures and pressures. They form either by accumulation and
cementation of fragments of rocks, minerals, the remains of plants or
animals, or as precipitates from sea water, surface water, or ground-
water. Sedimentary rocks often have a layered structure known as
bedding or stratification. Sedimentary rocks are classified into three
groups: clastics, chemical precipitates, and organic accumulations
(Hamblin and Howard, 1965).
CLASTIC sedimentary rocks are the result of the weathering, break-
ing down, and erosion of older parent rocks. Physical and chemical
weathering breaks down parent rocks into smaller fragments, which are
transported some distance from their source and deposited. These
deposits may then become compacted and cemented into solid rock.
Sandstone, for example, is the cemented counterpart of loose sand
deposits. Other representative plastic deposits are, in a descending
range of particle size: gravels, sands, silts, and clays.
Clastic deposits of sands and clays blanket most of Florida. The
ultimate source of Florida's clastics is from the Appalachian Mountains
to the north in Alabama and Georgia. Millions of years of weathering
and erosion wore down the mountains. Streams carried the debris south
to Florida, where subsequently stream and shoreline processes created
the present landforms.
Sandstone

Sandstone is a sedimentary rock composed of grains of quartz sand

cemented together. In Florida the most common cements are calcite or
silica, and sometimes iron oxides. Since most Florida quartz sand is
white or colorless, a sandstone's color is due to the type and amount of
cement. Colors of Florida sandstones range from white through various
tints of yellow, orange, red, or brown. Sandstones occur throughout the
State and may be associated with sands, clays, or carbonates. It may be
found as small nodules, as thin discontinuous strata, or in beds several
feet thick.

Clays

The term clay can have three implications: (1) it may refer to a natural
material that has plastic properties when wet, (2) it may referto particles
of very fine size, or (3) it can mean a composition of crystalline frag-
ments of minerals that are usually hydrous aluminum or magnesium
silicates. The term implies nothing regarding origin but is based on
properties, texture, or composition.
Clays form as the result of chemical or mechanical weathering and
erosion of parent rocks and minerals. Clay-sized particles are less than
0.004 mm in length. Much of the clay in Florida was deposited as mud in
streams, river deltas, lakes or sea beds. The predominant Florida clay
minerals include kaolinite, montmorillonite, illite, and palygorskite
(also called attapulgite). These usually have wide ranges in chemical
composition because of the possible inclusion of many impurities, such
as iron oxides, carbonates, mica, potassium, sodium, feldspar, and
others.
Clays mined in Florida at present are classified as: common clays,
fuller's earth, and kaolin. Except for kaolin, these clays are generally
composed of varying amounts of the minerals montmorillonite, illite,
paiygorskite, or kaolinite.

Common Clays

Common clays are composed of varying amounts of clay minerals,
quartz sand, calcite, iron oxides, organic materials, and other impuri-
ties. They can exhibit wide ranges of plasticity and color, depending on
mineralogy, amounts of impurities, and degree of weathering (Figure
1).
Common clays occur in most counties north of Lake Okeechobee
(Bishop and Dee, 1961). Escambia and Santa Rosa counties, and the St.
Johns River valley from Jacksonville to Lake George have large depos-
its of common clay. Smaller deposits of common clay occur in many of
the northern and panhandle counties.
These types of clays are used to manufacture bricks and light-weight
aggregate (construction materials), and as additives to Portland cement
and to sand for roads.

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Figure 1. Common clay from the Miccosukee Formation, northeastern
panhandle of Florida. The dark reddish-pink streaks and mottles in a
lighter pink matrix of these specimens are typical of the Miccosukee
Formation. Outcrops often show mottles of white kaolin clay. Florida
Geological Survey collection.

Fuller's Earth

Fuller's earth is an old colloquial name that refers to the ability of
certain clays to "full" or absorb oils from wools or textiles; the name has
no implication to mineralogy or composition. Florida's fuller's earth
clays are composed of the minerals palygorskite (attapulgite) and/or
varieties of montmorillonite, and sometimes illite. They are bluetogray
to light gray-green in color, and waxy and plastic (Figure 2).
Sizeable near-surface deposits occur in Gadsden, Marion, Pinellas,
and Manatee counties; small deposits occur in several other counties.
Active mining is done only in Gadsden and Marion counties, but fuller's
earth has been mined in the past in Manatee County (Bishop and Dee,
1961). Florida ranked second nationally in 1984 in output of fuller's
earth (U.S. Bureau of Mines, 1984).
High grade fuller's earth is composed of almost pure palygorskite and
is useful for its ability to gel, or coagulate. These gelling characteristics
are important in drilling mud, liquid fertilizer suspenders, paint thicken-
ers, and some medical drugs. Lower grades of fuller's earth, which are
mixtures of palygorskite, illite, and montmorillonite, are used in various
products, such as petroleum, vegetable and mineral oil absorbents, pet
litter, insecticides and fungicide carriers, and as additives in soaps,
paints, polishes, and some plastics.

Montmorillonite

Montmorillonite deserves special mention because of its outstanding
characteristic of "swelling or bloating" when wetted. This ability to
absorb large quantities of water and to expand considerably in volume
can cause severe problems and damage to man-made structures that
are built over deposits of it. This is one of the main reasons that building
codes require soil test borings for building foundations. As an additive
to certain types of driling muds, this property is put to beneficial use,
where the object is to plug the voids in porous rocks.

Kaolin

Kaolin is composed of the clay mineral kaolinite. Florida kaolin is
generally light-colored, soft, lightweight, and often chalk-like. It is por-
ous and willstick to the tongue, and will crumble rapidly when placed in
water.
There is only one active kaolin mine in Florida, in western Putnam
County, but large deposits also occur from southern Clay to northern
Highlands counties (Campbell, 1986). In the panhandle, a narrow belt of
deposits extends from Jackson County into Santa Rosa County.
High grade clay, called china clay, is used to manufacture china and
porcelain, and ceramics. Other uses include fillers in paints, paper,
soaps, tooth powders, crayons, textiles, and other products.
CHEMICAL PRECIPITATES are formed from sea water, ground-
water, or other solutions on the earth's surface. Representative Florida

Figure 2. Fuller's earth, Gadsden County, from the Hawthorn Group,
lower Miocene. This specimen has dried out and split apart along
laminated bedding planes. Florida Geological Survey Collection.

rocks are anhydrite and gypsum (discussed in the Mineral Identification
section), limestones (see below), and some types of dolomites (see
Mineral identification section).

