LETTER OF TRANSMITTAL 1986ufdcimages.uflib.ufl.edu/UF/00/00/11/63/00001/UF00001163.pdf · Value of...

STATE OF FLORIDADEPARTMENT OF NATURAL RESOURCESElton J. Gissendanner, Executive Director

DIVISION OF RESOURCE MANAGEMENTArt Wilde, Director

BUREAU OF GEOLOGYWalter Schmidt, Chief

INFORMATION CIRCULAR NO. 102

THE INDUSTRIAL MINERALSOF

FLORIDA

by

Kenneth M. Campbell

Published for theFLORIDA GEOLOGICAL SURVEY

TALLAHASSEE1986

-3-7

DEPARTMENTOF

NATURAL RESOURCES

BOB GRAHAMGovernor

GEORGE FIRESTONE JIM SMITHSecretary of State Attorney General

BILL GUNTER GERALD A. LEWISTreasurer Comptroller

RALPH D. TURLINGTON DOYLE CONNERCommissioner of Education Commissioner of Agriculture

ELTON J. GISSENDANNERExecutive Director

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LETTER OF TRANSMITTAL

Bureau of Geology

August 1986

Governor Bob Graham, ChairmanFlorida Department of Natural ResourcesTallahassee, Florida 32301

Dear Governor Graham:

The Bureau of Geology, Division of Resource Management, Depart-ment of Natural Resources, is publishing as its Information Circular No.102, The Industrial Minerals of Florida.

This report summarizes the geology, mining and beneficiation of indus-trial minerals found in Florida. Products, uses, economic trends and envi-ronmental aspects are outlined. This report will be useful to geologists,state and local governmental agencies and the citizens of the State andwill help the reader more fully realize the impact of mining on the econ-omy of Florida.

Respectfully yours,

Walter Schmidt, ChiefBureau of Geology

iii

Printed for theFlorida Geological Survey

Tallahassee1986

ISSN No. 0085-0640

iv

TABLE OF CONTENTS

Page

Introduction ........................................ 1

C em ent ........................................... 1D iscussion ..................................... 1Econom ic Trends ................................. 2Environmental Concerns ........................... 2

C lays ............................................. 5G eology ....................................... 5Mining and Beneficiation ........................... 7U ses . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . 7Transportation and Economic Trends .................. 9Reserves ....................................... 9Environmental Concerns ........................... 9

Heavy M inerals ..................................... 11G eology ........................... ... ......... 11

Trail Ridge Deposit ............................ 11Green Cove Springs and Boulougne Deposits ......... 12

Mining and Beneficiation ........................... 12Products and Uses ...... .......... .............. . 14Transportation and Economic Trends .................. 15Reserves ....................................... 15Environmental Concerns ........................... 16

Magnesium Compounds ............................... 16Processing ..................................... 16Uses ....................................... .... 16Econom ic Trends ................................. 17Reserves ....................................... 17Environmental Concerns ........................... 17

O il and G as ........................................ 17G eology ....................................... 17Products and Uses ............................... 18Transportation ................................... 19Production Trends ................................ 19Reserves ....................................... 19Environmental Concerns ........................... 19Byproduct Sulphur ................................ 23

Peat ............................................ 23

v

G eology ....................................... 23M ining ........................................ 24U ses .......................................... 2 5Transportation and Economic Trends .................. 25Reserves ....................................... 25Environmental Concerns ........................... 27

Phosphate ......................................... 28D iscussion ..................................... 28G eology ........................................ 29

Central Florida Phosphate District ................ . 29Southern Extension of the Central Florida Phosphate

D istrict ................ . ................. . 31Northern Florida Phosphate District ................ 31

M ining ........................................ 32Beneficiation of Phosphate Ore ...................... 33Products and Uses ............................... 34Transportation ................................... 34Economic Trends ................................. 34Reserves ....................................... 36Environmental Concerns ........................... 36

W ater Usage ................................. 36Power Consumption ........................... 36Radiation ................................... 36W ater Quality ................................ 37A ir Q uality .................................. 37Clay W aste Disposal ........................... 37W etlands ................................... 38

Byproduct Fluorine ............................... 38Recovery ................................... 38U ses ....................................... 39Economic Trends ............................. 39

Byproduct Uranium ............................... 39G eology .................................... 39Extraction ................................... 40Economic Trends ............................. 40Reserves .................................... 40

Sand and Gravel .................................... 41G eology ....................................... 4 1

Northwest Florida ............................. 41North Florida ................................. 42Central Florida ............................... 42South Florida ................................. 43

Mining and Beneficiation ........................... 43U ses .......................................... 44Transportation ................................... 44

vi

Econom ic Trends .................................... 44Reserves .......................................... 44Environmental Concerns ............................... 44

Stone ............................................ 4 6G eology ....................................... 46

Northwest Florida ............................. 46The Western One-Half of North and Central Peninsular

Florida .................................... 47Atlantic Coast ................................ 49Southw est Florida ............................. 49

Mining and Beneficiation ........................... 50Products and Uses ............................... 51Transportation ................................... 51Econom ic Trends ................................. 53Reserves ....................................... 53Environmental Concerns ........................... 53

References ........................................ 54

A ppendix ............... .......................... . 62Mineral Producers in Florida ......................... 62

Producers By Commodity .............................. 62

Commodities By County ............................... 89

FIGURES

Figure Page

1 Quantity and value of portland cement .............. 32 Quantity and value of masonry cement ............. 43 Fuller's earth mine, Marion County ................. 84 Quantity and.value of clays ...................... 105 Heavy minerals "wet mill" beneficiation plant ........ 136 Getty Oil drilling rig, East Bay, Santa Rosa County ..... 187 Past and present oil and gas production from Florida

fields ....................................... 208 Quantity and value of petroleum crude .............. 219 Quantity and value of natural gas .................. 22

10 Quantity and value of peat ....................... 2611 Location of the Florida phosphate districts ........... 30

vii

12 International Minerals and Chemicals Corp. Clear Springsphosphate mine, Polk County .. . ... . . . . . . . . . . . .. 32

13 Quantity and value of phosphate in Florida and NorthC arolina .................................... 35

14 Suction dredge used in sand mining ................ 4315 Quantity and value of sand and gravel .............. 4516 Limestone quarry, Citrus County ................... 5017 Limestone quarry, mining below water level with

dragline ..................................... 5118 Quantity and value of crushed stone ............... 52

TABLES

Table Page

1 Conversion factors for terms used in this report ...... . 1

viii

THE INDUSTRIAL MINERALSOF

FLORIDA

byKenneth M. Campbell

INTRODUCTION

Although Florida is not generally thought of as a mining state, it rankedfourth nationally in total value of non-fuel minerals produced in 1985(Boyle, 1986). In 1981, the total value of Florida's mineral production(including fuels) was in excess of 3.8 billion dollars. In 1983, the Floridaphosphate industry was reported to have led the nation in phosphateproduction for 90 consecutive years (Boyle and Hendry, 1985). Floridaand North Carolina produced 87 percent of the national production ofphosphate in 1983 and approximately 27.4 percent of the world produc-tion (Stowasser, 1985a). These figures indicate the great importance ofindustrial minerals, and mining activities, to the economy of the State ofFlorida and the nation as a whole.

This publication is intended to respond to the needs expressed by thegeneral public, governmental agencies, and industry, regarding informa-tion on Florida's Economic Minerals. The report will help the reader morefully realize the impact of the mining industry on Florida's, and ultimatelythe nation's economy. The units of measurement utilized in this reportare those commonly used by the respective industries. The metric con-version factors for terms used in this report are given in Table 1.

TABLE 1

MULTIPLY BY TO OBTAINinches 25.4 millimetersinches 2.54 centimetersfeet 0.3048 metersmiles (statute) 1.6093 kilometerscubic feet 0.0283 cubic meterscubic yards 0.7646 cubic meterston (short, 2000 Ib) 0.8929 long ton (2240 Ib)ton (short, 2000 Ib) 0.9072 metric ton (2204.62 Ib)

CEMENT

Discussion

Portland cement and masonry cement are produced from a finelyground mixture of lime, silica, alumina and iron oxide. Heating, or calcin-ing the mixture in a rotary kiln forms a silicate clinker, which is then

2 BUREAU OF GEOLOGY

pulverized. Carefully controlled proportions of these ingredients are nec-essary to produce a satisfactory product.

The chemical composition of portland cement varies, depending on theend product specifications but generally ranges from Ca3SiO, throughCaAlIFe2 O,, (Lefond, 1975). The primary ingredient of portland cementis lime (CaO) which is obtained from limestone. Secondary ingredientsare silica, alumina and iron. Quartz sand is utilized to provide silica. Clayprovides silica, alumina, and iron oxide.

The raw materials for cement production in Florida can all be foundwithin the state, although some manufacturers are importing variousingredients. Lime is provided primarily by limestones mined in Florida.One manufacturer, however, has imported aragonite from the Bahamasfor this purpose (Wright, 1974). Quartz sand used in the manufacturingprocess is mined within the state, as is much of the clay. Known reservesof suitable clay in Florida are becoming depleted and portland cementproducers are increasingly looking outside the state for other sources.One company is presently importing kaolin from Georgia to supplementthe clay obtained in Florida. Staurolite can be used to supply the aluminaand part of the iron that is required by the cement formula. The mineralstaurolite is a product of heavy mineral separation in the Trail Ridge areaof north Florida.

