Distribution of

Uranium in

Rich Phosphate Beds

of the Phosphoria

Formation

GEOLOGICAL SURVEY BULLETIN 988-D

Distribution of

Uranium in

Rich Phosphate Beds

of the Phosphoria

Formation

By M. E. THOMPSON

A CONTRIBUTION TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 988-D

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1953
UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, DC.- Price 15 cents (paper cover)
CONTENTS

Page 

Abstract.. .._______________________________________ 45

Introduction_________________________________ ____________________ 45

Acknowledgments. _-- _____________-___________________--_____ 46

Samples from Trail Canyon, Idaho (WT-365-1 through WT-365-26) _ _ _ _ 47

Samples from Reservoir Mountain, Idaho (WT-910-1 through WT910-31).____.__.._.-______________-_____-___-_-_-____----___ 51

Samples from Coal Canyon, Wyoming (WT-700-1 through WT-700-12). 63 

Samples from Brazer Canyon, Utah (WT-605-1 through WT-605-3, WT604-4 through WT-604-30, and WT-603-1 through WT-603-24)__ _ 56 

Conclusions_____________________________________________________ 61

Determination of organic matter in phosphate rock, by F. S. Grimaldi__ 64 

Index______________________________________________ 67

ILLUSTRATIONS

FIGURE 17. Results of Rosiwal analyses of samples from Trail Canyon,

Idaho______________.___________________ 48

18. Scatter diagrams of Trail Canyon samples WT-365-1

through WT-365-26____________________--.___-_-_____ 49

19. Variation in chemical components of Trail Canyon samples

WT-365-1 through WT-365-26_._____._________._: 50

20. Variation in chemical components of Reservoir Mountain

samples WT-910-1 through WT-910-3!__._______..__ 52

21. Scatter diagrams of Reservoir Mountain samples WT-910-1

through WT-910-31-_--__---_-_-_-___-----------____- 53

22. Variation in chemical components of Coal Canyon samples

WT-700-1 through WT-700-12____.___-__-___.________ 54

23. Scatter diagrams of Coal Canyon samples WT-700-1 through

WT-700-12_________ _________________________________ 55

24. Variation in chemical components of Brazer Canyon samples

WT-605-1, 2, 3, and WT-604-4 through WT-604-30_. 57

25. Scatter diagrams of Brazer Canyon samples WT-605-1, 2, 3,

and WT-604-4 through WT-604-30_ _ _ _ _ . . _ _ _ ------ 58

26. Variation in chemical components of Brazer Canyon samples

WT-603-1 through WT-603-24..______________________ 59

27. Scatter diagrams of Brazer Canyon samples WT-603-1

through WT-603-24___________________-_-___----_--_- 60

28. Comparison of correlation coefficients with average uranium

content _____________________________________________ 63

in
IV CONTENTS

TABLES

Page 

TABLE 1. Location of analyzed samples of phosphate rock__________ 46

2. Rosiwal analyses of Trail Canyon samples WT-365-1 through

WT-365-7 and WT-365-10 through WT-365-26._______ 48

3. Chemical and radiometric analyses of Trail Canyon samples

WT-365-1 through WT-365-26____.__-_________-.______ 50

4. Chemical and radiometric analyses of Reservoir Mountain

samples WT-910-1 through WT-910-31_________ 51

5. Chemical and radiometric analyses of Coal Canyon samples

WT-700-1 throughWT-700-l2________._____---.____ 56

6. Chemical and radiometric analyses of Brazer Canyon samples

WT-605-1, 2, 3, and WT-604-4 through WT-604-30. _ _ _ 56

7. Chemical and radiometric analyses of Brazer Canyon samples

WT-603-1 through WT-603-24.____...________,.______. 61

8. Relation of correlation coefficients to organic matter, phosphate.

and uranium content___________________________ _____ 62
A CONTRIBUTION TO THE GEOLOGY OF URANIUM

DISTRIBUTION OF URANIUM IN RICH PHOSPHATE BEDS 

OF THE PHOSPHORIA FORMATION

By M. E. THOMPSON

ABSTRACT

Five sets of "close" samples were analyzed radiometrically for uranium, and 

chemically for PjOs, CaO, organic matter, and loss on ignition. A Rosiwal 

analysis was made of thin sections of one set of samples. The results of the 

analyses have been plotted on graphs and on scatter diagrams, and coefficients of 

correlation are given for uranium with CaO, PjOs, organic matter, and loss on 

ignition. Preliminary studies indicate that the concentration of uranium in 

these samples of phosphate rock is not due wholly to phosphate content, but 

may depend in part on organic matter or on other components. The correlations of uranium with PjOs are poor in the groups of samples with smaller amounts 

of uranium but are good in the groups of samples containing more uranium.

INTRODUCTION

In the summer of 1949, some special samples, called "close" 

samples, were collected from the Phosphoria formation to measure 

variations, both chemical and mineralogical, across a small, apparently uniform lithologic unit of phosphate rock. A close sample is 

defined as one of a large number of small, contiguous samples taken 

across a single unit, where all the samples together represent the 

entire unit. Such samples were taken from four sections in Idaho, 

Wyoming, and Utah, as summarized in table 1.

Altogether, 123 samples were studied; they were analyzed chemically for CaO, P2O6, and organic matter. The methods of analysis 

for organic matter and loss on ignition are described by F. S. Grimaldi. 

Uranium was determined radiometrically; a few of the radiometric 

determinations were checked by chemical analysis. The differences 

between the results obtained by chemical and radiometric analyses 

are so slight that the terms uranium and equivalent uranium are 

used interchangeably in some parts of this report.

Thin sections of some of the samples were made, and Rosiwal 

analyses were made of 24 thin sections from Trail Canyon, Idaho. 

