Studies of Celadonite 

and Glauconite

GEOLOGICAL SURVEY PROFESSIONAL PAPER 614-F

Studies of Celadonite 

and Glauconite

By MARGARET D. FOSTER

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 614-F

A study of the compositional 

relations between celadonites 

and glauconites and an interpretation 

of the composition of glauconites

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HIGKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

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

Washington, D.C. 20402 - Price 40 cents (paper cover)
CONTENTS

Abstract.-_ ____-____-_--__-_-___--______-__-_______

Introduction.______________________________________

Selection of analyses and calculation of atomic ratios___

Relation between the composition of celadonites and

glauconites_ _ ___________________________________

High potassium celadonites and glauconites-_______

Low potassium celadonites and glauconites_________

Relation between Si, R+2 (VI), Al(VI), and R+3 (VI)_

Fl

1

2

3

7

Page 

Interpretation of glauconite coniposition___-___________ F13

Relation between trivalent iron and octahedral

aluminurn____________________________________ 13

The Fe+3 :Fe+2 ratio_______________________ 13

Relation between iron and potassium____________ 14

Fixation of potassium___________________________ 14

Deficiency in potassium content-_________________ 14

Relation between glauconite composition and geologic age_____________________________________ 15

References cited.___________________________________ 17

ILLUSTRATIONS

FIGURE 1. Chemical composition of representative celadonites and glauconites having more than 0.65

atom of potassium per half cell___________________________________________________ F8

2. Relation between Si+R+2 (VI) decrease and A1(IV) + R+3 (VI) increase in high potassiumhigh charge celadonites and glauconites_____________-_____-___-__-»__-____-__---___ 10

3. Relation between decrease in Si and decrease in R+2 (VI) in high potassium-high charge

celadonites and glauconites_____________________________________________________ 10

4. Relation between increase in Al(IV) and increase in R+3 (VI) in high potassium-high charge

celadonites and glauconites__..____________________________________________________ 10

5. Relation between excess of R+2 (VI) decrease over Si decrease and layer-charge deficiency-- 13

6. Relation between Fe+3 and Al(VI) in glauconites____________________________________ 13

7. Relation between total iron and potassium in glauconites__________________ __________ 14

8. Extreme and average compositions of Cretaceous and Tertiary glauconites-______________ 16

TABLES

Page 

TABLE 1. Chemical analyses of celadonites, together with their calculated atomic ratios _________ F4

2. Chemical analyses of glauconites having more than 0.65 potassium atom per half cell,

together with their calculated atomic ratios___-__-_____-__--_----~-_-----_--__-_--_ 5

3. Chemical analyses of glauconites having less than 0.66 potassium atom per half cell, together with their calculated atomic ratios_________________-__----_-_-_-__-___-__-_- 6

4. Range and median values of principal constituents in high potassium celadonites and

glauconites___________________________________________________________________ 6

5. Range and median values of principal constituents in low potassium celadonites and glauconites^ ______________________________________________________________________ 7

6. Al(IV)R+3 (VI) replacement of SiR+2 (VI) in high potassium-high charge celadonites and

glauconites-____________________________________________________________________ 11

7. A1(IV)R+3 (VI) replacement of SiR+2 (VI) in high potassium-low charge glauconites-______ 12

8. A1(IV)R+3 (VI) replacement of SiR+2 (VI) in low potassium celadonites and glauconites__ __ 12

m

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

STUDIES OF CELADONITE AND GLAUCONITE

By MARGARET D. FOSTER

ABSTRACT

A study based on 10 analyses of celadonites and 19 analyses 

of glauconites having high contents of potassium (more than 

0.65 ion per half cell) shows that both range widely in content 

of trivalent iron and octahedral aluminum, which seem to bear 

a reciprocal relation to each other. The relations among Si, 

R+3 (VI), Al(IV), and R+3 (VI) indicate that these micas belong 

to an isomorphous replacement series that starts with the generalized theoretical tetrasilicic dioctahedral end-member,

[(RJ5 Ra)Siw010 (OH) a].Ki.0 ,

and that is characterized by coupled replacement of Si and R+2 

(VI) by Al(IV) and R+3 (VI). In this series, celadonites, with 

Si ranging from 4.00 to 3.75, stand closest to the end-member, 

and represent lesser degrees of replacement than the glauconites, 

in which Si ranges from 3.80 to 3.55. Celadonites and glauconites 

having fewer than 0.66 potassium ion per half cell belong to the 

same replacement series, and are similar in layer composition 

to the high potassium celadonites and glauconites. Because 

celadonites and glauconites have the same crystal structure, are 

very similar in chemical composition, and are near members of 

the same replacement series, optical, X-ray, and thermal data 

at present contribute little to their differentiation.

In many celadonites and glauconites the decrease in R+2 (VI), 

compared to the theoretical end-member, is greater than the 

decrease in Si, and the increase in R+3 (VI) is greater than the 

increase in Al(IV). The fact that the excess of R+2 ( VI) decrease 

over Si decrease usually agrees closely with the excess of R+3 

(VI) increase over Al(IV) increase strongly suggests oxidation 

of bivalent iron to trivalent. The further fact that the excess 

of R^tVI) decrease over Si decrease also agrees closely with 

the layer charge deficiency, as compared with a charge of 1.00 

per half cell (the layer charge of the theoretical end-member) 

seems to suggest that originally all these celadonites and glauconites had layer charges close to 1.00, but that oxidation has 

reduced the layer charge by an amount equivalent to the bivalent iron oxidized.

The lack of correlation between iron and potassium in glauconites suggests that glauconitization is made up of two separate, 

unrelated processes, incorporation of iron into the octahedral 

layer, and fixation of potassium in interlayer positions, with incorporation of iron preceding complete fixation of potassium. 

According to this concept, the amount of iron incorporated into 

the glauconite structure is dependent on the iron concentration

of the specific environment, with the iron content of the glauconite reflecting the degree of iron richness of the environment. 

A low potassium content may indicate immaturity, or laclr of 

time for more complete fixation of potassium, if it is accompanied by high layer charge; or it may indicate degeneration, 

oxidation with attendant loss of layer charge and interlryer 

cations, if the layer charge is relatively low.

The great range in composition of Cretaceous and Tertiary 

glauconites suggests that factors such as specific environment 

of development, opportunity for potassium fixation, and exposure to oxidation are of greater importance in determining 

the composition of a glauconite than the geologic age in which 

it was formed.

INTRODUCTION

The relation between celadonite and glauconite is a 

subject of continuing controversy. A comparative study 

of 10 analyses of celadonite and 40 analyses of glauconite 

by Hendricks and Ross (1941) confirmed the close compositional relationship between the two minerals. However, they recommended (p. 708), retention of both 

names, as "the well established term 'glauconite' is used 

for a mineral of characteristic sedimentary or'^in 

whereas the term 'celadonite' is used for a mineral of 

quite different occurrence and paragenesis." Later 

workers, on the basis of optical, X-ray, and thermal 

data, as well as chemical analyses, have maintained that 

these minerals are identical. Schuller and Wohlmann 

(1951), on the basis of a single analysis of a celadonite, 

concluded that the composition of celadonite was near 

that of glauconite, except that silicon is partially replaced by trivalent iron in celadonite and by aluminum 

in glauconite. As their X-ray spacings were similar, 

they suggested their identity. A study of minerals from 

Karadagh, Crimea, convinced Savich-Zablotzky (1P54) 

that the names "celadonite" and "glauconite" refe1" to 

the same mineral, their only difference being mod^ of 

origin. Malkova (1956), after electron-microscope and 

thermal studies of one sample of celadonite, and comparison of its chemical composition with that of seven 

other celadonites and glauconites, concluded that cela-
F2 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

donite and glauconite are identical and suggested that 

the name "celadonite" be reserved for ferruginous 

varieties, and that aluminous varieties be called skolite, 

discarding the term "glauconite" entirely. Lazarenko 

(1956) also considered celadonite and glauconite identical, and, on the basis of electron micrographs, and 

X-ray, optical, and thermal data, placed glauconite, 

celadonite, and skolite in the hydromica group.

