Mineralogy and Alteration of the 

Phosphate Deposits of Florida 

U.S. GEOLOGICAL SURVEY BULLETIN 1914 
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Mineralogy and Alteration of the 

Phosphate Deposits of Florida 

By S.J. VAN KAUWENBERGH, J.B. CATHCART, 

and G.H. McCLELlAN 

A detailed study of the mineralogy and chemistry of the 

phosphate deposits of Florida 

U.S. GEOLOGICAL SURVEY BULLETIN 1914 
DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Any use of trade, product, or firm names in this publication is for descriptive 

purposes only and does not imply endorsement by the U.S. Government. 

UNITED STATES GOVERNMENT PRINTING OFFICE: 1990 

For sale by the 

Books and Open-File Reports Section 

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Library of Congress Cataloging-in-Publication Data 

Van Kauwenbergh, S. J. 

Mineralogy and alteration of the phosphate deposits of Florida : a detailed 

study of the mineralogy and chemistry of the phosphate deposits of Florida I 

by S.J. Van Kauwenbergh, J.B. Cathcart, and G. H. McClellan. 

p. em. - (U.S. Geological Survey bulletin ; 1914) 

Includes bibliographical references. 

Supt. of Docs. no.: I 19.3:1914 

1. Phosphates-Florida. 2. Geology, Stratigraphic-Neogene. 

3. Geology-Florida. I. Cathcart, James Bachelder, 1917- II. McClellan, 

Guerry H. Ill. Title. IV. Series. 

QE75.B9 no. 1914 

[TN914. U6F6] 

557.3 s-dc20 89-600376 

[553.6'4'09759] CIP 
CONTENTS 

Abstract 1 

Introduction 1 

Acknowledgments 2 

Methods of study 3 

Grain-size analyses 3 

Geology S 

Structure S 

Stratigraphy S 

Chemical analyses of phosphate ores 7 

Mineralogy 10 

Francolite 10 

Clays 17 

Carbonates 20 

Other minerals 21 

Discussion and conclusions 21 

References 23 

Appendix 27 

FIGURES 

1. Sketch map of Florida showing major structural features and phosphate 

mines 4 

2. Histograms showing variations in a-values of francolite in bulk and 

screened samples from the Bone Valley Member of the Peace River 

Formation 14 

3. Histograms showing variations in a-values of francolite in bulk and 

screened samples from the undifferentiated Peace River Formation 1S 

4. Contrasts in the depositional and postdepositional histories of the North 

Carolina and Florida phosphorite deposits 22 

5-23. Diagrams showing lithologic, stragraphic, mineralogic, and grain-size 

analyses of sections from Florida phosphate mines 

5. Swift Creek Mine 28 

6. Suwannee River mine 29 

7. Noralyn Mine 30 

8. Gardinier (Cargill) mine 31 

9. Nichols mine 32 

10. Ft. Meade mine 33 

11. Clear Springs mine 34 

12. C.F. Hardee complex 35 

13. Ft. Green mine 36 

14. Saddle Creek mine 37 

15. Lonesome mine 38 

16. Watson mine 39 

17. Phosphoria mine 40 

18. Rockland mine 41 

Contents Ill 
19. Haynsworth mine 42 

20. Lonesome mine 43 

21. Hookers Prairie mine 44 

22. Four Corners mine 45 

23. Kingsford mine 46 

TABLES 

1. Average grain sizes of samples of the Bone Valley Member of the Peace 

River Formation and undifferentiated Peace River Formation, Florida 5 

2. Stratigraphic nomenclature and lithologic descriptions, Florida phosphate 

districts 6 

3. Chemical analyses of bulk samples of Florida phosphate ores 8 

4. Comparison of the theoretical composition of fluorapatite and francolite 11 

5. Calculated francolite compositions of various commercial phosphate 

ores 12 

6. Unit-cell a-values of Florida phosphate ores 12 

7. Variations of francolite a-values and composition with stratigraphy, Florida 

phosphate ores 16 

8. Examples of a-values of less-altered francolite from various localities 16 

9. Francolite samples from Florida with a-values less than 9.330 

(±0.003 A) 16 

10. Chemical analyses of palygorskite samples from Florida phosphate 

deposits 18 

11. Characteristic d-spacings of smectite from Florida phosphate deposits 18 

12. Chemical and layer-charge analyses of selected Florida smectite samples 19 

13. X-ray analyses of Florida dolomite samples 20 

IV Contents 
Mineralogy and Alteration of the 

Phosphate Deposits of Florida 

By S.J. Van Kauwenbergh\ J.B. Cathcarf, and G. H. McCiellan3 

Abstract 

The Neogene phosphorites of Florida were deposited 

in a major phosphogenic province that extended from North 

Carolina into the Florida Peninsula. Although phosphate is 

present in all areas where Miocene strata occur offshore and 

onshore, both in outcro'p and the subsurface, economic or 

potentially economic Miocene and Pliocene deposits are 

known only from North Carolina, southern South Carolina 

and northern Georgia, southern Georgia and northern 

Florida, and central Florida. Identified resources in the 

phosphate province of the Atlantic Coastal Plain are 

estimated to be about 7 billion tons, and additional 

hypothetical resources are thought to be about 13 billion 

tons. The Florida phosphate deposits are the most 

productive in the world. About 1 billion tons of phosphaterock concentrate, containing an average of about 32 percent 

P20s, have been produced since the start of mining in 1888. 

Phosphate mining in Florida was initially confined to 

high-grade deposits in Polk and Hillsborough Counties. This 

mining district is commonly called the central Florida landpebble phosphate district. In recent years mining has 

progressed deeper into sections in this district and to the 

southern extension of the district in Hardee and Manatee 

Counties. In the future, mining could move even further south 

into DeSoto County. Two mines have been developed in 

north Florida. 

The phosphatic sediments of the Florida deposits are 

unconsolidated or partly consolidated sand, clay, and 

carbonate rock (limestone and dolomite). The deposition of 

phosphate was, in part, structurally controlled. Phosphate 

was deposited in basins on the flanks of structural or topographic highs. The economic deposits were reworked, 

concentrated, and enriched after deposition. Uneconomic 

phosphatic carbonate rocks are abundant below mined 

sections and in the deeper parts of basins. 

Manuscript approved for publication, October 6, 1989. 

1

Intemational Fertilizer Development Center, Muscle Shoals, 

AL 35662. 

2

U .S. Geological Sutvey, Denver, CO 80225. 

3

Department of Geology, University of Florida, Gainesviile, FL 

32611. 

The most abundant minerals of the Florida deposits 

include carbonate-fluorapatite (francolite), quartz, dolomite, 

and clay minerals. Francolite is the only economic phosphate 

mineral. Iron and aluminum phosphates are characteristic of 

the uneconomic, highly weathered parts of the deposits. 

Quartz is the principal gangue mineral. Dolomite is a source 

of unwanted magnesium in fertilizer processing, and mining 

is generally terminated when indurated dolostone beds are 

encountered. Clays are also a source of impurities and 

present a significant disposal problem. 

This study shows that all the Florida deposits are 

altered or are mixtures of more and less altered material. 

Changes in ore characteristics in individual sections and 

across the entire deposit are due to gross variations in 

mineralogic composition and more subtle variations in 

francolite and clay composition. These variations in mineralogic composition can be related to the depositional history, 

reworking, and weathering of the deposits. 

INTRODUCTION 

The Neogene phosphorite deposits of the 

southeastern United States were formed in a major 

phosphogenic province that extended along the Atlantic 

Coastal Plain from North Carolina to the center of the 

Florida Peninsula. Phosphate occurs onshore and 

offshore in rocks of Miocene age. Younger phosphatic 

strata are also present; much of this phosphate probably 

was derived from pre-existing Miocene rocks. Although 

phosphate grains are present in all areas where Miocene 

sedimentary rocks occur, economic or potentially 

economic Miocene and Pliocene deposits are present 

only in North Carolina, southern South Carolina and 

northern Georgia, southern Georgia and northern 

Florida, and central Florida. The identified recoverable 

resources of this vast deposit have been estimated by 

Cathcart and others (1984, p. 44) to be about 7 billion 

metric tons of concentrate, and additional hypothetical 

resources may be as much as 13 billion tons. 

The initial discovery of phosphate in the United 

States was near Charleston, South Carolina, and 

Introduction 1 
phosphate was first mined there in 1867. Mining of 

phosphate in Florida began in 1888 from phosphatebearing gravel bars along the Peace River in Polk County 

and the Alafia River in Hillsborough County. These were 

the so-called river-pebble deposits. The dredging that 

b~g~n in the rivers moved onto the flood plains, and 

mmmg finally spread to the uplands adjacent to the 

rivers. The upland material was called, logically enough, 

land pebble. Ore from the higher grade and more 

uniform land-pebble deposits became the mainstay of the 

phosphate market, and river-pebble mining ceased early 

in the 20th century. 

In the first half century of mining in Florida, only 

the plus 16-mesh fraction (pebble) was utilized. Flotation 

to separate fine-grained phosphate from quartz became 

technically and economically feasible in the mid-1930s. 

U!il~zin~ flotation technology, the Florida phosphatemmmg mdustry expanded; maximum production was 

reached in 1979 at approximately 42 million tons per 

year, and the total production of product (about 32 

percent P20s) from 1891 to 1984 approached 1 billion 

tons (Cathcart, 1985). 

The location of the economic phosphate deposits of 

the southeastern United States is in part controlled by 

structure (Cathcart, 1968; Freas, 1968; Freas and Riggs, 

1968; Riggs, 1984). Phosphate was deposited in basins on 

the flanks of topographic or structural highs. Although 

structure appears to be a prime factor in the location of 

the deposits, other factors such as reworking and 

secondary enrichment have contributed to the formation 

of economic deposits. Rooney and Kerr (1967) noted the 

extensively reworked nature of the North Carolina 

phosphorite and a general lack of alteration. Cathcart 

and Davidson (1952), Altschuler and others (1958), 

Altschuler and others (1964), and Altschuler (1965) have 

pointed out the importance of extensive reworking and 

secondary enrichment in the Florida deposits. 

The phosphatic sediments of the economic deposits 

of Florida are unconsolidated or partly consolidated clay, 

sand, and minor carbonate rock. All the Miocene 

~ediments of Florida contain phosphate particles (pellets, 

mterclasts, bone fragments, and other grain types), 

quartz, clay minerals, and carbonate minerals (dolomite 

and calcite). Phosphatic carbonate rocks, some of which 

are well cemented, are abundant below mined sections 

and in the deeper parts of the basins. A major part of the 

total resource is this type of material. Heavy minerals are 

presen! thr?ughout the phosphatic sediments, but they 

occur m mmor or trace amounts. Iron and aluminum 

phosphate minerals are the products of weathering in the 

surficial parts of the deposits. 

The most abundant minerals of the phosphate 

deposits of Florida are francolite (carbonatefluorapatite), quartz, dolomite, and various clay minerals. . Francolite is the only economic phosphate 

mineral. Quartz is the most abundant mineral in the 

deposits. The clay minerals are a major source of 

elemental impurities in the ore (Fe3

+, AJ3+, Mg2+ ). The 

disposal of the clay minerals in the slime fraction 

(generally minus 150 mesh) is a serious problem in 

Florida. Magnesium, mostly in dolomite, is difficult and 

expensive to remove by beneficiation or during chemical 

processing. Francolite, dolomite, and the clay minerals of 

the deposits have variable compositions that may indicate 

both the environment of deposition and diagenesis, and 

the discussion in this paper therefore focuses primarily 

on these mineral groups. 

Until recently, all mining of the high-grade landpebble deposits of the central Florida phosphate district 

was in Polk and Hillsborough Counties, and mining was 

generally restricted to the coarse phosphorite at the top 

of the sections. These coarse high-grade deposits in the 

upper parts of sections in the central district are 

becoming depleted, and therefore mining is progressing 

deeper into sections in the central district and, to the 

south, into the southern extension in Hardee, Manatee, 

and DeSoto Counties (Bernardi and Hall, 1980). Two 

mines have been developed in northern Florida (Swift 

Creek and Suwannee River). The deposits of the 

southern extension and northern Florida are lower in 

grade, and the easily beneficiated pebble (plus 16-mesh) 

fraction is less abundant and is contaminated by dolomite 

grains. The phosphate grains of the feed fraction (minus 

16 plus 150-mesh) are lower in P205 content and have 

greater amounts of mineral contaminants than the 

deposits in the central district. The changes in ore 

characteristics from the central district to the southern 

extension have been attributed to certain geologic 

factors. The southern deposits are less intensely altered, 

and there is a transition in the depositional environment 

from nearshore to offshore conditions (Riggs, 1979a, 

1979b; Bernardi and Hall, 1980; Cathcart, 1985). 

All the economic phosphate deposits of Florida 

have been altered or are mixtures of more and less 

altered material. Part of the change in ore characteristics 

from the central district to outlying areas and deeper in 

sections is due to systematic variations in the composition 

of the francolite constituent of the ore. Complex cycles of 

deposition, reworking, and subaerial weathering produced the deposits in their present state. 

Acknowledgments 

The field and laboratory studies that this paper 

summarizes have been part of a cooperative study 

between the U.S. Geological Survey (USGS) and the 

International Fertilizer Development Center (IFDC) 

under the auspices of the International Geological 

Correlation Program (IGCP) Project !56-Phosphorites. 

2 Mineralogy and Alteration of the Phosphate Deposits of Florida 
This paper represents the continued commitment of 

these organizations to phosphorite research. The 

association with the IGCP enables developing countries 

to use this research in developing their phosphate 

resources. 

We are indebted to many of our colleagues for 

their contributions to this work. T.M. Scott, Florida 

Geological Survey, was very helpful in unraveling 

stratigraphic details and assisting in some of the 

fieldwork. Z.S. Altschuler provided stimulating discussions on the geochemistry and mineralogy of the 

deposits. The following IFDC colleagues provided 

analyses: B.W. Biggers, M.R. Williams, B.A. Hamilton, 

T.C. Woodis, and D.W. Wright. M.R. Williams is 

particularly thanked for her efforts; much of the sample 

preparation and X-ray diffraction analysis was her 

responsibility. Marie Thompson and Marie Stribling 

cheerfully coordinated the artwork and word processing. 

Their staffs are gratefully acknowledged. 

We are deeply grateful to the mining and 

administrative staffs of the many companies engaged in 

phosphate mining in Florida for their wholehearted 

cooperation in allowing J .B. Cathcart access to operating 

pits in 1984. 

METHODS OF STUDY 

J.B. Cathcart collected 51 samples from mines in 

north, central, and south Florida during 1984 (fig.l). The 

samples represent currently mined economic zones 

(matrix). Stratigraphic correlations were made by J.B. 

Cathcart with the assistance ofT .M. Scott of the Florida 

Geological Survey. Several of the samples were collected 

over vertical distances of tens of feet, and some were 

composited from sections taken from different sites at 

the same mine. Therefore, some of the observed 

variations in mineralogy may be the result of 

homogenization. These samples should not be construed 

as representative of any particular mine. 

All chemical and XRD (X-ray diffraction) analyses 

were performed in the laboratories of IFDC. Copper 

radiation, at 50 kV (kilovolts) and 20 ma (milliamperes) 

with a graphite monochromator, was used for all XRD 

work. Chemical analyses were done by one or more of 

the standard analytical methods: X-ray fluorescence, 

atomic absorption, ion chromatography, gas evolution, 

and colorimetric and gravimetric determinations. Majorelement analyses were cross-checked by two methods. 

The samples were oven dried at 95°C, gently disaggregated by hand, and split to obtain representative 

samples for bulk chemical analyses and XRD studies. 

About half of each sample was placed in 1 L (liter) of 

distilled water containing 0.05 g (gram) of dispersant and 

allowed to stand overnight. Samples were wet screened 

on 20- and 200-mesh (Tyler) sieves to separate the plus 

20-(pebble ), minus 20- plus 200- (flotation feed), and 

minus 200-mesh (slime) fractions. The clay fraction ( < 2 

p.m (micrometer)) was separated from the minus 200-

mesh fraction by standard sedimentation techniques 

(Folk, 1974). 

Separated size fractions (pebble, flotation feed, 

slime, and clay) and bulk samples were X-rayed in 

random powder packs to determine their mineralogy. 

Mineral abundances were estimated from the XRD 

traces as major, minor, or trace (see appendix for 

details). These data are qualitative and are used only to 

identify the mineral assemblages and compare relative 

proportions of the minerals in the different size fractions 

and at the various mine localities. 

Air-dried, oriented clay samples were prepared by 

sedimentation onto glass slides for clay-mineral analysis. 

To facilitate identification of specific clay minerals, the 

oriented samples were glycolated and X -rayed again. 

These oriented samples were then heated to 350°C and 

X-rayed once more. Some clay samples were also treated 

by lithium saturation. Randomly oriented smectite 

samples that contained no detectable kaolinite were 

X-rayed to determine the d-spacings of the 060 

reflections. These characteristic d-spacings were utilized 

to determine the smectite component. 

Francolite unit -cell dimensions were determined 

by a high-resolution computer-assisted XRD technique, 

and data were reduced by an iterative hexagonal leastsquares method. These unit -cell dimensions have a 

standard error of ±0.003 A (angstrom). The a-value of 

the francolite unit cell shows the greatest variation and 

indicates isomorphic substitution in the apatite structure 

(McClellan and Lehr, 1969; McClellan, 1980). Thus, the 

a-value is the parameter rised in this report as an 

indicator of francolite composition. In general, the 

smaller the a-value, the greater the amount of C02, S04, 

and V04 that are substituted for P04 and sodium, and 

magnesium for calcium in the francolite. 

Grain-Size Analyses 

Average grain sizes of the Bone Valley Member 

and the economic undifferentiated part of the Peace 

River Formation are given in table 1. Grain-size data for 

individual sections are given in figures 5-23 (appendix). 

Bernardi and Hall (1980) listed similar grain-size data 

for the land-pebble district and southern extension using 

slightly different mesh sizes. Obviously, the Bone Valley 

Member, differentiated by its pebble content, is coarser. 

The remaining underlying undifferentiated part of the 

Peace River Formation has a higher content of feed 

fraction, but the proportion of slime is about the same. 

Methods of Study 3 
a~ ar 

CHATTAHOOCHEE', I 

ANTICLINE 

--- --- I GEORGIA \ 

-, / =-"-Fi:"oruo.A.-~--------t - ...; :(-. _ Swift Creek (\ 1 

o-0(:) / ' a'?d S~annee'-\ -<,.~ / '-R.!!!..er mmes 

6'0.J // '\ 

-',,,"'} 

JACKSONVILLE 

BASIN 

/ \ -t~~----------------~------+-----~--+-------------------~30° \ 

EXPLANATION 

---Boundary of land-pebble 

phosphate district 

- - -Boundary of southern 

extension 

Mine 

--- ---

0 

--- ---

R 27 E 

30 MILES 

0 30 KILOMETERS 

\ 

\ 

\ 

\ 

\ 

I 

I 

I 

0 

0 

I ST.JOHN'S 

( PLATFORM 

' \ .. r-\ 

\ 

\ 

\ 

CENTRAL 

FLORIDA 

PLATFORM 

9o 

\ SANFORD 

\ HIGH 

\ 

1'--/ 

\ BREVARD 

\PLATFORM 

\ 

\ 

\ 

-

OKEECHOBEE 

BASIN 

100 MILES 

100 KILOMETERS 

Figure 1. Sketch map of Florida showing major structural features and phosphate mines in central Florida. 

4 Mineralogy and Alteration of the Phosphate Deposits of Florida 
Table 1. Average grain sizes of samples of the Bone Valley 

member of the Peace River Formation and undifferentiated 

Peace River Formation, Florida 

[Values in percent) 

Tyler mesh sizes 

+20 -20+200 -200 

Bone Valley 31 50 19 

(22 samples) 

Peace River 19 60 21 

(24 samples) 

Data from this study show that the zone of overburden 

sand of probable Pleistocene age and noneconomic 

leached ore averages 5.5 m (meters) in thickness, and the 

ore zone (matrix) averages 4.5 m in thickness. The 

thicknesses of minable Bone Valley Member (2.1 m) and 

undifferentiated part of the Peace River Formation (2.5 

m) are roughly equal. 

GEOLOGY 

Peninsular Floria is underlain by gently dipping 

sedimentary rocks that range in age from Cretaceous to 

Holocene. The Floridian Platform, equivalent to all of 

peninsular Florida, has been structurally stable, subject 

only to minor uplift and warping since the Cretaceous 

Period (Vernon, 1951). 

Structure 

The structure of peninsular Florida is dominated 

by the Ocala uplift and to a lesser extent by several 

positive features, including the Sanford high (fig. 1). The 

Ocala uplift became a positive feature as early as the late 

Eocene, and uplift persisted into the early Miocene (for 

a review, see Olson, 1966). Tertiary sediments dip gently 

away from these positive features into the Jacksonville 

basin, the Central Florida platform, and the Okeechobee 

basin (fig. 1). Miocene sediments thicken markedly away 

from these positive features and reach maximum 

thicknesses in the Jacksonville and the Okeechobee 

basins; in the center of the basins these sediments are as 

much as 250 m thick. Phosphatic sediments occur 

throughout peninsular Florida except on the Sanford 

high and Ocala uplift. Currently mined economic 

deposits are confined to the northeast edge of the Ocala 

uplift and the central Florida platform just off the 

southern end of the uplift. Potentially economic deposits 

occur both to the north and the south of the Sanford high 

on the St. Johns platform (north) and the Brevard 

platform (south). 

Stratigraphy 

According to traditional stratigraphy, sediments of 

Miocene age in Florida were divided into the Tampa 

Formation at the base, the Hawthorn Formation in the 

middle, and the Tamiami Formation (south Florida) and 

equivalents at the top. Various names, both formal and 

informal, have been applied to the upper Miocene 

sediments in north Florida and south Georgia (Patterson, 

1974; Scott and Upchurch, 1982). Scott (1985, 1988) 

formally raised the Hawthorn Formation to group status 

and included most of the phosphatic sediments of Florida 

in this group. Details of Scott's (1985, 1988) stratigraphy 

and relationships to older usage are given in table 2. 

Scott's terminology is used on mine sections (figs. 5-23, 

appendix) and are followed, in general, in this work. 

The Bone Valley gravels were first described by 

Matson and Clapp (1909) from deposits near Bartow, 

and the term "Bone Valley Formation" was formally 

applied by Cooke (1945). The original formation 

description appears to have been of beds derived by 

reworking of older sediments; these beds are present as 

channel deposits cutting older sediments and as blanket 

deposits. Webb and Crissinger (1983) described these 

channel deposits as unit 6. As mining expanded and 

processing technologies improved, more of the phosphorite section was utilized, and the term "Bone Valley" 

began to include coarse phosphatic sediments older than 

the original type material (Scott, 1985). 