Economic Trends

Cement production is closely tied to construction activity. Demand forcement is expected to increase at an annual rate of about two percentthrough 1990 (Johnson, 1985). In 1984, production of portland cementin Florida was up seven percent from the levels of 1983, while masonrycement production was up 26 percent (Boyle and Hendry, 1985; Boyle,1986). Preliminary figures for 1985 indicate a decrease to approximately1983 levels for the production of portland cement, and an increase ofapproximately four percent in masonry cement. Value of portland cementincreased five percent from 1983 to 1984 while the value for masonrycement rose 26 percent. Preliminary figures for 1985 values indicate adecrease to 1983 levels for portland cement and an increase of approxi-mately seven percent for masonry cement (Boyle and Hendry, 1985;Boyle, 1986). There are presently five cement producers active in Flor-ida, with all operations located in the central and southern portion of thestate.

Environmental Concerns

The environmental concerns of prime importance with respect tocement manufacturing are air and water pollution. Control of fugitivedust is the main means of alleviating these problems. Current Environ-mental Protection Agency (EPA) regulations limit total suspended solids,pH and effluent temperature which can escape from kilns and clinker

QUANTITY (THOUSANDS OF SHORT TONS)

VALUE (MILLIONS OF DOLLARS)

p PRELIMINARY DATA

4.0 250

3.00 150

>. 3.5 200 o.I- u. N 0 v . 00

0m3.0 150 00

0o t "*

2.5 100 Cy to ,

0 0 0.

2.0 50s -0

1976 1977 1978 1979 1980 1981 1982 1983 1984 1985

YEAR

Figure 1. Quantity and value of portland cement (Boyle, 1986; U. S. Bureau of Mines,1977 - 1983).

wo

* QUANTITY (THOUSANDS OF SHORT TONS)

- VALUE (MILLIONS OF DOLLARS)

p PRELIMINARY DATAw 0-

= > ( 00 500 25 4

0 NN SN h.

SN a

400 20 " ) C

Coo a rrO

300 15 Ca o c 0NC4 G°)

Nym

200 .100

1005 5 a amU U UJ

0 10 II

1976 1977 1978 1979 1980 1981 1982 1983 1984 1985YEAR

Figure 2. Quantity and value of masonry cement (Boyle, 1986; U. S. Bureau of Mines,1977 - 1983).

INFORMATION CIRCULAR NO. 102 5

coolers and stacks. Electrostatic precipitators and glass bag dust collec-tors are widely utilized. When the chemical makeup of the dust is notorohibitive (excess alkali), the collected dust can be recycled to the firingand of the kiln (Hall and Ela, 1978) reducing the amount of dust whichmust be handled for disposal. EPA regulations require strict dust disposalcontrol to eliminate potential water pollution with limitations on quantityof suspended solids and runoff pH.

Energy demands may be considered as an environmental concern.Cement manufacturing is highly energy intensive. Oil and gas shortages,and sharply increased fuel costs have impelled cement producers to con-sider coal as a primary and/or back-up fuel. Reduction in energy con-sumption is possible with new plants being designed to be energy effi-cient. Energy efficiency may be enhanced by recycling waste heat, dryprocess grinding, blending and conveying, reduction in kiln size and com-puter process and blending control (Schmidt, et al., 1979).

CLAYS

Clay deposits are found in many parts of Florida, but only in certainlocations are they found with the proper mineralogy, purity and volumenecessary for commercial exploitation. External factors such as readyaccess to transportation facilities, power supply and the labor force mustalso be favorable.

The U.S. Bureau of Mines classifies clays into six groups. These arekaolin, ball clay, fire clay, bentonite, fuller's earth, and common clay(Ampian, 1985a). Clays that are presently mined in Florida includefuller's earth, kaolin and common clays for use as lightweight aggregate,cement ingredients and construction material. With the exception ofkaolin, these clays are generally composed of varying amounts of theminerals smectite, kaolinite, or palygorskite (formerly called attapulgite).

Geology

Clay is a general term for common materials which have a very fineparticle size and which exhibit the property of plasticity when wet.Strictly speaking, clay is both a size term and the name of a group ofminerals. Clay sized particles are those which are less than 0.000154inches (1/256 mm) in largest dimension. Clay minerals are composed ofhydrous aluminum or magnesium silicates forming the minerals kaolinite,smectite, illite, halloysite and palygorskite. These minerals combine witha large number of possible clay sized impurities including silica, ironoxides, carbonates, mica, feldspar, potassium, sodium and other ions(Hosterman, 1973). The large number of possible components increasesthe potential for variation from deposit to deposit.

The term fuller's earth is derived from the original use of the material,that of cleaning wool and textiles. Ampian (1985a) states that, "theterm has neither a compositional nor a mineralogical connotation and the

6 BUREAU OF GEOLOGY "

substance is defined as a non-plastic clay or clay-like material, usuallyhigh in magnesia, that has adequate decolorizing and purifying proper-ties." Fuller's earths are composed primarily of palygorskite or varietiesof smectite (Ampian, 1985a). Florida fuller's earths in the GadsdenCounty area are predominantly palygorskite while those located inMarion County consist primarily of smectite (Hosterman, 1973).

The fuller's earth deposits in Gadsden County occur as beds andlenses in the upper part of the Hawthorn Group of Miocene age. TheHawthorn Group in the Gadsden County area is composed primarily ofsand, silt and clay, thin limestone beds and minor amounts of phos-phorite. The fuller's earth generally occurs as two beds, each two toeight-feet thick, separated by a hard sandy bed as much as 11 -feet thick.Above this is a sequence of lenticular, reddish-brown, brown, andyellowish-brown clayey sands, clay beds, and local channel-fill graveldeposits known as the Miccosukee Formation. The upper part of theHawthorn Group and the Miccosukee Formation together constitute anoverburden thickness which ranges from a few feet to 75 or more feet.

The fuller's earth deposits located in Marion County represent thelower Hawthorn Group and are located on the edge of the Hawthornoutcrop belt. The fuller's earth clays are the only Hawthorn materialpresent (T. Scott, personal communication, 1983). The fuller's earth isunderlain by limestone of the Eocene Ocala Group, and is overlain byundifferentiated sands, clayey sands and sandy clays (Patrick, et al.,1983; T. Scott, personal communication, 1983).

The ore zone is approximately 26-feet thick and consists of severalbeds of clay containing various amounts of quartz sand and silt, phos-phorite granules and dendrites (Patrick, et al., 1983). The clay mineralspresent in the fuller's earth include illite, sepiolite, smectite and possiblypalygorskite (Patrick, et al., 1983). Up to 28 feet of overburden coversthe fuller's earth. The overburden is often much thinner where part of theoverburden material has been removed by erosion (Patrick, et al., 1983).

There is only one active kaolin mine in Florida, located in westernPutnam County. This deposit is of probable Pliocene age, although, at thepresent time, there is uncertainty as to the formation identity and age(Scott, 1978; personal communication, 1985). The kaolin comprisesless than 20 percent of the material mined (Calver, 1957); the remainderis predominantly quartz sand with minor amounts of mica, feldspar andheavy minerals.

Common clays occur in essentially all of the geologic formationsexposed at the surface in Florida and in most of the counties. At present,only one company is mining clay in Florida for use as lightweight aggre-gate. This deposit located in Clay County is a naturally bloating claycomposed primarily of smectite and kaolinite and is thought to belagoonal in origin (Edward Phillips, personal communication, 1983). Thedeposit is of Pliocene to Pleistocene age (T. Scott, personal communica-tion, 1983).

Approximately 10 feet of sand overburden must be removed to expose


the bloating clay. The upper bed is brown clay which averages 15 feet inthickness and contains a lower percentage of kaolinite than smectite.This upper bed is separated from a lower clay bed by two feet of whitequartz sand. The lower clay bed averages 20 feet in thickness and con-tains smectite as the dominant clay mineral. Both beds contain lenses ofshelly clay which are not used (Edward Phillips, personal communication,1983).

Mining and Beneficiation

All clays in Florida are mined by the open pit method. The overburdenis first removed by a dragline or earthmover. A dragline is utilized toremove the clay, which is then trucked to the plant for processing. Thekaolin-bearing sands are mined by a floating suction dredge.

The processing procedures vary widely due to the different purposesfor which the clay is mined. The processing required for fuller's earthconsists of drying, grinding, grading by size and packaging.

The kaolin-bearing sands are beneficiated by separation of the sandand clay and removal of impurities through a series of disaggregating,washing, screening, thickening, filtering, and drying operations. Thesand fraction is retained, further beneficiated and classified.

Clays for lightweight aggregate production are fired in a rotary kiln athigh temperatures. Two conditions are necessary for bloating (expand-ing) to occur. When the bloating temperature is reached, the clay massmust be in a pyroplastic condition and, at the same time, gasses must beevolving throughout the clay mass (Conley, et al., 1948). The product isa mass comprised of thin-walled bubbles produced by the gas expansion.The expansion process is dependent on impurities in the clay such as ironcompounds, alkaline earths (CaO, MgO) and alkalis (K,Na,0), carbon insome cases, and on pH (generally greater than 5) (Conley, et al., 1948).The clay structure seems to play little part in the bloating process. Afterfiring, the expanded product is graded by size.

Uses

Fuller's earth is a term applied to clays and clay-like materials whichhave adequate decolorizing and filtration properties. These clays wereoriginally used to "full" or remove oil from woolen cloth and fibers. Theterm is still used today although the primary uses of the clays havechanged. Fuller's earth is used primarily as an absorbent (oil dry, kittylitter, etc.), for drilling muds, as a carrier for insecticides and fungicides,and for filtering and decolorizing. The advantage in using fuller's earth asa drilling mud is that it does not flocculate (settle out) when salt water isencountered (Hosterman, 1973).