These mineral counts agreed closely with the chemical analyses for

45
46 A CONTRIBUTION TO THE GEOLOGY OF URANIUM

P2O6 and CaO; consequently, it did not seem necessary to obtain 

other sets of thin sections.

The results of the analyses have been plotted on semilogarithmic 

graphs (figs. 19, 20, 22, 24, and 26) for convenient comparison of the 

various components. Scatter diagrams (figs. 18, 21, 23, 25, and 27) 

show the comparison of equivalent uranium (etJ) in phosphate rock 

samples with other components.

TABLE 1. Location of analyzed samples of phosphate rock

Name of section

Trail Canyon. __ ..

Reservoir Mountain.

Brazer Canyon .......

County and state

Caribou County, Idaho ...

Rich County, Utah.. .....

Field unit 

no.1

RAH-183...

RAH-184... 

DFD-4769..

2061.........

RAH-105

RAH-106... 

RAH-107...

Laboratory nos.

WT-365-1 through WT-365-

26 

WT-910-1 through WT-910- 

31. 

WT-700-1 through WT-700-

12. 

WT-605-1 through WT-605-3

WT-604-3 through WT-604- 

30. 

WT-603-1 through WT-603- 

24.

Thickness 

(feet)

0.8

1.0 

.5

.1

1.0 

1.2

1 Abstracts of stratigraphic sections of the Phosphoria formation measured and sampled fh Montana, 

Idaho, Wyoming, and Utah: U. S. Qeol. Survey, field manual, 1947.

To express numerically the order of correlation of U with other 

components, as shown by these diagrams, correlation coefficients 

have been calculated. The formula used is that given by Snedecor. 1

where Xi is equivalent uranium and % is either P2O5, CaO, loss on 

ignition, or organic matter.

In general, this investigation has shown that the amount of uranium 

deposited is dependent not only upon apatite, but also upon one or 

more other factors. It is thought that the nature and amount of 

organic matter present may have had a considerable effect upon the 

concentration of the uranium. Further variation in the uranium 

content of the rock may have been due to variations in the amount 

of uranium available for deposition.

ACKNOWLEDGMENTS

The chemical analyses were made by the following chemists of the 

U. S. Geological Survey: Harry Levine, Jesse Greene, Henry Mela, 

Alice Caemmerer, and Marie Eiland. The author is especially grateful 

to Harry Levine, who made most of the determinations for CaO, P2O6,

> Snedecor, Q. W., 1946, Statistical methods applied to experiments in agriculture and biology, Iowa State 

College Press, p. 138.
DISTRIBUTION OF URANIUM IN PHOSPHORIA FORMATION 47

and loss on ignition; to Jesse Greene, who made most of the organic 

determinations; and to F. S. Grimaldi, who developed the method of 

analysis for organic matter used on these samples.

SAMPLES FROM TRAIL CANYON, IDAHO

[WT-366-1 through WT-385-26]

At Trail Canyon, Idaho, 26 close samples were collected over a 

stratigraphic thickness of 0.8 ft from the lower phosphate zone of the 

phosphatic shale member of the Phosphoria formation. The samples, 

numbered WT-365-1 through WT-365-26 from base to top, are from 

field unit no. RAH-184-47. Where possible, the stratigraphic top 

was marked on each sample, and the thickness of the sample and its 

height above the base of the unit were measured.

Thin sections of 24 samples were obtained for microscope study and 

for use with alpha plates. In the Rosiwal analysis of these thin sections 

four types of lithologic material were counted. The first, and generally 

the major part of each section, is referred to as pellet phosphate. It is 

gray brown, isotropic, and has an index of refraction of about 1.61. 

It occurs as grains which generally are rounded and is nonhomogenous 

in appearance owing to inclusions of small black round particles of 

organic matter.

The second material counted is called "cement" phosphate. Its 

index of refraction is about 1.61; it is iso tropic and in contrast to the 

pellet phosphate is brown, is homogenous in appearance, and lacks 

visible organic particles. It occurs both interstitially and as grains. 

Despite the occurrence of cement phosphate as grains and the fact 

that some of it makes up parts of grains, most of it is interstitial or 

lacks definite outline, and for these reasons, is called cement phosphate.

The third type of material counted includes all material that is too 

fine-grained to be counted separately. This material consists chiefly 

of fine-grained quartz and muscovite, and some clays, detrital minerals, 

and phosphate.

Grains of quartz that were large enough to count separately were 

counted as the fourth group. Calcite was observed in only one section 

and was counted separately. The results of the Rosiwal analyses are 

presented graphically (fig. 17) and in tabular form (table 2).

The Rosiwal analyses of the thin sections agree with the chemically 

determined P2O5, although, not all thin sections are entirely representative of the samples analyzed. The breakdown into mineral percentages does not reveal any relationships between the various 

minerals and the distribution of the uranium.
48 A CONTRIBUTION TO THE GEOLOGY OF URANIUM

TABLE 2. Rosiwal analyses of Trail Canyon samples WT-S65-1 through WT-S65-7 

and WT-S65-10 through WT-S65-26 (percent)

Sample no.

26_-.........._....__...._...._..._.___._._..___........._.

25.-..-.......- __..._.... ._.._ _..___._......__..__.

24

23-.._...._.._.._..__.._.........._.._..._.._____.__.._...

22 __________________ .. . _ ___ . . . .....

21... _________ . _______________ ..........

20 _____ .... ___ . _____________________

19. __________ . _____________ . .............

18..................................... __ ..............

17«-........--...._._._.._.__._.___.____._..._.____._.____

16-.........-........_.._..._._..__...__......._......____

15 __________ . ____ . _ ... _ __ .........

14 __________ . _______________ ..........

13............................................ . .........

12........................................................

11- ...................................................

10. ____ ................................................

7.........................................................