The Bone Valley was originally assigned to the 

Pliocene as was Webb and Crissinger's (1983) unit 6. The 

addition of older pebbly material that has faunas of 

middle to late Miocene age (Webb and Crissinger, 1983) 

widened the age limits of the Bone Valley Formation to 

include the Miocene and Pliocene. In the terminology of 

Scott (1985, 1988), the Bone Valley Formation is 

changed to a member of the Peace River Formation of 

the Hawthorn Group. The Miocene-Pliocene boundary 

is transgressed by the Bone Valley Member and includes 

all pebble beds at the top of the section. 

Where well developed, the Bone· Valley Member 

consists of two pebble beds separated by a sandy, clayey 

phosphorite (unit 4 of Webb and Crissinger, 1983). In the 

central land-pebble district, the contact between the 

Bone Valley Member and underlying sediments is 

distinct. The contacts are more subtle away from the 

center of the mining district. In many areas the lower 

pebble is missing; fine-grained sediments below an upper 

pebble bed may be difficult to classify. In Scott's 

terminology, the Bone Valley Member includes only the 

pebble beds at the top of the section. Fine-grained 

phosphorite beds below a single pebble bed are referred 

to as undifferentiated Peace River Formation. 

In the southern extension, the lateral and time 

equivalent of the Bone Valley Member is the Tamiami 

Geology 5 
Table 2. Stratigraphic nomenclature and lithologic descriptions, Florida phosphate districts 

Stratigraphy and lithology Stratigraphic nomenclature 

(Cathcart, 1985) (From Scott, 1985; 1989) 

Land-pebble district Southern extension Southern Florida Northern Florida 

Holocene Loose windblown sand and black swamp muck deposits. Unnamed, or combined with named units below. 

Unnamed terrace deposits 

Caloosahatchee Anastasia Pleistocene Bedded, loose to slightly clayey sand. Channel deposits of Formation Formation 

pebble phosphate at base. 10-40 ft thick. 

Bone Valley Formation 

Upper part 

Tamiami Citronelle and Pliocene Clayey sand containing trace to minor Formation Cypress head amounts of phosphate grains. Aluminum Formations and iron phosphate minerals where 

leached. 0-20 ft thick. Tamiami Formation 

Clay, sandy to sand, clayey. 

Contains abundant shells 

Bone Valley Formation and a trace of phosphate 

Lower part grains. 0-75 ft thick. Missing 

Phosphorite, sandy, clayey, bedded Bone A thin, pebbly phosphate 

and crossbedded. Conglomeratic at Valley bed containing the same 

base. Contains iron and aluminum Member vertebrate fossils as the 

phosphate minerals where leached. Bone Valley Member is 

0-50 ft thick. present at the top of the 

ore zone at the Suwannee 

River mine. 

Hawthorn Formation 

Upper clastic unit a. 

::1 

Northern part 0 

Gray-green sandy, silty clay. (; Peace Statenville Formation 

Massive, yellow, fossiliferous, Contains dolomite and c River Miocene phosphatic dolomite. 0-10 ft abundant fine phosphate. 0 Formation Coosawhatchie Formation 

thick. Possiblyeconomic. 20-150 .r. 

ft thick. ~ ('tl 

Central part Lower carbonate unit J: 

Interbedded dolomite, sandy Dolomite and limestone, Arcadia Marks Head 

clay, all with phosphate grains. fossiliferous, some Formation Formation 

10-70 ft thick. phosphate grains. 50-150 

ft. 

Tampa Formation 

Tampa 

Member Penney Farms 

Dolomite and limestone at Nocatee Formation 

Clay, sandy clay, some chert and top. Gray-green clay, some Member 

phosphate grains. 0-20 ft thick. phosphate at base. 0-50 ft 

thick. 

Formation. The Tamiami Formation consists primarily 

of clayey sands and abundant shell materials with minor 

phosphate. Although Scott (1985, 1988) considered the 

Tamiami equivalent to the Pliocene part of the Bone 

Valley Member, Cathcart (1985) regarded the Tamiami 

to be synchronous with the Bone Valley section. Peck and 

others (1979) presented evidence that the Tamiami, 

similar to the redefined Bone Valley Member of Scott 

(1985, 1988), transgressed the Miocene-Pliocene 

boundary. 

Thin pebbly phosphate beds containing vertebrate fossils 

similar to those in the Bone Valley Member of the 

central district are present at the top of the ore zone at 

the Suwannee River mine. 

In northern Florida, the Citronelle and Cypresshead Formations are partly equivalent to the Tamiami 

Formation. Sediments having the characteristics of the 

Bone Valley Member are missing or not well developed. 

Below the pebble beds of the Bone Valley Member 

in the land-pebble district lie the beds previously called 

the Hawthorn Formation. Detailed work in the 

phosphate district (Cathcart, 1968) has shown that the 

Hawthorn Formation can be informally divided into an 

upper unit composed predominantly of siliciclastic 

material and a lower carbonate unit. This terminology 

has been followed by Bernardi and Hall (1980) and 

Cathcart (1985) and is also commonly used by mine and 

exploration geologists in the district. Under the 

6 Mineralogy and Alteration of the Phosphate Deposits of Florida 
stratigraphic revision, the upper clastic unit of the 

Hawthorn Formation is assigned to the Peace River 

Formation (Scott, 1985, 1988). 

The Peace River Formation below the Bone Valley 

Member consists primarily of phosphatic, gray-green to 

blue clay, sand, and dolostone. Dolostone lenses are 

found at the base of the unit in the transition to the beds 

below. The undifferentiated Peace River Formation 

contains discontinuous pebble beds. Distinct pebble beds 

can be observed below indurated dolostones at the bases 

of many mines when water levels in drainage ditches are 

low. 

The Statenville and Coosawhatchie Formations of 

north Florida are equivalent to the undifferentiated 

Peace River Formation. The Statenville Formation 

consists of phosphatic to very phosphatic interbedded 

and cross-bedded sand and clay with minor carbonate 

beds. The underlying Coosawhatchie Formation is 

composed of phosphatic, dolomitic sand and clay. 

Phosphate production in north Florida is from the 

Statenville Formation. 

Below the Peace River Formation the carbonate 

unit of the Hawthorn has been renamed the Arcadia 

Formation (Scott, 1985, 1988, modified from Dall and 

Harris, 1892). The distinction between the Arcadia and 

Peace River Formations is the carbonate content. Where 

the carbonate content of the rock exceeds 50 percent and 

persists to depth, it is termed "Arcadia Formation". The 

Arcadia consists primarily of indurated dolostones. 

Phosphate grains and some nodules are present. It may 

not be possible to differentiate the Peace River and 

Arcadia Formations by outcrop alone; that is, if dolostone beds are found at the bottom of mining pits, they 

may either be carbonate lenses at the base of the Peace 

River or the top of the Arcadia Formation. 

Equivalents of the Arcadia Formation in north 

Florida are the Marks Head and Penney Farms 

Formations. The Marks Head Formation is a complexly 

interbedded sequence of phosphatic carbonate, sand, and 

clay. The underlying Penney Farms Formation lies 

unconformably on Eocene carbonates and consists of 

interbedded phosphatic dolomites and siliciclastics. The 

dolomites become more abundant at the base. 

The Tampa Formation has been reassigned as a 

member of the Arcadia Formation of the Hawthorn 

Group. The Tampa Member consists primarily of 

limestone and minor dolostone. A discontinuous darkgray to gray-green silty dolomitic clay occurs at the base. 

The Tampa Member pinches out north of the central 

Florida phosphate district and appears to be the time 

equivalent of the Penney Farms Formation in north 

Florida. 

CHEMICAL ANALYSES OF 

PHOSPHATE ORES 

The chemical analyses of bulk samples of 

phosphate ore (table 3) indicate their mineralogic 

composition. Each chemical component is present in one 

or more minerals. Each mineral, especially francolite and 

iron and aluminum phosphates, may have variable 

compositions. 

Beneficiation engineers and phosphate geologists 

commonly evaluate the chemistry of ore and phosphate 

concentrate in terms of major-element ratios such as 

CaO/P20s and F/P20s. The F!P20s ratio for a stoichiometric fluorapatite is 0.09, and for the most highly 

substituted francolite it is about 0.15 (McClellan, 1980). 

Similarly, the CaO/P20s ratio is 1.32 for fluorapatite and 

1.62 for francolite with maximum substitution. The 

presence of carbonates increases the CaO/P20s ratio 

above the ratio of the francolite that is present. 

Conversely, the presence of nonapatitic phosphates 

depresses this ratio. 

The P20 5 contents of the samples are highly 

variable both within mines and within the entire data set; 

thus, general trends are not apparent. P20s is a component of francolite and of iron and aluminum phosphate 

minerals. The average P20s content of the Florida 

deposits is listed in industry reports and trade journals as 

32 percent or about 70 percent bone phosphate of lime· 

(BPL), but this figure is for concentrated phosphate 

particles and not for the deposit in the ground. The 

arithmetic average of the P20s content of all the 

stratigraphically correlated matrix samples in this study is 

13.9 percent. Data in Pirkle and others (1967) show that 

13 matrix samples from the central district averaged 15.5 

percent P20 5 • If the data from north Florida and the 

southern extension are excluded, the samples of this 

study contain an average of 14.5 percent P20s. The Bone 

Valley Member, or equivalents, has a slightly higher P20s 

content (14.6 percent) than the minable undifferentiated 

Peace River Formation or equivalents (13.3 percent). 

Phosphate gravels of the Bone Valley Member are thin 

or absent to the south and east of the central district, and 

samples from north Florida and the transition to the 

southern extension are an indication of ore assays in the 

future; these samples average 9.5 percent P20s. 

The CaO content varies primarily with the francolite and carbonate contents but also with the clay and 

calcium-aluminum phosphate components. In 12 of the 

17 mines examined, having both the Bone Valley 

Member and the undifferentiated part of the Peace River 

Formation in the section, the CaO/P20s ratio increases 

with depth. In three mines, the ratio decreases; in two, it 

remains the same. Samples of the Bone Valley Member 

and its possible equivalent in North Florida have a lower 

average CaO/P20s ratio (1.44) than samples of the undifChemical Analyses of Phosphate Ores 7 
Table 3. Chemical analyses of bulk samples of Florida phosphate ores 

(Analyses in weight percent. BVE, Bone Valley Member equivalent; LBV, leached Bone Valley Member, 

Peace River Formation; BV, Bone Valley Member, Peace River Formation; UPR, undifferentiated Peace 

River Formation; S, = Statenville Formation] 

Mine and 

sample no. 

Swift CreekSuwannee River: 

1-84--------- BVE 

2-84-------- s 

3-84-------- s 

Noralyn: 

6-84--------- BV 

4-84--------- UPR 

5-84-------- UPR 

Gardinier 

(Cargill): 

8-84--------- BV 

7-84-------- BV 

Nichols: 

10-84----- BV 

9-84--------- UPR 

Fort Meade: 

13-84---- BV 

12-84----- UPR 

11-84------ UPR 

Clear Springs: 

16-84----- BV 

15-84-------- UPR 

14-84------ UPR 

Hardee Complex: 

17-84----- BV 

18-84----- BV 

19-84------ UPR 

Fort Green: 

20-84----- LBV 

21-84------- BV 

22-84----- UPR 

Saddle Creek: 

25-84 .......... BV 

24-84 .......... BV 

23-84 .......... UPR 

F 

8.0 14.8 1.3 

7.8 11.9 1.1 

10.1 15.5 1.5 

21.0 26.2 2.1 

22.5 32.6 2. 7 

11.2 17.0 1.5 

7.3 9.9 1.1 

21.0 32.3 2.6 

11.9 13.9 2.0 

13.8 20.0 1. 7 

16.5 24.4 2.0 

5.4 7.9 .8 

19.8 29.2 2.4 

29.6 42.4 3.0 

15.1 21.8 1.8 

9.2 13.8 1.2 

5.7 5.6 .6 

19.0 31.3 2.3 

20.2 30.0 2.6 

15.9 25.5 2.1 

22.4 38.4 2.1 

15.4 21.6 1.8 

15.5 23.3 1.8 

15.9 26.1 1.9 

15.6 22.6 1.9 

Analyses 

61.1 3.6 0.7 5.6 2.5 

63.8 6.7 1.5 1.7 1.0 

64.5 3.3 .9 1.4 .5 

39.5 5.2 .8 1.1 .2 

31.3 3.6 1.5 2.6 .4 

51.0 2.4 8.3 1.7 .9 

73.9 4.2 .6 .8 .2 

34.6 2.6 1.6 2.8 .3 

69.9 3.0 1.3 1.1 

56.5 2.6 .6 1.4 

46.3 3.9 

73.9 5.5 

33.1 3.4 

20.2 2.9 

51.5 3.1 

65.1 4.4 

80.5 4.0 

43.2 1.4 

3.2 2.2 

17.9 4.6 

2.1 2.1 

1.9 1.9 

48.9 4.3 

47.8 3.4 

50.0 3.3 

.73 1.9 

1.4 .9 

2.7 3.0 

.27 1.7 

.59 2.0 

.59 1.9 

.50 .7 

.55 2.7 

2.8 3.0 

.52 1.9 

.7 2.6 

1.5 1.8 

1.7 1.1 

1.8 1.4 

2.1 .9 

.1 

.2 

.3 

.3 

.6 

.1 

.2 

.4 

.1 

.2 

.4 

.2 

.3 

.3 

.3 

.5 

.7 

1.85 

1.52 

1.53 

1.25 

1.45 

1.52 

1.36 

1.54 

1.17 

1.45 

1.48 

1.46 

1.47 

1.43 

1.44 

1.50 

.98 

1.65 

1.48 

1.60 

1.71 

1.40 

1.50 

1.64 

1.44 

Ratios 

0.16 

.14 

.15 

.10 

.12 

.13 

.15 

.12 

.17 

.12 

.12 

.15 

.12 

.10 

.12 

.13 

.10 

.12 

.12 

.13 

.09 

.12 

.12 

.12 

.12 

ferentiated Peace River Formation (1.55). The increase 

in CaO/P20s ratio with depth is primarily due to increases 

in dolomite content; however, in sections devoid of 

detectable carbonate, the composition of the francolite 

appears to change. The presence of iron and aluminum 

phosphate minerals in near-surface samples i_s indicated 

by CaO/P20s ratios of less than 1.32. 

Francolite is the most common fluorine-bearing 

mineral in the deposits, although hydroxyl-bearing iron 

and aluminum phosphates may contain fluorine. The 

relatively low CaO/P 2 Os and high F /P 2 Os ratios in samples 

from the Gardinier (Cargill) and Nichols mines (table 3) 

suggest that other fluorine-bearing mineral phases may 

be present, although none has been identified. Although 

the average F!P20s ratio is the same (0.12) for the Bone 

Valley Member and the undifferentiated part of the 

Peace River Formation, it increases with depth in 9 of the 

17 mine sections examined, remains the same in 4 

sections, and decreases in 4 sections. The increase in the 

F/P20 5 ratio with depth in many mines suggests that, in 

general, the francolite is more highly substituted at 

depth. 

Si02 occurs primarily as quartz and clay minerals 

and to a lesser extent as feldspar and opal. Ah03 is 

8 Mineralogy and Alteration of the Phosphate Deposits of Florida 
Table 3. Chemical analyses of bulk samples of Florida phosphate ores-Continued 

Analyses Ratios 

Mine and Stratisample no. graphy PzOs CaO F SiOz Al203 Fe203 COz MgO CaO-PzOs F-PzOs 

Lonesome: 

26-84----- BV 11.1 13.2 1.1 47.6 12.3 3.5 0.2 0.9 1.19 0.10 

27-84----- UPR 21.0 27.6 2.2 31.6 5.9 2.9 1.0 .5 1.31 .10 

28-84----- UPR 12.4 16.4 1.4 54.2 3.9 5.9 .6 .3 1.32 .11 

Watson: 

29-84----- UPR 15.0 22.2 1.8 47.3 3.4 3.1 1.9 .8 1.48 .12 

Phosphoria: 

31-84----- BV 11.2 14.6 1.2 62.9 5.7 .88 .9 .3 1.30 .11 

30-84------ UPR 12.3 16.9 1.4 55.6 5.7 1.7 1.3 .4 1.30 .11 

30A-84------- UPR 9.5 14.0 1.2 52.0 6.1 7.3 1.3 .9 1.47 .12 

Rockland: 

32-84---- BV 10.0 11.6 1.0 61.2 7.9 1.4 .9 .5 1.16 .10 

33-84----- UPR 7.2 10.6 1.0 47.1 2.1 17.0 7.2 1.2 1.47 .14 

Haynsworth: 

34-84---- BY 18.3 25.9 2.1 46.4 1.7 .87 1.2 .24 1.41 .11 

35-84---- UPR 17.3 24.2 1.9 47.5 2.1 .93 1.5 .25 1.39 .11 

Lonesome: 

37-84---- BY 12.1 18.7 1.3 57.1 5.0 1.3 1.4 .49 1.54 .11 

36-84---- UPR 13.3 22.6 1.7 48.1 4.5 1.8 1.2 2.0 1.70 .12 

Hookers Prairie: 

41-84---- l.BV 20.2 28.4 2.3 37.4 4.1 .76 2.2 .29 1.40 .11 

40-84----- BY 13.7 23.0 1.7 50.1 4.4 1.4 2.1 .58 1.68 .12 

39-84----- UPR 10.6 22.0 1.4 41.0 3.6 1.7 7.5 4.2 2.07 .13 

38-84----- UPR 8.4 13.6 .8 66.6 3.6 1.8 1.3 .78 1.62 .09 

Four Comers: 

44-84---- BY 8.7 13.1 .8 74.0 1.1 .88 1.0 .2 1.50 .09 

43-84---- UPR 9.7 21.1 1.0 47.9 1.8 1.2 8.1 3.96 2.17 .10 

42-84----- UPR 9.5 14.7 .9 62.6 4.3 2.5 1.2 .59 1.54 .09 

Kingsford: 

47-84----- BY 12.6 18.8 1.2 53.9 5.1 1.9 1.1 .49 1.49 .09 

46-84--- UPR 15.4 28.6 1.8 28.6 2.7 4.4 9.1 3.59 1.86 .11 

45-84---- UPR 12.0 23.2 1.4 41.0 3.1 2.3 8.0 3.33 1.93 .12 

NorandaHopewell: 

48-84----- Unknown 22.8 33.2 2.4 27.4 4.6 1.6 2.2 .46 1.46 .10 

Beker-Wmgate 

Creek: I 

49-84---- Unknown 30.3 44.7 3.4 7.9 1.2 2.1 4.0 .49 1.47 .11 

50-84----- Unknown 13.7 32.6 1.6 17.3 1.4 1.9 16.9 7.6 2.38 .12 

1 Sample 49-84 is a -20+200 mesh concentrate; sample 50-84 is +20 mesh pebble. Mining is under water, so 

stratigraphy is unknown. 

present in the clay minerals, aluminophosphate minerals, the result of both varying amounts of the mineral 

and feldspar. Fe203 is highly variable and occurs as iron components and varying composition of the mineral 

oxides, in iron phosphate minerals, and in clay carbonate species. The proportions of the mineral phases present 

minerals. The C02 content varies with the amounts of may not be indicated by chemical data alone; however, 

francolite and rhombic carbonate minerals. Most MgO is changes in the CaO/P20s and FIP20s ratios can indicate 

in dolomite, but francolite and the clay minerals also variations of francolite composition both regionally and 

contain MgO. stratigraphically. The Bone Valley Member is only 

The chemistry of the samples from mine to mine slightly more phosphatic than the minable zones of the 

and within mines is highly variable, and differences are undifferentiated part of the Peace River Formation. 

Chemical Analyses of Phosphate Ores 9 
MINERALOGY 

Quartz and francolite are major components of the 

pebble fractions (plus 20-mesh), but potassium feldspars 

(both orthoclase and microcline) are in most samples in 

minor to trace amounts (figs. 5-23, appendix). Dolomite 

was commonly found at the base of many of the measured sections but is also present at the top of sections at 

the Swift Creek and Suwannee River mines (figs. 5, 6) in 

north Florida. This dolomite may have formed penecontemporaneously or may be reworked. Dolomite was 

present in the top sample at the Saddle Creek mine (fig. 

14), but the interpretation may be confused because 

there is a secondary carbonate caliche in the section. The 

pe~ble frac!i~n contains traces of smectite and palygorskite. Kaohmte was not detected in this fraction. The 

aluminum phosphate mineral wavellite is confined to the 

tops of economic zones or where shallow overburden 

exists. 

Quartz is the major mineral in the feed fraction 

(minus 20- plus 200-mesh), and francolite, although 

present in all samples, is in minor to trace amounts in 

most samples. Most of the samples contain potassium 

feldspar, and it appears in somewhat greater abundance 

than in the pebble fraction. Wavellite, the only aluminum 

phosphate mineral detected in the feed fraction, is 

gener~lly ~estricted to the top of sections. The only 

~xcephon I~ at the Saddle Creek mine (fig. 14), where it 

IS present m the bottom of the section. Clay minerals 

were not detected in the samples of the feed fraction. 

Quartz is the major component of the minus 200-

~esh (sl~me) fractions. Francolite shows an apparent 

mcrease m abundance with respect to quartz in both the 

pebble and feed fractions and is a major component of 

the slime fraction in the upper beds at many mines. This 

increase . in francolite results from formation of chalky, 

soft, white phosphate in weathering zones. This soft 

phosphate is comminuted in washing and screening. 

Wissa and others (1982) found an average of 9.9 percent 

P205 in 12 phosphatic clay samples (minus 44 ~m), and 

~romwell (1982) found an average of 12.5 percentP20 5 

m 16 samples of washer slimes; both studies concluded 

that francolite is the predominant nonclay mineral in 

slimes. Dolomite was commonly found at the base of 

most sections, although it was also present in the upper 

parts of some mine sections (Saddle Creek (fig. 14), 

Ho~ker.s ~rairie (fi~. 21), and Four Corners (fig. 22)). 

Albite IS m the mmus 200-mesh fraction at different 

levels at most mines, and potassium feldspar is abundant 

in this fraction. Wavellite is generally restricted to 

samples from the upper beds except at the Lonesome 

~i~e (fig. 15) and the Four Corners mine (fig. 22), where 

It . IS at the base. The calcium aluminum phosphate 

mmeral crandallite is common in this fraction and can be 

found throughout the sections, even at the base of mines 

where other evidence indicates the sedimentary rocks are 

relatively less altered (Four Corners, fig. 22). Smectite is 

present from the tops to bases of economic sections. 