In correlating dioctahedral potassium micas on the 

basis of their charge relations, Foster (1956) found that 

the Si4 end of the trisilicic-tetrasilicic diocathedral 

micas was represented by a celadonite from near Reno, 

Nev. In this celadonite, silicon exactly and completely 

filled the four cation positions (per half cell) of the 

tetrahedral layer. In another celadonite, silicon filled 

3.88 of the 4.00 tetrahedral cation positions, with aluminum occupying only 0.12 positions. In two glauconites 

included in the study, silicon occupied only 3.62 and 3.67 

tetrahedral positions, respectively. A similar relation 

between silicon occupancy in celadonites and glauconites 

is found in atomic ratios calculated from the analyses 

compiled by Hendricks and Ross (1941), with the atomic 

ratios per silicon ranging from 3.78 to 4.00 in the celadonites and from 3.44 to 3.84 in the glauconites. This 

difference in silicon occupancy in materials so closely 

related compositionally suggests the possibility that 

celadonites and glauconites are members of an isomorphic series.

Some of the confusion as to the relation between celadonites and glauconites may be attributed to the kind 

of specimens that have been compared. In previous 

studies of these minerals the importance of the potassium content was not realized, and the chemical composition of specimens containing 8-10 percent K2O were 

compared with others containing only 3 or 4 percent 

K2O, which are often interlayed, most commonly with 

montmorillonite, hydrous mica, or chlorite, or contain 

impurities like quartz, calcite, or apatite. In the present 

study many of the same analyses are used as were used 

in previous studies, but they are herein grouped for 

comparison according to potassium content and interlayer charge, in order to minimize as far as possible 

the disturbing effects of interlayering or contaminents.

SELECTION OF ANALYSES AND CALCULATION 

OF ATOMIC RATIOS

Most of the analyses used to study the compositional 

relationship between celadonites and glauconites having more than 0.65 potassium ion per half cell (that is, 

more than 7.0 percent K2O) were taken from the compilation of Hendricks and Ross (1941), although a few 

were taken from Smulikowsi's (1954) compilation and

a few from more recent literature. These analyses made 

by classical methods are considered more reliable for a 

study of this kind than analyses made on very small 

samples (less than 50 mg) by a combination of microchemical, spectrochemical, and colorinietric methods. 

The inaccuracy of the later analyses is indicated by their 

totals ranging, for example, from 98.78 to 102.34 in 

Burst's (1958) eight analyses, and from 98.56 to 102.50 

in the nine analyses of Bentor and Kastner (1965). 

Recalculating such analyses to obtain totals of 100.00, 

as Bentor and Kastner have done, only compounds the 

errors. In such a recalculation it is assumed that all the 

values found for the different constituents are equally 

in error, and the same correction is applied to all. However, it is more probable that only one or two values are 

in error, as some of the analytical techniques used are 

much more accurate than others. A slight error in the 

value obtained by one of the less reliable techniques is 

multiplied many times because of the very small samples used (less than 0.50 mg in some instances), and 

the very large factor required to convert the amount 

found to percent per gram. Analyses made by classical 

methods are usually made on much larger samples, thus 

avoiding such multiplication of error.

The samples analyzed by the longer classical methods 

were and are generally very carefully prepared by magnetic separation, heavy liquids, and handpicking, and 

examined under a petrographic microscope for 

impurities.

Under the conditions of occurrence of glauconite, 

calcite or apatite may be present, and their complete 

removal may be difficult. Consequently, any CO2 or 

P2O5 reported in an analysis used in this study was 

presumed to indicate calcite or apatite present as impurities, and their CaO equivalent was deducted from 

the CaO reported in the analysis before calculating the 

atomic ratios of the various constituents. Determination of CO2 and P2O5 is desirable in all analyses of 

glauconite, for proper allocation of the CaO reported 

in an analysis of glauconite. If not determined, CO2 

and P2O5 would escape detection in the course of the 

analysis, as CO2 would be driven off during the determination of inherent water, and any P2O5 present would 

be included in the value reported for A12O3 .

In calculating formulas for celadonites and glauconites, Hendricks and Ross (1941) followed the usual 

custom of assigning all the MgO to the octahedral layer. 

In their formulas the number of octahedral positions 

occupied ranged from 1.94 to 2.17 per half cell in the 

glauconites and from 2.01 to 2.24 in the celadonites. As 

the two celadonites having the highest octahedral occupancy, 2.22 and 2.24, were unusually high in MgO,
STUDIES OF CELADONITE AND GLAUCONITE F3

8.51 and 9.32 percent, respectively, Hendricks and Ross 

concluded (p. 706) that these two analyses "must have 

been made on impure material, as a magnesium silicate 

(serpentine or saponite?) must have been present to 

account for the high percentages of MgO." They 

therefore omitted them in formulating their interpretation of the chemical composition of celadonite. In 

their later study of montmorillonite (Ross and Hendricks, 1945), they, as usual, allocated all the MgO to 

the octahedral layer, and obtained octahedral occupancies as high as 2.24 positions. From this, they concluded 

that octahedral occupancy in some dioctahedral minerals is not necessarily limited to just two-thirds of the 

available cationic octahedral positions, as had been presumed, but that as much as a fourth of the "vacant" 

third positions might actually be occupied. However, a 

subsequent study by Foster (1951) of the exchangeable 

cations in some of the same montmorillonite samples 

showed that all of those examined contained some exchangeable magnesium. In each sample the amount of 

exchangeable magnesium found was exactly sufficient, 

on recalculation of the formulas, to reduce octahedral 

occupancy to 2.00±0.02 ions per half cell. This study 

demonstrated that, in such minerals as montmorillonite, 

magnesium can occupy two different positions in the 

crystal structure, octahedral and interlayer, just as 

aluminum can occupy both tetrahedral and octahedral 

positions. This study also suggests that an octahedral 

occupancy in excess of 2.02 may be indicative of interlayer magnesium.

Kelley and Liebig (1934) found that cation-exchange 

clays that had been treated with sea water contained 

more replaceable magnesium than replaceable sodium, 

48.35 and 39.13 milliequivalents, respectively. This relationship is due to the fact that, although the concentration of sodium in sea water is much greater than that 

of magnesium, its replacing power is much inferior. 

Because of the high replacing power of magnesium, 

exchangeable or interlayer magnesium is to be expected 

in any layer silicate mineral containing exchangeable 

cations if it comes from an environment that contains 

magnesium. Owens and Minard (1960) reported exchangeable magnesium in the two glauconites from 

coastal plain formations of New Jersey on which they 

had had cation-exchange determinations made. The 

presence of exchangeable magnesium in glauconites is 

not surprising as glauconites are commonly formed in 

a marine environment. The high octahedral occupancies 

calculated for many glauconites are probably due to allocation of all MgO present to the octahedral layer, 

whereas some of it is actually exchangeable and belongs 

in the interlayer. This is considered so probable that

in this study all octahedral cations in excess of 2.00 were 

considered to represent exchangeable magnesium and 

were transferred to the interlayer.