Lightweight aggregates are used to reduce the unit weight of concreteproducts without adversely affecting their structural strength. Someproperties of lightweight aggregates are: their relative light weight, high

8 BUREAU OF GEOLOGY

Figure 3. Fuller's earth mine, Marion County.Photo by Tom Scott.

fire resistance, substantial compressive strength, good bonding withcement, chemical inertness, and abrasion resistance.

Kaolin mined in Florida has uses which include ceramics, whiteware,refractory brick, wall tile, and electrical insulators. Additional industrialapplications include use in paint, paper, rubber and plastics (Ampian,1985a).

Common clays have a variety of uses, such as road construction, brickmanufacturing, and manufacturing of portland cement. Very little clay isutilized in road construction, as limestone is the major road base materialused in the state. Only a few county road departments maintain "clay"(usually a clayey sand) pits for local road construction and maintenance.


There is presently only one brick-manufacturing operation in the state,ocated at the Apalachee Correctional Institution at Chattahoochee. This.s not a commercial enterprise, and all of the bricks produced are used bystate agencies. All commercial brick manufacturing plants in Florida haveclosed due to economic reasons.

Clay is commonly used as a source of silica and alumina in the manu-facturing of portland cement. In the southern part of the state, knownclay deposits are very scattered and usually have a high content of impu-rities. One manufacturer of portland cement imports kaolin from Georgiafor use as a source of alumina while another uses staurolite, which isobtained as a by-product of the heavy minerals industry in Clay County.

Transportation and Economic Trends

Transportation of clays mined in Florida is primarily by truck and rail.Demand for the various types of clay is expected to increase 2-4 percentannually through 1990 (Ampian, 1985b). Production of clay increasedapproximately 13 percent in 1984 from 1983, while value (excludingkaolin) increased approximately eight percent (Boyle and Hendry, 1985;Boyle, 1986). Preliminary figures for 1985 indicate an increase ofapproximately 16 percent and 47 percent for production and valuerespectively over the 1984 figures (Boyle, 1986).

Reserves

The majority of the state, with the exception of south Florida, containsabundant quantities of common clays. The U.S. Bureau of Mines(Ampian, 1985a) states that Florida reserves of common clays are virtu-ally unlimited. Individual deposits, however, are not necessarily suitablylocated or suitable for specific purposes. Identified deposits of commonclays suitable for lightweight aggregate are quite limited. This situationprobably reflects lack of exploration and testing. Fuller's earth resourcesare estimated to be 300 million short tons (Ampian, 1985a). Reserves forkaolin are not specified by Ampian (1985a), but can be considered lim-ited to moderate.


Environmental concerns related to clay mining are primarily associatedwith air and water pollution. Dust control measures and settling pondsare used to help alleviate these problems in and around production plantsand storage areas. Timely land reclamation and revegetation will mini-mize the effects of dust and runoff from mining areas.

1300 50

00

1200 45 0

i QUANTITY ( THOUSANDS OF SHORT TONS )1100 40 N

S0 VALUE ( MILLIONS OF DOLLARS )

P PRELIMINARY DATA0

1000 35 * EXCLUDES KAOLIN VALUE

S 5 ,.:O " nCrV

> 900 30---

4 -J n V

_0 0

700 20 (

600 15

o500 10 ___ .. -1976 1977* 1978 1979* 1980* 1981 1982 1983 1984 1985

YEAR

Figure 4. Quantity and value of clays (Boyle, 1986; U. S. Bureau of Mines, 1977- 1983).

,il ,.,B,,g^^tT,...,., , i. .,,,,r. .. ,., . ,- ..


HEAVY MINERALS

Geology

The history of the Florida heavy mineral deposits began millions ofyears before their deposition in Florida sediments. The heavy mineralswere originally formed in the igneous and metamorphic rocks of the BlueRidge and the Piedmont regions in the southern Appalachians (Gilson,1959). Following extensive weathering and erosion of the crystallinerocks the heavy mineral grains were subjected to a lengthy period ofabrasion and winnowing as they were transported by fluvial and marinelongshore currents. Finally, they were deposited as sedimentary grains inFlorida. None of the economically important detrital minerals found inFlorida sediments are known to occur in Florida sedimentary rocks asprimary minerals (Garner, 1972).

Heavy minerals are associated with essentially all of the quartz sandsand clayey sands in Florida, however, economically valuable concentra-tions are much less widespread. The areas which are of economic impor-tance are the Trail Ridge and Green Cove Springs deposits located in thenortheast peninsula of Florida. All of the commercially valuable heavymineral deposits in Florida are inland from the present shoreline, and aregenetically associated with older, higher shore lines (Pirkle, et al., 1974).

TRAIL RIDGE DEPOSIT

The Trail Ridge is a sand ridge which extends southward from theAltamaha River in southeast Georgia into Clay and Bradford counties inthe peninsula of Florida, a distance of approximately 130 miles. Ridgecrest elevations range from approximately 140 feet in southern Georgiato approximately 250 feet near its southern end in Florida (Pirkle, et al.,1977).

The Trail Ridge heavy mineral ore deposit is located at the southern endof the Trail Ridge in Bradford and Clay counties. The ore body, which hasan average thickness of 35 feet, measures approximately 17-miles longby one or two miles wide. Heavy minerals (specific gravity greater than2.9) comprise approximately four percent of the deposit. The titaniumminerals rutile, ilmenite and leucoxene make up 45 percent of the heavymineral fraction (Carpenter, et al., 1953). Staurolite, zircon, kyanite,sillimanite, tourmaline, spinel, topaz, corundum, monazite and othersmake up the remainder of the heavy mineral fraction (Pirkle, et al., 1970).The base of the ore body rests either on barren quartz sands and clayeysands or on a compacted layer of woody and peaty materials includingtree branches, roots and trunks (Pirkle, et al., 1970).

The current hypothesis for the formation of the ore body is that TrailRidge was formed at the crest of a transgressive sea (rising sea level)which was eroding the sediments of the Northern Highlands of Florida(Pirkle, et al., 1974). The Trail Ridge is the highest and oldest shoreline

12 BUREAU OF GEOLOGY

along which commercial concentrations of heavy minerals have beenfound in Florida. The Trail Ridge deposit is significantly coarser in meangrain size than the sediments of the Northern Highlands because finesediments were winnowed out by wave and current activity. The compo-sition of the heavy mineral suite of the Trail Ridge deposit closelymatches that of the Northern Highlands (Pirkle, et al., 1974). Pirkle, et al.(1977) concluded from a study of heavy mineral grain sphericities thatthe high terrace sands of the Northern Highlands were the only possiblesource of sand for the Trail Ridge. Thus, this interpretation of the origin ofthe Trail Ridge is consistent with the mineral suite of the Northern High-lands as well as the physiographic and sedimentary features of the area(Pirkle, et al., 1977).

GREEN COVE SPRINGS AND BOULOUGNE DEPOSITS

The Green Cove Springs and Boulougne (now mined out) heavy min-eral deposits are located within the Duval Uplands. These deposits arebelieved to have formed within beach ridges on a regressional (falling sealevel) beach ridge plain associated with a sea level of 90-100 feet, withthe elevation becoming lower to the east (Pirkle, et al., 1974).

The Green Cove Springs ore deposit, which is oriented along a north-west to southeast trend, is located in southeastern Clay and northeast-ern Putnam counties. The deposit is approximately 12-miles long, 3/4-mile wide and 20-feet thick (Pirkle, et al., 1974). The Boulougne orebody (now mined out) is located several miles south of the Florida-Georgia border in Nassau County and measures three-miles long (N-Strend) by 1/2 to 3/4-mile wide and ranges from 5 to 25-feet thick (Pirkle,et al., 1974).

The Green Cove Springs and Bolougne heavy mineral deposits are finergrained than the Trail Ridge deposit. The sediment source for a regres-sional beach ridge plain would be, predominantly, sediments delivered bythe coastal littoral drift system. These sediments would tend to be rela-tively fine and would contain heavy mineral suites characteristic of theirsource areas. This can explain the finer texture of the Duval Uplandbeach ridge sediments as well as the occurrence of garnet and epidote inthe heavy mineral suite (Pirkle, et al., 1974).

Mining and Beneficiation

The mining process begins with harvesting any timber present andclearing the land of vegetation. Top soil, if present, is stockpiled for lateruse in reclamation. Heavy mineral sands are mined by a floating suctiondredge equipped with a cutter head. The dredge and wet mill float in aman-made pond. The dredge cuts into the banks of the pond, whilewaste sand, after processing in the wet mill, is backfilled into the pondbehind the dredge.

Initial heavy mineral separation is carried out within the wet mill by the


Figure 5. Heavy minerals "wet mill" beneficiation plant. Photo courtesyof the Florida Bureau of Mine Reclamation.

use of Humphreys Spiral Concentrators. Spiral concentrators treat an orewhich contains approximately four percent heavy minerals, and produce,after several stages, a concentrate which averages 85 percent heavyminerals (Garner, 1971). Based on the acreage mined in 1985 (FloridaBureau of Mine Reclamation figures) and assuming the 'average' thick-ness of the two deposits presently being mined (Trail Ridge and GreenCove Springs), approximately 43 million cubic yards of material wereprocessed through the wet mills, resulting in approximately 1.6 millioncubic yards of wet mill concentrate. Wet mill concentrates are pumped toland based dry. mills for further processing.