Palygorskite is generally confined to the base of sections 

but can be found higher in the beds of individual mines. 

Kaolinite is most abundant near the top of sections, 

although it was identified at all levels. Illite is restricted to 

the slime fraction. Sepiolite is rare and was detected only 

near the base of three of the mines. Goethite is found at 

the base of sections at many mines. 

In the minus 2-~m fraction, quartz is nondetectable 

or is present in trace amounts. Francolite abundance in 

this size fraction varies from trace to major amounts. 

Albite is found throughout sections and is the predominant feldspar, although potassium feldspar is at all 

levels in trace to minor amounts. Wavellite, which 

generally is at the top of sections, was found at the base 

of the section at the Lonesome mine (fig. 20), where the 

normal sequence seems inverted. Crandallite is most 

common in the upper altered beds but was found 

throughout the deposits. Smectite is the major clay 

mineral, and palygorskite is generally confined to 

samples lower in the sections. Kaolinite is generally at the 

top of sections, but locally it can be found to the base of 

sampling. Goethite, as in the minus 200-mesh samples, is 

common at the base of sections. 

In summary, quartz is the principal gangue mineral 

in the processed parts of the ore. Francolite is found in all 

particle-size fractions and is abundant in the slime 

fraction. Aluminophosphates are most common in the 

upper beds of individual sections. Smectite is the 

predominant clay mineral of the slime fraction and 

occurs throughout the deposits. Palygorskite generally 

occurs at the base of the sections, and kaolinite is 

generally found in the highest parts of the sections. In the 

coarser size fractions, potassium feldspar is the most 

common feldspar, and albite is the most abundant feldspar in the minus 200-mesh and clay fractions ( < 2 ~m ). 

Francolite 

In establishing a series of systematic relationships 

among francolites, Lehr and others (1967), McClellan 

and Lehr (1969), and McClellan (1980) used XRD, 

chemical analysis, and statistical methods to show that 

the contents of calcium, sodium, magnesium, phosphorus, C02. and fluorine can adequately describe most 

francolites. Studies of francolite in commercial 

concentrates of phosphate rock show that the replacement of Ca2 + by Na + and Mg2 + is systematic 

although limited. Thus, part of the Na + and Mg2 + in 

commercial concentrates is substituted within the francolite structure and cannot be removed by beneficiation. 

Similarly, carbonate substitutes for phosphate in a 1:1 

10 Mineralogy and Alteration of the Phosphate Deposits of Florida 
ratio, with the maximum amount of substitution limited 

to about 6 percent C02. Net charge imbalances are 

compensated by both cation and anion substitutions. An 

important economic result of these substitutions is the 

reduction of the maximum P20s content of a 100-percent 

francolite concentrate from 42.2 percent in fluorapatite 

to 34.0 percent P20s in the most highly substituted 

francolite. 

These substitutions have been shown to be 

represented adequately by a series with the following 

end-member empirical formulas (McClellan, 1980): 

Fluorapatite Ca1o(P04)6F2 

Francolite 

Ca1o-X-Y NaxMgy (P04)6-z(C03)zFo.4zF2. 

Because the unit -cell a-values decrease 

systematically with increasing carbonate substitution, the 

values for X, Y, and Z in the francolite model (McClellan, 1980) can be obtained by using the following 

formulas based on statistical models: 

z 

6-Z 

9.369-aobs 

0.185 

(Na)X =7.173(9.369-aobs), 

(Mg)Y =2.784(9.369-aobs), 

in which 

XRD, 

a obs =a-value in angstroms determined by 

z = moles of co~- in the francolite formula, 

X= moles of sodium in the francolite formula, 

Y = moles of magnesium in the francolite 

formula. 

The theoretical range of compositions between 

fluorapatite and francolite, based on calculations using 

the francolite model and empirical formulas, is shown in 

table 4. Francolite compositions have been computed by 

this method for typical concentrate samples from six 

well-known localities and are arranged in order of 

increasing substitution (table 5). Although these samples 

show a wide range of variability, they do not span the 

entire range of compositions shown by the end members. 

The a values measured from the suite of Florida 

samples show a wide range (9.323-9.368 A), both with 

respect to depth and within the size fractions of individual 

samples (table 6) and almost span the entire range of the 

francolite model (9.320-9.369 A). In general, a-values in 

any particular mine decrease or remain relatively 

Table 4. Comparison of the theoretical composition of 

fluorapatite and francolite 

[Values in weight percent] 

Constituent Fluorapatite 

Ca() -------------------- 55.6 

p 2 0 5 ----------------------- 42.2 

C02 ------------------------ 0 

F --------------------------- 3. 77 

Na2 0---------------------- 0 

MgO --------------------- 0 

CaO:P 1.318 2 0 5 -----------------

F:P 2 0 5 --------------------- .089 

Francolite (z/6-z...0.30) 

55.1 I, 

34.0 

6.3 

5.04 

1.4 

1.4 

1.621 

.148 

constant with depth within a given size fraction. Also, 

there is a trend in francolite composition from low to 

high a-values with the change from coarse to fine grain 

sizes, although there are exceptions. 

The changes in mean a-values for size fractions can 

be correlated with stratigraphy (table 7). The ranges and 

averages of P20s and C02 compositions were calculated 

from the a-value models; the highest grade francolites, 

approaching fluorapatite compositions, are present in the 

smaller size fractions. Histograms of a-values plotted 

according to stratigraphic position show the trends in 

a-values of francolite between size fractions and 

stratigraphy (figs. 2, 3). Although samples from the Bone 

Valley Member show slightly higher a-values as well as a 

greater range of values (standard deviation) than those 

from the undifferentiated part of the Peace River 

Formation, the data from these samples indicate that 

francolite compositions are not necessarily a reliable 

stratigraphic tool. 

Previous studies of the Florida phosphorites have 

indicated differences in francolite composition within the 

deposits. Whippo and Murowchick (1967) noted 

compositional and crystallographic differences in francolite samples from Polk and Manatee · Counties. The 

Manatee County samples (southern extension) were 

more highly substituted and contained 7 percent less P20s 

and 20 percent more C02 when calculated to an 

impurity-free basis. The data of Lehr and others (1967) 

indicated that francolites from Florida deposits have 

a-values ranging from 9.325 A to 9.339 A. 

Studies of the pebble fractions from central Florida 

deposits (Stow, 1976) indicated that progressive alteration of pebbles, related to color changes (black to brown 

to white), resulted in decreasing CaO/P20s and lower 

F!P20s ratios. Williams (1971) correlated the color of 

concentrates from north Florida with francolite 

composition by chemical analysis and lattice parameter 

measurements. In general, dark-colored concentrates 

Mineralogy 11 
Table 5. Calculated francolite compositions of various commercial phosphate ores 

[Values in weight percent] 

Source CaO MgO Na20 P205 C02 F 

Western United States-------------------- 55.6 0.13 0.26 40.1 1.59 4.09 

Tennessee------------------------------ 55.5 .24 .47 38.7 2.71 4.31 

Florida --------------------------------- 55.5 .36 .72 37.1 3.95 4.56 

Morocco---------------------------- 55.4 .43 .85 36.3 4.53 4.68 

North Carolina-------------------------------------- 55.3 .52 1.04 35.3 5.36 4.85 

Tunisia-------------------------------------- 55.2 .60 1.20 34.7 5.70 4.93 

Table 6. Unit-cell a-values of Florida phosphate ores 

[All values in angstrom units (A); standard error, less than 0.003 A; NA, not available] 

a-values, 

Tyler Mesh 

Mine Sample Depth Bulk +20 -20 +200 -200 

No. (feet) 

Swift Creek- 11-84 18-21 9.336 9.333 9.332 9.338 

Suwannee River. 22-84 24-46 9.337 9.331 9.334 9.347 

33-84 21-32 9.332 9.328 9.333 9.351 

Noralyn----------- 6-84 20-25 9.342 9.347 9.338 9.354 

4-84 25-34 9.337 9.336 9.347 9.345 

5-84 34-37 9.333 9.334 9.339 9.339 

Gardinier--------- 48-84 27-30 9.347 9.330 9.347 9.352 

7-84 34-40 9.332 9.332 9.346 9.358 

Nichols---------- 10-84 16-22 9.355 9.352 9.356 9.352 

9-84 22-25 9.347 9.342 9.346 9.339 

Fort Meade 13-84 19-29 9.330 9.328 9.332 9.344 

(Mobile). 12-84 29-41 9.333 9.328 9.334 9.345 

11-84 43-50 9.334 9.328 9.332 9.343 

Clear Springs------ 16-84 15-30 9.355 9.353 9.353 9.361 

15-84 30-38 9.338 9.337. 9.333 9.344 

14-84 42-46 9.336 9.338 9.334 9.337 

Haidee Complex--------- 17-84 16-22 9.348 9.368 9.343 9.346 

18-84 22-25 9.330 9.339 9.348 9.342 

19-84 25-29 9.335 9.332 9.350 9.350 

Fort Green-------- 520-84 12-14 9.335 9.329 9.336 9.341 

21-84 14-22 9.328 9.326 9.330 9.347 

22-84 22-26 9.330 9.326 9.332 9.337 

Saddle Creek------------ 25-84 8-16 9.349 9.344 9.347 9.350 

24-84 16-19 9.340 9.338 9.341 9.347 

23-84 19-22 9.350 9.348 9.343 9.353 

Lonesome--------- 26-84 22-25 9.355 9.354 9.340 9.353 

27-84 27-30 9.341 9.345 9.342 9.353 

28-84 30-34 9.340 9.336 9.349 9.349 

12 Mineralogy and Alteration of the Phosphate Deposits of Florida 
Table 6. Unit-cell a-values of Florida phosphate ores-Continued 

a-values, 

Tyler Mesh 

Mine Sample Depth Bulk +20 -20 +200 -200 

No. (feet) 

Watson--------------- 29-84 10.5-22.5 9.338 9.336 9.335 9.342 

Phosphoria------------------- 31-84 18-22 9.342 9.338 9.347 9.355 

30-84 22-31 9.345 9.345 9.347 9.352 

30A-84 31-33 9.336 9.336 9.337 9.355 

Rockland---------- 32-84 15-35 9.340 9.345 9.342 9.347 

33-84 35-37 9.335 9.328 9.337 9.345 

IIaynsworth---------------- 34-84 30-33 9.340 9.336 9.340 9.356 

35-84 33-36 9.345 9.337 9.339 9.357 

Lonesome-------- 37-84 16-26 9.346 9.344 9.340 9.345 

36-84 26-32 9.345 9.346 9.339 9.348 

Hookers Prairie----- 41-84 14-17 9.334 9.332 9.336 9.343 

40-84 17-23 9.332 9.333 9.335 9.345 

39-84 23-29 9.332 9.328 9.329 9.335 

38-84 29-35 9.338 9.331 9.332 9.338 

Four Comers-------- 44-84 14-19 9.340 9.332 9.330 9.327 

43-84 23-35.5 9.336 9.324 9.332 9.333 

42-84 37-43 9.336 9.328 9.335 9.349 

Kingsford-------------- 47-84 18-23 9.337 9.335 NA 9.360 

46-84 23-30 9.332 9.329 9.328 9.323 

45-84 30-42.5 9.334 9.330 9.335 9.329 

Noranda-Hopewell---- 48-84 Unknown 9.338 9.337 9.341 9.348 

Beker-Wingate6 _____________ 49-84 Concentrate 9.336 NA NA NA 

50-84 Pebble 9.331 NA NA 

lcombined sample. 

2Swift Creek mine. 

3suwannee River mine. 4Two samples from both the Bone Valley Member of the Peace River Fonnation and undifferentiated Peace 

River Fonnation collected 4 mi apart. 

50ne sample 20-84, leached Bone Valley Member, three samples (21-84), Bone Valley Member, three 

samples (22-84), undifferentiated Peace River Fonnation collected about 1 mi apart. 

contained the most highly substituted francolites. The 

color of francolite grains appeared to be related to 

several factors including enclosing lithology, lateral and 

vertical stratigraphic position, postdepositional history, 

and possibly grain size. Williams (1971) noted the cyclicity of sedimentation and reworking of parts of the 

deposits as evidenced by the presence of white (altered) 

francolite grains in dark-colored restricted marine or 

basinal sediments. 

Weathering, alteration, and enrichment of phosphate deposits have been described and interpreted 

chemically and mineralogically at sites in Morocco 

(Lucas and others, 1980), Senegal (Flicoteaux and Lucas, 

1984), and Togo (Fiicoteaux and Lucas, 1984). For each 

deposit, changes in chemical ratios and francolite 

crystallographic properties were noted that indicated a 

progressive decrease in carbonate content in the 

weathered zones. 

McArthur (1980) compared onshore and offshore 

Moroccan phosphorites and suggested that postdepositional weathering and interaction with ground 

water removes sodium, strontium, co3, and so4 from 

the structure of francolite. McArthur (1978) had earlier 

proposed the "constant composition hypothesis," 

according to which all primary francolites formed under 

similar conditions and therefore had similar compositions. McClellan (1980), working with a large sample 

base from deposits around the world, noted the 

variability of apatites in individual deposits with geologic 

time and proposed that through the combined effects of 

Mineralogy 13 
en 

w 

~ 40 

~ 

<( 

en 

...J 30 

~ 0 

1-

~ 20 

1-

z 

w 

~ 10 w 

0.. 

STANDARD DEVIATION 0.008 

9.33 9.34 9.35 9.36 9.37 

en 

w 

~ 40 

~ 

<( 

en 

....130 

~ 

~ 

~ 20 

1-

z 

w 

~ 10 w 

0.. 

0....___ __ _ 

A-VALUES, IN ANGSTROMS 

BULK SAMPLES 

STANDARD DEVIATION 0.007 

9~ ~33 9~ 9~ 9~ 

A-VALUES, IN ANGSTROMS 

-20 TO 200 MESH SAMPLES 

9.37 

en 

w 

~40 

~ 

<( 

en 

....130 

~ 

~ 

~ 20 

1-

z 

w 

~ 10 

~ 

50 

en 

w 

~40 

~ 

<( 

en 

....130 

~ 0 

1-

~ 20 

1-

z 

w 

~ 10 w 

0.. 

9.33 

9.33 

STANDARD DEVIATION 0.010 

9.34 9.35 9.36 9.37 

A-VALUES, IN ANGSTROMS 

+20 MESH SAMPLES 

STANDARD DEVIATION 0.008 

9.34 9.35 9.36 9.37 

A-VALUES, IN ANGSTROMS 

-200 MESH SAMPLES 

Figure 2. Histograms showing variations in a-values of francolite in 22 bulk and screened samples from the Bone Valley 

Member of the Peace River Formation, Florida. 

weathering, metamorphism, and time, francolites progressively alter from highly substituted varieties to 

essentially a fluorapatite composition. There are 

presently no known examples of reversal of this process, 

and thermodynamic considerations preclude this 

possibility (Chien and Black, 1976). 

Variations in the carbonate content of francolites 

have also been attributed to the depositional environment. Gulbrandsen (1970) postulated that the 

general eastward increase in the X-ray-determined 

carbonate content of francolites in the Phosphoria 

Formation indicated a general warming of the seas as the 

water shallowed. Cook (1970) observed similar 

variations across the Phosphoria Formation and 

concluded that variations in temperature, pH, salinity, 

and depth could have caused the variations, although the 

complexity of dissolved inorganic carbon equilibria 

prevented a definitive interpretation. McArthur (1985) 

correlated the published C02 data with data on depth of 

burial for the Phosphoria and concluded that the diagenetic and catagenetic alteration of the francolites was 

related to depth of burial, presumably as a response to 

increased temperature and pressure. 

The a-values of francolite from less altered 

deposits around the world generally are less than 9.330 A 

(table 8); the a-value of a primary francolite, however, is 

not known. These deposits are considered to be less 

altered because they show slight or no evidence of 

weathering. Both the Miocene phosphorites of North 

Carolina (United States) and the Eocene Togo Bed 2/3 

deposits of Africa (Johnson, 1987) are marine phosphorites that are now in a freshwater environment. The 

sample from the Congo River delta, west -central Africa, 

is Miocene in age and may have been subjected to 

freshwater in its history. The Tunisian samples are 

associated with calcareous marls and gypsum beds. 

Samples from the Miami Terrace and the West Florida 

Shelf are dredge samples thought to be of Miocene age. 

Most of these less altered francolites occur with calcite in 

the samples or are associated with calcite-bearing beds. 

14 Mineralogy and Alteration of the Phosphate Deposits of Florida 
(I) 

w 

~ 40 

~ 

< (I) 

-'30 

~ 

~ 

~ 20 

.... 

z 

w 

~ 10 

~ 

0'-----

STANDARD DEVIATION 0.005 

9~ ~~ 9~ 9~ 9~ 

(I) 

w 

~ 40 

~ 

~ 

-'30 

~ 

~ 

~ 20 

.... 

z 

w 

~ 10 w 

n.. 

A-VALUES, IN ANGSTROMS 

BULK SAMPLES 

STANDARD DEVIATION 0.006 

9.37 

9.~ 9.34 9.35 9.36 9.37 

A-VALUES, IN ANGSTROMS 

-20 TO 200 MESH SAMPLES 

(I) 

w 

~ 40 

~ 

< (I) 

-'30 

~ 

~ 

~ 20 

.... 

z 

w 

~ 10 w 

n.. 

(I) 

w 

50 

~ 40 

~ 

< (I) 

-'30 

~ 0 

.... 

~ 20 

.... 

z 

w 

~ 10 w 

n.. 

9.~ 

9.~ 

STANDARD DEVIATION 0.007 

9.34 9.35 9.36 9.37 

A-VALUES, IN ANGSTROMS 

+20 MESH SAMPLES 

STANDARD DEVIATION 0.008 

9.34 9.35 9.36 9.37 

A-VALUES, IN ANGSTROMS 

-200 MESH SAMPLES 

Figure 3. Histograms showing variations in a-values of francolite in 24 bulk and screened samples from the undifferentiated 

Peace River Formation, Florida. 

The dissolution and removal of carbonates is an 

important process in the upgrading of phosphorite 

deposits. Carbonates buffer the pore water and protect 

the associated francolite by increasing the field of 

stability of francolite (Nathan and Sass, 1981 ). It is only 

after the carbonates are minimized or disappear that the 

francolite begins to alter towards low-carbonate varieties 

or to iron and aluminum phosphates (Altschuler, 1973; 

Lucas and others, 1980). This important constraint on 

the geochemical system limits changes in the composition 

of the bulk sediment through a series of complex steps. 

The alteration of carbonate-bearing phosphatic sediments would progress from dissolution of calcite to 

dissolution of dolomite (if present) and, at some time in 

the latter stages of carbonate dissolution, the alteration 

of highly carbonate substituted francolites to lowcarbonate varieties. The actual mechanism of the latter 

process is not understood, but the process clearly results 

in the removal of some constituents from the francolite 

structure, in addition to C03. Solution and reprecipitation probably occur, although the scale of the process is 

not known. 

The a-value data for least altered francolites in 

Florida (less than 9.330 A, table 9) indicate that the 

highly carbonate substituted varieties are associated with 

the coarser fractions and with samples that contain 

dolomite or calcite. However, the presence of dolomite 

does not assure low a-values. For example, samples from 

the Saddle Creek (fig. 14) and Clear Springs (fig. 11) 

mines contain dolomite, but the a-values of the francolites are more than 9.340 A. These values suggest that 

the alteration of the francolite may have occurred before 

dolomitization in these beds or that mixing has occurred. 

The size fractions in only three samples (from Four 

Corners (fig. 22) and Kingsford (fig. 23) mines) deviate 

significantly from the typical sequence of increasing 

a-values with decreasing particle size (samples 47-84, 

Mineralogy 15 
Table 7. Variations of francolite a-values and composition with stratigraphy, Florida phosphate ores 

[X-ray P205 and C02 values, in weight percent, calculated by procedures from McOellan (1980)] 

Sample 

group 

(Tyler mesh) 

Range 

a-values 

(A±o.003) 

Mean 

a-value 

(A±0.003) 

Range 

X-ray C02 

Average 

X-ray C02 

Bone Valley Member of the Peace River Formation (22 samples) 

Bulk ----------------------------- 9.328-9.355 

+20 ---------------------------- 9.328-9.368 

-20 to +200.--------------------------------------- 9.330-9.356 

-200--------------------------------- 9.327-9.361 

9.341 

9.340 

9.341 

9.349 

35.86-39.14 

35.86-39.31 

36.12-36.94 

35.73-40.08 

37.65 

37.50 

37.65 

38.84 

4.93-1.87 

4.93-0.14 

4.72-1.74 

5.03-1.04 

3.53 

3.64 

3.53 

2.60 

Undifferentiated Peace River Formation (24 samples) 

Bulk ------------------------------ 9.330-9.350 

+ 20 ---------------------------------- 9.324-9.348 

-20 to +2oo.------------------~-------------------- 9.328-9.346 

-200----------------------------------- 9.323-9.357 

9.338 

9.334 

9.337 

9.343 

Table 8. Examples of a-values of less-altered francolite 

from various localities throughout the world 

(Values are in angstrom units (A)] 

Sample No. of Range Average 

locality samples (A±0.0001) (A...+0.0001) 

Congo, Africa (offshore)---- 5 9.320-9.327 9.324 

Togo, Africa (Bed 2!3)-------------- 5 9.325-9.333 9.329 

Tunisia------------------------- 5 9.320-9.331 9.327 

North Carolina---------------------- 18 9.318-9.332 9.323 

Miami Terrace ------------- 1 None 9.326 

West Florida Shelf----------------- 1 None 9.319 

46-84, 45-84). At the Four Corners mine (fig. 22), the 

beds below sample set 44-84 show a normal progression 

to higher a-values with decreasing particle size. In two of 

these three samples (44-84 and 47-84) as well as in 

sample 13-84 (fig. 10), aluminophosphates occur with 

less altered francolites in the pebble fraction. This 

unusual association may result from mixing of materials 

from different sources or may indicate that francolites do 

not have to progress to low-carbonate-substituted 

varieties before conversion to aluminophosphates can 

occur. 

The variability in francolite composition may result 

from many factors. Original composition, presence of 

carbonates, mixing of altered francolite with unaltered 

francolite, stratigraphic position or depth, degree and 

depth of weathering, depth and character of overburden, 

size of phosphate particles, possible sheltering effects of 

impermeable clay beds or indurated dolomite layers, 

26.12-39.00 

35.35-38.69 

35.86-38.84 

35.22-40.12 

37.22 

36.66 

37.08 

37.94 

4.72-2.48 

5.33-2.72 

4.93-2.60 

5.43-1.61 

3.87 

4.30 

3.98 

3.31 

Table 9. FrancoliteDsamples from Florida with a-values less 

than 9.330 (±0.003 A) 

Size 

fraction Carbonates 

Sample (fyler All size 

Mine No. mesh) a-value fractions 

Suwannee River--------- 3-84 +20 9.328 Dolomite, calcite. 