The two celadonite analyses that Hendricks and Poss 

(1941) considered to have been made on impure material, and that must have contained a magnesium silicate 

to account for their high percentages of MgO, yielded, 

on calculation, exceptionally high values for octahedral 

occupancy, 2.19 and 2.24 cations, respectively. Transference of the excess cations to the interlayer produced very 

high layer and interlayer charges, ±1.20 and 1.14 

and +1.16, respectively. Thus, these analyses produce 

irrational formulas both when all the MgO is considered 

octahedral and when the excess above 2.00 is considered 

interlayer. Similar irrational formulas were produced 

by several other analyses of celadonite. Following 

Hendricks and Boss, such analyses were considered to 

have been made on impure material and were not included in this study. Analyses whose excess octahedral 

cations, transferred to the interlayer as magnesium, did 

not produce irrationally high-layer and interlr.yer 

charges, were considered acceptable and were included.

Customarily, bivalent interlayer cations like calcium 

and magnesium are reported in terms of charges, not 

in terms of cations. However, in this study interlr.yer 

calcium and magnesium are recorded as cations, in accordance with the usage followed for all the other cations in the formula. Thus, the notation 

(K.74Na.o2Ca.o2Mg.o4) + *8 indicates a total of 0.82 interlayer cation that carries a combined positive charg^ of 

0.88.

RELATION BETWEEN THE COMPOSITION OF 

CELADONITES AND GLAUCONITES

Analyses of celadonite and glauconite are given in 

tables 1-3. Analyses 1-9 in table 1 are of celadorites 

whose calculated atomic ratio for potassium is greater 

than 0.65 atom per half cell; analyses 10-13 of celrdonites containing less than 0.66 atom of potassium. Table 

2 presents analyses of glauconites whose calculated 

atomic ratio for potassium is greater than 0.65 atom per 

half cell, and table 3 presents analyses of glauconites 

having less than 0.66 atom of potassium per half cell. 

The limiting value of 0.65 potassium atom per half cell 

for differentiating high and low potassium celadonites 

and glauconites was chosen arbitrarily. Range and 

median values for the principal constituents in high potassium celadonites and glauconites, in terms of ate mic 

ratios, for percent of octahedral positions occupied by 

bivalent cations, and for negative octahedral charge, are 

given in table 4. Similar data for low potassium celrdonites and glauconites are given in table 5.
F4 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 1. Chemical analyses, in percent, of celadonites, together with their calculated atomic ratios

Analysis. Cl C2 C3 C4 C5 C6 C7 C8 C9 CIO Oil C12 C13

CHEMICAL ANALYSES

Celadonites having more than 0.65 potassium atom per half cell

[n.d., not determined]

Celadonites having Ies"> than 0.66 

potassium atom per half cell

SlOj.... ................

A12 03 .....-.. .........

FeO.....--.._ ............

MgO. .....................

MnO... ...................

CaO. ...... ..._...........

NaaO.. ...................

K2O....... ................

TiOs....... ...............

H,0+............ .........

HaO-...-.... .............

................. 55.61

.- .-.. - .79

17 19

._ -.. .. 4.02

...... .. ....- 7.26

................. .09

.. .. -.- .21

.....-....._..... .19

...... -- 10.03

:=::::} H

56.20

2.05 10 ift

3 19

5.42

.27 ..

64

8.26

.10 ..

4.86]

OKI

53.23

9 11

20.46

4.14

5.67

7 95

< 

6. 18J

55.30

10 90

6.95

3.54

6.56

.47

Q Qfi

n.d.

5.21

1.30

54.38

5.41

14.22

3.56

6 40

.25 ..

.42

.05 ..

9

OQ

.14 ..

4.80] 

1.16J

ml 71

7.56

10 AA

* 3H

5.76

.00

7 4O

52.26

1.62

21 84

4.45

5.25

10.04

14.15

.10

52.53

4.97

18.62

4.58

5.35

.01

.58

7 03

.25

«4.31

1.15

53.54

12.02

8.21

3.21

6.99

.49

.07

8.43

.09

4.69

2.35

56.88

11.06

10.68

2.45

6.62

Trace

.94

.19

3.54

.20

4.691

2.29J

56.47

9.09

12.36

2.19

5.98

.12 ..

1.13

.86

6.49

.13

5.32J

51.36

1.69

23.72

1.40

6.34

.54

1.29

6.62

Trace

5.87

1.11

54.49

12.60

9.52

2.95

6.24

.05

.65

.48

7.41

Trace

3.59

1.60

Total................................ 100.27 100.42 99.76 99.61 2100.17 100.59 99.71 8100.31 100.09 9.54 100.14 99.94 99.58

CALCULATED ATOMIC RATIOS

Si................... . ____..____

Aliv - - .

Alvi . Fe«.... ------ .................

Few____ ... ...................

Mgvi .-.......---.......--.-.

Mn_.__. ........................

Octahedral cations.--------.--..

Layer charge.. -...-..--.....-...

Mg+2..... .......................

Ca+2---. ........................

Na... --..----. .......... .....

K. ......... .............. .......

Interlayer cations. ... _ ..--....

Interlayer charge _ ..-.. _ .....

........... 4.00

..-_.- .00

. -- . .07

 -__--_-_. .93

........... .24

........... .75

........... .01

.. .. . 2.00

........... -1.00

.. _ .. .03 ..

..-. .01

........... .03

09

.. _. . .99

........... +1.03

4.00

.00

.16

1.03

.19

.58

.00 ..

1.96 -.89

.02 ..

.09 ..

.75

.86

+.88

3 on

.10

.08

1.13

.25

.54

2.00 -.89

.08

.74

.82

+.90

3.88

.12

.78

.37

.21

.64

2.00 -.97

.04

.04

.00

84

.92

+1.00

3.88

.12

.34

.76

.21

.63

.02 ..

22.00 8-1.06

.05

.03 ..

.01 ..

84

.93

+1.01

3.86

.14

.49

.71

.31

.49

2.00 -.94

.12

.67

.79

+.91

3.83

«.17

.00

1.18

.27

.57

.00

2.02 -.95

.00

.00

.00

.94

.94

+.94

3.79

.21

.21

1.01

.28

.50

.00

2.00 -.99

.07

.05

.00

.73

.85

+.97

3.76

.24

.76

.43

.18

.65

.00

2.02

-1.01

.08

.04

.01

.76

.89

+1.01

3.89

.11

.79

.55

.14

.52

.00

2.00 -.77

.15 ..

.07

.02

.31

.55

+.77

3.88

.12

.62

.64

.13

.61

.01 ..

2.01 -.84

.08

.12

.57

.77

+.85

3.79 «.21

.00

1.25

.09

.66

2.00 -.96

.03

.04

.19

.62

.88

+.95

3.76

.24

.78

.49

.17

.56

.00

2.00 -.97

.08

.05

.06

.65

.84

+.97

i Ignition loss.

* Includes 0.15 percent LijO, equivalent to 0.04 atomic ratio of Li.

3 Includes 0.03 percent Cr2O3 .

4 Includes 0.03 atomic ratio of Fe«. 

«Includes 0.06 atomic ratio of Fe+3.

LOCATION OF SAMPLES AND REFERENCE

Cl. Eeno, Nev., 23 miles east of (Hendricks and Eoss, 1941, table 4, No. 1). In vesicular basalt. Analyst: E. C. Wells. 