The initial step in processing wet mill concentrates is scrubbing usingsodium hydroxide to remove organic coatings and clay minerals from thegrains. Scrubbed material is dried and then separated on a series of hightension separators which take advantage of the variation in the electricalconductivity of the different minerals (Garner, 1971). Titanium minerals(ilmenite, rutile, and leucoxene) have relatively good electrical conduc-tance and are separated from the heavy silicate minerals (includesstaurolite, zircon, kyanite, sillimanite, tourmaline and topaz) and quartzwhich pick up an electrical charge and adhere to the separator rotor(Evans, 1955). The concentrate is thus separated into titanium minerals,tailings composed of heavy silicate minerals and quartz, and a middlingfraction of poorly separated grains which is recycled through the hightension separator.Concentrate from the high tension separator is separated magnetically.The magnetic portion is shipped as ilmenite which contains 98 percenttitanium mineral and averages 64.5 percent TiO, (Garner, 1971). Thenonmagnetic fraction is recycled through high tension separators to sep-arate leucoxene and rutile as a product which analyzes 80 percent TiO2.After ilmenite, leucoxene and rutile are removed, tailings are recycled tothe initial high tension separators, and high intensity magnets separatestaurolite from zircon. Tailings from the staurolite separation are treatedin spirals to remove heavy silicates and quartz sand (Garner, 1971).Through continuous control and recycling of materials nearly all of theheavy minerals are recovered.

Products and Uses

The major use for the titanium-rich heavy minerals (ilmenite, rutile andleucoxene) is for titanium dioxide pigment (known for its whiteness,spreading quality and chemical stability). Ninety-nine percent of theilmenite and 84 percent of the rutile was utilized in the manufacture ofwhite pigments in 1984 (Lynd, 1985a).

Staurolite is an iron-aluminum silicate mineral containing 45 percentALO, and 13 to 15 percent Fe203. Staurolite product also contains tour-maline and spinel as well as silicates with magnetic inclusions. Thismaterial is utilized primarily as a source of iron and alumina in the manu-facture of portland cement and as an abrasive (Garner, 1971).

Zircon is found in economic quantities in the Trail Ridge area, and isrecovered from the ore after the ilmenite and rutile have been removed.Zircon is a silicate of zirconium with a theoretical composition of 67.2percent ZrO, and 32.8 percent SiO2 (Dana, 1946). It is a constituent ofpractically all stream and beach sands, however, it occurs in rather smallquantities in most deposits. The consumption of zircon in the U.S. in1984 was as follows: 45 percent was used in foundry sands, 20 percentin refractories, 12 percent in ceramics, six percent in abrasives and therest in making zirconium metal and alloys and in chemical manufacturing(Adams, 1985).


Monazite is a phosphate mineral which concentrates the rare-earthelements (cerium, yttrium, lanthanum, and thorium) and contains up to12 percent thorium oxide and one percent uranium oxide. Monazite is notpresent in commercial quantities in the Trail Ridge deposit but is pres-ently recovered from the Green Cove Springs deposit. Thorium that isderived from monazite is used as a fertile material in commercial high-temperature gas-cooled nuclear reactors and experimental nuclear reac-tors to produce fissionable U-233. The major use at present is to producecatalysts utilized in cracking petroleum crude. Non-energy uses includethe manufacture of gas mantles, high temperature alloys used in theaerospace industry, refractory materials, optical glass, and other miscel-laneous uses. Cerium is also extracted from monazite and is used in theproduction of iron alloys, mischmetal (a metallic mixture of rare earthelements), ferrocerium, carbon arc electrode cores, glass polishing proc-esses and other miscellaneous uses (Moore, 1980).


Heavy mineral concentrates are shipped primarily by rail. Covered hop-percars are utilized in bulk shipments (Lynd, 1980). Production and valuefigures for heavy minerals in general (and the individual mineral compo-nents) are withheld to protect the confidentiality of individual compan-ies. In 1983, Florida was the only U.S. producer of staurolite, rutile,zircon and rare earth minerals from mineral sands and was one of onlytwo states with ilmenite production (Boyle and Hendry, 1985). From a1984 level, demand for titanium sponge metal is expected to increase atan annual rate of five percent through 1990. Titanium sponge metal is aspongy metal produced by reducing purified titanium tetrachloride withsodium or magnesium in an inert atmosphere. Residual chlorides areremoved by leaching, inert gas sweep or vacuum distillation. The spongeis compacted and formed into ingots by vacuum arc melting (Lynd,1985b).

Demand for TiO2 pigments will increase from a 1981 base at twopercent annually (Lynd, 1985a). U.S. production of ilmenite in 1982 wasthe lowest since 1954 at 263,000 short tons of contained TiO, (Lyndand Hough, 1980; Lynd, 1985a).

Zirconium demand is expected to increase at a four percent annual ratethrough 1990 (Adams, 1985). Rare earth metals demand is expected toincrease at an annual rate of three percent through 1990 (Hedrick,1985).

Reserves

Florida reserves of titanium minerals consist of 5.2 million short tons ofcontained titanium from ilmenite and rutile (Lynd, 1985b). Reserves ofrare earth minerals are considered limited.



Environmental problems associated with heavy mineral mining in Flor-ida are relatively minor. Water quality problems related to suspension ofclay and organic material are the most prevalent and may require use ofsettling ponds to maintain water quality.

Land reclamation is required by the state of Florida on all land mined forheavy minerals. Recontouring and revegetation are among the require-ments. Timely reclamation will help minimize the impacts of mining.

MAGNESIUM COMPOUNDS

Florida ranked second in the nation in the production of caustic-calcined and refractory grade magnesium compounds recovered fromseawater in 1983 (Boyle and Hendry, 1985). One company producedmagnesium compounds in Florida.

Processing

Seawater is utilized as a source in the production of caustic-calcinedand refractory magnesia as well as magnesium metal (Kramer, 1985a).Carbonate and sulfate levels in the feed water must be reduced to pre-vent the precipitation of insoluble calcium compounds. Carbonate andsulfate level reduction is accomplished by treatment with slaked lime toprecipitate calcium carbonate (CaCO 3) or by treating with acid to releasecarbon dioxide (CO,). The treated solution is mixed with dry or slakedlime to precipitate magnesium hydroxide which is thickened, washedwith fresh water and filtered. The filter cake is then calcined to producecaustic-calcined or refractory magnesia or may be calcined and pelletizedprior to dead burning (Kramer, 1985a). Caustic-calcined magnesia is pre-pared at temperatures up to 16400 F and is water reactive. Dead burned,or refractory, magnesia is prepared at temperatures greater than 2640°Fand is not reactive with water (Kramer, 1985a).

Uses

In 1985, 85 percent of the magnesium consumed in the U.S. was inthe form of magnesium compounds. The majority of magnesium com-pound use is in the form of refractory magnesia (Kramer, 1985a; Adams,1984) used primarily by the iron and steel industry for furnace refracto-ries (Kramer, 1985a). Caustic-calcined magnesia is used primarily in themanufacture of chemicals (Kramer, 1985a). Magnesium compounds areused to prepare animal feeds, fertilizer, rayon, insulation, metallic magne-sium, rubber, fluxes, chemical manufacturing and processing, petroleumadditives and paper manufacturing (Kramer, 1985a; Adams 1984).


Economic Trends

Production figures for Florida are not available, to protect the confiden-tiality of individual company data. Adams (1984) shows the productioncapacity of Basic Magnesia Co. (the sole Florida producer) as 100,000short tons of MgO equivalent. Kramer, (1985b) estimates that in 1984,the magnesium compounds industry operated at almost 70 percent ofcapacity.

Reserves

Reserves of magnesium compounds from seawater are virtually unlim-ited. Magnesium is the third most common element in seawater with anaverage content of 0.13 weight percent (Kramer, 1985a).


Magnesium plants which utilize seawater as a source return the waterto the ocean after magnesia removal. Turbidity of the return water hasbeen a problem in the past, however, modern treatment processes havereduced the degree of turbidity. The return water is not noxious (Kramer,1985a).

OIL AND GAS

Florida's oil and gas production is from two widely separated groups offields. The first group is located in Collier, Dade, Hendry and Lee countiesand includes the Sunniland, Forty Mile Bend, Sunoco Felda, West Felda,Lehigh Park, Lake Trafford, Bear Island, Mid-Felda, Seminole, BaxterIsland, Townsend Canal, Raccoon Point, Pepper Hammock and Cork-screw fields. The other group, located in Santa Rosa and Escambia coun-ties includes the Jay, Mount Carmel, Blackjack Creek and SweetwaterCreek fields and a presently unnamed field. The Forty Mile Bend, Semi-nole, Baxter Island and Sweetwater Creek fields have been plugged andabandoned.

Geology

The south Florida fields produce from a combination of subtle struc-tural traps and stratigraphic traps in the Sunniland Formation of EarlyCretaceous Age. Production is from porous limestone containing abun-dant disoriented gastropods and pelecypods (rudistids) (Al Applegate,Florida Geological Survey, personal communication, 1983).

The oil and gas fields of northwest Florida produce from a combinationof structural and stratigraphic traps in the Jurassic Smackover Formation(Sigsby, 1976). The productive interval of the Smackover is a porousdolomite which includes a lower transgressive interval of mud flat and


Figure 6. Getty Oil drilling rig, East Bay, Santa RosaCounty. Photo by Walt Schmidt.

algal mat deposits and an upper regressive interval composed of hard-ened pellet grainstones (Ottmann, et al., 1973).

Products and Uses

Crude oil and natural gas are utilized primarily as fuels of various types.Gasoline, kerosene, diesel fuel, jet fuel, fuel oil and propane, ethane, andmethane gases are examples. Lubricants, synthetic fibers, plastics,asphalt and paraffin wax are examples of other products produced from


petroleum (U.S. Dept. of Energy, 1979). Sulphur is produced as a by-product from the northwest Florida fields.