Fort Meade------------------- 13-84 +20 9.328 Not detected. 

12-84 +20 9.328 Dolomite. 

11-84 +20 9.328 Dolomite. 

Fort Green ------------- 20-84 +20 9.329 Not detected. 

21-84 +20 9.326 Not detected. 

22-84 +20 9.326 Dolomite. 

Rockland--------------- 33-84 +20 9.328 Dolomite. 

Hookers Prairie--------- 39-84 +20 9.328 Dolomite. 

39-84 -20-200 9.329 Dolomite. 

Four Comers----------- 44-84 -200 9.327 Dolomite. 

43-84 +20 9.324 Dolomite. 

42-84 +20 9.328 Dolomite. 

Kingsford----------------- 46-84 +20 9.329 Dolomite. 

46-84 -20-200 9.328 Dolomite. 

46-84 -200 9.323 Dolomite. 

45-84 -200 9.329 Dolomite. 

hydrologic controls, and paleotopography all may have 

contributed to producing the francolite compositions of 

today. 

The general increase in a-values from coarser to 

finer size fractions may be due to preferential alteration 

of the fine sizes because of their greater relative surface 

area. Mixing of altered and prim~ry or less altered 

francolites in various particle sizes may have occurred 

16 Mineralogy and Alteration of the Phosphate Deposits of Florida 
during subaerial or subaqueous exposure and erosion of 

the phosphorites. The fine-grained altered francolite 

could have been preferentially moved offshore to be 

mixed with primary or less altered francolites, and the 

resultant a-values of such samples would then vary in 

proportion to the composition of the constituents. 

On the basis of francolite compositions, every 

section examined in this study shows some degree of 

alteration, even in the lowermost beds of the downdip 

facies in the southern extension of the central district. 

The precise stratigraphic position of the samples from 

the Wingate Creek mine cannot be ascertained because 

the section is mined by dredge; however, the samples 

show enough variation to indicate that they were from a 

zone of detectable alteration. The lowermost beds of the 

Kingsford mine (fig. 23) appear to be the least altered of 

the sections studied. 

In deeper sections, downdip to the south, and in the 

north where the phosphatic Miocene sediments of 

Florida are less altered, the francolites change in 

composition to more highly substituted varieties with 

decreasing P20s content and increasing impurity 

content. In general, the finer size fractions contain 

francolite with the lowest carbonate substitution, lowest 

impurity content, and greatest P20s concentration. 

Based on an average of 12.5 percent P20s in washer 

tailings (Bromwell, 1982) and an average a-value of 9.346 

A for combined beds of the Bone Valley Member and the 

undifferentiated part of the Peace River Formation, the 

francolite content of an aluminophosphate-free sample 

slime would be about 33 weight percent. Because most 

slime samples contain appreciable amounts of aluminophosphates, this is a maximum value. Deviations from 

the typical occurrence of most altered francOlite at the 

top of the sections and in the finer size fractions indicate 

the complex nature of the formation of the deposits. 

Clays 

The clay minerals in the phosphate deposits of 

Florida are a mixture of common (smectite, illite, and 

kaolinite) and less common (palygorskite and sepiolite) 

minerals. The general sequence of clay minerals in 

economic zones is, from top to base, kaolinite to smectite 

to smectite plus palygorskite (Altschuler and others, 

1964). Smectite is the most abundant clay mineral in the 

Florida Miocene sediments (McClellan, 1962; Weaver 

and Beck, 1977; Reik, 1982). The smectite may be 

original detrital material (Weaver and Beck, 1977), the 

result of diagenesis, or a mixture of the two. The kaolinite 

is thought to be a mixture of detrital material (Weaver 

and Beck, 1977) and material derived from the alteration 

of smectite (Altschuler and others, 1963). The illite in 

these sediments is considered to be detrital and is only a 

minor phase. 

Palygorskite ( attapulgite) and sepiolite, clay minerals with chain-type molecular structures similar to 

amphiboles, tend to be fibrous and range in size from less 

than 2 p.m to about 10 p.m. Sepiolite is rare and is 

generally restricted to the very base of sections. 

Commercially important deposits of palygorskite occur 

interbedded with the Miocene sediments of northwestern 

Florida and southwestern Georgia. The association of 

phosphorite and palygorskite is not unique to the Florida 

deposits; palygorskite is interbedded or closely associated 

with many phosphorite deposits in Africa and the Middle 

East. In general, palygorskite occurs at the base of the 

phosphate mines in Florida and higher in the sections 

where carbonates are present. It is also associated with 

endogangue in phosphate pebble and can be found high 

in sections where protected by relatively impermeable 

smectite beds. One occurrence of massive-bedded 

palygorskite in peninsular Florida is at the Clear Springs 

mine (Upchurch and others, 1982; Strom and Upchurch, 

1983, 1985). 

Chemical analyses of two nearly pure palygorskite 

samples from north and central Florida phosphorite 

deposits (table 10) are typical of palygorskite from 

deposits in the region (Weaver and Pollard, 1973). XRD 

patterns of the samples indicate a minor amount of 

intimately associated smectite, and a separation of the 

(121) and (12i) reflections indicates the monoclinic 

polymorph. Both samples proved to be the long-fiber 

variety (fiber lengths greater than 2 p.m) under scanning 

electron microscope observation. Weaver and Pollard 

(1973) and Weaver and Beck (1977) reported that the 

short-fiber variety (fibers averaging approximately 1 p.m 

in length) is the predominant type from commercial 

deposits in south Georgia and north Florida and 

interpreted their palygorskite XRD data to indicate 

orthorhombic symmetry. 

Palygorskite is known to form by hydrothermal 

alteration of mafic rocks, in soil zones under arid 

conditions, in deep-sea sediments, and in hypersaline 

playa lakes, and it is thought to form in restricted 

schizohaline lagoons or ephemeral lakes (for a review, 

see Singer, 1979). There is little evidence that palygorskite forms under normal marine conditions. 

Palygorskite-sepiolite in the Florida deposits has most 

recently been postulated to have formed in a perimarine 

environment (Weaver, 1984; Weaver and Beck, 1977) or 

in ephemeral lakes (Strom and Upchurch, 1983, 1985; 

Upchurch and others, 1982). Weaver and Beck (1977) 

proposed that primary deposition of the palygorskite and 

sepiolite in north Florida occurred prior to the 

transgression of the middle Miocene seas and that the 

association with the middle Miocene phosphates may 

largely be detrital, although some diagenetic palygorskite 

also is present in the deposits. The palygorskite in the 

Mineralogy 17 
Table 10. Chemical analyses of palygorskite samples from 

Florida phosphate deposits 

[Values in weight percent) 

Constituent Clear Springs mine 

SiO ----------------------- 2 

AI 0 --------------------- 2 3 

Fe 0 --------------------- 2 3 

MgO---------------------

K 0 -------------------- 2 

Na 0------------------- 2 

CaO--------------------

'IiO ---------------------- 2 

MnO-------------------

*H o+ ------------------- 2 

60.04 

9.76 

3.46 

12.15 

.57 

.18 

.00 

.41 

.03 

.lMQ 

Total------------------- 99.20 

Octahedral Al/Mg ----- .59 

·*Water retained above l05°C. 

Suwanne River mine 

58.65 

10.32 

4.94 

10.51 

.39 

.37 

.02 

.28 

.02 

12.23. 

98.43 

.71 

phosphate deposits of Florida may have resulted from 

the transformation of smectites by the addition of 

magnesium (Altschuler and others, 1956; Altschuler and 

others, 1964). 

The smectites of the Florida phosphorite deposits 

have been described as nontronitic (Altschuler and 

others, 1963) and iron rich (Strom and Upchurch, 1985; 

Bromwell, 1982). XRD analysis of clays from cores of 

phosphorites in northeastern Florida shows broad smectite peaks, which were interpreted by Reik (1982) as 

indicating mixed-layer types. 

Chemical, XRD, and thermal techniques were 

used in this study to investigate the nature of smectiterich clay samples. Several kaolinite-free smectite samples 

were X-rayed to determine their characteristic dspacings (table 11). The measurement of 060 reflections 

indicates an average value of 1.501 A, which nearly 

agrees with the 1.495-A value reported by Altschuler and 

others (1963) for their nontronitic montmorillonite. 

Brindley (1980) reported 060 values of 1.504-1.492 for 

various types of montmorillonites. Weir and GreeneKelley (1962) and Brindley (1980) report 060 values of 

1.498 A and 1.497 A, respectively, for beidellite. Nontronites have slightly larger 060 values of 1.522-1.525 

(Schneiderohn, 1964; Carroll, 1970; Chen, 1977). These 

data indicate that the smectite in the samples studied is 

beidellite or montmorillonite rather than nontronite. 

Lithium saturation, heat, and glycolation 

treatments, according to the method ofBrusewitz (1975), 

were performed on clay samples 26-84, 38-84, and 

42-84 (table 11 ). Using these treatments, montmorillonite may be distinguished from beidellite and nontronite. Changes in the observed 001 reflection also 

Table 11. Characteristic d-spacings of smectite from Florida phosphate deposits 

[Values in angstrom units. BV, Bone Valley Member of the Peace River Formation; UPR, undifferentiated Peace River Formation] 

d-spacing 

Mine and Air dried Glycolated Heated Randomly 

sample no. Stratigraphy (001) (001) (001)1 oriented(060)2 

Lonesome BV 14.66 17.36 10.08 1.500 

26-84 

Phosphoria: UPR 14.93 17.03 10.15 1.502 

30a-84 

Hookers Prairie: UPR 15.08 17.26 10.40 1.502 

38-84 

Four Comers: UPR 14.54 17.30 10.30 1.505 

42-84 

Kingsford: UPR 14.72 17.14 10.10 1.502 

45-84 

Hookers Prairie: UPR 15.43 17.55 10.15 1.498 

1985-1 

1 Heated at 350°C for 24 hours. 

2No kaolinite detectable by X-ray diffraction. 

18 Mineralogy and Alteration of the Phosphate Deposits of Florida 
indicate that the smectites associated with kaolinite-free 

samples are beidellite. These lithium- and heat-treated 

samples re-expanded with glycolation. 

Structural formulas derived from the chemical 

analyses of the clay samples confirm this interpretation. 

When the chemical data for some of these smectites 

(table 12) and that of Altschuler and others (1963) are 

converted to structural formulas using the methods of 

Marshall (1949) and Ross and Hendricks (1945), the 

results indicate that most of the charge occurs in the 

tetrahedral layer. This characteristic separates beidellite 

from montmorillonite (Greene-Kelly, 1955; Weir and 

Greene-Kelly, 1962). The charge division between the 

octahedral and tetrahedral layers of sample 26-84 

(Lonesome mine, Bone Valley Member of the Peace 

River Formation (fig. 15) is approximately equal; 

however, the sample reacted positively to the lithiumsaturation test. These structural formulas and layercharge calculations are not inerrant, but they may be 

useful data transformations when used in conjunction 

with other data. For a more complete discussion of the 

errors and limitations in the interpretation of such 

chemical data and structural formulas, see Schultz 

(1969). 

The high iron oxide contents in Florida smectite 

samples complicate the interpretation of the chemical 

data. Field and microscopic evidence indicate that some 

of the iron occurs as discrete clay-size iron oxide particles 

and surface coatings. Although routine chemical 

extraction of clay minerals should be avoided because of 

possible mineralogic changes, samples 26-84 and 42-84 

(table 12) were extracted with sodium dithionite (Mehra 

and Jackson, 1960). A reduction of 40-50 percent in the 

Fe2 03 content of these samples resulted in analyses very 

similar to those of the average montmorillonite-beidellite 

of Weaver and Pollard (1973, p. 56). XRD analyses 

before and after iron oxide extractions indicated no 

significant change in the smectite. The molar Mg!Fe ratio 

of unextracted samples is essentially 1, but the ratio of 

extracted samples is about 2. The contents of MgO in the 

samples suggest that these smectites are members of a 

beidellite-montmorillonite series rather than a beidellitenontronite series. 

Thermal analyses also confirm that these smectites 

are beidellites. Trauth and Lucas (1967) reported that 

nontronite dehydroxylates at approximately 500°C, 

whereas beidellite dehydrated at 550°C. Thermal 

analyses of the central Florida smectites indicate 

endotherms between 540 and 560°C. Schultz (1969) 

classified montmorillonites and beidellites into seven 

groups based on their composition, amount and 

distribution of their layer charge, thermal behavior, and 

properties that are revealed by Li + and K + treatments. 

Nonideal montmorillonites and nonideal beidellites can 

be distinguished from their ideal counterparts by their 

Table 12. Chemical and layer-charge analyses of selected 

Florida smectite samples 

[Analyses, in weight percent, corrected for identified apatite, dolomite, 

crandallite, and wavellite after chemical determination of P20s, CaO, 

MgO, C02, and Al20s. NA, no analysis] 

Sample no., location, and stratigraphic unit 

Constituent 26-841 SC12 FHPC 42-84 

Si02----------------- 57.25 56.91 53.38 55.46 

AJ"2 0 3------------------- 21.54 22.65 22.89 20.95 

Fe2 0 3

-------------------- 3.13 6.29 6.48 4.75 

FeO------------ None .11 NA NA 

MgO------------ 3.28 3.62 2.59 3.90 

KzO----------- 1.64 .74 1.32 1.41 

Na20--------- .21 .18 .87 0.06 

CaO.------------- .75 1.47 .67 .27 

TiO 2------------------- .95 .65 .76 .64 

MnO.------------ .03 NA .02 .04 

3H2o+ -------------------- .l.l.2.l 1.3! lQ.81 lL5! 

Total------------------- 99.99 99.96 99.85 99.02 

Octahedral charge----- -.18 -.05 +.01 -.10 

Tetrahedral charge-- -.15 -.30 -.35 -.22 

Total charge----- -.33 -.35 -.34 -.32 

lsodium dithionite extracted, original Fe2

o 3 analyses: 26-84, 5.1 

weight percent; 42-84, 10.6 weight percent. 

2From Altschuler and others (1963). 

3water present above l05°C. 

SAMPLE SOURCES 

26-84: Lonesome mine, Bone Valley Member of the Peace River 

Formation. 

SC1: Silver City mine, Bone Valley Member of the Peace River 

Formation. 

1985-1: Hookers Prairie mine, undifferentiated Peace River Formation. 

42-84: Four Corners mine, undifferentiated Peace River Formation. 

characteristic dehydroxalation endotherms (550-590°C 

for nonideal types versus 665-730°C for all other 

types). On the basis of thermal analyses and other data, 

the Florida smectites may be more appropriately termed 

nonideal beidellites. 

Wissa and others (1982) also performed lithiumsaturation tests on mixed slime samples and noted 

incomplete expansion with glycolation, which indicated 

the presence of a minor montmorillonite component and 

an undefined smectite. Montmorillonite may be present 

in the Florida phosphate deposits, and further studies are 

needed to define its relationship to the other clays of the 

deposit. 

XRD analysis of smectite-kaolinite mixtures from 

the upper, more weathered levels of the mines show 001 

smectite peaks that are broad and that contain multiple 

maxima, which suggest mixed-layer effects. Wissa and 

others (1982) and Bromwell (1982) studied washer and 

pond slimes and concluded that most of their samples 

Mineralogy 19 
contained a mixed-layer smectite of an unspecified 

nature. These samples represented mixtures of clays 

from many different areas undergoing active mining. The 

apparent mixed-layer effect in smectite-kaolinite 

mixtures may be due to transitional phases that form as 

smectites alter to kaolinite (Altschuler and others, 1963). 

The broad, diffuse nature of the 001 peaks of the 

smectite and responses to various treatments may be a 

function of the crystallinity of these phases rather than 

discrete mixed-layer conditions. 

The origins of the smectites in the Florida 

phosphate deposits are a matter of speculation. Weaver 

and Beck (1977) referred to the smectites as detrital 

material and suggested a volcanic origin (p. 186). Grim 

(1933), on the basis of the identification of isotropic 

fragments as glass shards, proposed that the clays of the 

Miocene deposits in the southeastern United States 

might be the result of alteration of volcanic debris. 

Mansfield (1940), Gremillion (1965), and Heron and 

Johnson (1966) all supported the interpretation that 

these clays, or parts of them, were derived from volcanogenic material. Kerr (1937), Espenshade and Spencer 

(1963), and McClellan (1964), however, did not find 

evidence of volcanic material in these sediments. Heron 

and Johnson (1966) believed the absence of glass shards 

to be inconclusive; vitreous volcanic material would 

probably be destroyed or altered by subsequent 

weathering or diagenetic alteration. Based on province 

studies using heavy and clay-mineral suites from the 

western, central, and eastern Gulf Coast Miocene 

sediments, Isphording (1973) argued against a volcanic 

origin for these clays. Just as Altschuler (1965) 

interpreted the phosphate in the central Florida deposits 

to have been repeatedly physically and chemically 

recycled, these smectites may have been similarly 

recycled and their original character obscured. 

Carbonates 

Dolomite is the most abundant carbonate mineral 

in the Florida phosphate deposits. Dolomite may be 

present as mineral grains dispersed in the phosphate 

sediments or as nearly pure indurated lenses. Dolomite is 

generally found in the lower beds of the minable ore in 

the central Florida phosphate district, and mining commonly ends at the occurrence of indurated dolostones or 

bed clays immediately above dolostone beds. In the south 

and north Florida districts, dolomite is more prevalent 

and occurs throughout the minable horizons. Much 

further downdip, and at depth, in the transition from the 

Arcadia Formation to its underlying Tampa Member, 

calcite is the predominant mineral (T.M. Scott, Florida 

Geological Survey, oral communications; Berman, 

1953). Siderite has been observed in the minus 200-

Table 13. X-ray analyses of Florida dolomite samples 

[CaCOs estimated graphically from diagrams based on iron-free 

dolomite (Reeder, 1983); the exact chemical compositions of the 

Florida samples are unknown] 

a-value c-value X-ray CaC03 X-ray CaC03 

(±0.002) (±0.007) by a-value by c-value 

Mine (angstroms) (angstroms) (percent) (percent) 

Hardee Complex ................ .4.814 

Hookers Prairie ................. .4.819 

Saddle Creek ..................... .4.819 

Suwannee River ................ .4.815 

16.026 

16.026 

16.047 

16.033 

51.8 

53.2 

53.2 

52.2 

51.1 

51.1 

52.0 

51.3 

mesh (Tyler) fraction of the bed clay in the Noralyn mine 

(this study) and associated with vivianite at the Clear 

Springs mine (Barwood and others, 1983). 

XRD analyses of indurated dolostones that occur 

at the base of several mine sections (table 13) indicate 

that these carbonates are well crystallized and slightly 

magnesium deficient (1-3 percent mol MgC03). Such 

calcium-rich, magnesium-deficient dolomites have been 

noted in northern Florida and southern Georgia in 

Miocene sediments and were interpreted to have formed 

penecontemporaneously under schizohaline conditions 

(Weaver and Beck, 1977). Replacement of preexisting 

calcite by dolomite has been proposed (Altschuler and 

others, 1964). Hanshaw and others (1971) also noted 

replacement dolomites in Tertiary rocks of Florida but 

explained this extensive dolomitization by ground-water 

circulation. 

Although seawater is the most logical source of 

Mg2 + for dolomitizing solutions, the breakdown of 

mineral components may also provide Mi + • One 

mineral source for dolomitizing constituents within the 

sediments is the degradation of smectite that releases 

Mg2 + into the environment (Altschuler and others, 

1963). Another possible source of Mg2 + and C02 for 

dolomitization is the alteration of francolite in the 

deposits (this study). A maximum substituted francolite 

(McClellan, 1980) contains about 5.72 weight percent 

C02 and 0.57 weight percent MgO as an integral part of 

its structure. As the francolite is altered, these 

constituents are removed and released into the pore 

fluids. Interaction with other magnesium-rich minerals 

undergoing alteration (palygorskite and sepiolite) could 

result in the formation of dolomite. 

Carbonates may have been precursors of the 

Florida deposits. One origin suggested for the phosphate 

in the Bone Valley Member of the Peace River 

Formation is the weathering of a source limestone or 

marl, removing carbonate and thereby concentrating 

phosphate (Altschuler and others, 1964). Riggs (1979a, 

1979b, 1984) stressed the primary nature of phosphorite 

formation in the deposits of the southeastern United 

States. Riggs (1979a) did not believe that the 

20 Mineralogy and Alteration of the Phosphate Deposits of Florida 
replacement of calcite by phosphate was significant in 

forming the phosphate deposits, although evidence 

suggests that this process has occurred. Gilliland (1976) 

provided an interesting model of the formation of the 

Florida deposits. This computer simulation is based on 

an energy-circuit model utilizing chemical reactions, 

reaction pathways, and mass balancing. Although the 

model is based on many assumptions, it attributes the 

occurrence of phosphate deposits in Florida to a 

combination of primary low-level deposition by the 

upwelling of deep ocean water to the surface and 

enrichment by the selective removal of carbonate from 

phosphatic carbonate source rocks since Miocene time. 

Other Minerals 

Reported heavy minerals from tailings sands (Stow, 

1968) include ilmenite, rutile, zircon, monazite, garnet, 

kyanite, sillimanite, tourmaline, epidote, and gahnite. 

Because these detrital heavy minerals are a very minor 

component of the deposits, they are not discussed in this 

paper other than to note their presence. 

Opal-CT also occurs in variable quantities in the 

Hawthorn Group (Strom and Upchurch, 1985), although 

it was not detected as a major component in the samples 

in this study. Its significance is unknown; does the 

dissolution of opal-CT contribute to the development of 

authigenic clays, or does the dissolution of clays lead to 

the formation of authigenic opal-CT? 

Both aluminophosphates and iron phosphates are 

common in the mining districts of Florida. Because the 

samples for this study were taken from producing 

horizons and excluded the leached uppermost zones of 

the mines, no iron phosphates were noted. Crandallite 

and wavellite ( aluminophosphates) were common 

components of the samples, particularly at the upper 

levels of mines. Altschuler and others (1956) first noted 

the progression: crandallite plus millisite (if conditions 

are correct) to wavellite. This sequence was generally 

observed in the sections used in this study. Wavellite 

appears in all size fractions of the ore, whereas crandallite appears only in the slimes and minus 2-~tm 

fraction. 