C2. Krivoi Bog, U.S.S.E. (Serdyuchenko, 1965, p. 566). Replacing aegerine and

riebeckite in fractures in iron-bearing quartzite. Analyst: M. M. Stukalova. 

C3. Brentonico, Monte Baldox, Italy (Hendricks and Boss, 1941, table 4, No. 2).

Amygdulite masses in basalt. Analyst: G. Levi. 

C4. Vesuvius, Italy (Hendricks and Boss, 1941, table 4, No. 7). Occurrence and

analyst not given. 

C5. Wind Biver quadrangle, sec. 3, T. 3 N., R. 73 W., Washington (Wise and Eugster,

1964, p. 1034, No. 15). Amygdulite filling in basalt. Analyst: O. von Knorring. 

C6. Vail, Arizona (Hendricks and Boss, 1941, table 4, No. 5). In basalt and basaltic

tuffs. Analyst: G. A. Koenig. 

C7. Kursk Mountain, 80 miles northwest of, U.S.S.R. (Sudovikova, 1956, p. 544).

In seams in iron-bearing quartzite of the Kursk magnetic anomaly. Analyst:

B. S. Kopelovich.

C8. Bug region, U.S.S.R. (Malkova, 1956, p. 308). Veins and vugs in metamorphic 

rocks. Analyst: K. M. Malkova.

C9. Dolgoye Pole, West Volynya, U.S.S.R. (Shashkina, 1961, p. 400, No. 2). Weathered basalt crust. Analyst: Mineral Chemical Laboratory of A.N., U.S.S.R.

CIO. Berestovets, West Volynya, U.S.S.R. (Shashkina, 1961, p. 400, No. 4). 

Weathered basalt crust. Analyst: Mineral Chemical Laboratory of A.N., 

U.S.S.R.

Gil. Zonguldak, Turkey (Bayramgil and others, 1952, p. 245). Cavities in basaltic 

tuff. Analyst: Th. Hiigi.

C12. Contessa Entellina, Palermo, Sicily (Scherillo, 1935, p. 73). Cavities in basalt. 

Analyst: A. Scherillo.

C13. Dolgoye Pole, West Volynya, U.S.S.B. (Shashkina, 1961, p. 400, No. 1). Weathered basalt crust. Analyst: Mineral Chemical Laboratory of A.N., U.S.S.K.
\> TABLE 2. Chemical analyses, in percent, of glauconites having more than 0.65 potassium atom per half cell, together with their calculat

3

SiOj. .....................

AljOs- ..... ... ...

Fei03 ............... ...

FeO. ............... . .

MgO...... ................

MnO-. ..................

CaO...... .......... ...

NaiO. ....................

KtO. .....................

TiO2 ... .............

H,0+. ................. ..1

H8 0-. -.......... ./

Total......... .....

Si..................

Aliv- ..................

Alvi- - ... ... ... ........

Fe«.. ....... .............

Mn._ .......................

Mg^. .....................

Na... ............... ....

K.... .....................

Gl G2 G3 G4 G5 G6 G7 G8 G9 G10

CHEMICAL ANALYSES

Gil

Glauconites having an interlayer charge higher than +0.88

52.74 

12.29 

9.35 

6.30 

4.05

.55 

.09 

7.97

5.93

«99.40

3.73 

.27

.79 

.50 

.37 

.34

2.00 

-.98

.08 .

.04 

.01

.72 

.85 

+.97

51. 35 49. 53 

9.47 5.84 

16.37 20.06 

4. 75 5. 95 

3. 17 2. 92

.63 .56 

1. 22 . 46 

7. 34 9. 31

4. 85 4. 91

2 99. 50 99. 54

3. 70 3. 67 

.30 .33

.50 .18 

. 89 1. 12 

.29 .37 

.34 .32

2.02 1.99 

-.87 -1.04

.02 .04 

.17 .07 

.68 .88 

.87 .99 

+.89 +1.03

50.20 

6.10 

23.30 

2.35 

2.70

.40 

.93 

8.95

5.25

100.18

3.67 

.33

.20 

1.28 

.14 

.29

1.91 

-1.03

.03 

.13

.83 

.99 

+1.02

1 Includes 0.13 percent F. 

* Includes 0.35 percent PzOs. Equivalent CaO deducted in calculation of atomic ratios.

51.00 48.75 48.66 46.90 48.80 47.88 

9.93 9.07 8.46 6.20 14.64 14.94 

18.69 18.31 18.80 21.45 11.90 17.13 

1.98 3.27 3.98 3.16 2.80 2.68 

3.85 3.63 3.56 4.20 3.62 2.45 

........ .001 .01 .02 .00 .............

.87 .39 .62 .70 .70 .56 

.35 .12 .00 .70 .60 .43 

7.66 8.17 8.31 7.25 8.20 8.04 

.-- .- .055 .......... .17 .12 -

, a, /5.23 4.62 .......... 5.52\ - Q1

a'°d \2. 16 1.94 2.60 3.49J D' yl

100.16 899.54 499.08 «100.27 100.39 100.02

CALCULATED ATOMIC RATIOS

3.64 3.63 3.62 3.58 3.55 3.43 

.36 .37 .38 .42 .45 .57

.47 .43 .36 .14 .81 .69 

1.00 1.03 1.05 1.23 .65 .92 

.12 .20 .25 .20 .17 .16 

.41 .34 .34 .43 .39 .23 

........ .00 .00 .00 .00 .... .....

2.00 2.00 2.00 2.00 2.02 2.00 

-.89 -.91 -.97 -1.05 -.95 -.96

.07 .00 .04 .06 .05 .04 

.05 .02 .00 .11 .08 .06 

.70 .77 .79 .71 .76 .73 

.82 .85 .88 .93 .89 .86 

+.89 +.91 +.97 +1.04 +.94 +.93

51.55 

4.03 

22.17 

3.54 

3.86

.69 

.55 

7.03

6.62

100.04

3.79 

.21

.14 

1 22 

!22 

.42

2.00 

-.85

.05 

.08 

.66 

.79 

+.84

G12 G13 G14 G15 G

Glauconites having an interlayer charge 

50.58 

6.72 

19.50 

2.96 

4.10

.34

.04 

8.26

7.76

« 100. 83

3.74 

.26

.32

1.08 

.18 

.42

2.00 

-.86

.03

.01

.78 

.82 

+.85

4 Includes 0.12 percent P2 0t. Equivalent CaO deducted in calculation. 

8 Includes 0.54 percent free SiOa and 6.32 ignition loss.

49. 89 52. 96 

7. 52 12. 76 

18.93 13.56 

3. 00 2. 34 

3. 75 4. 11

.25 --_--..-_.

.11 .47 

7. 52 8. 69 

.05 .... ..

J 6- u\ 4 01 

\2.34/ 4' 91

1 99. 69 99. 80

3. 72 3. 69 

.28 .31

.38 .74 

1.06 .71 

.19 .14 

.37 .43

2.00 2.02 

-. 84 -. 82

.05 ...........

.00 ...........

.02 .06

.72 .77 

.79 .83 

+.84 +.83

49.23 

7.11 

20.89 

3.06 

3.44

.11 

8.51

6.71

49.

10. 

15. 

1.

4. 

.

.

7.

.

re. 

\3.

99. 06 * 100. 

3.66 

.34

.28 

1.17 

.19 

.38

2.02 

-.85

.02 

.81 

.83 

+.83

7 Includes 0.22 percent P2 0s. 

lation. 