Limestone

A discussion of limestone is important because it occurs throughout
Florida, and because it figures so prominently in the natural and geolog-
ical histories of the State. Limestone production is a major industry in
Florida, with most of it being used to make cement and as crushed rock
for road surfacing. Other uses include rip-rap, soil conditioner, lime
production, building stone, and in the chemical industry.
Mineralogically, limestones are sedimentary rocks that contain more
than 50 percent of the mineral calcite (calcium carbonate, CaCO3).
Impurities may range up to 50 percent. Common impurities found in
Florida limestones are chert, quartz sand, clay, and iron oxides.
Most limestone in Florida is biogenic in origin. A great many species
of marine and fresh water animals and plants secrete calcium carbonate
as part of their life processes, forming shells and other internal and
external support structures. When an organism dies its calcitic remains
are incorporated into the sediments of the body of water. Over time
these biogenic remains may become cemented together, forming limes-
tone; coquina is an example. In Florida, as in many places in the world,
biogenic limestones constitute the major portions of layers of rock that
are hundreds or thousands-of-feet thick.
Chemical processes also contribute smaller quantities of calcite to
Florida sediments. Some is precipitated as crystals and some as crypto-
crystalline or massive varieties, such as travertine (cave deposits). Three
main varieties of limestone occur in Florida: fossiliferous limestone,
coquina, and oolitic limestone.
Fossiliferous limestone (Figure 3) may contain abundant fossils of
mollusks, echinoids, corals, Foraminifera, and other organisms. These
fossils are usually cemented with calcite, forming a rock. In general,
most Florida limestones are fossiliferous, although there may be local
zones that are unfossiliferous. Some fossiliferous limestones represent
ancient reef environments, such as the Key Largo Limestone, which
forms the upper Florida Keys.
Coquina (Figure 4) is a type of limestone composed of cemented
marine shell fragments. It sometimes contains much quartz sand. The
Anastasia Formation is predominantly coquina, extending along the
Atlantic coast from south of Jacksonville to Palm Beach County.
Oolitic limestone (Figure 5) is made of small, spherical calcite or
aragonite grains with concentric or radial structured "ooliths." The
ooliths range up to 2.0 mm in diameter and consist of calcitic layers
precipitated around foreign particles, such as sand grains, shell frag-
ments, fossils, or other matter. Calcite is the cementing agent. The
Miami Limestone, in southernmost Florida and the lower Florida Keys,
provides good exposures.

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Figure 3. Three of the many species of fossil corals that make up much
of the Key Largo Limestone, which comprises the upper Florida Keys.
Although they are usually fragmented, it is possible to find intact speci-
mens In outcrops or on spoil piles. Lower left: rose coral (Manicina sp.);
upper left: common brain coral (Diploria sp.); right: porous coral (Por-
ites sp.). Author's collection.

2 c

Figure 4. This coquina occurs along theAtlantic coast as the Anastasia
Formation. Fresh exposures may be weakly cemented and friable, but it
generally becomes "casehardened" and durable after exposure to the
elements. The old Spanish fort, Castillo de San Marcos in St. Augustine,
is made of locally quarried coquina. Florida Geological Survey
Collection.

Figure 5. Oolitic limestone from the Miami Limestone geological for-
mation, Big Pine Key, Monroe County. This whiteto light cream colored
limestone is composed almost entirely of tiny, spherical ooliths, each
less than 1.0 mm in diameter. Florida Geological Survey Collection.

Dolomite

Dolomite refers both to a type of sedimentary carbonate rock and to a
mineral (see mineral description). Most dolomite rock in Florida occurs
as massive, dense units associated with limestones. Color varies from
light to dark grays and browns. Because dolomite's chemical structure
(CaMg(CO,3)) is similar to calcium carbonate's (CaCO,), it can be used
for many of the same purposes as limestone. It cannot be used to make
cement because the magnesium (mg) interferes with the cement's set-
ting properties. Most of the dolomite produced in Florida is used as
agricultural lime and some is used for road surfacing. Small amounts
have been used as decorative building stone.

Phosphate

Phosphate, also called phosphorite, refers to deposits of phos-
phorus-bearing minerals. The principal mineral is francolite, calcium
fluorapatite CasF(PO4)3, although other elements can substitute for
calcium and fluorine to create a variety of phosphate minerals. Collo-
phane is the massive, cryptocrystalline variety that constitutes the bulk
of phosphate deposits and fossil bones; it usually contains some cal-
cium carbonates as impurities (Figure 6).
Scattered deposits are found southward from the Georgia-Florida
border in Hamilton and Columbia counties to Manatee and DeSoto
counties. The types of deposits are known as "hara rock," "land peb-
ble," and "river pebble." Hard rock deposits occur in the west-central
peninsula, consisting of a conglomeration of pebbles and boulders with
sands and clays. Hardrock phosphate occurs primarily as a replace-
ment mineral replacing limestone.
The main land pebble deposits occur east of Tampa in Hillsborough,
Hardee, Manatee, and Polk counties, consisting of hard, phosphatic
pebbles and sands in a matrix of quartz sands and clays; fossil teeth and
bones of marine and land animals are commonly found. Most of Flori-
da's phosphate rock is produced from these deposits.
River pebble deposits occur along or near stream channels. The
Peace River in Polk, Hardee, and DeSoto counties is a good example,
although mining ceased there several decades ago.
The raw rock is converted into a variety of finished products, mostly
fertilizers, with lesser amounts of phosphoric acid and animal feed
supplements.
Florida has enormous phosphorite deposits, with enough reserves to
continue the current rate of mining for more than 250 years. In 1983,
Florida and North Carolina accounted for 87 percent of the total U.S.
and 27 percent of the total world phosphate production (Campbell,
1986).
ORGANIC ACCUMULATIONS that occur in Florida are peat and lig-
nite, which are dark brown deposits produced by the partial decomposi-
tion of mosses, grasses, trees, and other plants that grow in wet, marshy
places (Figure 7). The composition of Florida peats vary from a fibrous,

Figure 6. Hard rock phosphate, from a mine in northeastern Citrus
County. This cut and polished specimen shows multi-hued brown band-
ing. Thomas M. Scott collection.

Figure 7. Fibrous, matted peat from the Everglades. Florida Geological
Survey Collection.

matted, turf-like material to a mud-like plastic ooze or slime. The most
extensive deposits occur in the Everglades, extending from Lake Okee-
chobee south to Florida Bay. Other deposits occur south of Lake Istok-
poga, and in the upper St. Johns River Valley, in Brevard and Indian
River counties. Many smaller peat deposits occur throughout the State
(Davis, 1946; Bond et, al., 1986).

OTHER ROCKS, MINERALS, AND RELATED MATERIALS

This section includes those types of rocks and mineral-related spec-
imens that occur in Florida, but which do not fit into the preceding
categories. Included are economic "minerals," fossils, and rock-forms
of minerals.

DIATOMACEOUS EARTH

Diatomaceous earth refers to deposits made almost entirely of the
siliceous (quartz) skeletons (frustule) of microscopic, one-celled plants
called diatoms. The great diversity and beauty of diatoms' open, silicic
skeletons can only be seen with a powerful microscope (Figure 8).
Usually associated with peat, diatomaceous earths are sometimes diffi-
cult to distinguish from the peat and organic mucks, although diatom
deposits may form thin, white or light-colored bands within the darker
peats (Davis, 1946). Thicker, consolidated beds resemble chalk or clay.
The diatoms' open, lattice-work skeletons make ideal filters for some
industrial and chemical processes. Diatomaceous earth has not been
commercially produced in Florida since 1945 (Davis, 1946).