6. __ - .............................. ... ..

6 __________ . __________ . _ . _ .. ... ___ ..

4........... __ ........................................

3.........................................................

2.........................................................

1 __________________ ..... _____ . .......

Pellet 

phosphate

75

60

52

67

59

64

67

65

61

42

49

48

54

45

52

36

30

41

36

24

70

72

69

64

"Cement" 

phosphate

17

26

35

34

26

22

23

20

21

10

12

12

14

23

22

26

16

17

21

17

16

16

20

23

Finegrained 

phosphate 

and silt

6

11

10

8

10

11

8

11

14

23

29

28

25

25

19

32

48

36

38

52

12

9

8

10

Quartz

2

3

3

1

6

3

2

4

4

9

10

12

7

7

7

6

6

6

5

7

2

3

3

3

1 Sample 17 contains 16 percent calcite. 

100

EXPLANATION

Pellet 

n

phosphate

EZ3

"Cement" phosphate

Matrix material

Quartz

x 2.6

SAMPLE NUMBERS 

FIGUBE 17. Results of Rosiwal analyses of samples from Trail Canyon, Idaho.

The scatter diagrams and the correlation coefficients (figs. 18 and 

19), compiled from data in table 3, show a much better correlation 

between the organic matter and uranium than between the P206 and 

uranium.

These Trail Canyon samples are the only group of analyzed samples 

that shows a positive correlation of organic matter with uranium.
ORGANIC x 

P2 0« 

IN PERCENT PERCENT 

II

o 

o 

rn 

TI

Tl omzH

O O

3) 

7) m

i

-gm

3§

H 0

C

p O

ro o

5 8 8 g

0

0

II

 *p

0>

o O 0

o X o o

oo o

0

o

o

00

o

o

o

o

-Qmn

H 0

c0

O

b 

ro o

JO CO 

oo

o°0

u

P 

01

ro

o o o

o

o

o

o o

o

o

0 
50 A CONTRIBUTION TO THE GEOLOGY OF UEANIUM

50

40

30

20 

4JO

ao

2J5

2.0

0-01

0.005

eU

5 10 15 20 25

SAMPLE NUMBERS 

FIGTTRX 19. Variation In chemical components of Trail Canyon samples WT-365-1 through WT-366-26.

TABLE 3. Chemical and radiometric analyses of Trail Canyon samples WT-865-1 

through WT-S65-26 (percent)

Sample no.

26... ___ . __ .............._..._.._.....

25.... __ . __ .............. __ .........

24.... __ ... __ ......... ____ ........

23 ..

22.. __ ..... __ ........................

21.........................................

20......... ____ . _____ ...............

19 ................... __ .. __ ... .....

18.........................................

17.......... __ ...........................

16........... ___ ...................... .

15.........................................

14.... ____ ..............................

13.............. __ .......................

12.........................................

11.........................................

10.........................................

9..........................................

8..........................................

7 ____________ . ___ ...... .......

6..........................................

5.......... ................................

4 _____ . ________ . ...............

3 ...

2..........................................

1 __ ....

eU

0.018

.017

.014

.017

.009

.011

.006

.005

004

.006

.005

.005

.005

.005

.005

.007

.007

.009

U

0.007

.012

.009

.010

.006

CfA

.006

.006

CaO

47.5

43 7

48.4

46.0

46.8

46.9

47.7

46.8

44.3

41.6

42.8

38.8

40.5

38.3

39.4

37.5

33.9

38.4

41.6

39_7

31.6

28.7

47.8

48.3

46.0

44.3

PiOs

33.9

29.8

32.6

32.4

32 9

32.8

32.2

33.5

31.1

27.5

29.1

27.3

28.8

27.2

29.3

27.0

24.1

27.7

29 3

26.2

20.8

19.9

33.0

35 1

32.9

30.7

Loss on 

ignition

1.82

2.22

2.46

2.68

2.40

2.62

2.10

1.82

1.75

1.84

1.78

1.58

1.80

1.96

2.02

2.42

3.20

3.38

2.92

3.34

3.72

3.90

1.84

1.76

1.78

1.70

Organic

2.6

2.7

2.9

3.3

2.6

2.7

2.1

2.2

1.9

L9

1.9

1.7

2.1

2.1

2.2

2 4

2.8

3.1

2.7

2.9

3.8

4.2

1.9

2.4

2.1

2.0

The product of the percent P205 and the percent organic matter 

shows a better correlation with uranium than either of the two 

separately. The correlation coefficient was calculated for the product
DISTRIBUTION OF URANIUM IN PHOSPHORIA FORMATION 51

instead of the sum of the P2O6 and the organic matter against uranium, 

for the following reason. To use the sum of the two components in 

this correlation would not be practical because the P2O6 is present in 

the range of 20 to 35 percent, and the organic matter is present in the 

range of 2 to 4 percent. Therefore the product of the two components is a better representation of their combined effect with 

respect to the uranium. When these two components of different 

magnitudes are multiplied, each is given its share of weight in the 

final figure.

The results suggest that the amount of uranium in this unit of 

phosphate rock is dependent chiefly upon organic matter and subordinately upon

SAMPLES FROM RESERVOIR MOUNTAIN, IDAHO

IWT-910-1 through WT-910-31]

Thirty-one close samples were collected over a stratigraphic thickness of one foot from the lower phosphate zone of the phosphatic 

shale member of the Phosphoria formation at Reservoir Mountain, 

Idaho. The samples, numbered WT-910-1 through WT-910-31 

from base to top, from field unit no. DFD-4769, were each of the 

same approximate thickness, and individual thicknesses were not 

measured.

The correlation coefficients and scatter diagrams for this set of 

samples (figs. 20 and 21), made up from data in table 4, show a very

TABLE 4. Chemical and radio-metric analyses of Reservoir Mountain samples, 

WT-910-1 through WT-910-S1 (percent)

Sample no.