8 Includes 0.07 percent Cr2 0a

3. 

.

.

.

.

.4

2.

-.8

.

....

.

.

.

+. 

Equ

0.0

8 Includes 0.001 percent SrO, 0.053 VjO«, and 0.33 P2 0{. CaO 

equivalent to P20t deducted in calculating atomic ratios.

"Includes 0.30 percent C02 and 0.27 P2O6. Equivalent CaO deducted in calculation.

LOCATION OF SAMPLES AND REFERENCE

Gl. Tosterup, Scania, Sweden (Hendricks and Ross, 1941, p. 693,

No. 30). Upper Cretaceous. Analyst: N. Sahlbom. 

G2. Eriksbre, Oland, Sweden (Hendricks and Ross, 1941, p. 692,

No. 23). Ordovician limestone. Analyst: N. Sahlbom. 

G3. Urals, U.S.S.R. (Hendricks and Ross, 1941, p. 692, No. 5).

Eocene sandstone. Analyst: Glinka. 

G4. Ghent, Belgium (Hoebeke and Dekeyser, 1955, p. 114, No. 14).

Eocene sand. Analyst: Not given. 

G5. Traktymirov, Kiev province, U.S.S.R. (Smulikowski, 1954,

table 3, No. 10). Tertiary sandstone. Analyst: Glinka. 

G6. Walsrode, Germany (Valeton, 1958). Tertiary. Analyst: Harre. 

G7. St. Joseph, Mo. (Hendricks and Ross, 1941, p. 692, No. 11).

Cambrian dolomite. Analyst: G. V. Brown.

G8. Dnieper River region, U.S.S.R. (Dyadchenko and Khatuntzeva, 1955, p. 152). Age: Not given. Analyst: Not given. 

G9. Tipchinvrah, Bulgaria (Atanasov, 1962, p. 145, No. 2). Jurrasic.

y Analyst: L. Ivchinova. 

G10. Cemovakoe, Niznij Novgorod, U.S.S.R. (Hendricks and Ross,

1941, p. 692, No. 1). Jurassic sandstone. Analyst: Glinka. 

Gil. Hokkaido, Japan (Hendricks and Ross, 1941, p. 692, No. 31).

Upper Cretaceous. Analyst: Yagi. 

G12. Sewell, N.J. (Hendricks and Ross, 1941, p. 692, No. 26). Upper

Cretaceous sand. Analyst: R. K. Bailey. 

G13. Tysmienica, Carpathian Mountains, U.S.S.R. (Smulikowski,

1954, table 3, No. 26). Lower Oliogocene sandstone. Analyst:

Szubartowski.

G14. Udrias, E.S.S.R. (Hendricks 

Ordovician limestone. Anal

G15. Big Goose Canyon, 15 mile

(Hendricks and Ross, 1941

Analyst: G. Steiger. 

G16. Milbnrn, Table Hill, Otago

1941, table 3, No. 10). Age: 

G17. Lewes, Sussex, England (He

No. 16). Age: Not given. An

G18. Nasanovo, near Smolensk, 

1941, p. 692, No. 10). Cretac

Glinka. 

G19. Penisola Salentina, Puglia, 

Cretacecus limestone. Anal
F6 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 3. Chemical analyses, in percent, of glauconites having less than 0.66 potassium atom per half cell, together with their

calculated atomic ratios

 ..... G20 G21 G22 G23 G24 G25 G26 G27 G28 G29 G30 G31 G32

CHEMICAL ANALYSES

Glauconites having an interlayer charge higher than +0.88

SiO2 ... _ .... _ ......

Fe»0t.... ..............

MgO. .................

MnO..... ..........

CaO____. ...... ........

Na2O. ............... .

T1O2 _. ................

H2O 

Total...-. -..

 _ . 50.36

........ ............ 7.04

 -. -_. 19.13

 . . .. 3.95

- -... .. 4.08

 . .06 .

.... . . -.. .91

 ___ .. 1.58

 ---. . 6.62

02

6.32

. - -_... 1100.34

49.4 

10.2 

18.0 

3.1 

3.5

.6 

1.4

5.1

8.3

99.6

49.0 

9.2 

19.5 

3.3 

3.6

.5 

.9 

6.3

7.6 

99.9

48. 5 47. 6 

9. 0 9. 9 

20. 0 21. 9 

3.1 1.5 

3. 7 3. 7

.4 .8 

1.5 1.4 

6. 1 5. 3

7.3 7.7 

99. 6 99. 8

49.29 

3.17 

21.72 

3.19 

3.85

.74 

.12 

6.02 

.12 .

J7.21 

\4.60 

2 100. 35

Gla aconites having an interlayer charge lower than +0.89

50.20 

7.80 

17.90 

1.80 

3.23

.81 

Trace 

6.42

11.27 

99.43

48.54 

7.82 

17.50 

3.07 

3.26

.68 

.22 

5.87

6.001 

6.71/ 

3 99. 86

49. 00 49. 53 

8. 35 13. 32 

20. 20 12. 19 

1. 80 2. 27 

3.31 3.89 

. ... .06

.77 1. 53 

Trace . 89 

6.80 6.02 

......... 1.28

in n? /4. 37 10- 07 \4.05 

100. 30 < 100. 48

48.10 

11.07 

14.67 

3.07 

3.78 

Trace 

1.92 

.56 

5.49 

1.78 

4.31 

4.56 

6 100. 51

48.19 

10.83 

17.80 

.97 

3.19

1.06 

.48 

637

1.49 ...

4.741 

4.41/ 

« 100, 22

49.09 

15.21 

10.56 

3.06 

2.65

.55 

1.21 

6.05

11.64 

100.02

CALCULATED ATOMIC RATIOS

Si..............................

Aljv-. ...... ....... ...... .

Alvi...... ......... ..............

Fe«..... ........................

Fe+2.. . _ --..-.--..-...-. .....

Mgvi.. 

Mn...._ .... _ ...........

Octahedral cations.. ............

Layer charge... ..... _ -....

MgM.... _ ......... __ ........

Ca«... ..... .................

Na...._- .......................

K... ............................

Interlayer cations.... __ .......

Interlayer charge _____ _ . ...

.......... 3.68

. ...... .32

.......... .29

.......... 1.05

........... .24

.......... .44

rtrt

.......... 2.02

.......... -.98

.......... .00

.......... .05

-- . .22

.... ... ... .62

.......... .89

.......... +.94

3.62

.38

.50

.99

.19

.32

2.00 -.89

.06

.05

.20

.48

.79

+.90

0 Art

.40

.39

1.08

.20

.33

2.00 -.93

.06

.04

.13

.59

.82

+.92

q K7

.43

.35

1.11

.19

.35

2.00 -.97

.06

.03

.21

.58

.88

+.97

q An

.51

.35

1.21

.09

.35

2.00 -.96

.06

.06

.20

.50

.82

+.94

q cq

.17

.12

1.27

.21

.40

00

2.00 -.78

.05

.03

.02

.60

.70

+.78

3 7Q

.21

.49

1.02

.11

.36

1.98 -.74

.00

.07

.00

.62

.69

+.76

3.75

.25

.46

1.01

.20

.33

2.00 -.78

.05

.04

.03

.58

.70

+.79

3.66

.34

.40

1.14

.11

.37

2.02 -.76

.00

.06

.00

.65

.71

+.77

3.66

.34

.82

.67

.14

.37

Art

2.00 -.85

.04

.01

.13

.57

.75

+.80

3.65

.35

.64

.84

.19

.33

rtrt

2.00 -.87

.10

.03

.08

.53

.74

+.87

3 63

.37

.60

1.01

.06

.33

.00 ..