FOSSILS

Fossils are the remains of plants or animals of the past that have been
preserved in the earth's crust. Under the right conditions any organism
can be converted into a fossil. Many fossils have been preserved
through petrifaction, a mineralization process whereby organic sub-
stances are turned to stone by circulating mineralized groundwater.
Petrified wood is a perfect example of this kind of fossil, where the wood
(cellulose) has been replaced by silica (quartz, opal) (Figure 9).
The bones and teeth of most vertebrates are the mineral calcium
phosphate, and are often preserved relatively unchanged. Fossils of
larger land vertebrates that may be found in Florida are the teeth and
bones of saber-toothed tigers, mammoths, mastodons, rhinoceroses,
horses, camels, sloths, and bears. Marine vertebrate fossils include
sirenians (manatee-like animals), and whales. Shark teeth are plentiful
in some strata (Figure 10). A more detailed description of some Florida
vertebrate fossils can be found in Fossil Mammals of Florida (Olsen,
1959).
The most numerous fossils found in Florida are of invertebrate marine
animals, which illustrate a common method of preservation (Figure 11).

Figure 8. Photographs of diatom frustules taken with a microscope,
showing the open frameworks that make them useful as filters. A =
Coscinodiscus vetustissimus, B = Fragilaria sp., C = Navicula direct, D
= Biddulphia reticulum. All 600x magnification. Photographs courtesy
of Ron Hoenstine. Samples A and C from St. Johns County; samples B
and D from Indian River County.

Figure 9. Petrified wood from a phosphate mine in southwestern Polk
County. This cut and polished section shows near perfect preservation
of the tree's original cellular structure through replacement by silica.
Thomas M. Scott collection.

0 1

Figure 10. At upper right is a mammal tooth from a sinkhole exposed
in a limestone mine, Citrus County. The fossil shark teeth are from a
phosphate mine in south-central Florida: upper left, Hemipristis; center,
Carcharodon; lower left, Carchirinus; lower right, Isurus. Note the
"steak knife" serrations on the shark teeth. Thomas M. Scott Collection.

0 2

C m

Figure 11. Casts and molds of fossil sea shells cemented together by
clay and lime mud, Coosawhatchie Formation, from the Jacksonville
area. Richard Johnson collection.

20
Many marine invertebrates, such as oysters, clams, echinoids, and
corals, possess hard shells of calcite and/or aragonite. Aragonite is
responsible for the "mother of pearl" luster of oyster shells. When one of
these animals dies, its soft parts decay, but its hard shell may become
covered with sediment. With the passage of time, a variety of chemical
and physical processes can work on the shell and the surrounding
matrix of sediment. As the sediment becomes cemented or compacted,
the shell may be dissolved, leaving a hollow in the shape of the shell-a
mold. If the mold shows the outside details of the shell, it is an external
mold; if it shows the inside of theshell, it is an internal mold. If the mold
becomes filled with sediment, it forms a cast.
The carbonate shells and bones of animals also can be replaced by
quartz, resulting in "agatized" fossils. Agatized coral, with its blue and
gray banding, is prized by collectors (Figure 12). Agatized mollusk
shells may appear to be made of translucent glass.

DISTRIBUTION OF ROCKS IN FLORIDA

To anyone studying or collecting rocks and minerals, a knowledge of
their modes of occurrence and associations is very helpful. The types
and distribution of rocks that occur near the surface in Florida are
shown on the maps in the appendix. It should be noted that much of
Florida is covered by deposits of sands and clays that range from a few
inches to several hundred feet thick. Therefore, a specific location on
the map that shows limestone could be covered by a veneer of sand. It
may be necessary to scout an area to discover places where a particular
type of rock crops out at the surface.

MINERALS

A mineral is a naturally occurring substance with a characteristic
internal structure determined by a regular arrangement of the atoms or
ions within it, and with a chemical composition and physical properties
that are either fixed or that vary within a definite range. This definition
excludes all manufactured products, such as glass, cement, and steel.
Also, a strict interpretation excludes synthetic rubies and diamonds,
although they are chemically, structurally, and physically identical with
their natural counterparts. Ice and snow are included by some mine-
ralogists because they meet the criteria of the definition.
Many minerals occur as compounds, which are chemical combina-
tions of two or more elements. Some "native elements," such as gold,
silver, and copper often occur in their pure elemental state, uncombined
with other elements. These elements are also minerals; however, none
are known to occur in Florida.

PHYSICAL PROPERTIES

Each mineral is either an element or a chemical compound, each with
a unique internal structure. The internal structure is determined by a

20
Many marine invertebrates, such as oysters, clams, echinoids, and
corals, possess hard shells of calcite and/or aragonite. Aragonite is
responsible for the "mother of pearl" luster of oyster shells. When one of
these animals dies, its soft parts decay, but its hard shell may become
covered with sediment. With the passage of time, a variety of chemical
and physical processes can work on the shell and the surrounding
matrix of sediment. As the sediment becomes cemented or compacted,
the shell may be dissolved, leaving a hollow in the shape of the shell-a
mold. If the mold shows the outside details of the shell, it is an external
mold; if it shows the inside of theshell, it is an internal mold. If the mold
becomes filled with sediment, it forms a cast.
The carbonate shells and bones of animals also can be replaced by
quartz, resulting in "agatized" fossils. Agatized coral, with its blue and
gray banding, is prized by collectors (Figure 12). Agatized mollusk
shells may appear to be made of translucent glass.

DISTRIBUTION OF ROCKS IN FLORIDA

To anyone studying or collecting rocks and minerals, a knowledge of
their modes of occurrence and associations is very helpful. The types
and distribution of rocks that occur near the surface in Florida are
shown on the maps in the appendix. It should be noted that much of
Florida is covered by deposits of sands and clays that range from a few
inches to several hundred feet thick. Therefore, a specific location on
the map that shows limestone could be covered by a veneer of sand. It
may be necessary to scout an area to discover places where a particular
type of rock crops out at the surface.

MINERALS

A mineral is a naturally occurring substance with a characteristic
internal structure determined by a regular arrangement of the atoms or
ions within it, and with a chemical composition and physical properties
that are either fixed or that vary within a definite range. This definition
excludes all manufactured products, such as glass, cement, and steel.
Also, a strict interpretation excludes synthetic rubies and diamonds,
although they are chemically, structurally, and physically identical with
their natural counterparts. Ice and snow are included by some mine-
ralogists because they meet the criteria of the definition.
Many minerals occur as compounds, which are chemical combina-
tions of two or more elements. Some "native elements," such as gold,
silver, and copper often occur in their pure elemental state, uncombined
with other elements. These elements are also minerals; however, none
are known to occur in Florida.

PHYSICAL PROPERTIES

Each mineral is either an element or a chemical compound, each with
a unique internal structure. The internal structure is determined by a

0 1 in

2 cm

Figure 12. Agatized fossil coral, dredged from Tampa Bay. This speci-
men, which has been cut longitudinally, shows blue and gray banding
on the cut edge and subtle donations of blue, gray, and brown on the
interior walls. Author's collection.

regular arrangement of atoms or ions within it, which also determines its
chemical and physical properties. All of these parameters are either
fixed or may vary within a definite range. Although the physical proper-
ties of minerals may vary slightly, they are usually constant within
narrow limits. Some diagnostic properties can be determined from a
visual examination, and others from a few simple tests. The categories
of physical properties given below (and in the Mineral Description
section) are not meant to be all-inclusive, but they will be sufficient to
identify common Florida minerals. For more information see a rock and
mineral field guide.
Color is one of the most obvious physical properties. While some
minerals are constant in color, many exhibit a range of colors due to
impurities or variations in chemical composition. With practice one can
become familiar with the more typical colors of minerals. A freshly
broken surface should be used to determine color, because tarnish or
weathering of an exposed surface usually alters normal color.