The presence of aluminophosphates throughout 

sections of individual mines confirms the extensive 

weathering these phosphorites have undergone. 

Wavellite and crandallite can occur deep in sections with 

minerals that represent less altered phosphorite 

(dolomite, low a-value francolites, and palygorskite) and 

are evidence for mixing of materials with differing origins 

(Hookers Prairie (fig. 21 ), Four Corners (fig. 22), and 

Kingsford (fig. 23) mines). These minerals are detrital 

where they occur with less altered phosphorite in that 

they are derived from local reworking of preexisting 

altered phosphorite. Little information exists on the 

stability of these minerals in various environments. 

Feldspars are a minor component of all the 

phosphorite sections at all levels of the mines. The 

interesting characteristic of the feldspar mineralogy is 

that albite is found in the slimes and clay fractions, 

whereas potassium feldspar predominates in the coarser 

size fractions. Albite has been noted in less altered 

phosphorites in North Carolina (Rooney and Kerr, 1967) 

and in the finer size fractions of palygorskite-sepiolite 

deposits in northern Florida (Weaver and Beck, 1977). 

Weaver and Beck attributed the presence and mixed 

mineralogy of the feldspars to detrital particles from 

differing source areas. 

DISCUSSION AND CONCLUSIONS 

The observed variations in mineralogy through the 

Florida phosphate districts result from primary 

depositional and compositional differences as well as 

superimposed postdepositional alteration. Primary 

compositional differences may result from mixing or 

changing of the source areas, mixing of primary minerals 

with altered, recycled minerals, winnowing and resultant 

lag deposits of larger and( or) heavier minerals (that is, 

apatite), and the result of the effects of changing climatic 

and environmental conditions. Postdepositional alteration is the result of all the changes in physical and 

chemical factors that have modified the sediment since 

deposition. 

Altschuler (1965) stressed the precipitated and 

recycled nature of the phosphate in the Florida landpebble deposits. Altschuler's cyclic model, based 

primarily on petrographic and field evidence, equated the 

reworked character of the phosphorite deposit with 

periods of submergence and emergence and associated 

wave activity. These numerous cyclic episodes of 

reworking and weathering left multiple imprints upon the 

Florida deposit. The multiplicity of these episodes and 

the contrasting depositional and postdepositional 

histories of the North Carolina and Florida deposits are 

made apparent by combining the data of Webb and 

Crissinger (1983) with that of Riggs (1984), based on the 

sea-level curves of Vail and Mitchum (1979) (fig. 4). 

At the northern end of the phosphogenic province, 

the North Carolina phosphorites appear to have been 

continually deposited in a marine environment. The 

deposits have been essentially preserved in their original 

state. The deposits in Florida, however, were subjected to 

many episodes of subaerial exposure and nearshore 

sedimentary processes. Deposition of the lower undifferentiated part of the Peace River Formation (units 1 and 

0 of Webb and Crissinger, 1983 (fig.4)) corresponds to a 

general rising in sea level in the early to middle Miocene. 

Discussion and Conclusions 21 
EPOCHS 

~ (I)(/)~ za:w 

e<a: 

-wa. :j>w 

-u..a: :iEee 

5 

LL 

w 

m 

10 

15 

20 

North Carolina phosphorite deposition 

and cycles of relative changes in sea level based on coastal on lap (from Vail 

and Mitchum, 1979; Riggs, 1984) 

RISING 

Florida phosphorite deposition and weathering cycles 

(modified from Webb and Crissinger, 1983) 

Central 

district 

Southern 

district 

Vertebrate 

fauna 

Terrestrial, reworked 

marine 

Marine and terrestrial 

at higher elevations 

Marine 

Marine and terrestrial 

Terrestrial 

Marine with minor 

terrestrial in Unit 1 

Figure 4. Contrasts in the depositional and postdepositional histories of the North Carolina and Florida phosphorite deposits. 

Dotted pattern shows major phosphate deposition; diagonal-line pattern shows some phosphate deposition. 

Similarities to North Carolina phosphorite deposition 

and global sea-level curves end with the apparent 

regression of the sea and the occurrence of vertebrate 

terrestrial fauna in the Peace River Formation (unit 2) 

near the middle of the time of deposition of the Pungo 

River Formation (fig. 4 ). Although deposition of the 

Pungo River Formation continued under rising sea level, 

a hiatus is seen in central Florida after the deposition of 

unit 2. At the end of Pungo River Formation deposition, 

sea level fell, and unit 3 was deposited in Florida. Unit 4 

appears to have been deposited under rising sea-level 

conditions. Unit 5 (lower and middle part of the Bone 

Valley Member or its time equivalent) is apparently 

associated with another major lowering of sea level. Time 

of deposition of unit 6 (upper part of the Bone Valley 

Member or its time equivalent) is enigmatic, similar to 

that of unit 2, in that terrestial fauna are present during 

interpreted conditions of rising global sea level 

concurrent with the deposition of phosphorite in North 

Carolina. 

There is a narrow range in composition for the 

highly carbonate substituted francolites from the 

relatively unaltered North Carolina deposit at the 

northern extremity of the phosphogenic province and 

other unaltered deposits around the world. In contrast, 

francolites in the Florida phosphorite deposits range 

from highly substituted varieties, indicating primary 

formation, to altered varieties approaching a fluorapatite 

composition. Because the Florida deposits have never 

been subjected to deep burial or intense heat, these 

compositional variations must be attributed to repeated 

subaerial exposure and weathering. Altered francolites 

found in beds below less altered francolite point out the 

complexity of sedimentation, weathering, reworking, and 

primary phosphorite formation. 

The dissolution and removal of carbonates is an 

important process in the upgrading of phosphorite 

deposits, and francolites cannot be altered to lowcarbonate-substituted varieties until the buffering 

influence of carbonates is minimized. Before the cyclic 

episodes of emergence and submergence, deposition was 

in a marine environment; dolomite is a common 

constituent of the lowermost beds of the Peace River 

Formation. Relicts of dolomite and palygorskite found 

with less altered francolites in the coarser fractions in the 

reworked parts of the deposit suggest an origin similar to 

22 Mineralogy and Alteration of the Phosphate Deposits of Florida 
the noneconomic carbonate-rich beds deeper in sections 

and downdip. With each period of emergence, freshwater 

conditions would have removed carbonates, and 

alteration of the francolites would have occurred. 

Dolomite within and below phosphorite beds 

indicates diagenetic influences. These sediments have 

been exposed to the repetitive influence of freshwater, 

seawater, and mixed waters under both phreatic and 

vadose conditions. Mixed-water conditions may be 

conducive to the formation of dolomite (Folk and Land, 

1975). 

The effects of weathering are also indicated by the 

variations in clay mineralogy with depth. Aluminophosphates and kaolinite formed at the top of the deposits, 

but unstable palygorskite and sepiolite are preserved at 

the base. The presence of aluminum-rich smectites (beidellites) also may indicate the overall degree of 

weathering of the deposits. 

It is difficult to decide what aspects of the 

mineralogy and chemistry of the deposits are cumulative 

or are the result of the last weathering overprint. Every 

section examined in this study showed some degree of 

alteration even in the lowermost beds of the downdip 

facies in the southern extension. The significant trends of 

francolite composition suggest that the most recent 

weathering cycle overshadowed all other events. 

However, the extent and degree of alteration caused by 

early weathering cycles are masked by successive 

weathering cycles. Although most of the major periods of 

sedimentation and subaerial exposure can be documented (fig. 4), the shorter term effects of minor sealevel fluctuations and possibly changing paleoclimatic 

conditions are unknown. 

As mining progresses into leaner, less altered parts 

of the deposits, changes in ore characteristics will vary 

with the degree of weathering of specific parts of the 

deposit or with proportions of unaltered and altered 

material. The transition from mining altered ores to less 

altered ores will result in the processing of phosphate 

containing greater amounts of endogange contamination 

and more highly carbonate substituted francolites. The 

inevitable depletion of high-grade phosphate ores must 

be accompanied by the development and refinement of 

processing technology if the Florida phosphate industry is 

to remain economically viable. 

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Patterson, S.H., 1974, Fullers earth and other industrial mineral 

resources of the Meigs-Attapulgus-Quincy district, 

Georgia and Florida: U.S. Geological Survey 

Professional Paper 828, 43 p. 

Peck, D.M., Missimer, T.M., Slater, D.H., Wise, S.W., Jr., and 

O'Donnell, T.H., 1979, Late Miocene glacial-eustatic 

lowering of sea level-Evidence from the Tamiami 

Formation of south Florida: Geology, v. 7, p. 285-288. 

Pirkle, E.C., Yoho, W.H., and Webb, S.D., 1967, Sediments of 

the Bone Valley phosphate district of Florida: Economic 

Geology, v. 62, p. 237-261. 

Reeder, R.J., 1983, Crystal chemistry of the rhombohedral 

carbonates, in Reeder, R.J., ed., Carbonates-Mineralogy and chemistry: Mineralogical Society of America, 

Reviews in Mineralogy, v. 11, p. 1-47. 

Reik, B.A., 1982, Oay mineralogy of the Hawthorn Formation 

in northern and eastern Florida, in Scott, T.M., and 

Upchurch, S.B., eds., Miocene of the southeastern 

United States: Florida Bureau of Geology, Special 

Publication 25, p. 247-250. 

Riggs, S.R., 1979a, Petrology of the tertiary phosphate system 

of Florida: Economic Geology, v. 74, p. 195-220. 

___ 1979b, Phosphorite sedimentation in Florida-A model 

phosphogenic system: Economic Geology, v. 74, 

p. 285-314. 

___ 1984, Paleoceanographic model of Neogene phosphorite deposition, U.S. Atlantic continental margin: 

Science, v. 223, p. 123-131. 

Rooney, T.P., and Kerr, P.F., 1967, Mineralogic nature and 

origin of phosphorite, Beaufort County, North Carolina: 

Geological Society of America Bulletin, v. 78, 

p. 731-748. 

Ross, C.S., and Hendricks, S.B., 1945, Minerals of the 

montmorillonite group: U.S. Geological Survey 

Professional Paper 205-B, 79 p. 

Schneiderhohn, P., 1964, Nontronit von Hoben Hagen und 

Chloropal vom Meenser Steinberg bei Gottingen: 

Tschermaks Mineralogische und Petrographische Mitteilungen, v. 10, p. 385-399. 

Schultz, L.G., 1969, Lithium and potassium absorption, 

dehydration temperature and structural water content of 

aluminous smectites: Clays and Clay Minerals, v. 17, 

p. 115-149. 

Scott, T.M., 1985, The lithostratigraphy of the central Florida 

phosphate district and its southern extension, in Cathcart, J.B., and Scott, T.M., eds., Florida land-pebble 

phosphate district: Geological Society of America, 

annual meeting, Orlando, Fla, October, 1985, Field-trip 

guidebook, p. 28-38. 

___ 1988, Lithostratigraphy of the Hawthorn Group (Miocene) of Florida: Florida Geological Survey Special 

Publication 59, 148 p. 

Scott, T.M., and Upchurch, S.B., eds., 1982, Miocene of the 

southeastern United States: Florida Bureau of Geology 

Special Publication 25, 318 p. 

Singer, A., 1979, Palygorskite in sediments-Detrital, diagenetic or neoformed-A critical review: Geological 

Research, v. 68, p. 996-1008. 

Snyder, S.W.P., 1983, Seismic stratigraphy within the Miocene 

Carolina phosphogenic province-Chronostratigraphy, 

paleotopographic controls, sea level cyclicity, Gulf 

Stream dynamics, and the resulting depositional 

framework: Chapel Hill, University of North Carolina 

M.S. thesis, 183 p. 

Stow, S.H., 1968, The heavy minerals of the Bone Valley 

Formation and their potential value: Economic Geology, 

v. 63, p. 973-977. 

___ 1976, Effects of weathering on the chemical and heavy 

mineral composition and physical properties of 

phosphate pebbles from the Bone Valley Formation of 

Florida: Southeastern Geology, v. 18, p. 83-98. 

Strom, R.N., and Upchurch, S.B., 1983, Palygorskite 

( attapulgite )-rich sediments in the Hawthorn Formation-A product of alkaline lake deposition? in The 

central Florida phosphate district: Geological Society of 

America, Southeastern Section, guidebook, p. 73-82. 

___ 1985, Palygorskite distribution and silicification in the 

phosphatic sediments of central Florida, in Snyder, Scott, 

ed., Guidebook, Eighth international field workshop and 

symposium (southeastern United States): Paris, France, 

International Geological Correlation Program, Project 

156-Phosphorites, p. 118-126. 

Trauth, N., and Lucas, J., 1967, Thermal methods in the study 

of clay minerals: Groupe Francaise Argiles Bulletin, v. 

19, p. 11-24. 

Upchurch, S.B., Strom, R.N., and Nuckels, M.G., 1982, 

Silicification of Miocene rocks from central Florida, in 

Scott, T.M., and Upchurch, S.B., eds., Miocene of the 

southeastern United States: Florida Bureau of Geology 

Special Publication 25, p. 251-284. 

References 25 
Vail, P.R., and Mitchum, R.M, 1979, Global cycles of relative 

changes of sea level from seismic stratigraphy, in Watkins, J.S., Montadert, L., and Dickerson, P.W., eds., 

Geological and geophysical investigations of continental 

margins: American Association of Petroleum Geologists 

Memoir 29, p. 469-472. 

Vernon, R.O., 1951, Geology of Citrus and Levy Counties, 

Florida: Florida Geological Sutvey Bulletin 33, 256 p. 

Weaver, C.E., 1984, Origin and geologic implications of the 

palygorskite of the S.E. United States, in Palygorskitesepiolite, occurrences, genesis and uses: New York, 

Elsevier Publishing Co., p. 39-58. 

Weaver, C.E., and Beck, K.C., 1977, Miocene of the S.E. 

United States-A model for chemical sedimentation in a 

perimarine environment: New York, Elsevier Publishing 

Co., 234 p. 

Weaver, C.E., and Pollard, L.D., 1973, The chemistry of clay 

minerals: New York, Elsevier Publishing Co., 213 p. 

Webb, S.D., and Crissinger, D.B., 1983, Stratigraphy and 

vertebrate paleontology of the central and southern 

phosphate districts of Florida, in The central Florida 

phosphate district: Geological Society of America, 

Southeastern Section, field-trip guidebook, p. 28-72. 

Weir, A.H., and Greene-Kelly, R., 1962, Beidellite: American 

Mineralogist, v. 47, p. 137-146. 

Whippo, R.E., and Murowchick, B.L., 1967, The crystal 

chemistry of some sedimentaty apatites: Society of 

Mining Engineers Transactions, v. 19, no. 4, p. 257-263. 

Williams, G.K., 1971, Geology and geochemistty of the 

sedimentary phosphate deposits of northern peninsular 

Florida: Tallahassee, Florida State University Ph.D. 

dissertation, 124 p. 

Wissa, A.E.Z., Fuleihan, N.F., and Ingra, T.S., 1982, Evolution 

of phosphatic clay disposal and reclamation methods, in 

Mineralogy of phosphatic clays: Bartow, Fla., Florida 

Institute of Phosphate Research, v. 2, 55 p. 

26 Mineralogy and Alteration of the Phosphate Deposits of Florida 
APPENDIX 

Figures 5-23 

Lithologic, stratigraphic, mineralogic, and grain-size analyses of sections from Florida phosphate mines 

Samples 1-84 to 47-84 

Figures 5-23 contain lithologic notes, stratigraphic interpretations, mineralogy, francolite a-values, and screen data for the 

samples used in this study. In the mineralogy section, major minerals (in capital letters) have a most intense peak (1/h = 100) greater 

than 50 percent of the most intense peak determined. Mineral components with a most intense peak less than 50 percent and greater 

than 10 percent are termed minor (m). Trace minerals (tr.) have a 1/11 = 100 peak that is less than 10 percent of the most intense 

peak. Analyses by X-ray diffraction by the authors. Screen data are in Tyler mesh. Names in capital letters in the Lithology column 

are local terminology. K, potassium. 
N 

(X) 

3: 

3" 

CD 

.. II) 

0 

CQ 

'< 

II) 

::s 

a. 

)> 

;::; 

CD 

.. II) 

g. 

::s 

2. 

... 

::s" 

CD 

"tt 

::s" 

0 

UJ 

, 

::s" 

II) 

S' 

c 

, 

CD 

0 

UJ 

;::; 

UJ 

2. 

., 

Q 

a: 

II) 

Depth Sample (feet) No. lithology 

OVERBURDEN 

o-2 None Swamp muck. Muck is absent 

31/2 mi northeast, but there 

is 2ft of black, organic sand. 

2-8 None Sand, brown, iron stained. 

Only 3ft of white sand 31h 

mi northeast. 

8-18 None Sand, clayey, gray green. Unit 

is 8ft thick 3172 mi northeast. 

Gradational contact. 

MATRIX 

18-24 1-84 Sand, brown, pebbly, clayey. 

Unit is 3ft thick, 3172 mi northeast. Sharp, irregular contact. 

24-46 2-84 Sand, tan and gray, slightly 

clayey. Bedded and cross bedded. Abundant finegrained phosphate pellets. 

Thin green clay lenticles. 

~ ·;; 

0 

c. 

~ 

a 

~ 

;p. 

c. 

::I 

e 

CJ 

c 

0 

.&: 

j 

IV 

:I: 

Age and 

Stratigraphy 

HOLOCENE 

PLIOCENE-PLEISTOCENE 

Undifferentiated 

MIOCENE-PLIOCENE 

Unnamed equivalent to 

Bone Valley Member, 

Peace River Formation 

MIOCENE 

Statenville 

Formation 

.... 

! 

~ n.. 

::::! 

~ 

.... 

co 

N 

~ n.. 

::::! 

<( 

(/) 

SAMPLE 

NO . 

1-84 

2-84 

SAMPLE 

NO. 

1-84 

2-84 

Figure 5. Swift Creek mine. SW1ANW1fil sec. 36, T. 1 N., R. 14 E., Hamilton County. 

+20 mesh 

FRANCOLITE 

QUARTZ 

DOLOMITE 

Palygorskite (tr.) 

FRANCOLITE 

QUARTZ 

K feldspa~ } (m) Palygorskite 

Bulk Sample 

9.336 

9.337 

Mineralogy 

(Screen size) 

-20 +200 mesh -200mesh 

QUARTZ 

DOLOMITE 

QUARTZ Francolite Smectite I (m l 

Franco~ite } (tr.) Albite 

Dolomite K feldspar 

Wavellite (tr.) 

Crandallite 

Palygorskite 

QUARTZ 

Francolite Kaolinh~ llml 

FRANCOLITE Dolomite 

QUARTZ Albite 

K feldspar (m) K feldspar (tr.) 

Crandallite 

Palygorskite 

FRANCOLITE A-VALUES 

(t0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.333 9.332 

9.331 9.344 

SCREEN DATA (IN PERCENT) 

-2 JLm 

I 

SMECTITE 

PALYGORSKITE 

Kaolinite (m) 

Francolite } Illite 

Albite (tr.) 

Wavellite 

J 

Crandallite 

SMECTITE 

PALYGORSKITE 

KAOLINITE 

Albite (m) 

Francolite (tr.) 

-200 mesh 

9.338 

9.347 

0 ~ 100 .I I I I· I I I I d ···_::·.:::· ").·::::_··'<::.:::.- :_::::::_:: ·.: :\.:.\::t ;:: •. ::; .·•'.• .. •I 

EXPLANATION 

~ Plus 20-mesh 

v.::_::;_.:(:.::·.J Minus 20- plus 200-mesh 

~ Minus 200-mesh 
"TI 

cS" 

c 

; 

UJ 

w 

~ 

~ 

Depth Sample 

(feet) No. 

Lithology 

OVERBURDEN 

0-2 None Sand, black, organic. 

2-10 None Sand, red brown, iron 

stained. Unit is gray 

and 8ft thick 2 mi 

northeast. 

10-18 None Sand, clayey, yellow. 

Unit is 3ft thick 2 mi 

northeast. 

MATRIX 

18-21 1-84 Sand, clayey, leached; some white and brown 

phosphate. 

21-32 3-84 Sand, clayey, mottled 

rust and blue gray. 

Thin green clay lenses. 

Unit is 6ft thick 2 mi 

northeast and is underlain 

by 6ft of interbedded hard, 

thin dolomite and graybrown phosphatic sand. 

These units are bedded 

and cross bedded. Underlain by yellow bedded 

dolomite. 

~ ·;;; 

0 

a. 

Q) 

a 

B 

~ 

~ 

a. 

:l 

0 

(; 

1::: 

0 

.r:. 

~ nl 

:I: 

Age and 

Stratigraphy 

HOLOCENE 

PLEISTOCENE 

Irregular, sharp contact 

MIOCENE-PLIOCENE 

Unnamed equivalent to 

Bone Valley Member, 

Peace River Formation 

MIOCENE 

Statenville 

Formation 

I 

I 

oct 

~ 

~ a.. 

::E 

~ 

oct 

00 

M 

~ a.. 

::E 

~ 

SAMPLE 

NO. 

1-84 

3-84 

SAMPLE 

NO. 

1-84 

3-84 

+20 mesh 

FRANCOLITE 

QUARTZ 

DOLOMITE 

Palygorskite (tr.) 

FRANCOLITE 

QUARTZ 

Kfeldspar } Palygorskite (tr.) 

Calcite 

Bulk Sample 

9.336 

9.332 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

DOLOMITE 

QUARTZ Smectite j (m) Francolite 

Franco!ite } (tr.) Albite 

Dolom1te K feldspar 

Wavellite (tr.) 

Crandallite 

Palygorskite 

QUARTZ QUAmL Smectite 

Palygorskite 

l 

(m) Francolite } Francolite Dolomite (tr.) Albite K feldspar K feldsp~r (tr.) Crandalhte 

FRANCOLITE A-VALUES 

(t0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.333 9.332 

9.328 9.333 

SCREEN DATA (IN PERCENT) 

-2 JLm 

SMECTITE 

PALYGORSKITE 

Kaolinite (m) 

Francolite } Illite 

Albite (tr.) 

Wavellite 

Crandallite 

SMECTITE 

Palygorskite } (m) Albite 

Francolite (t ) Dolomite r. 