2.00 -.75

.03

.02

.07

.61

.73

+.78

3.62

.38

.94

.59

.19

.29

2.01 -.83

.00

.04

.17

.57

.78

+.82

1 IncludesO.Ol percent Li2O and 0.26 PaO5. CaO equivalent to P2O5 deducted before 

atomic ratio calculation.

2 Includes 0.32 percent P2Os. Equivalent CaO deducted before atomic ratio 

calculation.

3 Includes 0.05 percent S and 0.14 PjO6. CaO equivalent to PaOs deducted before 

atomic ratio calculation.

4 Includes 0.96 percent COj and 0.12 P2O6. CaO equivalent to COj and PjOs deducted before atomic ratio calculation.

6 Includes 0.67 percent CO2 and 0.53 P2O6 . CaO equivalent to COj and PaOj deducted before atomic ratio calculation.

8 Includes 0.39 percent COa and 0.30 P2O5 . CaO equivalent to COj and PaOj deducted before atomic ratio calculation.

LOCATION OF SAMPLES AND REFERENCE

G20. Monte Brume, Garda Lake, Italy (Hendricks and Ross, 1941, p. 692, No. 21). 

Age: not given. Analyst: Schwager.

G21. Northwest of Norwalk, Wis. (Hendricks and Ross, 1941, p. 692, No. 14). Cambrian sandstone. Analyst: T. B. Brighton.

G22. Woodstown, N.J. (Hendricks and Boss, 1941, p. 692, No. 6). Cretaceous marl. 

Analyst: T. B. Brighton.

G23. Near Norwalk, Wis. (Hendricks and Ross, 1941, p. 692, No. 3). Cambrian 

dolomite. Analyst: T. B. Brighton.

G24. San Pedro, Calif. (Hendricks and Ross, 1941, p. 692, No. 2). Pleistocene marl. 

Analyst: T. B. Brighton.

G25. Whare Flat, East Taieri, Otago Land, New Zealand (Smulikowski, 1954, 

table 3, No. 21). Tertiary sandstone. Analyst: Seelye.

G26. Villers-sur-mer, France (Smulikowski, 1954, table 4, No. 39). Cretaceous sand. 

Analyst: Sabatier.

G27. Kahoko Creek, Otepopo, Otago Land, New Zealand (Smulikowski, 1954, 

table 3, No. 23). Tertiary sandstone. Analyst: Seelye.

G28. Cuise-la-Mothe, France (Smulikowski, 1954, table 3, No. 13). Tertiary sand. 

Analyst: Sabatier.

G29. Monte Bonifato di Alcamo, Italy (Pirani, 1963, p. 37, No. 3). Age: not given. 

Analyst: Pirani.

G30. Monte Barbara di Sigesta, Italy (Pirani, 1963, p. 37, No. 2). Ace: not given. 

Analyst: Pirani.

G31. Monte Bonifato di Alcamo, Italy (Pirani, 1963, p. 37, No. 1). Age: not given. 

Analyst: Pirani.

G32. Ashgrove, Elgin, Scotland (Hendricks and Ross, 1941, p. 692, No. 15). Cretaceous oolitic limestone. Analyst: not given.

TABLE 4. Range and median values of principal constituents in high potassium O0.65 atom per half cell) celadonites and glauconites

in atomic ratios

Celadonites Glauconites

Principal constituents Interlayer charge >+0.87 (9 analyses) Interlayer charge >+0.88 (10 analyses) Interlayer charge <+0.89 (9 analyses)

Median Range Median Range Median

Si

Al(IV) __ _______________

A1(VI)__ __ ___ _ __ .

Fe+3 __ ____ ______ _ .

Fe+2 __ _ __ ______ _ .

Mg_ ___ __ __ _ __ __

Percent R+2 (VI) _ __ __,

Percent R+3 (VI) _ _ _ ___

Octahedral charge. _______

._-_.__ 4.

_ ____ 38.

____ _ 49.

00- 3. 76

00- . 24

00- . 78

37- 1. 18

18- . 31

49- .78

9 -50. 8

2 -61 1

77 . 94

3. 88 ±

1 9-4-

. 39±

. 77 ±

.25±

.64±

A.A. Q _|_

55. 2 ±

-.85 +

0. 12

. 12

.39

.41

.07

. 15

6. 0

6. 0

-.09

3

19

64.

_

73- 3. 43

27- .57

14- . 81

50- 1. 28

12- . 37

23- . 43

5 -35. 5

5 -80. 5

39 . 71

3. 58±

.42±

.48±

89 +

.25±

.33±

97 P; 4-

72.5 ±

-.55 +

0. 15

. 15

.34

. 13

. 10

8.0

8.0

-.16

3. 79- 3. 56

. 21- . 44

. 14- . 74

. 71- 1. 37

11- 22

.27- .43

21. 3 -32. 0

68. 0 -78. 7

-. 37 . 64

3. 67±

.33±

.44±

1. 04±

.16±

.35±

26.6 ±

73.4 ±

-.50 +

0 11

. 11

30

33

06

.08

5 3

5 3

-. 14
STUDIES OF CELADONTTE AND GLAUCONITE F7

TABLE 5. Range and median values of principal constituents in low potassium (<Z.0.66 atom per half cell) celadonites and glaucon.ites

in atomic ratios

Principal constituents

Celadonites Glauconites

Interlayer charge <+0.89 (4 analyses) Interlayer charge >+0.88 (5 analyses) Interlayer charge <+0.89 (8 analyses)

Range Median Median Range Median

Si ___ -_---_._. _ ..-.__.___ _ 3.89- 3

Al (IV)__ ____________________ .11-

Al (VI)._____.____. _____________ .00-

Fe+3 _ . _ _____________________ .49- 1

Fe+2 ____-.._.___._._-_...____ . 09-

Mg __ ____ ____ -___. __ __ . 52-

Percent R+2 (VI) _ _ .___ _ __ 33.0-37

Percent R+3 (VI) _ __ ____ __ 62.5-67

Octahedral charee_ _ __ __ _-__ .66 - 

76 3. 82± 0

24 . 18±

79 . 40±

25 87 +

17 . 13±

66 . 59±

5 35. 2 ± 2

0 64. 5 ± 2

75 -.71+-

07 3

07

40

38

04

07

2 22

5 66

04 -

68- 3. 49 3. 59 ± 0

32- . 51 . 42±

29- . 50 . 40±

99- 1. 21 1. 10±

09- . 24 . 17 ±

32- . 44 . 38±

0 -33. 6 27. 8 ± 5

4 -78. 0 72. 2 ± 5

44 . 62 -. 53+ 

10 3. 83- 3

10 . IT11 . 12-

11 . 59- 1

08 . 06-

06 . 29-

8 17. 0 -26

8 73. 5 -80

09 -. 38 

62 3. 72± 0

38 . 28±

82 . 47±

27 . 93±

21 . 14±

40 . 35±

5 21. 7 ± 4

5 76. 5 ± 3

61 -.49+-

10

10

35

34

08

06

7

5

11

HIGH POTASSIUM CELADONITES AND 

GLAUCONITES

The data given in table 4 show distinct differences 

between high potassium celadonites and glauconites, as 

well as certain differences between high potassium glauconites having an interlayer charge greater than +0.87 

per half cell, and those having less. Silicon in the high 

potassium celadonites ranges from 4.00 to 3.76 cations 

per half cell, as compared with 3.73 to 3.43 cations in 

high potassium glauconites, both in glauconites with interlayer charges above and in those with interlayer 

charges below +0.88. Magnesium in the celadonites 

ranges from 0.49 to 0.78 cation per half cell (median 

value 0.64), as compared with 0.23 to 0.43 cation in the 

glauconites (median 0.33). The median value for bivalent iron, 0.25 cation, is the same in the celadonites and 

the high-charge glauconites, although the range is somewhat narrower in the celandonites. Thus, the difference 

in the percentage of octahedral positions occupied by 

bivalent cations, 44.9 percent in the celadonites and 27.5 

in the high-charge glauconites, is due principally to the 

higher magnesium content of the celadonites, not to 

significant differences in bivalent iron content. Conversely, the median octahedral occupancy by trivalent 

cations is lower in the celadonites than in the highcharge glauconites, 55.2 percent as compared with 72.5 

percent, but both range widely in relative content of 

octahedral aluminum and trivalent iron.