31 . .. ... .. 30 _______ _ __ __ .

29

28

27.. .......... . .. ...

26..................... ..................

25.........................................

24

23.................. _ ..-...........-.. -

22.........................................

21.....-.................... ............

20 ...... .............................

19 .................. ........ ............

18 ___ . ____________ ...... ___ .

17.................... ..................

16...... ...................................

16....... ...............................

14........................ .............

18..... ............. ....................

12................................ ......

11...... ....... ...................... ......

10.... ________ ... __ ....... _ ....

Q

8. __ . _ ..... .. _ ..... . .. ...

7 ___

6 __ ......................................

5

4....................... ...................

8...... ..... . _... ...........

2.

1 _____ __ . __ __ .. .

U

0.008

.023

.033

.013

eU

0.007

.008

.008

.007

(VUt

.011

.011

nns

.009

.010

.022

.019

.017

.017

.015

.012

.016

.021

.023

.025

.030

.030

.026

.023

.022

ftIS

.013

.013

.013

.019

.022

CaO

48.22

50.59

48.83

49.98

48 7A

48.83

48.53

50.13

49.67

46.39

47.76

47.84

48.53

49.52

50.13

49.29

47.92

49.67

47.31

47.00

49.98

48; 68

48.45

51.12

46.85

48.76

47.46

48.07

48.22

48.68

48.15

PiOs

33.60

35.48

34.32

35.46

34.62

34.79

34.32

35.61

35.49

32.81

33.38

33.57

34.09

35.30

35.22

34.42

33.32

34.41

32.81

33.29

35.80

34.72

34.47

34.71

32.58

33.78

33.23

33.06

31.14

81.89

32.05

Loss on 

ignition

2.1

1.8

1.7

1.6

1.5

1.1

1.2

1.3

1.2

1.2

1.1

1.1

1.2

1.2

1.2

1.1

1.1

1.0

1.0

1.1

1.3

1.0

1.2

1.0

1.4

1.2

1.4

1.4

1.4

1.2

1.0

Organic

2.3

1.5

1.6

1.4

1.4

.9

1.0

1.3

1.2

1.3

.9

1.1

1.2

1.2

1.1

1.3

1.0

1.1

1.2

1.0

.7

.8

.9

1.1

1.3

.7

.7

1.3

1.1

.7

1.1
52 A CONTRIBUTION TO THE GEOLOGY OF URANIUM

uj O 

o: in CL

50

40

30

CaO

J * , _J L_T~I , *-i_r- -u.._|

_ ^j _ .--_*- n __.- - -- - _ j"""'1 «»---

P2°5

UJ

o 

cc

UJ

a.

2.0

1.0

0.5

bf^r

Organic

UJ

o 

a:

UJ

a.

2.0

1.0 

0.6 Loss on ignition

0.005

25 30

SAMPLE NUMBERS

FIGURE 20. Variation in chemical components of Reservoir Mountain samples WT-910-1 

through WT-910-31.

poor correlation, if any, between the uranium and CaO or P2OS . The 

CaO and P2O5 content is high and remains almost constant. The 

uranium content, on the other hand, varies considerably and seems 

to be independent of the P2OS . Samples 5 through 11 show a stepped
DISTRIBUTION OF URANIUM IN PHOSPHORIA FORMATION 53

increase in equivalent uranium content from 0.013 percent to 0.030 

percent; then there is a similar decrease to 0.012 percent equivalent 

uranium (sample 16), as illustrated in figure 20. Variations of this 

nature (cyclic?) have been noted in other sets of samples, and may 

reflect a seasonal control of deposition.

z

Ul

o

cc 3

Ul °

0.

z

^^*r 2

Z

O

1 I

CO

CO

0

o

o 

o

<8

to o oooo

OO o O

0

o

0 0

r= 0.59

5

'

3

o

z

<t

o

H

Ul

o 

o:

Ul 1 

QL *

o

o

00

o

o ' °° 00 

O o O

8 o

o oo

o 

o 

ooo

0 0

r=0.58

(X01 0.02 0.03 

PERCENT eU

0.01 0.02 0.03 

PERCENT eU

60

o

0

o

z-50

Ul

o 

<r

UJ

tL

40

o

oo

o

*b° " 6"oo

Oo ° O 

0 °

o

a

00 °

oo o

r=-0.l7

o

ID 

O

bO

)

i 

40

30

o

°ss o o o 

oo o o< 

o oo o

o

r=-0.!7

o ° o 

ogo o

0.01 0.02 0.03 

PERCENT eU

0.01 0.02 0.03 

PERCENT eU

r=COEFFICIENT OF CORRELATION 

FIGURE 21. Scatter diagrams of Reservoir Mountain samples WT-910-1 through WT-910-31.

SAMPLES FROM COAL CANYON, WYOMING

[WT-700-1 through WT-700-12]

At Coal Canyon, Wyo., 12 close samples were collected over a 

stratigraphic thickness of half a foot from the upper phosphate zone 

of the phosphatic shale member of the Phosphoria formation. The 

samples were numbered WT-700-1 through WT-700-12, from the 

base to the top of field unit no. 2061. The samples were approxi-
54 A CONTRIBUTION TO THE GEOLOGY OF URANIUM

UJ

o

UJ 

0.

UJ

40

30

20

10

CaO 1 - ' * > ____

1 1

t P

JtO

10

8 

6

4

 I

1 ' Organic

i I

Loss on ignition L__

1 « __ ^ -

0.06

0.05

0.04

0.03

j 0.02 

j

0.01

0.005

369 12

SAMPLE NUMBERS 

FIQTTRX 22. Variation in chemical components of Coal Canyon samples WT-700-1 through WT-700-12.
DISTRIBUTION OF URANIUM IN PHOSPHORIA FORMATION 55

mately the same thickness, and individual thicknesses were not 

measured.