Transportation

All crude oil produced in Florida is shipped by pipeline or barge torefineries in other states (Christ, et al., 1981). Crude oil from the southFlorida fields is shipped by truck and pipeline to Port Everglades fordistribution. Crude from the northwest Florida fields is transported by16-inch pipeline to storage facilities in Alabama (Christ, et al., 1981).

Natural gas from the northwest Florida fields is shipped by pipeline andtruck after natural gas liquids are stripped from the gas. Florida GasTransmission Pipeline Company and Five Flags Pipeline Company marketnatural gas to residental, commercial and industrial customers within thestate (Sweeney and Hendry, 1981).

Production Trends

In 1978, Florida ranked ninth nationally in production of petroleumcrude with 1.4 percent of the national production (Independent Petro-leum Association of America, 1979). Production of petroleum and natu-ral gas in Florida has been declining since 1978. Estimated 1985 oilproduction is down 76 percent from the 1978 figure and 20 percent from1984. Natural gas production is down 77 percent from 1978 and 15percent from 1984. This trend is expected to continue unless additionalreserves are discovered in the near future (Florida Bureau of Geology,unpublished data).

Reserves

Proven crude oil and natural gas reserves as of December 31, 1984,consisted of 82 million barrels of oil and 90 billion cubic feet of naturalgas (U.S. Dept. of Energy, 1985). Statewide cumulative oil production,through 1984, totals 474.976 million barrels. Cumulative natural gasproduction totals 483.877 billion cubic feet (Applegate and Lloyd,1985). In 1984, 76.5 percent of the crude oil production and 98 percentof the natural gas was from the northwest Florida fields (Florida Bureauof Geology, unpublished data).


The environmental concerns associated with oil and gas drilling inFlorida center on fresh water resource protection, protection of environ-mentally sensitive lands and endangered species. Aquifer protection isensured by proper well construction techniques, which are designed toisolate freshwater aquifers from deeper saline water zones by cementingcasing in place through the entire fresh water zone and into the salt

50,000 1 %

lm- OIL IN THOUSANDS OF BARRELS I •

45,000 ,,- GAS IN THOUSANDS OF MCF II

40,000 I

35,000

30,000 m

C25,000 1 \

I \ 00

15,000 | m

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1943 1945 1950 1955 1960 1965 1970 1975 1930 1935

Figure 7. Past and present oil and gas production from Florida fields (FloridaBureau of Geology figures).

70 1400

*O QUANTITY (MILLIONS OF BARRELS) (1 BARREL-42 U.S. GALLONS)

S2 VALUE (MILLIONS OF DOLLARS)>60 1200 -

p PRELIMINARY DATA

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QUANTITY ( BILLIONS OF CUBIC FEET

D VALUE I MILLIONS OF DOLLARS )p PRELIMINARY DATA

50 100 A 6 n 1 f)

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Figure 9. Quantity and value of natural gas (production: Florida Bureau of Geology figures;value: Independent Petroleum Association of America 1978 - 1984).


water zone. Personnel from the Florida Bureau of Geology, Oil & GasSection, inspect the well construction.

Proposed well locations in the Big Cypress Swamp of south Florida areinspected by the Big Cypress Swamp Advisory Committee which wasset up by the Governor and Cabinet of Florida. This five-member commit-tee consists of the State Geologist, a professional hydrologist and aprofessional botanist, as well as one representative from a statewideenvironmental group, and one member from industry. Well drilling andrelated plans are modified as necessary to minimize the impact on wild-life and surface habitats.

Byproduct Sulphur

Crude oil from Jay Field area contains 87 percent hydrocarbons, 10percent hydrogen sulfide and three percent carbon dioxide and nitrogen(Ottmann, et al., 1973). The gas produced in this area also containshydrogen sulfide. The removal of the hydrogen sulfide from crude oil andnatural gas has resulted in a significant byproduct sulphur resource. Aplant treating 12,000 barrels a day will produce 80 long tons (89.6 shorttons) of sulphur per day (Ottmann, et al., 1973). Sulphur is shipped bytruck in liquid form to Mobile, Alabama.

PEAT

The following discussion is summarized in large part from a detailedFlorida Geological Survey publication on the peat resources of Florida(Bond, et al., 1984) entitled An Overview of Peat in Florida and RelatedIssues.

Geology

The conditions under which peat occurs in Florida are highly variable.The geological and hydrologic relations of peat to adjacent materials arepoorly understood. Davis (1946) divided the peat deposits of Florida intoa number of groups based on their locations. These groups include: 1)Coastal associations, including marshes and mangrove swamps, lagoonsand estuaries as well as depressions among dunes, 2) large, nearly flat,poorly-drained areas as exemplified by the Everglades, 3) river-valleymarshes such as the marsh adjacent to the St. Johns River, 4) swamps ofthe flat land region, 5) marshes bordering lakes and ponds, 6) seasonallyflooded shallow depressions, 7) lake bottom deposits, and 8) peat layersburied beneath other strata. In Florida, peat deposits may be either wetor dry, (Davis, 1946; Gurr, 1972). Wet peat deposits occur if the water-table remains relatively high. Peat may be actively accumulating in thesedeposits. Certain areas within the Everglades, the coastal mangrovepeats, and some lake-fringing peat deposits, such as the one associatedwith Lake Istokpoga, are examples of undrained deposits in the state. In


other instances, peat deposits are dry. This drainage may have beeninitiated to enhance the land for agricultural use. The Everglades agricul-tural region contains numerous tracts drained for this purpose. Otherdeposits have apparently been drained as a result of regional lowering ofthe water table.

Peat forms when the accumulation of plant material exceeds itsdestruction by the organisms which decompose it. Certain geologic,hydrologic and climatic conditions serve to inhibit decomposition byorganisms. Ideally, areas should be continually waterlogged, tempera-tures generally low, and pH values of associated waters should be low(Moore and Bellamy, 1974).

Certain geologic characteristics are associated with waterlogged sur-face conditions. The tendency toward waterlogging is enhanced if topo-graphic relief is generally low and topographic barriers exist whichrestrict flow and allow water to pond. Additionally, waterlogging isencouraged if highly permeable bedrock is covered with material of lowpermeability (Olson, et al., 1979).

The chemical nature of the plant litter may also serve to reduce itssusceptibility to decomposition. Moore and Bellamy (1974) note theassociation of cypress and hardwood trees with peats characteristic ofthe hammocks or tree islands of the Everglades. These hammocks occuron peat deposits which are situated on limestone bedrock. The trees,which are responsible for the peat beneath them, contain enormousamounts of lignin, an organic substance somewhat similar to carbohy-drates which occurs with cellulose in woody plants. Lignin is very resist-ant to decay and acts as a 'preservative' (Moore and Bellamy, 1974).

Rates of peat accumulation computed from radiocarbon age dating aregrouped about an average of 3.6 inches per 100 years. The rate of peataccumulation can vary with climate (which also varies with time), theposition of the water table, and nutrient supply (Moore and Bellamy,1974).

Mining

Almost all peat presently mined in Florida is utilized for agricultural orhorticultural purposes. Draglines and other earthmoving equipment areutilized in removing vegetation and peat. Moisture must be reduced toapproximately 90 percent for the bog to bear the weight of machinery.Drainage is an integral and necessary first step in most large scale miningoperations. After excavation, the material is partially air dried and shred-ded or pulverized (Davis, 1946). If peat is utilized on a larger scale forfuel, more technologically advanced methods will need to be employedand will probably be similar to current European peat technology. Thisimplies that peat will be air dried and burned directly (Kopstein, 1979).


Uses

The principal extractive use of Florida peat is as a soil conditioner, withlarge amounts used for lawns, golf courses, and in nurseries and green-houses. The benefits derived from the use of peat result largely fromimproved physical conditions in the soil. Also, peat's ability to hold eightto 20 times its own weight in water makes it valuable in the improvementof soils.

Farming is the major consumptive nonextractive use of peat in Florida.One major effect of farming is the deterioration of peat by the variousprocesses which result in subsidence. Subsidence occurs when organicsoils decrease in volume and is the net result of a number of causes: 1)shrinkage due to desiccation, 2) consolidation which occurs with loss ofthe buoyant force of water, as well as from loading, 3) compactionaccompanying tillage, 4) erosion by wind, 5) fire damage, and 6) bio-chemical oxidation (Stephens, 1974). Biochemical oxidation results inactual soil loss, as opposed to volume decrease. It is the primary cause ofdeclining soil thickness in south Florida.


Both bulk and packaged peat are shipped primarily by rail and truck(Searls, 1980). In 1984 Florida ranked first in U.S. peat production(Davis, 1985a). Florida peat production reported in 1984 increased dra-matically from 114,000 short tons in 1983 to 263,000 short tons in1984 due to a large increase in companies reporting production (Boyle,1985). The U.S. Bureau of Mines production figures up to 1983 repre-sented production reported by five companies. In 1984, there were 21peat producers in Florida (Bond, et al., 1984), however, only 15 reportedproduction to the U.S. Bureau of Mines. Nationwide demand is expectedto increase from a 1983 base at an annual rate of approximately 3.3percent through 1990 (Davis, 1985b).

Reserves

The known original reserves of peat in Florida were estimated by Soperand Osbon (1922) at 2 billion short tons (air dried). Recent reserve esti-mates have varied widely. The American Association of Petroleum Geol-ogists (1981) reported the estimate of 6.8 billion short tons (air dried).Griffin, et al. (1982) report that, 'It is now estimated that Florida couldproduce 606 million tons of moisture free peat' of fuel grade if no otherconstraints were present (cost, environmental problems, land use con-flict, etc.).