Because of their greater content of bivalent octahedral 

cations and lesser content of trivalent octahedral cations, 

there is a greater deficiency of positive charges in the 

octahedral layer of high potassium-high charge celadonites than in that of high potassium-high charge 

glauconites. The positive charge deficiency ranges from 

0.85±0.09 in the high potassium high-charge celadonites 

as compared with 0.55 ±0.16 in the high potassiumhigh charge glauconites. In a few celadonites, in 

which the tetrahedral layer is completely occupied by 

silicon, as for example, those from Reno, Nev., and

Krivoi Kog, U.S.S.R., Nbs. Cl and C2, table 1, the entire 

negative layer charge is due to deficiency of positive 

charges in the octahedral layer. In this sense, therefore, 

the total negative layer charge in these celadonites may 

be thought of as originating in the octahedral layer.

High potassium glauconites with interlayer charges 

less than + 0.88 are very similar in composition to those 

with interlayer charges greater than +0.87, except for 

their respective contents of bivalent and trivalent iron. 

In the high-charge glauconites the medians and ranges 

for bivalent and trivalent iron are 0.25±0.13 and 0.89 

±0.39, respectively, whereas in the glauconites with 

lower charges they are 0.16±0.06 and 1.04±0.33, 

respectively. With respect to content of other bivalent 

and trivalent cations, there is little difference, the highcharge glauconites having 0.33 ±0.10 cation of magnesium and 0.48±0.34 cation of octahedral aluminum, the 

lower charge glauconites having 0.35±0.08 cation of 

magnesium and 0.44±0.30 cation of octahedral aluminum. The lower interlayer charge in these glauconites 

is attributable, therefore, to their lesser content of 

bivalent iron and greater content of trivalent iron.

The differences in composition between high potassium celadonites and glauconites are shown graphicrlly 

in figure 1. In these diagrams the left-hand column represents percent occupancy of the octahedral layer by 

Al+3 , Fe+3, Fe+2, and Mg, the middle column represents 

percent occupancy of the tetrahedral layer by Si+4 r.nd 

Al+3, and the right-hand column indicates the number 

of potassium and exchangeable cations, Na, Ca, r,nd 

Mg, present per half cell. The figures at the tops of the 

columns indicate the positive-charge deficiencies in the 

octahedral and tetrahedral layers (cols. 1 and 2, respectively) and the positive interlayer charge (col. 3). T'he 

sum of the octahedral and tetrahedral deficiencies 

should agree closely with the positive interlayer 

charge. These diagrams demonstrate graphically the 

higher magnesium content of the celadonites and their 

lower content of tetrahedral aluminum as compared
F8 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

A. Celadonites, interlayer charge >+0.88 S. Glauconites Interlayer charge >+0.88

100

Reno, Nev. 

Table 1, No. Cl 

-1.00 -0. 03

Wind River, Wash. 

Table 1,No. C5 

-0.94 -0.12

Vesuvius, Italy 

Table 1, No. C4 

-0.85-0.12

Urals , U.S.S.R. 

Table 2, No. G3 

-0.71-0.33 ,

St. Joseph, Mo. 

Table 2, No. G7 

-0.59 -0.38

Tipchin vrah, Bulgaria

Table 2, No. G9 

-0.50 -0.45

C. Gtauconites, interlayer charge <+0,89

100

Puglia, Italy 

Table 2, No. G19 

-0.37-0.44

Carpathian Mts. 

Table 2, No. G13 

-0.56 -0.28

Udrias, E.S.S.R. 

Table 2, No. G14 

-0.51 -0.31

EXPLANATION

Exchangeable cations

FIGURE 1. Ohemical composition of representative celadonites and glauconites having more than 0.65 potassium atom per half 

cell. Figures above the first and second columns of each diagram indicate the positive-charge deficiencies of the octihedral 

and tetrahedral layers:; figures above the third column indicate the positive interlayer charge.
STUDIES OF CELADONITE AND GLAUCONITB F9

with glauconites. They also illustrate the greater occupancy of the octahedral layer by bivalent cations, 

Mg and Fe+2, in celadonites. On the other hand, the 

diagrams show that the celadonites and glauconites are 

similar in that both range widely in content of octahedral aluminum and trivalent iron. In some celadonites 

and glauconites, iron is the greatly predominant trivalent octahedral cation; in others, aluminum is equal to, 

or even dominant, over iron. These two octahedral cations bear a general reciprocal relation to each other 

in that decrease in trivalent iron content is usually accompanied by increase in octahedral aluminum.

LOW POTASSIUM CELADONITES AND GLAUCONITES

Comparison of tables 4: and 5 shows that the range 

values for Si, Al (IV), Al (VI), and Mg in low potassium celadonites fall within or close to the range values 

for these constituents in high potassium celadonites, but 

that the range values for Fe+2 in the low potassium celadonites is lower than in the high potassium celadonites, 

0.09-0.17 cation as compared with 0.18-0.31 cation, respectively. This decrease in Fe+2 content is reflected in 

the slightly higher range values for Fe*3 in the low 

potassium celadonites, in their lower occupancy by 

bivalent cations, and in their lower range of octahedral 

charge.

The low potassium glauconites, like the high potassium glauconites, are divided into two groups, depending on their interlayer charges. The first group, composed of five (table 3, G20-G24), have interlayer 

charges in excess of +0.88, because of their high contents of exchangeable cations, notably sodium, which 

contribute between 0.32 and 0.45 positive charge to the 

interlayer. These five glauconites are very similar to 

each other, as indicated by the small ranges in the values 

of their principal constituents. They are also similar, 

in composition, to diagram G7, figure 1, except for their 

low content of potassium and high content of exchangeable cations.

The second group of low potassium glauconites, consisting of eight (table 3, G25-G32), are characterized 

by interlayer charges of less than +0.89 per half cell. 

The ranges of values of the principal constituents in 

them are very similar to those of the low charge-high 

potassium glauconites. Like them, and also like the 

high charge-high potassium glauconites, they differ 

widely in content of trivalent iron and octahedral aluminum, but they are quite uniform in content of silica, 

tetrahedral aluminum, and magnesium. Compared with 

the high-charge glauconites, these glauconites are somewhat lower in bivalent iron content. Most of them are 

similar in exchangeable cation content, but others, notably G29, G30, and G32, have high contents of exchangeable cations.