The scatter diagrams and correlation coefficients for this set of 

samples (figs. 22 and 23), based on data in table 5, show a very high 

positive correlation between uranium content and CaO or P2OS 

Both the calcium phosphate content and the uranium content have a 

wide variation. It is probably this wide variation that makes 

obvious the definite correlation between uranium and calcium phosphate. At the same time, however, there is a negative correlation 

between the organic matter and uranium.

£fc« §*< 7 UJ

o °-

w z 4 </>

3 

<

40 

30

0 

o 

O

§20 

£

UJ 

Q.

10

5

o

o

o

r=-0.82

00 o°o

3.01 0.03 0. 

PERCENT eU

30

o

o

o

o 

o 

o °

r= 0.92

05

0

11

°10

o

(E Q

PERCENT 0

00O> vj

30

0

* *>

H 

Ul

O

or.

Ul

o 

o

0

D 

3

O O

o

o

r=-0.73

0

° 0 

0 0

-

o

.01 0.03 0.05 

PERCENT eU

o

o

o

0 0 

O 0 

0

r=0.92

o

0.01 0.03 0.05 0.01 0.03 0.05 

PERCENT eU PERCENT eU

r = COEFFICIENT OF CORRELATION 

FIOUBI 23. Scatter diagrams of Coal Canyon samples WT-700-1 through WT-700-12.
56 A CONTRIBUTION TO THE GEOLOGY OF URANIUM

TABLE 5. Chemical and radiometric analyses of Coal Canyon samples WT-700-1 

through WT-700-12 (percent)

Sample no.

12..._......--...-.................__......

11. ___ .. __ .... ________ .. .......

10 .................. -.-....-.. . ....

9 _________________________

g ____ . _ .

7 ____ ..... _________ . ____ ...

6 _ __ . . ________ . __ .

6-.._.._..._-.... - ....... 

4... ____ ... __ . ____ .... _ ........

3-........... .......... .................

2 ________ _____ _ _ __ ..

I............ ...........................

U

0.037

.060

.014

.004

eU

0.039

.044

.045

.040

.048

.065

.021

.022

.025

.006

.006

.011

CaO

44.51

45.76

47.75

46.72

46.05

43.77

11.48

13.96

23.97

2.06

1.98

6.62

PjOs

31.45

32.71

34.35

33.55

33.15

31.37

7.64

9.50

16.21

.83

.73

3.71

Loss on 

ignition

3.4

3.3

3.4

3.6

3.6

4.2

6.2

5.6

6.0

5.7

5.8

5.8

Organic

6.1

6.2

6.6

6.7

6.5

6.3

10.1

8.7

12.6

9.3

9.9

12.1

SAMPLES FROM BRAZER CANYON, UTAH

lWT-605-l through WT-605-3, WT-604-4 through WT-604-30, and WT-603-1 through WT-603-24]

Thirty close samples were collected across a stratigraphic thickness 

of 1 ft in the upper phosphate zone of the phosphatic shale member 

of the Phosphoria formation at Brazer Canyon, Utah. The samples 

were numbered WT-605-1, 2, 3, and WT-604-^ through WT-604-30 

from the upper 1 inch of field unit no. RAH-105 to the top of 

field unit no. RAH-106. The samples represent layers of the same 

approximate thicknesses, although the individual thicknesses were 

not measured.

The correlation coefficients and scatter diagrams (figs. 24 and 25), 

compiled from data in table 6, for these samples show very poor 

correlations of uranium with CaO, P2O5, and organic matter.

TABLE 6. Chemical and radiometric analyses of Brazer Canyon samples WT-605 1, 

2, S, and WT-604-4 through WT-604-30 (percent)

Sample no.

WT-604-30

29 _________________ ^.

28. _. ....._.-......_........

27...............................

26 ________ . __ .. .........

25 __ . ...

24 ___________ . ............

23 _ ............................

22... _______ . ___ . ........

21...............................

20 _ ............................

19 _________ . _______ ...

18 ____ . ___________ . ...

17 ________ . _______ . ....

16...............................

15 ___ . _________ .... __ ..

14 _ ............................

13 _ ............................

12 _ ............................

11..... .......................

10 _ ............................

9 ____ . __ _ .. _ ...

8 ___ .... __ .. _ . ......

7 _________ ....... .....

6 __ ........................

5

4...............................

WT-605-3 _ ............................

2 _ .................... . ...

1 ___ .... _ ............. _ ...

U

0.033

.010

eU

0.014

.014

.011

.oy

.010

.010

.014

.015

.017

.029

.014

.015

.013

.011

.012

.010

.023

.015

.011

.012

.010

.010

.008

.010

.010

.009

.010

.009

.010

.014

CaO

16.43

38 53

18.65

23.31

42.04

46.25

47.01

44.95

46.02

47.62

43.72

43 VT

44.48

45.63

23.50

91 QSt

38.15

35.02

31.44

33.95

34.11

<M R7

41.13

40.90

41.66

42.35

41.58

40.74

39.68

46. Q9

PaO.

10.85

23.36

12.30

14.90

29.51

32.77

33.58

32.09

32.76

33.70

31.21

30.78

31.31

32.91

15.59

14 96

26.73

24.37

21.89

23.86

23.05

23.37

29.04

28.50

29.50

9O 01

23.88

28.47

27.57

32.15

Loss on 

ignition

6.0

5.0

5.5

5.3

3.2

3.0

3.0

3.2

3.4

3.0

2.5

3.6

2.9

3.1

6.2

6.2

5.3

5.1

5.1

5.2

5.2

5.5

5.7

5.8

6.6

5.5

5.4

5.4

4.8

4.9

Organic

9.6

7.3

8.9

8.7

4.6

4.1

4.3

4.6

5.3

4.7

3.8

4.7

3.8

3.9

7.5

7 8

7.1

6.4

6.8

6.8

6.3

6.8

7.7

7.7

6.6

6.6

6.6

6.7

6.3

5.4
DISTRIBUTION OF URANIUM IN PHOSPHORIA FORMATION 57

IUl

o

£

Q.