STREAK

Streak is the color of the residue produced by scratching a specimen
on a white, porous porcelain plate (not glazed ceramic). Because streak
color for a given mineral will be more consistent than the surface colors
among specimens, streak is a better diagnostic technique than a visual
estimate of color. Streak color may differ considerably from the speci-
men's color.

HARDNESS

The resistance of a mineral to scratching is an indication of its hard-
ness. The Moh's hardness scale, below, is the standard system used by
geologists to determine relative hardness of minerals. The scale goes
from the softest (1, Talc) to the hardest (10, Diamond).
1. Talc 6. Feldspar (Orthoclase)
2. Gypsum 7. Quartz
3. Calcite 8. Topaz or beryl
4. Fluorite 9. Corundum
5. Apatite 10. Diamond
Most of the common Florida minerals have a hardness of 7 or less.
Their hardness can be estimated using the following materials:
Fingernail: 2 to 2.5
Copper coin: up to 3
Knife blade: up to 5.5
Window glass: up to 5.5
Steel file: 6 to 7
To determine the hardness of an unknown mineral, test to find out
which of the minerals of known hardness it will just scratch; the
unknown mineral is somewhat harder than that known mineral. A test
from a smooth, clean surface or crystal face is best.

SPECIFIC GRAVITY

The specific gravity (SG) of a mineral is a number that expresses its
weight compared to the weight of an equal volume of water. For exam-
ple, the specific gravity of quartz is 2.65, which means that any given
volume of quartz weighs 2.65 times as much as an equal volume of water.
FORM

The form of a mineral is the characteristic shape of its crystals. If
minerals happen to grow in a favorable environment, most will form
distinctive crystalline shapes. Crystals are regular geometric forms
bounded by smooth, planar, crystal faces (Figure 13). Crystals often
end in sharp, faceted ends, called terminations.

MINERAL DESCRIPTIONS

Many of the minerals that occur in Florida can be found as macro-
specimens, that is, specimens large enough to examine without magni-
fying lenses. Except where noted, the following detailed descriptions of
physical properties have been written for the identification of macro-
specimens. These descriptions have been condensed into a Mineral
Identification Table at the end of this section, to provide a convenient
reference in the field. Mineral descriptions compiled from Bishop and
Dee (1961) and Hurlbut (1963).

Hexagonal O
cross section
of crystal

Figure 13. The crystal form of quartz, showing terminations and cross
section. Drawing adapted from Hurlbut (1963). Crystals from the
author's collection. Crystals are not from Florida, place of origin
unknown.

ANHYDRITE
(Figure 14)

COMPOSITION: CaSO4, anhydrous calcium sulfate (see gypsum).
COLOR: White, gray, brown.
STREAK: White.
HARDNESS: 3 to 3.5.
SPECIFIC GRAVITY: 2.89 to 2.98
FORM: Massive.
OCCURRENCE: Found in Florida only from rocks that are deeply
buried. It is often associated with gypsum.
USE: Not commercially produced in Florida.
REMARKS: Massive variety may resemble calcite or gypsum, but it is
harder and has a higher specific gravity than both of them.

Figure 14. Anhydrite is the white mineral in this rock; the darker mineral
is dolomite. This is a cut and polished section from a core taken during
oil-test drilling in south Florida, on Key Largo. This core came from
below 10,000 feet depth and is Lower Cretaceous in age. Author's
collection.

ARAGONITE

COMPOSITION: CaCO3, calcium carbonate. A relatively unstable form
of calcium carbonate.
COLOR: Colorless, white, yellow, various tints.
STREAK: White.
HARDNESS: 3.5 to 4.
FORM: The iridescent, pearly layer of many shells is aragonite.
OCCURRENCE: In shells, or associated with gypsum from deep wells.
USE: Not commercially produced in Florida, although some oolitic
aragonite has been imported into Florida from the Bahamas as a raw
material for cement production (U.S. Bureau of Mines, 1984).
REMARKS: Distinguished from calcite by its higher specific gravity and
its lack of rhombohedral cleavage. It is harder than calcite.

CALCITE
(Figures 15, 16, 17)

COMPOSITION: CaCO3, calcium carbonate.
COLOR: White or colorless; commonly various tints of yellow, orange,
or gray.
STREAK: White or colorless.
HARDNESS: 2.5 to 3.
SPECIFIC GRAVITY: 2.72.
FORM: Over 300 massive to various crystal forms have been described.
It readily breaks into rhombohedrons that resemble distorted cubes.
OCCURRENCE: Found throughout Florida, mainly as limestones.
Crystalline forms usually found in voids in limestone. In caves it forms
stalactites, stalagmites, and other varieties of travertine deposits, such
as those at Marianna Caverns, Jackson County. Banded varieties result
from changes in the types and amounts of dissolved minerals in the
water that circulate through the host rock. Cleaner water, for example,
tends to produce lighter colors, while dissolved iron minerals produce
reds or oranges.
USE: See limestone.
REMARKS: Massive varieties can resemble dolomite, but calcite effer-
vesces freely in cold hydrochloric acid, whereas dolomite does not.
Dolomite is harder, 3.5 to 4.

0 1 in

2 cm

Figure 15. Calcite crystals in a fan-shaped aggregate, showing well
formed terminations. In Florida, calcite crystals usually form in cavities
in limestone. Individual crystals can vary in size from microscopic to
several inches long and wide. These crystals formed in a void in lime-
stone, central Citrus County. Thomas M. Scott collection.

*-.E~

E
.c J

'j -

Figure 16. Massive form of calcite showing characteristic rhombohed-
ral shape. Author's collection.

w? l

'I.~

, *

- J;1

Figure 17. Stalactites are massive varieties of calcite, which result from
precipitation in cavities of rocks or in caves. The circular, transverse, cut
and polished section of a stalactite shows concentric rings. Each ring
represents the addition of a layer of precipitated calcite. The longitudi-
nal, cut and polished section of a stalactite shows a hollow, straw-like
channel extending through its length. Water seeps out of a crack in a
cavity's ceiling, runs down the internal tube, and drips off the end. In this
way, stalagmites grow upward from the floor of a cave. These stalactites
formed in a cavity in limestone, central Citrus County. Thomas M. Scott
collection.

DOLOMITE

COMPOSITION: CaMg(CO,),, calcium and magnesium carbonate.
COLOR: Various shades of gray or brown.
STREAK: White.
HARDNESS: 3.5 to 4.
SPECIFIC GRAVITY: 2.85.
FORM: Massive.
OCCURRENCE: Found throughout Florida, usually associated with
limestone.
USE: Most of the dolomite produced in Florida is used for agricultural
limes. Some dolomite is crushed and used for road surfacing.
REMARKS: Distinguished from limestone and calcite by poor reaction
to cold hydrochloric acid and its hardness. It can precipitate directly
from sea water where circulation is restricted and salinity is abnormally
high, or limestone can alter to dolomite by the addition of magnesium
ions. There is evidence that both processes have operated to produce
various dolomites in Florida.