320 6.4 n

QUANTITY (THOUSANDS OF SHORT TONS) 0

280.5,6 5-50 5 VALUE (MILLIONS OF DOLLARS) An

P PRELIMINARY DATA

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1Figure I U. Uuantity and value of peat (Bovle. 1 9B: U. S. S. Breau of Mirmin. 1.977- 1 0&) ___



Drainage, or water level control undertaken in order to create a work-able substrate affects the vegetation in two primary ways. Within thearea to be mined and also in areas designated for processing, storage,roads, and parking lots, vegetation must simply be cleared or eliminated.The ditch system devised for drainage lowers the water table bothbeyond and within the boundaries of the area to be mined (MinnesotaDeparment of Natural Resources, 1981). The lowering of the water tableaffects vegetation in that original plants adapted to wetland situationswill be replaced by plants tolerant of drier conditions. The elimination ofvegetation destroys wildlife habitat and results in displacement of wild-life. The changes in vegetation which accompany drainage will result inchanges both in population and species make-up of wildlife inhabiting anaffected area (Minnesota Department of Natural Resources, 1981).

Surficial waters will be affected by drainage. Ditches used in drainagemay disrupt flow down slope from a bog. Drainage may also alter thehydrologic budget of a peatland. Evapotranspiration will be reducedbecause the water resides deeper within the ground due to the loweringof the water table. It is thus more difficult for moisture to reach thesurface. The Minnesota Department of Natural Resources (1981) reportsthat changes in evaporation and water stored must affect runoff, but theeffects are poorly understood. It seems that drainage results indecreased peak runoff so that runoff is distributed more uniformlythroughout the year.

Recharge to the shallow aquifer occurs in Florida's wetlands (McPher-son, et al., 1976). Drainage canals constructed in the Everglades haveresulted in accelerated runoff which, in consequence, has reduced theamount of water available to recharge the shallow aquifer (McPherson,et al., 1976). This relationship between canals, runoff, and water avail-able for recharge should be considered if peat mining requires drainage.The effects will, of course, depend on the size of the area to be minedand its relation to the regional aquifers.

The last implication of drainage is that of peat subsidence. The caus-ative relationship between drainage and subsidence is well known inFlorida. Experience in the Everglades has shown that subsidence itselfhas very serious implications. Stephens (1974) reviews various aspectsof drainage and subsidence in the Everglades.

Most environmental problems associated with construction of pro-cessing, storage, and transportation facilities are short-lived. Excavationand landscaping will temporarily be associated with increased erosionand sediment in runoff water (Minnesota Department of NaturalResources, 1981). The construction and presence of roads, parking lots,and buildings will result in some further decrease in wildlife habitat.Certain species will be vulnerable to traffic. The low permeability ofpaving materials will generate some further increase in runoff.

The effects of mining universally include both removal of peat from the


site and alteration of the configuration of the landscape (MinnesotaDepartment of Natural Resources, 1981). If drainage is required, thepreviously discussed environmental effects of drainage must be consid-ered. Wet mining methods do not require drainage. The effects of wetmining on water quality and quantity depend strongly on the design ofthe operation. Specifically, if the mined area discharges to surfacestreams, both water quality and quantity may be affected (MinnesotaDepartment of Natural Resources, 1981). Additionally, and critically,given the already enormous demand for water in Florida, wet miningmethods may require water beyond that available in the peatland.

Since peat is characterized by a high moisture content, dewatering isoften necessary during processing. This water may contain an abun-dance of peat fibers as well as nutrients. Water released during dewa-tering, as well as waste water from gasification operations, can generatewater quality problems, although the effects may be mitigated if wastewater is treated (Minnesota Department of Natural Resources, 1981).The effects of exhaust emission and noise creation are universal in allphases of mining operations.

Peat, due to its high moisture content is heavy. The large amounts of itnecessary for fuel operations cannot be economically transported. Forthat reason peat will probably be burned near the site at which it ismined. Emissions from peat combustion are similar to those resultingfrom combustion of coal. These include nitrogen oxides, sulphur oxides,carbon monoxide, carbon dioxide, hydrocarbons, particulates and com-pounds of trace elements, including mercury and lead (Minnesota Depar-ment of Natural Resources, 1981).

PHOSPHATE

Discussion

River pebble phosphate was discovered in central Florida in the early1880's in the Peace River near the town of Fort Meade. The river haderoded away the overburden and finer fractions of the Bone Valley Mem-ber, leaving behind concentrations of pebble-size phosphate rock (knownas "river pebble") on the river bottom and in the sand bars.

The earliest mining of these deposits was in the river channel byhydraulic dredging. The residual or spoil material was returned to theriver, thus obliterating any visual record of the activity. Mining of thistype was intermittent and records of ore removal are poor. However, itappears that approximately 1.3 million long tons were removed over aperiod of 20 years before extraction costs caused cessation of opera-tions (Zellars-Williams, 1978).

Land pebble phosphate was discovered in the late 1880's, also in thevicinity of Fort Meade. It was this discovery that led to the eventualdemise of the hard rock phosphate (so named because it is found as areplacement mineral in limestone) and soft rock phosphate (mined from


the waste ponds of hard rock phosphate operations) industries. The hardrock phosphate district is located in portions of Taylor, Lafayette, Dixie,Gilchrist, Alachua, Levy, Marion, Citrus, Hernando and Sumter counties.Land pebble has larger reserves, is easier to mine, and has lower benefi-ciation costs. The vast majority of phosphate produced in Florida is landpebble, with only a few small companies producing colloidal (soft rock)phosphate.

The land pebble deposits of economic importance at the present timeare the Central Florida Phosphate District, the Southern Extension of theCentral Florida Phosphate District and the Northern District. The Centraldistrict is located in portions of Polk, Hillsborough, Hardee and Manateecounties, and the Southern Extension in portions of Hardee, DeSoto,Manatee, Sarasota and Charlotte counties. The Northern District islocated in parts of Hamilton, Columbia, Baker, Suwannee, Union, Brad-ford, Alachua and Marion counties (Zellars-Williams, 1978).

Geology

CENTRAL FLORIDA PHOSPHATE DISTRICT

The Central Florida Phosphate District encompasses the southwestcorner of Polk County, the southeast corner of Hillsborough County, andextends southward into Hardee and Manatee counties. The phosphatedeposits occur as a thin sheet of highly reworked marine and estuarinesediments deposited on the southern flank of the Ocala Arch. The phos-phate appears to have been deposited (for the most part) during theMiocene in warm shallow seas and generally near shore.

The Bone Valley Member, Peace River Formation, Hawthorn Group isthe primary phosphorite horizon being mined in the phosphate district.The most popular explanation for the formation of the Bone Valley phos-phate deposits is summarized by Altschuler, et al. (1964), "The BoneValley Formation (Member) is a shallow water marine and estuarinephosphorite ... (it) ... is an excellent example of marine transgressionduring which the phosphate was derived, by reworking, from the under-lying, weathered, Hawthorn Formation (Group)".

The Hawthorn Group, in the Central Florida Phosphate District consistsof sandy, phosphatic dolomite or dolomitic limestone of the Arcadia For-mation which is overlain by a predominantly clastic unit of interbeddedphosphatic sands, clayey sands, clays and dolomite of the Peace RiverFormation, including the Bone Valley Member. The Bone Valley Memberis the uppermost unit of the Peace River, and may contain several uncon-formities (Scott, 1986). In the central and northern part of the district,the Bone Valley overlies the Arcadia Formation unconformably. In thisarea, the bottom of the "matrix" (ore zone) is generally marked at thecontact between the eroded carbonate surface of the Arcadia and thephosphate-rich sands and clays. Occasionally, a palygorskite-rich clayunderlies the matrix. In the southern portion of the Central Florida Phos-

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phate District the Peace River Formation (undifferentiated) has not beenremoved by erosion (Scott, 1986).

The Bone Valley sediments are generally represented by approximatelyequal amounts of quartz, clays (chiefly smectite) and carbonate-fluorapatite, although proportions may change significantly within shortdistances (Altschuler, et al., 1956). Post-depositional alteration of theBone Valley Member has been severe, and may either diminish or enrichthe phosphate concentration. Weathering in the sub-tropical climates ofFlorida has resulted in lateritic types of leaching, mobilization and super-gene enrichment of phosphate. The weathering results in the alterationof carbonate-fluorapatite to calcium phosphates and aluminum phos-phates. Aluminum phosphates are less soluble than the calcium phos-phates and remain after the upper zones have been leached. Enrichmentof uranium is widespread within the leached zone. The more solublecalcium phosphates enrich the lower (ore) zones.

The Pleistocene sediments overlying the Bone Valley Member consistof loose quartz sands. The origin of these sands is a subject of debate.Altschuler and Young (1960) consider these sands to be a weatheringresiduum of the Bone Valley, while Cathcart (1962), supports a primarydepositional origin as the result of transgressive Pleistocene seas. Pirkle,et al. (1965) states that the surface sands are not the result of in situweathering of the Bone Valley Member.