50

40

30

20

10

8

6

4

<--

u

Organic

.. .J L.

_M 

PERCENT

6 

5

4 

3

n

,i *v» i _i r -f~\jr -%-j " r^

Loss on ignition pf r~* t r* ^LJ

0.030

12345 10 15 20 

SAMPLE NUMBERS

FIQUKE 21. Variation in chemical components of Brazer Canyon samples WT-605-1, 2, 3, and WT-604-4

through WT-#H-30.

From the base to the top of field unit no. RAH-107, 24 close 

samples were collected over a stratigraphic thickness of 1% ft in the 

upper phosphate zone of the phosphatic shale member of the Phosphoria formation at Brazer Canyon, Utah. The samples were numbered WT-603-1 through WT-603-24. The samples were approximately the same thickness, and the individual thicknesses were not
58 A CONTRIBUTION TO THE GEOLOGY OF URANIUM

IGNITION, LOSS ON 

PERCENT IN <fc Ck)O»l 

0

o' o 

> o

' o

 ; 

f> 8

>° 0°

o

o

r =

o

-0.37

0.010 0.020 

PERCENT eU

ORGANIC PERCENT 

<T> <*4«O00 & <J1 

0 <

?

< 

§ 

c

«

o

o 

o

o 

o

00

0 '

0

o

0°

o

r = -0.2-

o

*

40

30

£

20

= + 0.22

0.010 0.020 

PERCENT eU

30 

05s1

§20

K 

Ul 

0.

 <

e

e

0

t

O 1

'o e

e

e 

o

0

r =

0

+ 0.2! >

0.010 0.020 

PERCENT eU

0.010 0.020 

PERCENT eU

r = COEFFICIENT OF CORRELATION

FIGURE 25. Scatter diagrams of Brazer Canyon samples WT-605-1, 2, 3, and WT-W4-4 

through WT-604-30.

measured. These samples were taken stratigraphically immediately 

above the 30 samples in WT-604 and 605.

The scatter diagrams and the correlation coefficients (figs. 26 and 

27, from table 7) show a very good correlation between uranium content and CaO or P2O5 . The correlation coefficient for CaO with U 

is +0.79 and for P2O5 with U is +0.78 (fig. 27). The negative correlation between uranium and organic matter, although not as strong, 

is nevertheless noticeable. The imrovement in correlation between 

uranium and the other measured constitutents in these samples over 

the first-mentioned set of samples from Brazer Canyon (WT-605-1, 2, 

3, and WT-604-4 through 30) is difficult to explain, but it may be 

due to an increase in the supply of uranium made available for deposition by unmeasured factors.
DISTRIBUTION OF URANIUM IN PHOSPHORIA FORMATION 59

8 

or 

u 

a.

§

gUJ 

Q.

10

Loss on ignition ^i-^-^ij^n.^-

0.040

0.030

0.020

0.010

0.005

5 10 15

SAMPLE NUMBERS 

FIGURE 26. Variation in chemical components of Brazer Canyon samples WT-603-1 through WT-003-24
60 A CONTRIBUTION TO THE GEOLOGY OF URANIUM

PERCENT" N <Osi 

2?

0 

P

Z

o

0) 

CO 0

3 3

o

0 o

Q 

0

o 

o

r=-0.50

0

< 

o

8*

n

o 

o

9

0

z

O 7

O

hz

UJ

0 5 o: 3

UJ

o.

3

o

w

o

o

o

o

o

> 00

o 

88 o °

o r = -0.

o

o

61

0.010 0.020 0.030 

PERCENT ell

0-.010 0.020 0.030 

PERCENT eU

40

O

° 30

$

UJ

p20

10

3

'

O

0

O

O

OO

f

£>

O

o

o

o

40

0*30

^

£UJ

o 

Q£ UJ*20 U

Q.

10 o

'

o

o

o

o

0

0 O o

'<» 0 0

& o

0.010 0.020 0.030 0.010 0.020 0.030 

PERCENT eU PERCENT eU

r=COEFFICIENT OF CORRELATION 

FIGURE 27. Scatter diagrams of Brazer Canyon samples WT-603-1 through WT-603-24.
DISTRIBUTION OF URANIUM IN PHOSPHORIA FORMATION 61

TABLE 7. Chemical and radiometric analyses of Brazer Canyon samples, WT-60S-1 

through WT-60S-24 (percent)

Sample no.

24..........._......__.._.........__..._.__

23. ___ . ___________________

22-.-..-.._............._..... _______ .

21.....__..._......__....._.._...__.._._.._

20.....................__.._ _____ ......

19.................... __ ...... .. ...

18 .................. __ -.. --. -......

17........... __ ................... __ .

16............................. ____ .....

15. _______________________

14. ________________________

13............. __ ............ ____ . __

12.........................................

11. ____ . _________________ ...

10.........................................

9............ __ .........................

8.. __ ..................... ___ .........

7..........................................

6..................... __ . ____ ........

6.. ______________________ ..

4...................................... ..

3... _____ .. _______________ ..

2... ____________________ ....

1... _________ . _________ ....