Crandallite 

-200 mesh 

9.338 

9.351 

0 ~ 100 

~ ... >: ...... ::~_~_; · .' :_:.-.:: .. · -~:·:.:· · .. ;.:· .. Y .·.~:>; .. : :-:-: ._: :~-=-· :.::: :·: :· .-r.-1 I I I I I I I I I 

020 ,,: .'· ·.::·:n· ...... _.,· .······:·:.: :. ':·.·.· •. ,'. ···•·····:.rl 

EXPLANATION 

m5R Plus 20-mesh 

1:·.-: .. :).:(:_:.::j Minus 20- plus 200-mesh 

~ Minus 200-mesh 

Figure 6. Suwannee River mine. SW1ANW1A sec. 30, T. 1 S., A. 16 E., Hamilton County. 
~ Depth Sample 

(feet) No. 

s:: 

s· 

CD 

; 

0 

CQ 

'< 

I» 

:::s 

Q. 

~ 

<D 

; 

... 

o· 

:::s 

a 

... 

::r 

CD 

., 

::r 

0 

en 

"C 

::r 

I» 

<D 

c 

(I) 

"C 

0 

en 

;::; 

en 

a 

., 

g 

a: 

I» 

0-11 None 

11-20 None 

20-25 6-84 

25-34 4-84 

34-37 5-84 

Lithology 

OVERBURDEN 

Sand, white, loose at top, 

slightly clayey at base. 

Sand, clayey, white beds 

of coarsely vesicular 

textured sandstone. 

c 

.2 

Sand, clayey, white, "iO 

contains pebbles of e 

soft, white phosphate. 0 

LL 

~ a: 

MATRIX ~ IV 

CD 

Sand, clayey, gray-brown, a.. 

mottled white, bioturbated. 6. 

Clayey and laminated at base. :::1 

e 

CJ 

c 

0 

.c 

RESIDUUM i 

J: 

Clay, sandy, red brown and 

yellow brown. 

Base exposure. 

Yellow dolomite exposed 

in pit bottom. 

EXPLANATION 

Age and 

Stratigraphy 

HOLOCENE and 

PLEISTOCENE, 

undifferentiated 

MIOCENE-PLIOCENE 

Leached Bone Valley 

Member 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

Peace River 

Formation 

~~~~ Plus 20-mesh 

lr--.. ~_;:_:\:.~:::_::_.:J Minus 20- plus 200-mesh ~ Minus 200-mesh 

.. 

OJ> 

CD 

w 

...J 

a.. 

::.!: 

<( 

en 

.. 

CXl 

...;. 

~ a.. 

::.!: 

~ 

.. 

CXl 

&b 

~ a.. 

::.!: 

<'j 

SAMPLE 

NO. 

6-84 

4-84 

5-84 

SAMPLE 

NO. 

6-84 

4-84 

5-84 

Figure 7. Noralyn mine. NE1ASE1A sec. 22, T. 30 S., R. 24 E., Polk County. 

+20mesh 

FRANCOLITE 

QUARTZ 

K feldspar (tr.) 

FRANCOLITE 

Quartz (m) 

K feldspar (tr.) 

FRANCOLITE 

QUARTZ 

K feldspar } ( ) Goethite m 

Dolomite (tr.) 

-- -- ----

Bulk Sample 

9.342 

9.337 

9.333 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

QUARTZ FRANCOLITE 

Francolite } ( ) Crandallite } ( ) K feldspar m Goethite m 

K feldspar (tr.) 

FRANCOLITE QUARTZ 

QUARTZ FRANCOLITE 

Wavellite } Smectite (m) K feldspar (tr.) Wavellite (tr.) 

QUARTZ 

QUARTZ FRANCOLITE 

Francolite } K feldspar (tr.) Albite (m) Palygorskite } 

Siderite 

------- -'-

FRANCOLITE A-VALUES 

(t0.003 ANGSTROMS) 

+20mesh -20 +200 mesh 

9.347 9.338 

9.336 9.347 

9.334 9.339 

SCREEN DATA (IN PERCENT) 

-2J..Lm 

SMECTITE 

FRANCOLITE 

ILLITE 

Ka~linite } (m) Alb1te 

Wavellite (tr.) 

No clay 

fraction 

I 

available 

PALYGORSKITE 

KFELDSPAR 

Francolite } Goethite (m) 

Albite 

Smectite (tr.) 

-

-200 mesh 

9.354 

9.345 

9.339 

0 ~ 100 -'''''1 : ':·.. : '·. ' . ;; J~:'!:@·;:,:·.:o. .. ·:.(l., < .. •: .• j 

ii20ii0\?~··:·,;·:··,,·,.> .. <::·.; .•. :,:···· ... ·,::·:l 
., 

Ui' 

c 

; 

fn 

~ 

w 

.... 

Depth 

(feet) 

0-2 

2-13 

13-27 

27-30 

30-34 

34-40 

40-43 

Sample 

No. 

None 

None 

None 

8-84 

Not 

sampled 

7-84 

None 

Lithology 

OVERBURDEN 

Sand, loose, white, 

wind blown. 

Sand, brown and 

light gray. 

Sand, gray, clayey. 

Unit is 10ft thick 

7 mi southwest. 

Sand, clayey, gray, 

leached. Contains 

soft white phosphate 

pebbles. 

Clay, sandy, gray, 

green, and red 

mottled. Minor 

black and brown 

phosphate. 

MATRIX 

Sand, slightly clayey, 

gray. Graded bedding. 

Very coarse pebbles at 

base, finer grained, 

more clayey at top. 

Unit is 4ft thick 7 mi 

southwest and rests 

directly on hard yellow 

dolomite. 

Clay, green, laminated, 

slightly sandy, minor 

phosphate. 

!3 

·;;; 

0 

0. 

(I) 

c 

B 

cu 

... 

~ 

c:: 

.g 

cu 

e 

0 

LL. 

~ ~ 

(I) 

C) 

cu 

(I) 

a.. 

0. 

:::1 

e 

(!) 

c:: 

0 

.&:. 

j 

cu 

:I: 

Age and 

Stratigraphy 

HOLOCENE 

PLEISTOCENE 

MIOCENE-PLIOCENE 

Leached Bone Valley 

Member 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

I 

..,. 

co 

00 

~ a.. 

~ 

~ 

..,. 

co 

...:. 

~ a.. 

~ 

<( 

(I) 

SAMPLE 

NO. 

8-84 

7-84 

SAMPLE 

NO. 

8-84 

7-84 

~ 

Figure 8. Gardinier (Cargill) mine. NW1ANE1A sec. 9, T. 32 S., R. 25 E., Polk County. 

+20 mesh 

FRANCOLITE 

QUARTZ 

FRANCOLITE 

QUARTZ 

K feldspar (tr.) 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

QUARTZ Francolite 

Sm~me l (m) 

Francolite } Albite 

K feldspar (tr.) K feldspar 

Wavellite (tr.) 

Crandallite 

Kaolinite 

QUARTZ 

QUARTZ Semectite ~ Francolite } Francolite (m) 

K feldspar (tr.) Albite 

Crandallite (tr.) 

~-- ---~---

Bulk Sample 

9.347 

9.332 

FRANCOLITE A-VALUES 

(t0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.330 9.347 

9.332 9.346 

EXPLANATION 

~ Plus 20-mesh 

1;·:;.:._>\t>·.:j Minus 20- plus 200-mesh 

~ Minus 200-mesh 

-2J.Lm 

SMECTITE 

Kaolinite (m) 

Francolite } Dolomite 

Albite 

Wayellite (tr.) 

Crandallite 

Illite 

SMECTITE 

Francolite } Albite 

Crandallite 

Kaolinite (tr.) 

Illite 

Palygorskite 

-200 mesh 

9.352 

9.358 
w Depth N (feet) 

!: 

s· 

CD 

.. ., 

c8 

'< 

., 

::J 

a. 

)> 

i 

Gl 

.. 

0 

::J 

2. 

.. :::r 

CD 

"'0 

:::r 

0 

0 

, 

:::r 

; 

i' 

-g 

0 

it 

2. 

~ "" 

a: 

., 

0-2 

2-6 

6-10 

10-16 

16-22 

22-25 

Sample 

No. 

None 

None 

None 

None 

10-84 

9-84 

Lithology 

OVERBURDEN 

Sand, black, organic. 

Sand, brown, unconsolidated, iron stained. 

Sand, clayey, white. A few 

fragments of vesiculartextured aluminum 

phosphate-cemented 

sandstone. 

Same as above, but 

yellow brown, iron 

stained. 

MATRIX 

Sand, red brown, clayey. 

Phosphate, pebble and 

sand size, brown, black, 

gray. 

Sand, clayey, blue gray, 

tan, yellow mottled, 

bioturbated. Sand size 

phosphate is abundant. 

Total depth 36ft, could 

only sample top 3ft. 

Yellow dolomite in pit 

bottom. 

~ ·;;; 

0 

0.. 

Q) 

c 

~ 

~ 

;p_ 

c 

.2 

IV 

e 

0 

u.. 

~ a: 

Q) 

(J 

ca 

Q) 

a.. 

0. 

:::J 

e 

CJ 

c 

0 

..c 

j 

ca 

J: 

Age and 

Stratigraphy 

HOLOCENE 

PLEISTOCENE 

MIOCENE-PLIOCENE 

Leached 

Bone Valley 

Member 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

I 

I 

i 

i 

I 

..,. 

00 

0 

.... 

~ a.. 

:E 

~ 

..,. 

00 

a, 

~ a.. 

:E 

~ 

SAMPLE 

NO. 

10-84 

9-84 

SAMPLE 

NO. 

10-84 

9-84 

Figure 9. Nichols mine. SEV..NEV.. sec. 21, T. 30 S., R. 23 E., Polk County. 

+20 mesh 

QUARTZ 

Francolite (m) 

Wavellite } Crandallite (tr.) 

K feldspar 

FRANCOLITE 

QUARTZ 

Dolomite (m) 

Goethite . } (tr.) Palygorskite 

-- J......_ 

Bulk Sample 

9.355 

9.347 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

QUARTZ CRANDALLITE 

Francolite (tr.) FRANCOLITE 

Wavellite (tr.) 

QUARTZ QUARTZ 

SMECTITE Francolite (m) FRANCOLITE K feldspar (tr.) KFELDSPAR 

-- ~------

FRANCOLITE A-VALUES 

(t0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.352 9.356 

9.342 9.346 

SCREEN DATA (IN PERCENT) 

-2f.Lm 

KAOLINITE 

ILLITE 

CRANDALLITE 

FRANCOLITE 

ALBITE 

SMECTITE 

PALYGORSKITE 

Quartz } Francolite (tr) Albite · 

Crandallite I 

I 

---.!...-- ------

-200 mesh 

9.352 

9.339 

0 ~ 100 

It-•'·: .t . t:':' .; ... ~\<_·:_•::'·:. ·_:·,_-r(_ :·'· :.:':;.· •. -.. ,': ... ' ........ ~._. :I_> .. 

EXPLANATION 

.. Plus 20-mesh 

~~-... ~.::\.r~.:::.;J Minus 20- plus 200-mesh 

~ Minus 200-mesh 
-n 

,]j" 

c 

; 

0 

~ w 

w 

w 

Depth Sample 

(feet) No. 

0-2 None 

2-9 None 

9-15 None 

15-19 None 

19-29 13-84 

29-41 12-84 

41-43 Not 

sampled 

43-50 11-84 

Lithology 

OVERBURDEN 

Sand, black, organic. 

Sand, white and tan, 

unconsolidated. 

Sand, clayey, gray, 

leached. Boulders of 

sand cemented by 

aluminum phosphate. 

Sand, clayey, gray ~reen. 

Leached. Soft whate 

phosphate. 

MATRIX 

Sand, gray green, 

pebbly. Graded bedding. 

Sand, clayey, yellow 

and gray ~reen. Finegrained p osphate 

pellets abundant. 

Clay, sandy, yellow 

green with some 

phosphate pellets. 

Sand, clayey, mottled 

brown and gray. Phosphate pebble and pellets. 

Graded. Blue clay clasts 

abundant at base. 

Yellow dolomite in pit 

bottom. 

B-~ calll ._o 

--a. 

~~ 

c: 

~ ca 

e 

0 

LL 

~ a: 

CD 

(,) 

ca 

CD 

0.. 

0. 

::I 

0 

~ c: 

0 

.s:. 

~ ca 

:I: 

EXPLANATION 

~~~ Plus 20-mesh 

Age and 

Stratigraphy 

HOLOCENE 

PLEISTOCENE 

MIOCENE-PLIOCENE 

Leached 

Bone Valley 

Member 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

j;":·_.::.:'.:~>~:::_:::·:;/1 Minus 20· plus 200-mesh ~ Minus 200.mesh 

..,. 

co 

~ 

~ 0.. 

~ 

~ 

..,. 

co 

~ 

~ 0.. 

~ 

<( 

(/) 

..,. 

~ ... 

~ 0.. 

~ 

~ 

SAMPLE 

NO. 

13-84 

12-84 

11-84 

+20 mesh 

FRANCOLITE 

QUARTZ 

Wavellite } K feldspar (tr.) 

FRANCOLITE 

QUARTZ 

K feldspar (m) 

FRANCOLITE 

Quartz (m) 

Goethite (tr.) 

Bulk Sample 

9.330 

9.333 

9.334 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

QUARTZ FRANCOLITE 

Wavellite } Sm~M J Francolite (tr.) Albite (m) 

K feldspar Wavellite 

Kaolinite 

Palygorskite (tr.) 

QUARTZ 

QUARTZ Smectite J Francolite } Francolite (m) Dolomite (tr.) K feldspar 

K feldspar Crandallite (t ) Illite r. 

QUARTZ 

FRANCOLITE 

QUARTZ Albite 1 

Francolite (m) K feldspar 

K feldspar (tr.) Paly~orskite (m) 

Kaolinite 

Crandallite 

Dolomite(?) (tr.) 

FRANCOLITE A-VALUES 

(±0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.328 9.332 

9.328 9.334 

9.328 9.332 

SCREEN DATA (IN PERCENT) 

-2 Jlm 

SMECTITE 

FRANCOLITE 

Illite } Wavellite (m) 

Kaolinite (tr.) 

SMECTITE 

K ltliM feldspar J (m) 

Quartz 

Francolite (tr.) 

PALYGORSKITE 

SMECTITE 

ALBITE 

Francolite } Dolomite (tr.) 

K feldspar 

-200 mesh 

9.344 

9.345 

9.344 

SAMPLE 0 50 100 

:~~ -;:\<:;.I:Jli;),·\;J'::{;:;::-t,·,J~::~~~:['·.··j' I 

Figure 10. Ft. Meade mine. NW1ANW1A sec. 28, T. 31 S., R. 25 E., Polk County. 
~ Depth 

(feet) 

3: 

3' 

CD 

.. I» 

0 

cc 

'< 

I» 

::s 

a. 

)> 

; 

; 

ct 

0 

::s 

a 

... 

':1' 

CD 

., 

':1' 

0 

en , 

':1' 

I» 

S' 

c 

CD , 

0 

en 

;::;' 

en 

a 

., 

[ 

a: 

I» 

0-2 

2-15 

15-30 

30-38 

38-42 

42-46 

Sample 

No. 

None 

None 

16-84 

15-84 

Not 

sampled 

14-84 

Lithology 

OVERBURDEN 

Sand, gray-black, organic. 

Sand, white, loose at 

top, tan-brown and 

slightly clayey at base. 

Sand, clayey, irregular 

bedding, phosphatized 

crusts throughout and 

abundant white-cream 

clay-size francolite. 

MATRIX 

Clay, sandy, gray-green, 

bedded, crust of secondary 

precipitated francolite in 

middle of unit. Black 

phosphate pellets abundant. 

Sharp contact at base. 

BEDROCK 

Dolomite, hard, yellow, 

phosphate bearing. 

Irregular gradational 

contact. 

Clay, dolomitic, soft 

with some phosphate 

and quartz sand. 

!! 

·;; 

0 

a. 

~ 

tJj 

~ 

~ 

c 

.~ 

cv 

E 

0 

LL 

~ ~ 

CD 

(.) 

Ill 

CD 

a.. 

0. 

::;, 

e 

C) 

c 

0 

.J::. 

i 

Ill 

J: 

EXPLANATION 

IB Plus 20-mesh 

Age and 

Stratigraphy 

HOLOCENE 

PLEISTOCENE 

MIOCENE-PLIOCENE 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

,,·.:~:::;:i:X~.:J Minus 20- plus 200-mesh 

~ Minus 200-mesh 

Figure 11. Clear Springs mine. Sec. 11, T. 30 S., A. 25 E., Polk County. 

J 

I 

i 

..,. 

co 

cD 

... 

~ a.. 

~ 

~ 

..,. 

co 

,;, 

... 

~ a.. 

~ 

~ 

..,. 

co 

...;. 

... 

~ a.. 

~ 

~ 

SAMPLE 

NO. 

16-84 

15-84 

14-84 

SAMPLE 

NO. 

16-84 

15-84 

14-84 

+20mesh 

FRANCOLITE 

Quartz (m) 

Wavellite (tr.) 

FRANCOLITE 

QUARTZ 

K feldspar (tr.) 

QUARTZ 

Francolite (m) 

Dolomite (tr.) 

Bulk Sample 

9.355 

9.338 

9.336 

Mineralogy 

(Screen size) 

-20 +200 mesh -200mesh 

QUARTZ QUARTZ 

Francolite (m) FRANCOLITE 

Wavellite Wavellite } ( ) (tr.) Crandallite tr. 

QUARTZ SMECTITE 

QUARTZ Francolite } FRANCOLITE Dolomite (tr.) Albite } K feldspar K feldspar (tr.) 

SMECTITE 

QUARTZ QUARTZ 

Francolite } (t ) FRANCOLITE 

Dolomite r. K feldspar (m) 

Albite (tr.) 

FRANCOLITE A-VALUES 

(±0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.353 9.353 

9.337 9.333 

9.338 9.334 

SCREEN DATA (IN PERCENT) 

-2 JLm 

FRANCOLITE 

Kaolinite (m) 

Crandallite (tr.) 

SMECTITE 

Francolite (m) 

Kaolinite (tr.) 

SMECTITE 

Illite (m) 

Fra~c~lite } (tr) Sep1ohte · 

-200 mesh 

9.361 

9.344 

9.337 

0 ~ 100 

-

.... ~ .. :::·.:.:1'''1 :-.:: • •. • • •• •f t • e • "• • •• 1 • • :• • • • 0 • I 

0 

• .·.1-----t 

jfJ;.:_··_::_. · .. ·.:.·::::<: ::.··:·.:.·:.·<.I. 
-n 

fE 

c 

; 

• 

~ 

w 

Cll 

Depth 

(feet) 

0-2 

2-15 

15-16 

16-22 

22-25 

25-29 

Sample 

No. 

None 

None 

None 

17-84 

18-84 

19-84 

Lithology 

OVERBURDEN 

Cl) Sand, gray, organic. .iii 

0 

a. 

Q) 

0 

Sand, white, unconsoli- 8 

n:l 

... dated. Tan and slightly 

clayey at base. ~ 

Sharp, irregular contact. 

Clay, gray green, leached. 

Some fragments of 

cemented sand. 

c 

0 

·.;::; 

n:l 

E 

MATRIX 0 

LL. 

Sand, slightly clayey, ~ tan gray, leached with a: 

soft white phosphate. Q) 

(J 

n:l 

Q) 

ll.. 

Sand, gra~, pebbly, ~lightly b. clayey. hosphate ts ::1 

mostly black. e 

<.!) 

c 

0 

.r; 

~ n:l 

:::r: 

Sharp contact. 

Sand, clayey, gray green, 

bedded with some pebble. 

Yellow dolomite in pit 

bottom. 

EXPLANATION 

Ell Plus 20-mesh 

Age and 

Stratigraphy 

HOLOCENE 

PLEISTOCENE 

MIOCENE-PLIOCENE 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

t:·-~.:::::··::(:·:·:j Minus 20- plus 200-mesh ~Minus 200-mesh 

...,. 

00 

~ 

~ ll.. 

~ 

~ 

...,. 

00 

00 

.... 

~ ll.. 

~ 

~ 

...,. 

00 

~ 

~ ll.. 

~ 

~ 

SAMPLE 

NO. 

17-84 

18-84 

19-84 

SAMPLE 

NO. 

17-84 

18-84 

19-84 

+20 mesh 

QUARTZ 

Franco!ite } (m) Wavelhte 

FRANCOLITE 

QUARTZ 

FRANCOLITE 

Quartz (m) 

Dolomite } ( ) K feldspar tr. 

Bulk Sample 

9.348 

9.330 

9.335 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

QUARTZ Francolite (m) 

Francolite } Smectite } Wavellite (tr.) Wavellite (tr.) 

Crandallite 

SMECTITE 

QUARTZ QUARTZ 

Francolite } (tr) Francolite } (m) K feldspar . · K feldspar 

Crandallite (tr.) 

QUARTZ 

QUARTZ Smectite } 

Francolite } (tr) Francolite (m) 

K feldspar · Kfeldspar 

Kaolinite (tr.) 

FRANCOLITE A-VALUES 

(±0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.368 9.343 

9.339 9.348 

9.332 9.350 

SCREEN DATA (IN PERCENT) 

-2~m 

SMECTITE 

WAVELLITE 

QUARTZ 

Kaolinite J (m) Illite 

Francolite (tr) K feldspar · 

SMECTITE 

lllite(m) 

Kaolinite } Francolite (tr.) 

SMECTITE 

Kaolinite } ( ) Illite m 

Albite (tr.) 

-200 mesh 

9.346 

9.342 

9.350 

0 ~ 100 

I I I I II ~;i~.:iff;~;;;}:i:~i:(?·i;.-:·.j . .,,. 

Figure 12. C.F. Hardee complex. SE1ANW1A sec. 5, T. 33 S., R. 24 E., Polk and Hardee Counties. 
~ Depth 

(feet) 

s:: 

s· 

CD 

; 

0 

CQ 

'< 

I» 

::J 

Q. 

)> 

;: 

; 

... 

cs· 

::J 

2. 

... 

::T 

CD 

"tJ 

::T 

0 

0 

, 

::T 

I» 

; 

c 

CD , 

0 

0 

;: 

2. 

"TI 

0 

.. 

a: 

I» 

0-1 

1-3 

3-8 

8-12 

12-14 

14-22 

22-26 

Sample 

No. 

None 

None 

None 

None 

20-84 

21-84 

22-84 

Lithology 

OVERBURDEN 

!! 

Sand, black and gray, ·;;; 

0 organic. c. 

Q) 

c 

Sand, white, unconsoli- ~ 

dated, windblown. E 

.! 

Sand, white, unconsolidated, 

fine to medium grained. 

Sand, gray tan to yellow tan, 

clayey at base. Unit is 15ft 

thick 1f2 mi southeast, and 

12ft thick 2 mi southwest. 