SOUTHERN EXTENSION OF THE CENTRAL FLORIDAPHOSPHATE DISTRICT

The Southern Extension of the Central Florida Phosphate Districtencompasses portions of Hardee, Manatee, DeSoto, Sarasota and Char-lotte counties. Initial exploration efforts within the Southern Extensionwere directed toward the location of high grade deposits similar to theCentral District. It was soon realized, however, that the deposits of theSouthern Extension had an entirely different depositional history andgeologic setting from the Bone Valley type deposits. The Southern Exten-sion contains vast reserves of lower grade material (lower BPL, increasedcontaminants, especially MgO) which are predominantly containedwithin an upper clastic section (Peace River Formation) of the HawthornGroup (Hall, 1983). The sediments of the upper clastic section of theHawthorn are highly variable in lithologic composition both horizontallyand vertically and exhibit evidence of reworking of previously depositedmaterial (Hall, 1983). The traditional Bone Valley type sediments arefound only in northwestern Hardee County (Hall, 1983).

NORTHERN FLORIDA PHOSPHATE DISTRICT

The Northern Florida Phosphate District is present in parts of Hamilton,Baker, Columbia, Union, Bradford, Suwannee, Marion and Alachua coun-ties. This area is within the Northern Highlands physiographic province of


Figure 12. International Minerals and Chemicals Corp. Clear Springsphosphate mine, Polk County. Photo by Kenneth Campbell.

Florida (White, 1970). The Miocene beds pinch out against the flanks ofthe Ocala Arch to the west. Tertiary sediments deposited earlier than theMiocene in this area are predominantly porous marine limestones whichform the Floridan Aquifer.

The Miocene sediments are phosphatic sands, clays, clayey sands andcarbonates, primarily dolomite. The Hawthorn Group consists of fourbasic units (Scott, 1983): A basal dolomite is overlain by sands and clayswhich are overlain by a dolomitic unit. The uppermost unit is a quartzsandy and clayey phosphatic unit. The uppermost clastic unit is the onlyportion of commercial interest.

Sediments overlying the Hawthorn are predominantly comprised ofreworked Hawthorn material, marine terrace sediments or fluvial sedi-ments associated with topographic lows. The Pliocene and Pleistocenesediments comprise overburden in the phosphate district approximately30-feet thick.

Mining

Although there are several types of phosphate deposits found in Flor-ida (land pebble, hard rock, and soft rock), land pebble is the only sourcebeing extensively mined today. The land pebble deposits include the vastmajority of the Central Florida and North Florida phosphate districts.


Modern day mining techniques include the almost exclusive use (inFlorida) of large electrically powered walking draglines equipped withbuckets as large as 71 cubic yards. Only one company has mined withdredges in the recent past. Draglines remove overburden and place iteither on adjacent unmined land or into the preceding mined-out cut.After stripping of overburden, the dragline removes the matrix which isthen placed in a shallow pit where it is slurried with high pressure waterand pumped to the beneficiation plant.

Beneficiation of Phosphate Ore

Beneficiation of phosphate ore prior to 1929 was a relatively simpleand extremely wasteful process. Screens were utilized to separate andrecover the coarse phosphate. The sand-sized phosphate was not recov-erable, because no technique existed to separate the sand-sized phos-phate from the quartz sand. More phosphate was lost to the waste"debris" than was recovered.

In 1929 a process was introduced which revolutionized the phosphateindustry. The advent of the froth flotation process allowed separation ofsand-sized phosphate grains from waste grains (primarily quartz sand) ofessentially the same size, and resulted in a significant increase in thepercent of phosphate recovered from the matrix. Specific reagents areutilized to create a froth to which the treated material adheres, while theother material sinks. Either the phosphate or the waste material can betreated to cause them to float. In a "reverse" process, two flotationstages are utilized to float first phosphate then to float the waste mate-rial which was included in the first float. The reagents used create eitheran oily or a soapy film on the treated particles. Fuel oil, pine oil, causticsoda, fatty acids, and oleates are examples of the reagents used (Hoppe,1976). In a typical beneficiation plant, the rougher flotation utilizesanionic reagents (crude fatty acid, fuel oil/kerosene) in agitated tankswith the feed material dewatered to 65 percent solids. Addition ofammonia controls pH (between 9.0-9.5) and helps promote absorptionof the reagent coating. Prior to entering the cleaner flotation stage (cat-ionic) the rougher flotation products are scrubbed with water and sulfuricacid to remove the anionic reagents. The cleaned rougher product goesto the cleaner circuit where amine reagents (chemical derivatives ofammonia in which the hydrogen atoms have been replaced by radicalscontaining carbon and hydrogen: ex. methyl amine) and kerosene condi-tion the surface of any sand particles remaining causing them to float(Hoppe, 1976).

Typical recovery from a two stage flotation circuit rejects 99 percentof the free quartz sand and recovers 80 percent of the phosphate grainsfrom the feed (Zellars-Williams, 1978). Flotation concentrate comprisesbetween 10-25 percent of the ore weight.


Products and Uses

Essentially all of the Florida phosphate rock destined for the domesticmarket is utilized to form wet process phosphoric acid. The rock isdigested by sulfuric acid to produce phosphoric acid and waste gypsum(too impure to be commercially useful). Phosphoric acid is then utilized toproduce normal superphosphate, triple superphosphate (TSP) andnitrogen-phosphorous-potassium (NPK) complete fertilizer. Phosphoricacid is also reacted with ammonia to produce diammonium phosphate(DAP) and monoammonium phosphate (MAP).

Defluorinated phosphate rock is utilized for mineral supplements tolivestock and poultry feed. Defluorination is necessary because fluorineis toxic to animals (Opyrchal and Wang, 1981).

Elemental phosphorus is utilized in the production of sodium phos-phate detergents among others. Elemental phosphorus is obtained bysmelting phosphate rock with coke and quartz in electric furnaces (Opyr-chal and Wang, 1981).

Approximately 90 percent of the phosphate produced in recent yearshas been utilized for agricultural fertilizers. The remainder is utilized invarious industrial applications mostly as elemental phosphorus. Some ofthe common uses include: food preservatives, dyes for cloth, vitaminand mineral capsules, hardeners for steel, gasoline and oil additives,tooth paste, shaving cream, soaps and detergents, bone china, plastics,optical glass, photographic films, light filaments, water softener, insecti-cides, soft drinks, flame resistant lumber, fire fighting compounds andaluminum polish (Florida Phosphate Council, 1984a).

Transportation

Approximately 85 percent of phosphate rock is transported by rail toport facilities or fertilizer plants. The remainder is transported by truck.Truck transport is utilized during periods of peak production to augmentrail transportation, when rail service is interrupted or where low volumesare involved (Opyrchal and Wang, 1981).

Transportation by rail and ship or barge is utilized for the majority ofshipments out of the state. In 1979 phosphate rock and phosphate prod-ucts accounted for 93 percent of all exports from the Port of Tampa(Boyle and Hendry, 1981). Extensive exports are also shipped from Jack-sonville.

Economic Trends

In 1983, Florida and North Carolina accounted for 87 percent of thetotal U.S. and 27 percent of the total world phosphate production (Sto-wasser, 1985a). According to data collected by the U.S. Bureau ofMines, phosphate production increased 10 percent in 1983 from the1982 figures. Preliminary 1984 figures indicate an increase of approxi-

QUANTITY (MILLION METRIC TONS)

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Figure 13. Quantity and value of phosphate in Florida and North Carolina (Boyle,1986; U. S. Bureau of Mines, 1977-1983). w


mately 18 percent from 1983's depressed levels (Stowasser, 1985a).From a 1983 baseline, phosphate rock demand is expected to increase atan average annual rate of about 1.8 percent through 1990 (Stowasser,1985a).

Reserves

The Florida phosphate districts contain 520 million metric tons ofphosphate rock reserves (cost less than $35.00 per metric ton) and areserve base (reserves and resources recoverable at a cost of less than$100 per metric ton) of 2.4 billion metric tons (Stowasser, 1985b).Florida reserves will last more than 250 years at current mining rates(Florida Phosphate Council, 1984b).


The environmental concerns generally associated with phosphate min-ing include water consumption and power demands, radiation, water andair quality, waste disposal, and wetlands. Steps are being taken to miti-gate these concerns.

WATER USAGE

Reduction of water usage required by the phosphate industry is beingaddressed in several ways. Recirculation of mine process water is exten-sive and averages 90 percent throughout the industry. The major mineprocess which uses water is the clay settling system. Progressive claysettling techniques such as sand-clay mixing, the dredge mix processand chemical flocculation all speed the initial release of this water.

Recharge wells are being utilized in pre-mining dewatering. The waterin the surficial aquifer is gravity fed into the Floridan Aquifer. This has thedua! advantage of recharging the aquifer to some extent and reducingpumping requirements for mine cut water control.

POWER CONSUMPTION

Power consumption can be reduced by elimination of phosphate rockdrying except where actually necessary. Optimum mine planning canprovide an efficient operation thus reducing power consumption. In addi-tion, co-generation of power at chemical plants may afford reduction inthe quantity of purchased electrical power.

RADIATION

Uranium is associated with the phosphate ore. The majority of theuranium in the ore can be extracted as a byproduct. Some uraniumremains in overburden materials and waste sands and clays. Radium-226, a decay product of uranium, has received the most attention


because its decay generates radon gas (Zellars and Williams, 1978).There are not any established limits for allowable radiation in reclaimedmined lands. Pre-mining and post-reclamation radiation readings are nowrequired by the Florida Department of Health and Rehabilitative Services(HRS) which will provide a data base for future decisions. HRS has, inproposed rules, set a limit of 0.020 annual average working level concen-tration of radon gas in new residences built on reclaimed land after theeffective date of the rules (Mason Cox, personal communication, 1985).Proposed HRS rules also include recommended construction techniquesto ameliorate radon gas concentrations. The primary construction tech-niques include "ventilated crawl space designs" and "improved slabdesigns" which provide a barrier to radon gas migration.