U

0.023

,038

.005

eU

0.022

022

.022

.022

.022

.021

.021

.029

.026

.021

.020

.031

.025

.029

.036

.026

.016

.009

.011

.011

.015

.015

.012

.007

CaO

45.08

45.48

44.79

44.64

40.67

44.26

45.18

49.98

48.01

46.78

46.71

46.78

47.62

46.48

43.49

28.89

27.21

16.74

15.44

18.73

35.93

39.29

21.87

4.13

P»0«

33.91

31.72

31.33

31.32

31.22

31.01

31.51

33.68

33.62

32.87

33.01

32.75

33.41

32 91

30.49

19.53

18.69

11.38

9.41

12.39

25.16

27.74

14.97

2.98

Loss on 

ignition

2.6

3.1

3.7

3.6

3.1

3.4

3.3

3.2

3.4

3.5

4.0

3.9

4.2

4.6

4.3

7.4

7.1

7.4

7.2

7.0

6.7

*7

4.4

6.4

Organic

3.2

4.1

4.8

4.8

4.2

4.4

4.1

4.2

3.9

4.2

4.8

4.7

5.1

5.6

6.4

8.7

9.0

7.8

8.4

8.6

7.0

7.0

7.2

9.1

CONCLUSIONS

The results of these analyses must be evaluated with caution. 

Some of the correlations may be spurious, not due to any direct 

genetic relationship. In high-grade phosphate rock of the Phosphoria formation there are generally only three major components: 

apatite, organic matter, and quartz silt, which make up nearly 100 

percent of the rock. (Calcite may be a fourth major component.) 

If apatite and organic matter together composed most of the rock, 

and if uranium content were directly proportional to apatite content, 

then the uranium would appear to be related to organic matter by 

inverse proportion. However, the third major component of phosphate rock quartz silt may be considered a diluting agent. If, 

as in these samples, much silt is present, the amount of organic matter 

is not necessarily a function of the amount of apatite. Thus the 

correlations are probably reliable.

As it has been found that the uranium in the Phosphoria formation 

generally occurs in the highest-grade phosphate beds, positive correlations between uranium and apatite are to be expected. Poor 

correlations between uranium and apatite probably mean that unmeasured factors made available only a small amount of uranium 

for deposition.

Correlations between uranium and organic matter are less easily 

explained. A positive correlation between uranium and organic matter may indicate that uranium and organic matter accumulated under 

the same conditions or that one acts as a precipitant for the other. 

It has been suggested by K. B. Krauskopf (personal communication)
62 A CONTRIBUTION TO THE GEOLOGY OF URANIUM

that several of the apparent negative correlations of uranium with 

organic matter may be due to stratigraphic control. The points 

plotted in the scatter diagrams of uranium against organic matter 

show, in general, not a tendency to linearity, but rather a tendency to 

group together in bunches. The samples are divided into bunches 

principally according to their stratigraphic position. This tendency 

to bunch is demonstrated particularly well in the group of samples 

from Coal Canyon, WT-700. In the scatter diagram (fig. 23) where 

loss on ignition is plotted against uranium, the stratigraphically lower 

six samples are bunched in the upper left-hand corner of the diagram, 

and the higher six samples are bunched in the lower right-hand corner. 

The samples from Brazer Canyon, WT-603, (fig. 27) also exhibit this 

tendency. In these two groups of samples, at least, the negative 

correlations of uranium with organic matter may be due in large 

part to stratigraphic control.

The essential information gained from these analyses is presented 

in table 8. General conclusions that may be drawn from inspection 

of the information in this table are as follows:

1. Uranium and P2O6 correlations are better in the groups where 

the average percent equivalent uranium is high (WT-603, WT-700), 

and poorer in the groups where the average percent equivalent uranium 

is lower (WT--365, WT-910, WT-605, 604).

2. The only positive correlation between uranium and organic 

matter is in the group that has the lowest average percent equivalent 

uranium (WT-365).

3. The inverse correlations between uranium and organic matter 

are poor for the groups that have low average percent equivalent 

uranium (WT-604, WT-605) and better for the groups that have 

higher average percent equivalent uranium (WT-603, WT-700, 

WT-910).

TABLE 8. Relation of correlation coefficients to organic matter, phosphate, and

uranium content

Sample no. and 

locality

WT-606, 604. ............

Brazer Canyon 

WT-603... .... .......

Brazer Canyon 

WT-700 . ......_..

Coal Canyon 

WT-365.... .. ...........

Trail Canyon 

WT-910.. ...............

Reservoir Mountain

eU x 10 * (percent)

Range

8-29 

7-36 

6-65 

4-28 

7-30

Average

13 

20 

31 

8 

16

PiOi (percent)

Range

12-34 

3-34 

1-34 

20-35 

31-36

Average

26 

26 

20 

30 

34

Organic (percent)

Range

4-10 

4-9 

6-12 

2-4 

1-2

Average

6 

6 

8 

2.6 

1

Correlation coefficients

U/Pi05

+0.2 

+.8 

+.9 

+.1 

-.2

U/Organic

-0.2 

-.«

-.7 

+.5 

-.6
DISTRIBUTION OF UPANIUM IN PHOSPHORIA FORMATION 63

0.030

3 

s 0.020

o tc.

Ul

0.

0.010 

H.C

o

o

L

A

A

o

 /

_A*=

±=

«_

*~

'Cool Canyon

Brazer Canyon 

(WT-603)

Reservoir Mountain

Brazer Canyon 

(WT-604,605)

Trail Canyon

-0.6 -0.2 0 +0.2 +0.6 +1.0 

CORRELATION COEFFICIENTS

EXPLANATION

o A 

Organic I^Og

FIGURE 28. Comparison of correlation coefficients with average uranium content.

In figure 28, the correlation coefficients for organic matter and P2O6 

with equivalent uranium have been plotted against the average 

amount of uranium in each group of samples.