GYPSUM

COMPOSITION: CaSO4 2HO, hydrous calcium sulfate. Anhydrite
changes to gypsum by the absorption of water (see anhydrite).
COLOR: White to various shades of gray, yellow, brown.
STREAK: White.
HARDNESS: 2 (can be scratched with fingernail).
SPECIFIC GRAVITY: 2.32.
FORM: Massive or crystals.
OCCURRENCE: In Florida it is usually only found associated with
anhydrite from deep wells. Bishop and Dee (1961) reported that small
deposits of gypsum have been found at several localities: Sumter
County (east-half of Section 23, T20S, R21E); Orange County (three
miles east of Christmas at a depth of four feet); and in dredge spoils from
the Gulf of Mexico and Tampa Bay in Pinellas, Pasco, and Hillsborough
counties.
USE: A raw material for gypsum wallboard, and cement. Produced as a
by-product of phosphate processing, but not sold commercially.
REMARKS: Its softness distinguishes It from anhydrite.

HEAVY MINERALS

Mineralogists have arbitrarily classified as "heavy minerals" certain
minerals that have specific gravities greater than quartz (2.65). Species
of heavy minerals found in Florida are: garnet, zircon, ilmenite, kyanite,
leucoxene, monazite, rutile, sillimanite,staurolite, tourmaline, andalus-
ite, pyroxene, corundum, spinel, and epidote. These minerals are dis-
seminated throughout the sands of Florida, where they occur as small,
rounded, sand-sized particles. Their tiny grain sizes mean that they can
only be examined with a microscope or hand lens. Therefore, while
detailed descriptions of the physical properties of macro-specimens
have been omitted, the Mineral Identification Table does include their
basic characteristics.
They generally comprise one percent or less of the total amounts of
sand particles (Pirkle, et al., 1977). However, wind and wave action
along shorelines tend to concentrate them, producing zones of higher
percentages (Figure 18). Because most of them are dark colored (red-
browns or black) they can be distinguished from the lighter colored
quartz sand grains. Zircon is an exception in that it is usually colorless
and glassy. Thin, dark bands of heavy minerals can be revealed by
trenching across a beach.
Heavy mineral production in Florida is a multi-million dollar industry.
At present, mining is only done in Clay and Bradford counties and is
restricted to the Trail Ridge and Green Cove Springs deposits (Camp-
bell, 1986). Trail Ridge is a prominent (up to 250 feet above sea level),
north-south oriented, 130-mile-long sand ridge that begins in southern
Georgia and extends approximately 40 miles into north Florida, ending
in the southern parts of Clay and Bradford counties. This sand body is
thought to represent a shoreline beach ridge created by an ancient,
higher sea level (Pirkle, et al., 1977). This environment concentrated
heavy minerals to such an extent that mining them is currently econom-
ical. Pirkle, et al. (1977) state that Trail Ridge sands contain an average
of three percent heavy minerals, 45 percent of which are ilmenite,
leucoxene, and rutile. Other heavy minerals of economic importance
are staurolite, zircon, kyanite, sillimanite, and monazite.
Species of heavy minerals that occur in Florida sands, but which are
of limited industrial and economic value include: garnet, tourmaline,
spinel, andalusite, pyroxene, corundum, and epidote.
I Imenite, leucoxene (an altered form of ilmenite), and rutile are known
as "titanium minerals" because they are important sources of titanium
metal. Because of its resistance to heat and corrosion, titanium is used
in the aircraft, aerospace, and chemical industries. Titanium minerals
are used to produce welding rod coatings and fluxes, carbides, stainless
and heat-resistant steel alloys. Titanium dioxide (TiO,) pigment, from
ilmenite, is produced in greater quantities than any other white pigment.
These pigments are used in the manufacturing of paper, paint, plastics,
rubber, ink, and ceramics. In 1984 Florida was the only producer of
rutile and one of two states with ilmenite shipments (U.S. Bureau of
Mines, 1984).

-' -:

2 2
; .- .
4

in

CMr

Figure 18. Dark, heavy minerals concentrated in lighter, quartz beach
sand, giving a salt-and-pepper appearance. Florida Geological Survey
Collection.

33

Most zircon is used as foundry sands due to its resistance to heat. Its
hardness makes it useful for sandblasting and polishing, and in ceram-
ics, glazes and enamels. Zirconium-based chemicals are used in the
paint, textile, and pharmaceutical industries. The aircraft and nuclear
power industries use zirconium alloys. Florida was the only U.S. pro-
ducer of zircon in 1984 (U.S. Bureau of Mines, 1984).
The aluminum silicate minerals, kyanite, sillimanite, and staurolite,
are utilized as foundry sands, as additives for portland cement, and as
ingredients in ceramic products. Florida was the only state reporting
production of staurolite in 1984 (U.S. Bureau of Mines, 1984).
Monazite, a phosphate mineral of several rare-earth metals ceriumm,
lanthanum, yttrium, and thorium), is used primarily in petroleum cata-
lysts, metallurgical alloys, ceramics and glass, electronics, nuclear
energy, and lighting. Florida was the only state in 1984 that produced
rare earths from mineral sands mining (U.S. Bureau of Mines, 1984).

LIMONITE
(Figure 19)

COMPOSITION: FeO(OH) H20, brown hematite, bog-iron ore.
COLOR: Dark brown, orange-brown, yellowish-brown, black.
STREAK: Yellowish-brown.
HARDNESS: 1 to 5.5 depending on form and degree of consolidation.
SPECIFIC GRAVITY: 3.6 to 4.
FORM: Hard concretions or nodules; yellow ochre, which is soft, earthy
with varying amounts of clay minerals.
OCCURRENCE: Bishop and Dee (1961) reported that a deposit of
limonite exists near Chiefland, Levy County. They also reported a de-
posit of yellow ochre in Flagler County. Limonite gives rust-colored
stains to soils, limestones, and clays; in larger amounts it acts to cement
sand grains and clay particles into hardpans or concretionary forms.
USE: According to Bishop and Dee (1961) the deposit of bog-iron ore
near Chiefland was mined by the Confederacy to make cannon and
cannon balls; and the yellow ochre in Flagler County was mined until
1953 for paint pigment.

. ^'

r"x

V '

Figure 19. Limonite, showing typical forms of occurrence. From left to
right: dark reddish-brown, smooth nodule; dark red, rough nodule with
cemented sand grains; a tabular piece of sandy, limonitic hardpan.
Florida Geological Survey Collection.

r~tfl
im

MICA

COMPOSITION: KAI3Si30,o(OH)2, a complex aluminum silicate.
COLOR: White or translucent (muscovite), black biotitee).
STREAK: Colorless.
HARDNESS: 2 to 2.5
SPECIFIC GRAVITY: 2.76 to 3.1.
FORM: In its massive form mica occurs as foliated "books" that split
apart easily, producing thin, flexible laminae.
OCCURRENCE: Found in Florida only as small, shiny detrital flakes in
sands and clays.
USE: Fireproofing and insulating materials are its chief commercial
uses. Not commercially produced in Florida.