Gradational contact. 

c 

Sand, clayey, white, 0 

iO leached. Soft white phos- § phate. Unit thickens to 6 0 ft to southeast but is LL 

absent to the southwest. ~ a: 

MATRIX Q) 

(J 

Cll 

Sand, gray white, graded £ 

bedding. Bottom 3 ft 6. 

::J very pebbly. Unit is 5 ft e thick to the southeast and (!) 

is14 ft thick 2 mi to the c southwest. 0 

.r:. 

~ Sand, clayey, brown .. Cll 

:I: Bedded. Fme sand-s1ze 

phosphate unit is 14ft 

thick to the southeast, 

but thins to only 1 ft 2 

mi to the southwest. 

Yellow dolomite in bottom 

of the pit. 

EXPLANATION 

1m Plus 20-mesh 

Age and 

Stratigraphy 

HOLOCENE 

PLEISTOCENE 

PLIOCENE-PLEISTOCENE 

Bone Valley Member(?) 

MIOCENE-PLIOCENE 

Leached 

Bone Valley 

Member 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

jr·-.::::_:~:-:r~.:·:.J Minus 20- plus 200-mesh ~ Minus 200-mesh 

oo:t 

co 

6 

N 

~ 0.. 

~ 

~ 

oo:t 

~ N 

~ 0.. 

~ 

~ 

~ 

N 

N 

~ 0.. 

~ 

~ 

SAMPLE 

NO. 

20-84 

21-84 

22-84 

SAMPLE 

NO. 

20-84 

21-84 

22-84 

Figure 13. Ft. Green mine. NW1ANWV.. sec. 25, T. 32 S., R. 23 E., Polk County. 

+20 mesh 

FRANCOLITE 

QUARTZ 

FRANCOLITE 

QUARTZ 

FRANCOLITE 

Quartz } K feldspar (m) 

Bulk Sample 

9.335 

9.328 

9.330 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

QUARTZ FRANCOLITE 

Franco!ite } (tr) Kaolinite } Wavellite (m) Wavelhte · Crandallite 

Albite (tr.) 

QUARTZ QUARTZ 

FRANCOLITE Francolite (m) 

Wavellite Kaolinite } ( ) (tr.) K feldspar tr. 

SMECTITE 

QUARTZ 

QUARTZ FRANCOLITE 

Francolite (m) Albite (m) 

K feldspar (tr.) Dolomite } Illite (tr.) 

K feldspar 

FRANCOLITE A-VALUES 

('t0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.329 9.336 

9.326 9.330 

9.326 9.332 

SCREEN DATA (IN PERCENT) 

-2fJ.m 

KAOLINITE 

FRANCOLITE 

Illite (m) 

Wavellite (tr.) 

SMECTITE 

FRANCOLITE 

K feldspar Kaolinite } (ml 

Illite 

Albite (tr.) 

SMECTITE 

Illite (m) 

Kaolinite } Francolite (tr.) 

-200 mesh 

9.341 

9.347 

9.337 

0 50 100 

-''1 ... :.: ·.·. ~--~- .. ···>: .. ·. ::,:.·:,. :· . .y; . _-:. ;' ·-:~~:·;.·'·:·:}:·:~;·:! . . .. ·::.~·-:- ·:·. :_. ... ·:.· :- ·:.: :: -~·:. ~<· ... : ··.; --~-~: ... -:-. . . . : .. · .. .. -:· ..... · . ····.: .. "; ·. ·. ·. · .... ·1 

. : .;::~: . :/;_·_ ':}:'.: .. ·<:::::: .:·:· ... ::;_·:~ _::·_·. :~·:··:·::_·:::·:·~:·: .. ·~~:. : .. < .. ::·:·::·: .:>' ::·._,:\._:. ·-:~:; ·.· :::·.' 
"11 

cO 

c 

(; 

0 

w 

~ 

w 

..... 

Depth 

(feet) 

0·2 

2-8 

8-16 

16-19 

19-22 

Sample 

No. 

None 

None 

25-84 

.24-84 

23-84 

Lithology 

OVERBURDEN 

Sand, unconsolidated, 

gray, organic rich. 

Sand, unconsolidated, 

tan. Fragmental horse 

teeth (Equus sp.). 

Sharp contact. 

MATRIX 

Sand, light gray, slightly 

clayey. Abundant white 

phosphate pebble in 

three distinct beds in 

top, middle, and base 

of this bed. 

Sharp, irregular contact. 

Sand, brown, clayey, 

pebbly. Pebble is brown, 

some white, and finer 

than in bed above. 

Irregular contact. 

Sand, claye~ brown. 

Abundant ine sandsize phosphate. Minor 

pebble. 

EXPLANATION 

~~~ Plus 20-mesh 

~ 

"iii 

0 

c. 

(I) 

0 

~ 

~ 

~ 

c: 

.~ 

iQ 

E 

0 

LL 

a; 

> 

a: 

(I) 

() 

Ill 

(I) 

a.. 

0. 

:::1 

e 

C) 

c: 

0 

.c: 

j 

Ill 

::r: 

Age and 

Stratigraphy 

HOLOCENE 

PLEISTOCENE 

PLIOCENE-PLEISTOCENE 

Channel deposit 

Bone Valley 

Member 

MIOCENE-PLIOCENE 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

1;·:: .. ·:\)::.'·J Minus 20- plus 200-mesh 

~ Minus 200-mesh 

..,. 

CXl 

.;, 

N 

~ a.. 

~ 

<( 

fJ) 

..,. 

CXl 

..t 

N 

w 

...J 

a.. 

~ 

<( 

fJ) 

..,. 

CXl 

cJ> 

N 

w 

...J 

a.. 

~ 

<( 

fJ) 

SAMPLE 

NO. 

25-84 

24-84 

23-84 

SAMPLE 

NO. 

25-84 

24-84 

23-84 

Figure 14. Saddle Creek mine. SWY4 sec. 19, T. 28 S., R. 25 E., Polk County. 

+20 mesh 

FRANCOLITE 

QUARTZ 

Dolomite (m) 

Smectite (tr.) 

FRANCOLITE 

QUARTZ 

Dolom.ite } (tr.) Smect1te 

FRANCOLITE 

QUARTZ 

Wavellite (m) 

K feldspar (tr.) 

Bulk Sample 

9.349 

9.340 

9.350 

Mineralogy 

(Screen size) 

-20 +200 mesh 

QUARTZ 

Francolite } K feldspar (tr.) 

QUARTZ 

Francolite } K feldspar (tr.) 

QUARTZ 

Francolite (m) 

K feldspar } Wavellite (tr.) 

-200 mesh 

QUARTZ 

FRANCOLITE 

Crandallite (m) 

Kaolinite (tr.) 

QUARTZ 

FRANCOLITE 

Crandallite } Palygorskite 

Albite 

K feldspar 

Dolomite(?) 

QUARTZ 

FRANCOLITE 

CRANDALLITE 

(m) 

(tr.) 

K FELDSPAR 

Palygorskite (tr.) 

FRANCOLITE A-VALUES 

(±0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.344 9.347 

9.338 9.341 

9.348 9.343 

SCREEN DATA (IN PERCENT) 

-2 Jim 

SMECTITE 

Crandallite Kaolinite } 

Francolite 

Albite 

(tr.) 

K feldspar 

Kaolinite 

Palygorskite 

Smectite 

Francolite 

Crandallite 

K feldspar 

Albite 

j 

(m) 

(tr.) 

SMECTITE 

FRANCOLITE 

PALYGORSKITE 

Crandallite (tr) 

Quartz } 

Albite · 

K feldspar 

-200 mesh 

9.350 

9.347 

9.353 

0 ~ 100 

-~~~~~'I ;:;·: :·. :: .~,: .;r; .. :. ·~ ;:,?i:::~·,·::::?: ,:~r;::.i~ i::~·; :~;.- ~:,::1 ) I 
w Depth 00 (feet) 

s:: 

:;· 

.,. 

... 

Q) 

0 

CQ 

"< 

Q) 

::s 

Q. 

~ 

; 

! 

c;· 

::s 

2. 

.. '::r 

.,. 

"'0 

'::r 

0 

en , 

'::r 

i 

c 

.,. 

, 

0 

~ en 

2. 

., 

Q 

a: 

Q) 

0-2 

2-10 

10-22 

22-25 

25-27 

27-30 

30-34 

Sample 

No. 

None 

None 

None 

26-84 

Not 

sampled 

27-84 

28-84 

Lithology 

OVERBURDEN 

Sand, unconsolidated, 

gray, organic. 

Sand, unconsolidated, 

brown and white. 

Sand, unconsolidated 

to slightly clayey, 

brown and gray. 

MATRIX 

Sand, clayey, white, 

yellow, and red mottled. 

Leached. Soft white 

phosphate. 

Clay, sandy, green and 

red mottled. Minor 

phosphate. 

Sand, clayey, white. 

Phosphate pellets and 

pebbles. 

Gradational contact. 

Sand, clayey, cream and 

~ellow brown mottled. 

ina-grained phosphate 

pellets, less abundant at 

base. 

Pit bottom at 34 ft. 

EXPLANATION 

~ Plus 20-mesh 

~ 

'iii 

0 

c. 

Q) 

0 

B 

E 

~ 

c:: 

.~ 

iii 

E 

0 

u.. 

Q; 

> a: 

Q) 

() 

Ill 

Q) 

0.. 

o_ 

:::1 

e 

C) 

c:: 

0 

.r::. 

~ Ill 

::1: 

Age and 

Stratigraphy 

HOLOCENE 

PLEISTOCENE 

MIOCENE-PLIOCENE 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

, .. ~.·).·(·.·/~ Minus 20- plus 200-mesh 

~ Minus 200-mesh 

...,. 

co 

cb 

N 

w 

..J 

0.. 

~ 

<( 

en 

...,. 

co 

...:. 

N 

~ 0.. 

~ 

<( 

en 

...,. 

co 

00 

N 

~ 0.. 

~ 

~ 

SAMPLE 

NO. 

26-84 

27-84 

28-84 

+20 mesh 

QUARTZ 

Wavellite F"ncolite ~ 1 m 1 

Smectite 

K feldspar (tr.) 

FRANCOLITE 

QUARTZ 

Wavellite } K feldspar (tr.) 

FRANCOLITE 

QUARTZ 

Goethite (m) 

Bulk Sample 

9.355 

9.341 

9.340 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ QUARTZ 

Francolite } Francolite } ( ) Wavellite (tr.) Smectite m 

K feldspar Goethite (tr.) 

QUARTZ QUARTZ 

Francolite (m) FRANCOLITE 

Wavellite } Smectite (m) 

K feldspar (tr.) Wavellite } Crandallite (tr.) 

QUARTZ 

QUARTZ FRANCOLITE 

Francolite } Wavellite (m) 

K feldspar (tr.) Kaolinite } Crandallite (tr.) 

K feldspar 

----

FRANCOLITE A-VALUES 

(t0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.354 9.340 

9.345 9.342 

9.336 9.349 

SCREEN DATA (IN PERCENT) 

-2J.Lm 

SMECTITE 

Francolite } Illite (tr.) 

Wavellite 

SMECTITE 

Wavellite Francolite l (m) 

K feldspar 

Illite 

Crandallite (t ) Quartz r. 

Dolomite 

SMECTITE 

WAVELLITE 

Francolite (m) 

tllite } Goethite 

Crandallite (tr.) 

Dolomite 

-200 mesh 

9.353 

9.353 

9.349 

SAMPLE 0 50 100 

2::, -:::;j I I : I I I I 

::::: ~-:_ .. ::._---;:·;;3;. __ :_i_{.'i.(:' .. _.-;.;:1_-,_._ :•-~--·1 Figure 15. lonesome mine. Sec. 16, T. 31 S., R. 22 E., Hillsborough County. 
Depth 

(feet) 

221/2-24 

Sample 

No. 

None 

Lithology 

Gray, sandy, dark redbrown, dolomitic. Minor 

phosphate. 

Yellow dolomite in pit 

bottom. 

!! 

'iii 

0 

a. 

Q) 

c 

B 

~ 

~ 

c: 

o.·g 

::s"' oE 

...... 

(,!)0 LL c: ... ... Q) 

0> 

-=·- ja: 

~~ Q) 

0.. 

Age and 

Stratigraphy 

HOLOCENE 

PLIOCENE(?)-PLEISTOCENE 

MIOCENE 

Undifferentiated 

~ Figure 16. Watson mine. Sec. 11, T. 32 S., R. 25 E., Polk County. c 

Cil 

, 

w 

~ 

w 

CD 

• co 

a, 

N 

~ 0.. 

:::2: 

~ 

SAMPLE 

NO. 

29-84 

SAMPLE 

NO. 

29-84 

+20 mesh 

FRANCOLITE 

QUARTZ 

Crandallite } (tr) K feldspar · 

Bulk Sample 

9.338 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

SEPIOLITE 

QUARTZ 

QUARTZ FRANCOLITE 

Francolite } (tr) Goethite ~ Palygorskite (m) K feldspar · K feldspar 

Dolomite 

Crandallite (tr.) 

FRANCOLITE A-VALUES 

(±0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.336 9.335 

SCREEN DATA (IN PERCENT) 

-2 JUTl 

SMECTITE 

PALYGORSKITE 

SEPIOLITE 

Kaolinite K feldspar 1 (m) 

Francolite 

Cranda.llite (tr) Dolom1te • 

-200 mesh 

9.342 

0 ~ 100 

., : ' .• p.:~:_·.' ..•. ·;·,:'· • __ ,-~_.,._.'.' . .-:.::.'·.·.·.-/::! I I 

EXPLANATION 

~~~~ Plus 20-mesh 

1."/.':\~:~::.:·:J Minus 20- plus 200-mesh 

~ Minus 200-mesh 
~Depth (feet) 

s:: 

S" 

CD 

; 

0 

CQ 

"< 

It 

:s 

a. 

)> 

; 

; 

.. 

0 

:s 

2. 

:;: 

CD 

., 

:r 

0 

fl) 

, 

:r 

It 

i 

c 

CD 

'8 

0 

if 

2. 

"'" 

~ a. 

It 

0-4 

4-11 

1 1-18 

18-22 

22-31 

31-33 

Sample 

No. 

None 

None 

None 

31-84 

30-84 

30A-84 

Lithology 

OVERBURDEN 

Sand, gray, and white, B-~ cuCil unconsolidated. Top 1 .... o '-Q. 

ft of sand is black and ~~ highly organic 1 mi 

northeast. 

Sand, clayey white, 

contains abundant round, 

vesicular boulders of 

sandstone cemented by 

aluminum phosphates. 

Bed is missing 1 mi northeast and is a gray clayey 

sand. 

Sand, gray, clayey, c:: 

leached. Zone is 4ft of .g 

vesicular aluminum cu 

phosphate 1 mi north- E 

0 east. Zone is underlain LL 

by 2-ft intervals that 

contain soft white ~ phosphate pebbles. a: 

B 

cu 

Q) 

ll.. 

0. 

MATRIX ~ 

e 

(!) Sand, gray and white, E pebbly. Zone is 2 ft 0 thick 1 mi northeast. .c:: 

i 

cu 

Sand, clayey, gray-green 

and rust mottled. FineJ: 

grained phosphate pellets. 

Bed is 10ft thick 1 mi 

northeast and rests on yellow dolomite. 

RESIDUUM 

Clay, very sandy, brown. 

Some fine-grained phosphate pellets. Absent 1 

mi northeast. 

EXPLANATION 

Bl Plus 20-rnesh 

Age and 

Stratigraphy 

PLEISTOCENE and 

HOLOCENE 

MIOCENE-PLIOCENE 

Leached 

Bone Valley 

Member 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

1>.::.':'_-:t:::~J Minus 20- plus 200-mesh ~ Minus 200-mesh 

..... 

op 

c;; 

w 

-l 

ll.. 

~ 

~ 

..... 

00 

g 

~ a.. 

~ 

<( 

en 

..... 

00 

~ ~ ll.. 

~ 

~ 

SAMPLE 

NO. 

31-84 

30-84 

30A-84 

SAMPLE 

NO • 

31-84 

30-84 

30A-84 

Figure 17. Phosphoria mine. SE1A sec. 12, T. 31 S., R. 23 E., Polk County. 

+20mesh 

FRANCOLITE 

QUARTZ 

FRANCOLITE 

Quartz (m) 

K feldspar (tr.) 

FRANCOLITE 

Quartz (m) 

Smectite } Palygorskite (m) 

Bulk Sample 

9.342 

9.345 

9.336 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

FRANCOLITE 

QUARTZ Smectite ~ FRANCOLITE Crandallite (m) 

Kaolinite 

K feldspar (tr.) 

QUARTZ 

QUARTZ 

Francolite } Francolite Smectite ~ (m) K feldspar (tr.) KfeldsparCrandallite (tr.) 

QUARTZ 

FRANCOLITE 

QUARTZ Albite Smect~ 1 (m) 

K feldspar (m) Francolite 

Dolomite (tr.) Crandallite 

Palygorskite (tr.) 

FRANCOLITE A-VALUES 

(±0.003 ANGSTROMS) 

+20mesh -20 +200 mesh 

9.338 9.347 

9.345 9.347 

9.336 9.337 

SCREEN DATA (IN PERCENT) 

-2f.Ull 

Smectite Francolite j (m) 

Albite 

Wavellite (tr.) 

Illite 

SMECTITE 

Illite Kaolinite I 

Crandallite 

Francolite (tr.) 

Albite 

K feldspar 

Dolomite 

SMECTITE 

Illite } Palyorskite 

Goethite (tr.) 

Francolite 

Albite 

-200mesh 

9.355 

9.352 

9.355 

0 ~ 100 

• ,,1:'''1 ii!i;,\;:1);/J~r\\;:;;,!rt\'-::ilr_/ii~~( .. :-:(:' >I 
'TI 

~ c 

; 

tit 

w 

~ 

.. .... 

Depth Sample 

(feet) No. 

Lithology 

OVERBURDEN 

0-2 None Sand, gray, uncon- solidated, organic. 

2-12 None Sand, brown and tan. 

Slightly clayey at base. 

12-15 None Sand, clayey white. Some 

soft, white phosphate and 

vesicular boulders. 

MATRIX 

15-35 32-84 Sand, clayey, gray green. 

Interbedded clay lenses 

and pebbly sand beds. 

RESIDUUM 

35-37 33·84 Clay, very sandy, red 

brown. Abundant 

brown phosphate 

pellets. 

Yellow dolomite in pit 

bottom. 

~ ·; 

0 

a. 

Q) 

Q 

8 

E 

~ 

c: 

.g 

«< 

e 

0 

u. 

~ a: 

~ «< 

Q) 

Cl.. 

b. 

::I 

E 

C) 

c: 

0 

.r:. 

~ «< 

:I: 

Age and 

Stratigraphy 

HOLOCENE 

PLEISTOCENE 

MIOCENE-PLIOCENE 

Leached 

Bone Valley 

Member 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

Figure 18. Rockland mine. NWV.. sec. 30, T. 31 S., R. 23 E., Polk County . 

... 

co 

r:., 

("I) 

w 

..J 

Cl.. 

::E 

~ 

... 

co 

~ 

~ Cl.. 

::E 

~ 

SAMPLE 

NO. 

32-84 

33-84 

SAMPLE 

NO . 

32-84 

33-84 

+20 mesh 

FRANCOLITE 

QUARTZ 

Wavellite (m) 

Dolomite } (tr.) K feldspar 

FRANCOLITE 

QUARTZ 

K feldspar (m) 

Dolomite } (tr ) Palygorskite · 

Bulk Sample 

9.340 

9.335 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

QUARTZ Smectite } F"'ncolite } Francolite (m) 

Wavellite (tr.) K feldspar 

K feldspar Wavellite (tr.) 

Illite 

SEPIOLITE 

QUARTZ Palyg~rskite } (ml Goethrte K feldspar (m) Quartz Franco lite (tr.) Francolite (tr.) 

K feldspar 

FRANCOLITE A-VALUES 

(t0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.345 9.342 

9.328 9.337 

SCREEN DATA (IN PERCENT) 

-2JLm 

SMECTITE 

Kaolinite ) Illite 

Crandallite 

Wavelli~e (tr.) Francolite 

K feldspar 

Albite 

Quartz 

PALYGORSKITE 

Smectite } Albite (tr.) 

Francolite 

-200 mesh 

9.347 

9.343 

0 00 100 ._,,,,,,,1 

;;;.-.·: :: ·::: ·:·~···. ~\·'· :·:<.:\}1 

EXPLANATION 

.. Plus 20-mesh 

~~·.· .. ~.:·.:~ ... :t:·::.:J Minus 20- plus 200-mesh 

~ Minus 200-mesh 
,. Depth Sample N (feet) No. 

s:: 

s· 

CD 

; 

0 

c.a 

'< 

I» 

:s 

Q. 

)> 

~ 

~ 0 

:s 

2. 

:;: 

CD 

"tl 

::T 

0 

0 

., 

::T 

I» 

; 

i' ., 

0 

0 

;::; 

0 

2. 

"T1 

~ a: 

I» 

0-2 None 

2-13 None 

13-30 None 

30-33 34-84 

33-36 35-84 

Lithology 

OVERBURDEN 

Sand, gray, organic 

rich. 

Sand, unconsolidated, 

brown, iron stained. 

Sand, unconsolidated, 

white. Slightly clayey 

at base. 

MATRIX 

Sand, black, pebbly . Graded bedding. 

Coarse black phosphate 

conglomerate at base. 

Sharp contact. 

Bioturbated. Fine sandsize phosphate ab·undant. 

Water level in pit is 36 

ft. Prospecting indicates 

this unit extends to 65ft 

below surface. 

~ ·;; 

0 

a. 

Cl) 

0 

B 

~ 

~ 

c:: 

0 

·.;::::; 

"' E 

0 

u. 

~ a: 

8 

"' Cl) 

0.. 

0. 

::3 

e 

(.!) 

c:: 

0 

..c:: 

~ 

::I: "' 

Age and 

Stratigraphy 

HOLOCENE 

PLIOCENE-PLEISTOCENE 

MIOCENE-PLIOCENE 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

I 

..,. 

co 

..t 

('I) 

~ 0.. 

~ 

~ 

..,. 

co 

.;, 

('I) 

~ 0.. 

~ 

<( 

(/) 

SAMPLE 

NO. 

34-84 

35-84 

+20 mesh 

FRANCOLITE 

QUARTZ 

K feldspar (tr.) 

FRANCOLITE 

QUARTZ 

K feldspar (tr.) 

Bulk Sample 

9.340 

9.345 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

FRANCOLITE 

QUARTZ Wavellite 1 Francolite } Crandallite (m) 

K feldspar (tr.) Smectite 

Albite 

Kaolinite (tr.) 