The coefficients of correlation of P2O5 with uranium, as plotted on 

this graph, tend to form a simple pattern of improving correlation 

with increasing percent uranium. The coefficients of correlation of 

organic matter with uranium form a curve that crosses the zero axis 

at about 0.010 percent equivalent uranium. According to this graph, 

a group of such samples averaging 0.010 percent equivalent uranium 

would show no correlation of uranium with organic matter, and little 

or no correlation of uranium with P2O5.

Work of this nature yields only tentative conclusions. Other 

approaches will be necessary to solve the problem of the part that 

organic matter may have played in the precipitation of uranium. 

Attempts will be made to correlate uranium content with time by 

assuming that the size of the phosphate pellets reflects the length of 

time of their formation. The validity of this assumption is, of 

course, open to question.

The samples that have been discussed in this report, are now being 

analyzed for F and CO2. The results of these investigations will be 

reported later.
64 A CONTRIBUTION TO THE GEOLOGY OF URANIUM

METHODS FOR DETERMINATION OP ORGANIC MATTER 

IN PHOSPHATE ROCK

BY F. S. GBIMALDI 

METHOD I

1. Weigh 0.5 g of sample into a Monroe crucible. Add 15 ml of 

(1+2) HC1 and place the crucible (upright) in a platinum dish containing enough (1+2) HC1 (1 part H2O+2 parts cone HC1) to cover 

one-third of the crucible.

2. Place the dish on a steam bath for about 15 min.

3. Remove the crucible and drain it on a suction filter. Wash 

with 1 percent HC1.

4. Remove the crucible from the filter apparatus. Add 5 ml HF 

and 5 ml of (1+2) HC1 to the crucible.

5. Place the crucible in a platinum dish on the steam bath for 1 hr. 

Filter and wash with 1 percent HC1.

6. Fill the crucible with (1+2) HC1 and again place it upright in 

a platinum dish containing some (1+2) HC1. Heat on the steam 

bath long enough (30 min to 1 hr) to decompose any insoluble 

fluorides. Add more HC1 if necessary.

7. Filter and wash with 1 percent HC1.

8. Dry at 110 C and weigh.

9. Ignite and weigh again.

The percent organic matter equals the loss in weight from steps 

8 to 9 multiplied by 100 and divided by the weight of the sample.

Notes on method I. Steps 1 to 3 are designed to remove acidsoluble constituents such as calcite and apatite.

Steps 4 and 5 are used to decompose silicates, to remove silica, 

and to dissolve such oxides as those of Fe and Al.

Step 6 is necessary to dissolve any fluorite or other fluorides formed 

in steps 4 and 5.

Appraisal oj method I. Errors that produce too low a result are 

due to the attack and dissolution, by the chemical reagents, of organic matter. Errors that produce too high a result are due to 

certain sulfides and silicates that remain undissolved and are counted 

as organic matter.

METHOD II

1. The sample is heated to constant weight at 230 C and again 

to constant weight at 450 C. The percent organic matter is taken 

as the difference in weights at the two temperatures divided by the 

weight of the sample and multiplied by 100.
DISTRIBUTION OF URANIUM IN PHOSPHORIA FORMATION 65

Notes on method II. The heating at 230 C is designed to remove 

loosely held water. A temperature this high is necessary because 

of the clay minerals that may be present.

The heating at 450 C is designed to burn off the organic matter 

and yet not decompose carbonates or distill off combined (fixed) 

water.

Appraisal of method II. Errors that give too high a result are 

due to the fact that all loosely held water is not driven off at 

230 C but is lost at 450 C and is therefore counted as organic 

matter. Another reason for too high a result is that some fixed water 

is lost at 450 C and is counted as organic matter.

Too low an answer may result if all the organic matter is not burned 

off at 450 C.

INDEX

Page 

Acknowledgments ..... _. 46

Apatite.................... ..............46,61,64

Analyses, chemical.. . ..... ... 45,50,56,61

radiometric......................... 45,50,56,61

Rosiwal....-. .-.-.- _-.....-. . 45-48

Brazer Canyon, Utah...__,___ 46,56-57,61-62

Calcite.. . . -- -- 47,61,64 

"Cement" phosphate...._.________ 47

"Close" samples, definition..........._..... 45

area from vhich collected..... 45,47,51,53,56-57

Coal Canyon, Vyo..................... 46,53,56,62

Coefficient of correlation, equation for.... __ 46

Conclusions..__.___.__............ 61-63

Correlation of uranium with, apatite.... __ 46

CaO .................... ...... 52,55-56,58

Loss on ignition..._____...._.... 47

PiOi... .. ... 48,50,52,55-56,58,62-63 

oiganic matter. 46,48,50-51,55-56,58,61,63-65 

other measured constituents...-..-.--.-.- 58 

time...................................... 63

Decomposition, fluorides...._____.._. 64-65 

oxides..-.---..--.----...---..--.----.... 64-65 

silicates . . ..- .. - 64-65

Deposition of uranium, seasonal control...... 46,53

Page

Factors influencing concentration of uranium. 48,58

Index of refraction, cement phosphate... .. 47 

pellet phosphate..... ...----.-. 47

Location from which samples were taken.. 45-46,56 

Loss on ignition..___.._.....__.... 45-47,56

Methods of analysis, appraisal............. 45,64-65

phosphate rock......... ......---... 61,64-65

Muscovite________........... ... 47

Phosphatic shale member, lower phosphate

member.____.....__.... 46-47,51

Quartz..--.--. ...-_.--.--.-.,_ ..... 47

Reservoir Mountain, Idaho________ 46,51,62

Silica. 64

Trail Canyon, Idaho..___..---.-...-.. 45-48,62

Uranium, equivalent.____._.__ 46-49,53,62 

use of term..._...... 45

Water, fixed.................................. 65

loosely held.... . . .. 65

67

 fr U. S. GOVERNMENT PRINTING OFFICE: 1954 O 322131