PYRITE

COMPOSITION: FeS2, iron sulfide.
COLOR: Yellow, brassy.
STREAK: Black.
HARDNESS: 6 to 6.5.
SPECIFIC GRAVITY: 5.02.
FORM: Cubic crystals with striated faces. Fresh specimens have a
bright, brassy luster, hence its name of "fools gold."
OCCURRENCE: From deep well cores in Florida. Bishop and Dee
(1961) reported it had been found at one unspecified surface locality in
Ocala. Found in some sediments in Florida as fine particles.

QUARTZ
(Figures 12, 13, 20)

COMPOSITION: SiO8, silicon dioxide.
COLOR: May be any color due to impurities. Quartz sand is usually
white or colorless, and may be rusty-stained by iron oxide coating, or
black by organic.
STREAK: White.
HARDNESS: 7.
SPECIFIC GRAVITY: 2.65.
FORM: A great many forms of quartz exist. Crystalline forms often grow
in cavities in limestone or dolomite, being elongated with six-sided
(hexagonal) cross section and terminated in steep, pyramidal facets
(Figure 13). Florida specimens are usually colorless, called rock crystal,
while purple or violet crystals are called amethyst. An extremely fine-
grained variety of chert or flint occurs as nodules, concretions, or as
lining in cavities; banded varieties are called agate (Figure 20). Colors
range from grays to bright shades of blue, red, yellow, and orange.
OCCURRENCE: Quartz sand is found throughout Florida. Crystalline,
fine-grained or massive varieties are associated with limestone and
dolomite through the State. In the western and northern counties, larger
specimens can often be found along stream channels, especially those
that have eroded deeply into limestone.
USE: Quartz sand is widely used in construction industries for road
base and fill; major industrial uses are glass making and foundry sand.
Good crystalline specimens are in demand by collectors. Colored or
banded varieties can be made into semi-precious gemstones by cutting
and polishing. Agatized coral is much desired by collectors; it is des-
cribed in the Fossils section (Figure 12).

Figure 20. Chert, variety of quartz, often occurs as nodules. This
nodule has been broken to show the conchoidal fractures which pro-
dice razor-sharp edges, a property that was highly prized and utilized by
primitive people to make projectile points and other stone tools. Florida
Geological Survey Collection.

VIVIANITE
(Figures 21 and 22)

COMPOSITION: Fe3(PO)2 8H20, hydrous ferrous phosphate.
COLOR: Very dark blue or bluish-green. Crystals are clear when first
exposed but change to blue after exposure.
STREAK: Grayish-blue.
HARDNESS: 1.5 to 2.
SPECIFIC GRAVITY: 2.58 to 2.68.
FORM: Usually in prismatic crystals, also in nodular, earthy forms.
OCCURRENCE: A rare mineral that has been found in some phosphate
mines in central Florida.
USE: Not commercially produced in the United States.

Figure 21. Vivianite crystals in a phosphatic dolomite matrix, from a
phosphate mine in Polk County. These bladed, very dark blue crystals
have a metallic luster. Thomas M. Scott collection.

'Sir

Figure 22. Vivianite crystals, transparent, very light blue-green. From a
phosphate mine near Bartow, Polk County. Photo by A. Gricius, magni-
fication approximately 18x.

WAVELLITE
(Figure 23)

COMPOSITION: A13(OH)3(PO4)2 5H,)
COLOR: Translucent, white, yellow, green, brown.
STREAK: Colorless.
HARDNESS: 3.5 to 4.
SPECIFIC GRAVITY: 2.33.
FORM: Radiating aggregates, crystals rare.
OCCURRENCE: A rare mineral that has been found in some phosphate
mines in central Florida.
USE: Not commercially produced in the United States.

Figure 23. Wavellite crystals in radiating aggregates. These are nearly
colorless and transparent. From a phosphate mine near Bartow, Polk
County. Photo by A. Gricius and D. Benke, magnification approxi-
mately 75x.

MINERAL

Anhydrite
CaSO4

Aragonite
CaCO0
Calcite
CaCO,

Dolomite
CaMg(CO3)2

Francolite
CasF(P04)3

Garnet"
(Ca,Cr,Fe,Mg,Mn,A1)
(SiO4)3

Gypsum
CaS4 2H20
Illite
KA,2 (OH)2(AISi3(O,OH)1l

Ilmenite* FeTiO3

Kaolinite
AI4(Si4010) (OH,)

Kyanite AI2SIOs

MINERAL IDENTIFICATION TABLE
Compiled from Bishop and Dee (1961) and Hurlbut (1963).
*Denotes heavy mineral species; found in Florida only as sand-size grains.

SPECIFIC
COLOR STREAK HARDNESS GRAVITY

white, gray white 3-3.5 2.89-2.98

white, yellow white 3-5.4 2.95

white, gray, white 2.5-3 2.72
yellow

gray, brown white 3.5-4 2.85

green, blue, 5 3.1
brown, violet, colorless

red to black 6.5-7.5 3.5-4.3

white, gray,
yellow, brown

white, gray

white

5.5-6

2-2.5

5-7

4.7

2.6

3.56-3.66

REMARKS

absorbs water and changes
to gypsum over time

"mother of pearl" in shells

reacts with cold HCI acid

poor reaction with cold
HCI acid

phosphate forming mineral

Complex silicates of
varying composition

see Anhydrite

clay mineral

clay mineral

Leucoxene*
FeTiO3
Limonlte
FeO(OH) H20)

Mica
KAl3Si3Oio(OH)2

Monazlte*
(Ce,La,Y,Th)PO4

Montmorillonite
(MgCa)0 A120 5 8102

Palygorskite
(AI,Mg)o SiO2 HO2

Pyrite FeS2

Quartz SiO2

Rutile* TiO2

Sillimanite*
AlSiO,
Staurolite*
FeAlO,7(SIO4)4(OH)

Tourmaline'
(Ca,Na,AI,Fe,Li,Mg) Ale
(BO3)3 (SiO,,) (OH)4

Vivianite
Fe3(PO4)2 8H20

Wavellite
A3 (OH)3(PO4)2 5H20

Zircon* ZrSiO4

brown, yellow
black

white, black

yellowish to
reddish-brown

H20

yellow

white, varies

red to black

brown

red to black

brown, black

clear, turns dark
blue on exposure
to light
white, yellow
green, brown

colorless

yellow-brown

colorless

black

white

gray-blue

colorless

1-5.5

2-2.5

5-5.5

6-6.5

7

6-6.5

6-7

7-7.5

7-7.5

1.5-2

3.5-4

7.5

3.6-4

2.76-3.1

5.0-5.3

5.02

2.65

4.18-4.25

3.23

3.65-3.75

3-3,25

2.58-2.68

2.33

4.68

an altered form of ilmenite

low grade "iron" ore

platy, small, shiny flakes

phosphate of rare-earth
metals

clay mineral, "swelling clay"

clay mineral (fuller's earth)

"fools gold"

other forms = chert, opal,
agate, flint, chalcedony

complex silicate of varying
composition

prismatic crystals

radiating aggregates

glassy

44
SELECTED REFERENCES

Bishop, Ernest W. and Lawrence L. Dee, Jr., 1961 (reprinted 1981),
Rocks and Minerals of Florida, A Guide: Fla. Geological Survey Special
Publication 8, 41 p.