Illite 

QUARTZ 

QUARTZ FRANCOLITE 

Francolite } (tr) Smectite } 

K feldspar · Crandallite (m) 

K feldspar 

Kaolinite (tr.) 

FRANCOLITE A-VALUES 

(±0.003 ANGSTROMS) 

+20mesh -20 +200 mesh 

9.336 9.340 

9.337 9.339 

SCREEN DATA (IN PERCENT) 

-2J.Ull 

SMECTITE 

Illite Kaolinite l (m) 

Francolite 

Wavellite 

Crandallite (tr 1 K feldspar · 

Sepiolite 

SMECTITE 

Francolite (m) 

K~olinite } (tr) Illite · 

-200 mesh 

9.356 

9.358 

SAMPLE 0 50 100 

NO. -1 1. 1 1 1 I~ 34-84 . . . :·:·_:::=._:::.·:_:~;-~.··::·~.:·::.:::=:···;. :-.~- ·~-:; :}:;_:._:::'·:_>_:: :.:l:>: ~-.: .. · ..: :.- ·-.:~.; :_::_;.: 

as.s• ==== .. .. .. ;. . . . . 1 . . : : . . . - -. •, ... : . . .. : . . . . ·.• .' ... .'. . . . . .. ~ ·.: : . . . . .. . 

EXPLANATION 

~~~~ Plus 20-mesh 

, .... ~.':(:X:.:·:)} Minus 20· plus 200-mesh 

~ Minus 200-mesh 

Figure 19. Haynsworth mine. SEY..SWY.. sec. 8, T. 31 S., R. 23 E., Polk County. 
"TI 

<E" 

c 

~ 

CD 

(I) 

(,.) 

~ 

ol:a 

(,.) 

Depth Sample 

{feet) No. 

Lithology 

OVERBURDEN 

0-16 None Sand, unconsolidated, 

gray at top, white and 

brown below. Slightly 

clayey at base. 

MATRIX 

16-26 37-84 Sand, clayey, brown and 

gray. Abundant sandsize, brown, cream, and 

gray phosphate pellets. 

Some pebble. Unit is 

missing 1 mi southwest. 

Top is leached. 

26-32 36-84 Clay, sandy, red and green 

mottled, some pebble. 

Yellow and dolomitic at 

base. Unit is tan, brown, 

and red, and is bioturbated 

1 mi southwest. Rests on 

hard yellow dolomite. 

!l 

'iii 

0 

c. 

~ 

s 

~ 

~ 

c: 

.~ 

n; 

E 

0 

LL 

~ a: 

CD 

CJ 

ell 

CD 

ll.. 

b. 

::J 

e 

Cl 

c: 

0 

.r::. 

j 

ell 

J: 

Age and 

Stratigraphy 

PLEISTOCENE 

and 

HOLOCENE 

MIOCENE-PLIOCENE 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

..... 

co 

...:. 

M 

~ ll.. 

~ 

<( 

(/) 

..... 

co 

cb 

M 

~ ll.. 

~ 

~ 

SAMPLE 

NO. 

37-84 

36-84 

+20 mesh 

QUARTZ 

Francolite (m) 

Wavellite } K feldspar (tr.) 

Palygorskite 

FRANCOLITE 

QUARTZ 

K feldspar (tr.) 

Bulk Sample 

9.346 

9.345 

Mineralogy 

{Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

FRANCOLITE 

QUARTZ Crandallite } (m) Francolite (m) Albite 

K feldspar (tr.) Kaolinite 

Smectite (tr.) 

Wavellite 

QUARTZ 

FRANCOLITE 

PALYGORSKITE 

QUARTZ 

KFELDSPAR Goethite Smectite l (m) 

Francolite (m) Dolomite 

K feldspar Wavellite (tr.) 

Sepiolite 

FRANCOLITE A-VALUES 

(t0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.344 9.340 

9.346 9.339 

SCREEN DATA (IN PERCENT) 

-2JUll 

SMECTITE 

Palygorskite1 Albite (m) 

Francolite 

K feldspar Crandallite (tr.) 

1 

SMECTITE 

PALYGORSKITE 

Sepiolite (m) 

Dolomite } Francolite (tr.) 

Crandallite 

-200mesh 

9.345 

9.348 

SAMPLE 0 50 100 

NO ... I I I I I I I I 

:~:: ~_. ;(· , ·: ;:)\";. /( ... ·; · __ :·_:·.,;·;.:.~:;~~-'. ·' .... ··:,;·( ,J 

EXPLANATION 

~~~~ Plus 20-mesh 

j:·~.·:' ... :(:.:·.;d Minus 20· plus 200-mesh 

§§ Minus 200-mesh 

Figure 20. Lonesome mine. NEV.. sec. 16, T. 31 S., R. 22 E., Hillsborough County. 
t Depth Sample 

(feet) No. 

i: 

s· 

CD 

; 

;g 

'< 

• :::J 

a. 

~ 

S' 

; 

... 

c;· 

:::J 

2. 

g. 

CD 

., 

:::T 

0 

II) 

"tJ 

:::T 

i 

c 

CD 

"tJ 

0 

II) 

:::+ 

II) 

2. 

., 

0 

.. 

a: • 

0-14 None 

14-17 41-84 

17-23 40-84 

23-29 39-84 

29-35 38-84 

Lithology 

OVERBURDEN 

Sand, white, unconsolidated. 

Sand is only 3ft thick 1 mi 

east and is overlain by 4ft of 

swamp muck . 

MATRIX 

White pebbly sand, slightly 

clayey. Unit not present at 

section 1 mi east. 

c: 

~ 

Sand, pebbly, gray-green, e "' 

clayey. Coarse phosphate 0 

at base. A graded bed is LL 

same thickness and lith- Q; 

ology at the mine section > 

a: 1 mi east. Sample 40-84 G) 

is a composite from both (.) 

"' localities. Q,) 

a.. 

o_ 

::1 

E 

Sand, clayey mottled gray Cl 

and red-brown. Dolomitic. c: 

Fine-sand size phosphate 0 

.t:: more abundant than coarse 

phosphate. Upper contact ~ 

sharp and irregular. Unit 4 ::c "'

ft thick at section 1 mi east. 

Clay, very sandy, brown. 

Sand-size brown phosphate. 

Minor fine pebble size. Unit 

not present at section 1 mi 

east. 

Yellow dolomite in pit bottom. 

FRANCOLITE A-VALUES 

(t0.003 ANGSTROMS) 

Age and 

Stratigraphy 

HOLOCENE 

Swamp deposit 

PLEISTOCENE 

Terrace sands 

MIOCENE-PLIOCENE 

leached 

Bone Valley 

Member 

Bone Valley 

Member 

(Graded bedding) 

MIOCENE 

Undifferentiated 

SAMPLE Bulk Sample +20 mesh -20 +200 mesh -200 mesh NO. 

41-84 9.334 9.332 9.336 9.343 

40-84 9.332 9.333 9.335 9.345 

39-84 9.332 9.328 9.329 9.335 

38-84 9.338 9.332 9.332 9.338 

..,. 

..,. 

~ 

~ a.. 

~ 

<( 

en 

..,. 

(X) 

~ w 

__, 

a.. 

~ 

<( 

en 

..,. 

(X) 

~ w 

__, 

a.. 

~ 

<( 

en 

..,. 

(X) 

~ w 

__, 

a.. 

~ 

<( 

en 

+20 mesh 

FRANCOLITE 

QUARTZ 

K feldspar (m) 

FRANCOLITE 

Quartz (m) 

K feldspar } r Palygorskite (t .) 

FRANCOLITE 

Quartz } K feldspar (m) 

Dolomite 

Palygorskite (tr.) 

QUARTZ 

Francolite (m) 

K feld~par } (tr) Smect1te · 

SAMPLE 0 

NO. 

41-84 

40-84 

39-84 

38-84 ~·. 

-20 +200 mesh 

QUARTZ 

Francolite (m) 

K feldspar (tr.) 

QUARTZ 

Francolite } K feldspar (tr.) 

Palygorskite 

QUARTZ 

Francolite (m) 

K feldspar (tr.) 

QUARTZ 

Francolite } K feldspar (tr.) 

Smectite 

Mineralogy 

(Screen size) 

-200 mesh 

FRANCOLITE 

QUARTZ 

Smect~e K feldspar j (m) 

Wavellite 

Crandallite 

Kaolinite (tr.) 

Illite 

Palygorskite 

QUARTZ 

SMECTITE 

FRANCOLITE 

CRANDALLITE 

KFELDSPAR 

Albite } (tr) Palygorskite · 

QUARTZ 

DOLOMITE 

Francolite } Smectite 

Palygorskite (tr.) 

Goethite 

K feldspar 

QUARTZ 

KFELDSPAR 

Smectite (m) 

Palygorskite } (t ) Francolite r. 

SCREEN DATA (IN PERCENT) 

50 

EXPLANATION 

-2J.Lm 

SMECTITE 

KAOLINITE 

ILLITE 

FRANCOLITE 

Albite (tr.) 

SMECTITE 

~lomlre ) Kaolinite 

Illite 

Crandallite (tr.) 

Francolite 

Albite 

K feldspar 

No clay 

sample 

SMECTITE 

Palygorsklre } Goethite 

Quartz r Francolite (t .) 

Albite 

Wavellite 

100 

~~~ Plus 20-mesh k.~:·::::.<:<.J Minus 20· plus 200-mesh ~ Minus 200-mesh 

Figure 21. Hookers Prairie mine. SE1ANE1A sec. 7, T. 31 S., R. 24 E., Polk County. 
., 

~ 

c 

;; 

., 

w 

~ 

.. 

Ul 

Depth 

(feet) 

0-14 

14-19 

19-23 

23-35112 

351h-37 

37-43 

Sample 

No. 

None 

44-84 

Not 

sampled 

43-84 

Not 

sampled 

42-84 

Lithology 

OVERBURDEN 

(I) 

Sand, black at top, gray, "C 

c: white, and brown below (0 

and slightly clayey at en 

base. B 

~ 

~ 

MATRIX 

Sand, pebbly, dark gray 

to black. Phosphate 

pellets and pebbles, 

most black, some gray 

and brown. 

c: 

0 

~ 

BEDROCK e 

0 

LL 

Hard, fossiliferous, yellow Q) 

dolomite. Pebbles and > 

grains of phosphate. a: 

Upper contact sharp CD 

0 

and irregular. ftl 

CD 

flSand, clayey, gray-green b. 

and blue. Laminated. :I 

0 

Sand-size phosphate (; pellets. Pebbly sand c: near middle. Rubble 0 zone of partly phos- .r:. 

phatized dolomite ~ nodules at base. ftl 

J: 

Very, sharp, irregular 

contact. 

Yellow phosphatic 

dolomite. 

Sand, gray brown. Fine 

sand-size phosphate 

pellets. Water level at 

43ft. 

EXPLANATION 

am Plus 20-mesh 

Age and 

Stratigraphy 

PLEISTOCENE 

and 

HOLOCENE 

MIOCENE-PLIOCENE 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

jr:·.~:.:\.::?:_::{j Minus 20- plus 200-mesh ~ Minus 200-mesh 

..,. 

CX) 

.,f. 

..,. 

~ fl-

::':E 

<( 

en 

..,. 

CX) 

M 

..,. 

~ fl-

::':E 

~ 

..,. 

CX) 

N 

..,. 

~ fl-

::!E 

~ 

SAMPLE 

NO. 

44-84 

43-84 

42-84 

+20 mesh 

QUARTZ 

Francolite (m) 

K feldspar (tr.) 

FRANCOLITE 

DOLOMITE 

Quartz (m) 

K feldspar (tr.) 

FRANCOLITE 

KFELDSPAR 

Quartz (m) 

Wavellite (tr.) 

Bulk Sample 

9.340 

9.336 

9.336 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ 

QUARTZ SMECTITE 

Francolite } FRANCOLITE 

K feldspar (tr.) Crandallite } K feldspar (tr.) 

Dolomite 

QUARTZ DOLOMITE 

Francolite (m) Smectite } 

Dolomite } Quartz 

K feldspar (tr.) Goethite (tr.) 

Francolite 

SMECTITE 

QUARTZ 

QUARTZ Palygorskite! Francolite (m) 

Francolite } Goethite 

K feldspar (tr.) Dolomite 

K feldspar Wavellite (tr.) 

Crandallite 

FRANCOLITE A-VALUES 

(!0.003 ANGSTROMS) 

+20mesh -20 +200 mesh 

9.332 9.330 

9.324 9.332 

9.328 9.335 

SCREEN DATA (IN PERCENT) 

-2 JLm 

SMECTITE 

KAOLINITE 

FRANCOLITE 

lllite(m) 

SMECTITE 

Illite } Dolomite (m) 

Kaolinite (tr.) 

SMECTITE 

Francolite } Albite 

K feldspar 

Palygorskite (tr.) 

Illite 

Goethite I 

I 

-200mesh 

9.327 

9.333 

9.349 

SAMPLE 0 50 100 

NO. II' I I i I I I I I :: ~· .:·.:·:.:·· ... ::_-··. ·:;~: :·~·:· ....... :::·:I 

42-84 . ·.: .. ·.· ...... :· . .-;. -~ ·.· ·• -::..-~ :·.: :·-. .-.·. :_. .... · .·.· :·-.-.1 

Figure 22. Four Corners mine. NWV..NWV.. sec. 2, T. 33 S., R. 22 E., Hillsborough County . 
* c 

!:n 

c;) 

0 

< 

m 

::0 

z 

3:: 

m 

z 

-t 

"'0 

::0 

z 

-t 

z 

c;) 

0 

"11 

"11 

0 

r':' 

i8 

~ 

~ 

~ 1\) 

~ Depth O» (feet) 

3: 

:;-

CD 

iil 

0 

cc 

'< 

I» 

::r 

a. 

> i 

iil 

~ 

0 

::r 

2. 

.. :::r 

CD 

"tJ 

:::r 

0 

0 

"C 

::T 

I» 

i 

c 

(I) 

"C 

0 

0 

::; 

0 

2. 

-n 

[ 

c: 

I» 

0-14 

14-18 

18-23 

23-30 

30-421/2 

Sample 

No. 

None 

None 

47-84 

46-84 

45-84 

Lithology 

OVERBURDEN Cl) 

Sand, unconsolidated, 1:1 

c: gray and organic in top en "' 2ft, white below. ~ 

Bottom 6 ft is red brown, ~ 

iron stained. ~ 

RUBBLE ZONE 

Sand, gray white, slightly 

clayey. Contains abundant 

boulders of vesicular 

leached rock. 

c: 

.2 

~ 

E 

MATRIX 0 

u. 

Sand, clayey to sandy clay, ~ a= mottled yellow and gray Q) 

green. Abundant sand- (J 

size phosphate pellets, "' Q) 

some pebbles. Unit is 241h 0.... 

b. ft thick 100ft east. :I 

!: 

CJ 

c: 

0 

.s::. 

~ 

BEDROCK :I: "' 

Interbedded, thin, hard 

yellow dolomite and 

pebbly, clayey sand 

containing abundant 

coarse phosphate 

pebble. Pit base at 421/2 

ft. 

EXPLANATION 

~~~~ Plus 20-mesh 

Age and 

Stratigraphy 

PLEISTOCENE 

and 

HOLOCENE 

MIOCENE-PLIOCENE 

Leached 

Bone Valley 

Member 

Bone Valley 

Member 

MIOCENE 

Undifferentiated 

1:·:.:./:.:~:·· .. \J Minus 20- plus 200-mesh ~Minus 200-mesh 

..,. 

(X) 

..,. 

~ 

w 

..J 

0.... 

~ 

~ 

..,. 

(X) 

cb 

..,. 

w 

..J 

0.... 

~ 

<{ 

en 

..,. 

(X) 

.;., 

..,. 

~ 0.... 

~ 

~ 

SAMPLE 

NO. 

47-84 

46-84 

45-84 

SAMPLE 

NO. 

47-84 

46-84 

45-84 

Figure 23. Kingsford mine. NEV4NE1A sec. 30, T. 30 S., R. 23 E., Polk County. 

+20 mesh 

FRANCOLITE 

QUARTZ 

Wavellite } (tr.) K feldspar 

FRANCOLITE 

QUARTZ 

Dolomite (m) 

K feldspar (tr.) 

FRANCOLITE 

Quartz. } (m) Dolomite 

K feldspar (tr.) 

Bulk Sample 

9.337 

9.332 

9.334 

Mineralogy 

(Screen size) 

-20 +200 mesh -200 mesh 

QUARTZ SMECTITE 

Francolite } (tr.) QUARTZ 

K feldspar FRANCOLITE 

SMECTITE 

QUARTZ DOLOMITE 

K feldspar (m) Francolite } (m) Francolite (tr.) Quartz 

Palygorskite (tr.) 

DOLOMITE 

QUARTZ Quartt } Francolite 

K feldspar (m) K felds,Par (tr.) Francolite (tr.) Smectite 

Palygorskite 

Kaolinite 

FRANCOLITE A-VALUES 

(±0.003 ANGSTROMS) 

+20 mesh -20 +200 mesh 

9.335 N.A. 

9.329 9.328 

9.330 9.335 

SCREEN DATA (IN PERCENT) 

-21J.m 

SMECTITE 

Illite } Quartz 

Francolite (tr.) 

K feldspar 

Crandallite 

SMECTITE 

(m) 

g~~o~ite Francolite I 

Albite 

K feldsp~r (tr.) Crandalhte 

Illite 

Palygorskite 

Sepiolite 

SMECTITE 

Albite (m) 

Quartt } Francolite 

Dolomite (tr.) K feldspar 

Palygorskite 

Illite 

-200 mesh 

9.360 

9.324 

9.329 

0 ~ 100 

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SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS 

Periodicals 

Earthquakes & Volcanoes (issued bimonthly). 

Preliminary Determination of Epicenters (issued monthly). 

Technical Books and Reports 

Professional Papers are mainly comprehensive scientific reports of 

wide and lasting interest and importance to professional scientists and engineers. Included are reports on the results of resource studies and of 

topographic, hydrologic, and geologic investigations. They also include 

collections of related papers addressing different aspects of a single scientific topic. 

Bulletins contain significant data and interpretations that are of lasting scientific interest but are generall:y more limited in scope or 

geographic coverage than Professional Papers. They include the results 

of resource studies and of geologic and topographic investigations; as well 

as collections of short papers related to a specific topic. 

Water-Supply Papers are comprehensive reports that present significant interpretive results of hydrologic investigations of wide interest 

to professional geologists, hydrologists, and engineers. The series covers 

investigations in all phases of hydrology, including hydrogeology, 

availability of water, quality of water, and use of water. 

Circulars present administrative information or important scientific 

information of wide popular interest in a format designed for distribution 

at no cost to the public. Information is usually of short-term interest. 

Water-Resources Investigations Reports are papers of an interpretive nature made available to the public outside the formal USGS publications series. Copies are reproduced on request unlike formal USGS 

publications, and they are also available for public inspection at 

depositories indicated in USGS catalogs. 

Open-File Reports include unpublished manuscript reports, maps, 

and other material that are made available for public consultation at 

depositories. They are a nonpermanent form of publication that may be 

cited in other publications as sources of information. 

Maps 

Geologic Quadrangle Maps are multicolor geologic maps on 

topographic bases in 7 1n.- or 15-minute quadrangle formats (scales mainly 1 :24,000 or 1 :62,500) showing bedrock, surficial, or engineering geology. Maps generally include brief texts; some maps include structure 

and columnar sections only. 

Geophysical Investigations Maps are on topographic or planimetric 

bases at various scales; they show results of surveys using geophysical 

techniques, such as gravity, magnetic, seismic, or radioactivity, which 

reflect subsurface structures that are of economic or geologic significance. 

Many maps include correlations with the geology. 

Miscellaneous Investigations Series Maps are on planimetric or 

topographic bases of regular and irregular areas at various scales; they 

present a wide variety of format and subject matter. The series also includes 7 1/2-minute quadrangle photogeologic maps on planimetric bases 

which show geology as interpreted from aerial photographs. Series also 

includes maps of Mars and the Moon. 

Coal Investigations Maps are geologic maps on topographic or 

planimetric bases at various scales showing bedrock or surficial geology, stratigraphy, and structural relations in certain coal-resource areas. 

Oil and Gas Investigations Charts show stratigraphic information 

for certain oil and gas fields and other areas having petroleum potential. 

Miscellaneous Field Studies Maps are multicolor or black-andwhite maps on topographic or planimetric bases on quadrangle or irregular areas at various scales. Pre-1971 maps show bedrock geology 

in relation to specific mining or mineral-deposit problems; post-1971 

maps are primarily black-and-white maps on various subjects such as 

environmental studies or wilderness ntineral investigations. 

Hydrologic Investigations Atlases are multicolored or black-and· 

white maps on topographic or planimetric bases presenting a wide range 

of geohydrologic data of both regular and irregular areas; principal scale 

is 1:24,000 and regional studies are at 1:250,000 scale or smaller. 

Catalogs 

Permanent catalogs, as well as some others, giving comprehensive listings of U.S. Geological Survey publications are available Wlder 

the conditions indicated below from the U.S. Geological Survey, Books 

and Open-File Reports Section, Federal Center, Box 25425, Denver, 

CO 80225. (See latest Price and Availability List) 

"Publications of the Geological Survey, 1879-1961" may be purchased by mail and over the counter in paperbaek book form and as a 

set of microfiche. 

"Publications of the Geological Survey, 1962-1970" may be purchased by mail and over the counter in paperback book form and as a 

set of microfiche. 

"Publications of the U.S. Geological Survey, 1971-1981" may be 

purchased by mail and over the counter in paperback book form (two 

volumes, publications listing and index) and as a set of microfiche. 

Supplements for 1982,1983, 1984, 1985,1986, and for subsequent 

years since the last permanent catalog may be purchased by mail and 

over the counter in paperback book form. 

State catalogs, "List of U.S. Geological Survey Geologic and 

Water-Supply Reports and Maps For (State)," may be purchased by mail 

and over the counter in paperback booklet form only 

"Price and A vallabillty List of U.S. Geological Survey Publications," issued Bmlually, is available free of charge in paperback booklet form only. 

Selected copies of a monthly catalog "New Publications of the U.S. 

Geological Survey" available free of charge by mail or may be obtained 

over the counter in paperback booklet form only. Those wishing a free 

subscription to the monthly catalog "New Publications of the U.S. 

Geological Survey" should write to the U.S. Geological Survey, 582 

National Center, Reston, VA 22092. 

Note.--Prices of Government publications listed in older catalogs, 

announcements, and publications may be incorrect Therefore, the 

prices charged may differ from the prices in catalogs, announcements, 

and publications.