WATER QUALITY

Water discharged from phosphate mines must meet requirementsspecified in discharge permits. The primary water quality problems of thepast were associated with breaks in the walls of clay settling ponds.There have been no such breaks since 1971 when the State instituteddam construction standards and mandated regular inspection and main-tenance programs (Zellars and Williams, 1978). Timely land reclamationand revegetation, as now required by the State, minimizes water qualityproblems associated with mined land.

AIR QUALITY

Air quality problems associated with phosphate mining are relativelyminor. Airborne dust is generated by earth moving activities and expo-sure of bare soil materials and by the dry grinding of phosphate rock.Dust from these sources will be reduced from past levels by timely landreclamation and reclamation of previously mined but unreclaimed lands.As more plants are built utilizing wet grinding, or are converted to thewet process, airborne dust from that process will be limited. Fluorine isextracted from flue gases as an environmental safeguard and is utilizedas a byproduct.

CLAY WASTE DISPOSAL

Conventional clay waste disposal has been done by above groundsettling ponds. The clays present in the "matrix" (predominantly smec-tite and palygorskite) are disassociated when the ore is slurried andpumped to the beneficiation plant. These materials are highly resistant tosettling and require more storage space as waste clay than they occupiedprior to mining. Large quantities of water are thus removed from therecirculating water system both as interstitial water and by evaporationfrom the settling ponds. Reclamation of full settling ponds is delayed formany years as the clays gradually dewater and settle. The current trend


is to minimize the surface area covered by settling areas and to maxi-mize clay storage in existing settling ponds (R. Bushey, Florida Bureau ofMine Reclamation, personal communication, 1986). This will require theuse of alternative methods of dewatering waste clays such as mixingwith sand tailings, dredging pre-settled clay and mixing with sand tail-ings, capping of pre-thickened clays and chemical flocculation (Yon,1983). These methods are capable of producing ultimate solids contentsof 36-42 percent compared to 31 percent for conventional clay settling(Lawyer, 1983, citation in Yon, 1983).

WETLANDS

The State of Florida contains approximately 20 percent of the wet-lands remaining in the U.S. (Zellars and Williams, 1978). These areas areof use as wildlife habitat, for surface water retention, sediment removaland nutrient uptake. In some areas the wetlands may enhance aquiferrecharge. Swamps, marshes and river flood plains are common examplesof these areas. The decision to mine wetland areas must take intoaccount the value of the phosphate, as well as the ability to reconstruct afunctioning wetland.

Byproduct Fluorine

Fluorine production, in the form of fluosilicic acid (H2SiF.), in Florida isa byproduct of wet-process phosphoric acid production (Boyle and Hen-dry, 1985). The most common ore of fluorine is the mineral fluorite(CaF,) which is commonly known as fluorspar. U.S. reserves of fluoriteare not sufficient to meet U.S. demand to the year 2000 (Pelham, 1985).By the end of the century, phosphate rock may be the primary domesticsource of fluorine (Pelham, 1985).

RECOVERY

Phosphate rock (fluorapatite) contains 3-4 percent fluorine (Nash andBlake, 1977). When fluorapatite is treated by the wet-acid process, solu-ble phosphates are formed and part of the fluorine contained in the phos-phate rock is volatilized as HF. HF reacts with silica which is present asan impurity in the fluorapatite, forming the volatile gas silicon tetraf-luoride (SiFj).

As SiF, gas evolves it is scrubbed from the gas column and hydrolyzes,fluosilicic acid and silica are formed (Nash and Blake, 1977). Nash andBlake (1977) state, "In the wet acid process about 41 percent of thefluorine in the phosphate rock is volatilized, 13 percent remains in theconcentrated acid, and 46 percent is discarded with the gypsum filtercake." Stowasser (1985b) states that overall recovery is rarely greaterthan 75 percent of the fluorine in the phosphate rock. The remainder isretained as waste in the coolant water pond. U.S. Environmental Protec-


tion agency regulations require that volatile fluorine be scrubbed fromstack gasses (Opyrchal and Wang, 1981).

USES

Fluorine is required in the manufacturing of aluminum, steel, and manychemical compounds (Opyrchal and Wang, 1981), as well as for waterfluoridation (Boyle and Hendry, 1985). In 1983 fluosilicic acid from Flor-ida phosphate was used to produce synthetic cryolite, aluminum fluorideand sodium silicofluoride and for water fluoridation (Boyle and Hendry,1985).

ECONOMIC TRENDS

In 1985, byproduct fluosilicic acid production from phosphoric acid(nationwide) totaled 63,000 tons, the equivalent of 110,000 tons offluorspar (Pelham, 1986). Estimated primary fluorspar production for thesame period is 70,000 tons. Demand for fluorine is expected to increaseat an annual average rate of 3.7 percent through 1990 (Pelham, 1986).Resources of fluorine in U.S. phosphate rock are estimated to be 35million tons of fluorspar equivalent (Pelham, 1986).

Byproduct Uranium

GEOLOGY

Uranium is produced as a byproduct of Florida's phosphate mining andbeneficiation in the Central Florida Phosphate District and its southernextension. Uranium was discovered to be associated with the phos-phates found in Florida in 1949 (Altschuler, et al., 1956). Because of thelack of suitable technology, only recently has it become economicallyfeasible to remove the uranium from phosphate rock. Uranium is presentin the pebble-size phosphate of the Central Florida Phosphate District atconcentrations ranging from 0.010 percent to 0.020 percent, and from0.005 percent to 0.015 percent in the finer phosphates (Cathcart,1956). The phosphate deposits of North Florida contain an average of0.006 percent uranium which is not presently economically recoverableby the wet process method. The uranium content of the quartz sandfraction of the matrix is generally less than 0.001 percent while phos-phatic waste clays generally have a uranium content of less than 0.005percent.

A potential source of uranium, phosphate, and alumina in the CentralFlorida Phosphate District is the leach zone. This zone overlies the phos-phate matrix and derives its name from its being a residuum of weather-ing of the matrix. It is also known as the aluminum phosphate zone, asthe leaching has enriched the phosphate in aluminum. Because of its lowphosphate content, it is not always sent to the plant for processing. The


average thickness of this zone is six to seven feet, and its uraniumcontent ranges from 0.010 percent to 0.015 percent (Altschuler, et al.,1956).

EXTRACTION

Uranium is extracted from phosphate by a two phase solvent extrac-tion system. In the first phase, the uranium is removed from wet processphosphoric acid by solvent extraction. The resulting uranium-bearingsolution then undergoes a second solvent extraction and stripping stageto produce specification grade uranium oxide (U308 ) called yellow cake(Sweeney and Windham, 1979). One ton of U30, yields one pound of fuelgrade U2,a.

ECONOMIC TRENDS

In 1980, the only year for which information is available, Florida ura-nium oxide production was approximately 1.5 million pounds (750 shorttons). Nuclear Exchange Corporation (1986) reports that in 1985 3.3million pounds (1650 short tons) of uranium oxide were produced fromphosphoric acid. The vast majority of this would be from Florida phos-phate rock.

The U.S. Bureau of Mines (Stowasser, 1985b) reports five companieswith a combined annual recovery potential of 1,870 short tons of U30Ofrom the Central Florida Phosphate District. Based on the productioncapacity figures above, up to 15 percent of the U.S. uranium demandcould be met by byproduct uranium recovery from Florida phosphaterock (Sweeney, 1979).

RESERVES

Florida's reserves of uranium are directly dependent on the reserves ofphosphate. Only the uranium oxide contained in phosphate rock treatedby the wet-process phosphoric acid method is economically feasible forrecovery. The central and southern Florida phosphate deposits containapproximately 1.5 billion short tons of phosphate rock recoverable at$15-20 per short ton (Zellars and Williams, 1978). Assuming an averageuranium oxide content of 0.015 percent, approximately 225,000 shorttons of uranium oxide are present in the deposits (Sweeney, 1979). Ingeneral, for central and southern Florida deposits one pound of U,30 canbe extracted from one short ton of P205 (Sweeney, 1979).


SAND AND GRAVEL

Geology

Quartz sand is one of Florida's most abundant natural resources.Almost all of Florida is blanketed with a veneer of sand. Very few areaswithin the state do not have deposits of general purpose sand locatedwithin reasonable distances (Scott, et al., 1980). Commercial quantitiesof gravel are present only in the western panhandle of Florida, associatedwith modern day river deposits.

The identification of terraces and previous shorelines has been basedon elevation. Terraces which have been mapped in Florida include theSilver Bluff, Pamlico, Talbot, Penholoway, Wicomico, Sunderland, Coha-rie and the Hazelhurst. Shorelines associated with these terraces were atapproximately 10, 25, 50, 70, 100, 170, 220 and 320 feet, respectively(Cooke, 1945; Healy, 1975).

The sand deposits associated with the marine terraces are composedprimarily of quartz sand with various amounts of silt, clay and organicmatter. According to Cooke (1945) the older (high) terraces contain thecoarsest material while the younger (low) terraces contain finer sand plusclay and carbonate. In addition, the lower deposits are thinner and con-tain more clay, silt and organics in south Florida relative to the northerndeposits (Cooke, 1945).

Scott, et al. (1980) divided sand and gravel deposits in Flo

LETTER OF TRANSMITTAL 1986ufdcimages.uflib.ufl.edu/UF/00/00/11/63/00001/UF00001163.pdf · Value of...

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Transcript of LETTER OF TRANSMITTAL 1986ufdcimages.uflib.ufl.edu/UF/00/00/11/63/00001/UF00001163.pdf · Value of...