Bond, Paulette, Kenneth M. Campbell, and Thomas M. Scott, 1986, An
Overview of Peat In Florida and Related Issues: Fla. Geological Survey
Special Publication 27, 151 p.

Calver, J. L., 1957, Mining and Mineral Resources: Fla. Geological
Survey Bulletin 39, 132 p.

Campbell, Kenneth M., 1986, The Industrial Minerals of Florida: Fla.
Geological Survey Information Circular 102, 94 p.

Davis, J.H., Jr., 1946, The Peat Deposits of Florida: Fla. Geological
Survey Bulletin 30, 250 p.

Deuerling, R., 1981, Environmental Geology Series Tarpon Springs
Sheet: Fla. Bureau of Geology Map Series 99.

Hurlburt, Cornelius S., Jr., 1963, Dana's Manual of Mineralogy: John
Wiley & Sons, NY, 609 pp.

Knapp, M. S., 1978, Environmental Geology Series Gainesville Sheet:
Fla. Bureau of Geology. Map Series 79.

1978, Environmental Geology Series Valdosta Sheet:
Fla. Bureau of Geology Map Series 88.

,1980, Environmental Geology Series Tampa Sheet:
Fla. Bureau of Geology Map Series 97.

Lane, E., 1980, Environmental Geology Series West Palm Beach Sheet:
Fla. Bureau of Geology Map Series 100.

1981, Environmental Geology Series Miami Sheet:
Fla. Bureau of Geology Map Series 101.

Michael S. Knapp, and Tom Scott, 1980, Environ-
mental Geology Series Ft. Pierce Sheet: Fla. Bureau of Geology Map
Series 80.

Lloyd, Jacqueline M., 1985, Annotated Bibliography of Florida Base-
ment Geology and Related Regional and Tectonic Studies: Fla. Geolog-
ical Survey Information Circular 98, 72 p.

Olsen, Stanley J., 1959, Fossil Mammals of Florida: Fla. Geological
Survey Special Publication 6, 75 p.

Pirkle, E. C., W. A. Pirkle, and W. H. Yoho, 1977, The Highland Heavy-
Mineral Sand Deposit on Trail Ridge in Northern Peninsular Florida: Fla.
Bureau of Geology Report of Investigation 84, 50 p.

Schmidt, W., 1978, Environmental Geology Series Pensacola Sheet: Fla.
Bureau of Geology Map Series 78.

1978, Environmental Geology Series Apalachicola
Sheet: Fla. Bureau of Geology Map Series 84.

1979, Environmental Geology Series Tallahassee
Sheet: Fla. Bureau of Geology Map Series 90.

R. W. Hoenstine, M. S. Knapp, E. Lane, G. M. Ogden,
Jr., and Thomas M. Scott, 1979, The Limestone, Dolomite and Coquina
Resources of Florida: Fla. Bureau of Geology Report of Investigation 88,
64 p.

Scott, T. M., 1978, Environmental Geology Series Orlando Sheet: Fla.
Bureau of Geology Map Series 85.

1978, Environmental Geology Series Jacksonville
Sheet: Fla. Bureau of Geology Map Series 89.

,1979, Environmental Geology Series Daytona Beach
Sheet: Fla. Bureau of Geology Map Series 93.

R. W. Hoenstine, M. S. Knapp, E. Lane, G. M. Ogden,
Jr., R. Deuerling, and H. E. Neel, 1980, The Sand and Gravel Resources
of Florida: Fla. Bureau of Geology Report of Investigation 90, 41 p.

Sorrell, Charles A., 1973, Rocks and Minerals, A Guide to Field Identifi-
cation: Golden Press, NY, 280 p.

U.S. Bureau of Mines, 1984, The Mineral Industry of Florida, in: Minerals
Yearbook, 1984, vol. II, 669 p.

Zim, H. S., various editions, Rocks and Minerals, Golden Press, NY,
160 p.

SELECTED DEFINITIONS

AGATE: A banded, colored variety of silica (quartz).

AGGREGATE: Composed of a mixture of substances (minerals and
rocks) separable by mechanical means.

AMORPHOUS: Without form; applied to rocks and minerals having no
definite crystalline structure.

CHERT: A dense sedimentary rock consisting of microscopic particles
of silica (quartz). Occurs in layers and as isolated masses.

CONCRETION: A nodular or irregular concentration of minerals
formed by localized deposition of material from solution, generally
about a central nucleus. Harder than surrounding rock. Examples are
clay and ironstone nodules.

CORAL: A tiny, bottom-dwelling marine animal that secretes an exter-
nal skeleton of calcium carbonate. Some are solitary but most grow in
colonies. The calcareous skeleton of a coral or group or colony of
corals.

CRYPTOCRYSTALLINE: Crystalline, but so fine grained that the indi-
vidual components cannot be seen with a magnifying glass.

DETRITAL DEPOSITS: (Clastic) Fragments of rocks that have been
transported from.their place of origin to the place of deposition.

ECHINOID: Free-moving, marine invertebrate animals with external
skeletons of calcium carbonate. Bodies range from spherical to flat-
tened disclike forms; many have spines. Examples are sea urchins and
sand dollars.

ELEMENT: A substance that cannot be decomposed into other
substances.

EROSION: The natural processes of weathering, disintegration, dis-
solving, and removal of rock and earth material, mainly by water and
wind.

EFFERVESCE: To bubble and hiss, as limestonewhen acid is poured on
it.

FLINT: A dense sedimentary rock consisting of microscopic particles of
silica (quartz). Occurs in layers and as isolated masses. Also called
chert.

FORAMINIFERA: One-celled animals, mostly of microscopic size, that
secrete shells of calcium carbonate, or build them of cemented sedi-

mentary grains, consisting of oneto many chambers arranged in a great
variety of ways. Most are marine, but some live in fresh water.

FOSSIL: Remains or traces of plants or animals which have been pre-
served by natural causes in the earth's crust.

HYDROUS, HYDRATED: A compound formed by the union of water
with some other substance. Containing water chemically combined.

INTERBEDDED: Occurring between beds, or lying in a bed parallel to
other beds of a different material.

IRIDESCENCE: The exhibition of colored reflections from the surface
of a mineral; a play of colors, as from the pearly layer of sea shells.

MACROCRYSTALLINE: A textural term applied to rocks in which the
constituents are distinguished with the naked eye.

MARINE: Refers to sediments deposited in sea water, or to animals that
live in the sea.

MOLLUSKS: A large group of invertebrate animals, both marine and
fresh water and land. Many secrete external shells or internal structures
-of calcium carbonate; examples are oysters, clams, squid, snails.

NODULES, NODULAR: A general term for rounded concretionary
bodies, which can be separated as discrete masses from the formation
in which they occur.

OUTCROP: That part of a stratum of rocks which appears at the surface.
To crop out.

STALACTITES: Conical or cylindrical deposits of minerals, usually
calcite or aragonite, hanging from the roof of a cavern.

STALAGMITES: Columns or ridges of carbonate rock rising from a
limestone cave floor, and formed by water charged with calcium carbo-
nate dripping from the stalactites above. Stalactites and stalagmites
often meet, forming a column from floor to ceiling.

APPENDIX

These maps are modified from the Bureau of Geology's Environmental
Geology Map Series. The color Environmental Map Series maps show
more detailed lithology because of their larger size (22" x 34", at a scale
of 1:250,000). Maps from this series may be ordered by remitting $1.00
for each map; check or money order must accompany all requests for
maps, made payable to "Florida Bureau of Geology." Specify maps
wanted, for example: Map Series 85, Orlando Sheet. Send orders to:

Florida Bureau of Geology
903 West Tennessee St.
Tallahassee, FL 32304-7795

0 Alabama
P V

Mc.icl I1ron, SaL. h 7, 7 Map I Se Sr, r. 5TPaca Sier Gulf of Mexico

Gravel and Coarse Sand Clayer Sand

LIIMedium-Fine Sand and Silt j Sandy Clay and Clay

inni a gue to urfac laIthoiogy. Each
Alare oaIW do n no: maI y
Gravl ad or SC ey Sandl

. d~lmnt

m Br Vel end C0ore Sead ~ Limestone

gi~iiimm Nedlum-pIn. Send @nd Slt w CIllo, Sand

Dolomite Lek*
Modiifld Irm Schtr"L 181g, MOP Se"" 9D. IWOA Z ZW.

Shell Boed

Sandy Clay

Modfled from Schmidt. 1978. MaO Berieu 4, Ap dkaolA Seet.

Clayey Sand

Medium-Fine Sand and Slit

Limestone E Dolomite

F Limaetone/Dolomite

Thk mnp 1I m..nt a- 9lrt
gwik wrIm l.tt- IBy. FIwh
mu outlked m thi map my
Wolan o4f monr them on kind of
.bnurfatv adkImnt.

lE Clayey Sand S helly Sand and Clay

Medium Fle Sand and Silt

Cw

Em Shelly Sand and Clay

Medium Fine Sand and Silt

Clayey Sand

( Lake
Modified froin 19in, Ms Up S&Fft 93, Dwo- aawh ~s

Lak e : : a::::.
L

... ... .. .. .. :NNUM...

::..............

M4+46Eium we Sn aj nItCaeWad

Io 21fo Sot17 anSre 5 Olm ht
.............. num : .. 2:2:

::::.... ....;;........

:::::i:::::::i~.............:m

S~ h~lly Sand and Clay Limauton.

liii~iB Medium Pine Sand and Sil~t t~i~Clay.; Sand

Mo44,4Ied from Scott 17 Seci,; +5. Ordo Yn& t

P Leat
Lake

iGrl|des Okeechobee

0 5 10 mi nA h nw..t a n M
I" A&M ft ee hotogY Each
N l uAllm.d on vH p m W
10 km c o f nr thm n kW.d of
ounrh.. r r.c -.

Shelly Sand and Clay j Peat

Medium Fine Sand Cilayy Sand
and Sit

Mddfi.d Irn Le, t L., 190, M.p S- F Pi- "',. (. Lake

0 5 10 mi

10 km

Thls M It m--nt a a0 n
Mh to WFa lithakw. Each
W .idM -d an k r m f .1

burrm washmen

Ji Shelly Sand and Clay

Med. Fine Sand and Slit

SLimePeatr
Limestone

Modifid irm La-n 1980. hlp Serie 100, WHSt P.an Bach Sha-

10 km

A WU mp ah .n. a e Iwal
Apa a Arho Zda4. Euh
NN .. "an rA V. .. mWWY
-- ~ m of o n 4 I"0 of

i Peat

i l iShelly Sand and Clay

5= Limetlone

0 5 10 mi

10 km

Thl map h man.t a a ginral
kido to murim ~ololiy. EIch
arm outlkdal on thi man miay
raheit of mre thd i one hled o
a aurf fa admlinat

All biirr
and *d

Sandy Clay

j Clayey Sand

SLimestone

SLimestone/Dolomite

Shelly Sand and Clay

Medium Fine Sand and Slit

Modilied f-rm Knappr 1i0O, MAp S-aoo 97. Taropa Shet

0 5 10 ml
N

10 km

Medium Pine Sand
and Silt

Limestone

Tml ml if m.' r ..t .gra
guiia m rfab IlthoLgy. Each
r outlined on Ith IMp msy
nskst of mso tn i t kl.nd of
uburf-e sdi-MInt.

|::j Clayey Sand

_i__ Dolomite

Modifled from D.uerlinm. 181. Map SsrlY 99, TVrp Sp ir D SIMt.

Thk map L meant e general
plide to wurfet lheol t- Ech
6ea cualkead on the rnap may
oni s of more hn onm kind cf
iluberlaee eaddmec,

MOdled from Knap, 19lq, Map Serie t6, tain.awl Shet.

I | Clayey Sand

Medium Fine Sand and Slit

1 Limestone

f Limestone/Dolomite

4 \Dolomite

Lake
0>1 ~O~l-a
J a)--

FLORIDA DEPARTMENT OF NATURAL RESOURCES

BUREAU OF GEOLOGY
FLORIDA GEOLOGICAL SURVEY
903 WEST TENNESSEE STREET
TALLAHASSEE, FLORIDA 32304-7795

Walter Schmidt, Chief
Peter M. Dobbins, Admin. Asst. Alison Lewis, Librarian
Jessie Hawkins, Custodian Sandie Ray, Secretary

GEOLOGICAL INVESTIGATIONS SECTION

Thomas M. Scott, Senior Geologist/Administrator
Albert V. Applegate, Geologist Ed Lane, Geologist
Ken Campbell, Geologist Margaret Lehey, Staff Asst.
Cindy Collier, Secretary Jacqueline M. Lloyd, Geologist
Richard Howard, Laboratory Tech. John Morrill, Core Driller
Richard Johnson, Geologist Albert Phillips, Asst. Driller
Jim Jones, Draftsman Frank Rupert, Geologist
Ted Kiper, Draftsman Wei Wuchang, Research Asst.

OFFICE OF MINERAL RESOURCE INVESTIGATIONS
AND
ENVIRONMENTAL GEOLOGY SECTION

J. William Yon, Senior Geologist/Administrator
Paulette Bond, Geologist Ron Hoenstine, Geologist
Shelton Graves, Research Asst. Steve Spencer, Geologist

OIL AND GAS SECTION

L. David Curry, Administrator
Pete Parker, Engineer Scott Hoskins, Geologist
Brenda Brackin, Secretary Barbara McKamey, Secretary
Robert Caughey, Geologist David Poe, Geologist
Joan Gruber, Secretary Joan Ragland, Geologist
Don Hargrove, Staff Asst. Clay Roark, Staff Asst.
Charles Tootle, Engineer

DEPARTMENT OF NATURAL RESOURCES
BUREAU OF GEOLOGY

This publication was produced at an annual cost of
$3,824.67, or $1.91 per copy to disseminate
geologic data.

	Front Cover
	Letter of transmittal
	Title Page
	Table of Contents
	List of Figures
	Foreword
	Collecting rocks and minerals
	Rocks
	Other rocks, minerals, and related...
	Distributions of rocks in...
	Minerals
	Mineral descriptions
	Reference
	Selected definitions
	Appendix: Maps showing distribution...
	Back Cover

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