Thus, this study shows that celadonites, whether of 

high or low potassium content, are very similar in content of silicon, tetrahedral aluminum, bivalent iron, 

and magnesium content; but both groups range widely, 

and reciprocally, in content of trivalent iron and octahedral aluminum. Likewise, high and low potassium 

glauconites are relatively uniform in content of silicon, 

tetrahedral aluminum, and magnesium, and in percentage of octahedral positions occupied by bivalent cations,- but they range widely, and reciprocally, in content of trivalent iron and octahedral aluminum. As 

a group, the celadonites are higher in silicon and IE agnesium and in bivalent-ion octahedral occupancy than 

the glauconites, and are lower in tetrahedral alumir um 

and trivalent-ion octahedral occupancy.

RELATION BETWEEN Si, B+2 (VI), Al(IV), AND R+s'VI)

It has been shown (Foster, 1956) that progress ve 

replacement in dioctahedral potassium micas of trivalent octahedral cations, R+3 (VI), by bivalent cations, 

R+2 (VI), is accompanied by equivalent increase in 

silicon and decrease in tetrahedral aluminum, A1(]V). 

Starting with muscovite, [Al2.o(Si3.oAli.0)Oio(OB")2]' 

KI.O, the end result of such replacement is tetrasiTcic 

dioctahedral potassium mica in which half of the 

octahedral cations are trivalent and half are bivalent, 

as [(R+3i.oR+2i.o)Si4 .oO1 o(OH)2]-K1 .o. Although analyses 

of natural micas representing all steps of this replr cement may be found, Foster noted that, whereas the 

first part of this replacement series is represented by 

micas in which aluminum is the dominant octahedral 

cation, the latter part is represented by glauconites 

and celadonites, minerals in which iron is usually the 

dominant octahedral cation.

Thus, neither aluminum nor iron, as the dominant 

trivalent octahedral cation, appears to form a complete 

series from trisilicic to tetrasilicic or vice versa, but 

each a partial series, one starting at trisilicic (murcovite) end, the other at the tetrasilicic end, with neither 

extending, apparently, much beyond the middle of the 

range as,

[Al2.0 (Si3. 0Al1 .0 )010 (OH) 2 ]-K1 .o-^ 

[(Al, 5R+2.5 ) (Si8JtAl..)010 (OH) J -KLO, 

and

oR^o) Si4. 0 010 (OH) 2 ] K^-* 

.R*.) (Si3 .5Al.5 ) 010 (OH) 2 ] K . 

In these formulas bivalent-octahedral cations are represented by the general expression, R+2, as the bivalent 

cations in both series are usually made up of both m^g336-373 69-
F10 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

nesium and iron. The replacements taking place in both 

series can be represented by the expression

or by the formula

[ (R+VXBX+2 ) (Si4_yAly ) Oio (OH) 2 ] (K, Na, Ca) . 

If the high potassium-high charge celadonites and 

glauconites belong to such a series, with a tetrasilicic 

mica as the starting point, then in each sample the decrease in the atomic ratios of Si and of E+2 (VI) and the 

increase in the atomic ratios of Al (IV) and of E*3 (VI) , 

with respect to the theoretical tetrasilicic end-member, 

should agree closely, and the sum of the decreases in Si 

and E+2 (VI) should correspond with the sum of the 

increases in Al(IV) and E+3 (VI). Table 6 shows the 

atomic ratios for Si, E+2 (VI), Al(IV), and E+3 (VI), 

the amount of decrease or increase with respect to the 

end-member, the sums of the decreases in Si and E+2 

(VI), and the increases in Al(IV) and E+3 (VI). Comparison of the amounts of Si+E+2 (VI) decreases with 

Al(IV) +E+3 (VI) increases for the samples studied 

shows that these sums correspond to each other within 

0.02 atomic ratio, except for those for C2 and G4, which 

differ by 0.07 and 0.09 atomic ratio, respectively. The 

close agreement between the decreases in Si+E+2 (VI) 

and the increases in Al(IV) +E+3 (VI) is shown graphically in figure 2, in which these two sets of values are 

plotted against each other. All the points, except those 

for C2 and G4 fall on, or very close to, the 1 : 1 diagonal.

1.20

l.OQ

p 0.80

0.60

± 0.40

0.20

0.00

C2

Cl/

c&/

C3S*C7 

P*4

G

Z

.... ,

G4 

G

G7,G8^

G14JS G13^<2T

3 ,oXG2 

>^G12

EXPLAIX

G18^ /

< ®^G9 

6®^17 

LXGfi,Gfi

G15

ATI ON

G10,x

G19

 Celadonite, interlayer charge >+0.88 

x Glauconite, interlayer charge >+0.88

® Glauconite, interlayer charge <+0.89

0.20 0.40 0-60 0.80 

AI(IV)+R+3(VI)-ATOMIC RATIO

1.00 1.20

FIGURE 2. Relation between Si+B+2 (VI) decrease and Al(IV) 

-)-R+3 (VI) increase in high potassium-high charge celadonites 

and glauconites.

However, the decrease in Si and the decrease in B-+2 (VI) 

are not the same in all the samples, nor is increase in Al 

(IV) always in agreement with increase in P.+3 (VI). 

These relations are shown graphically in figures 3 and 4,

0.60

0.50

0.40

O

< 

cz

O 

O

.1 0.30 

w

z

0.20

0.10

0.00

| EXPLANATION 

 Ceiadonite, interlayer charge

x Glauc

® Glauc

/

onite, interlayer charge 

onite, interlayer charge

C9.

C7e / 

C5/.C4

/*

C6 

C3

,C2

>+0.88

>+0.88

<+0.89

XG8

/

G3/ G 

x /

/ G2

3,1

(

/

G9x/

/

XG7 XG6

®G14

®G13 

5>G12

/G10

/

G19®

f

G18 

017

5 G4 

X

0.10 0.20 0.30 0.40 0.50 

DECREASE IN R+2 (VI)-ATOMIC RATIO

0.60

FIGUKE 3. Relation between decrease in Si and decrease in R+2 

(VI) in high potassium-high charge celadonites and 

glauconites.

0.60

0.50

0.40

0.30

0.20

0.10

0.00

EXPLANATION 

 Celadonite, interlayer charge >+0.88 

x Glauconite, interlayer charge >+0.88

® Glauc

C5,

/Z\

onite, interl

C9.

/& 

>/f*

-C2.

ayer charge

G3

X(

XCB

'.

C6 

,C3

<+0.89 

XG8

/ G2

31 

<

®GU

/4*

XG7 XG6

G5 X ® 

G15® XQ

®G14

®G13 

W

Aw

G19®

~G1B 

2 >G17 

G16 

4

0.10 0.20 0.30 0.40 0.50 

INCREASE IN R+3(VI)-ATOMIC RATIO

0.60

FIGUEE 4. Relation between increase in Ai(IV) and increase in 

R43 (VI) in high potassiuni-high charge celadonites and 

glauconites.
STUDIES OF CELADONITE AND GLAUCONITE Fll

respectively. The agreement between decrease in Si and 

decrease in R+2 (YI) and between increase in Al(IY) 

and increase in R+^YI) is very good in about one-half 

of the samples, Cl, C4, C5, C7, 08, Gl, G3, G7, and G9. 

In two samples, C9 and G8, the decrease in Si is greater 

than the decrease in R+2 (YI), and the increase in Al 

(IY) is greater than the increase in R+^YI) by more

than 0.03 atomic ratio. In the other eight samples- decrease in R+2 (YI) is greater than the decrease in Si, and 

the increase in R+3 (YI) is greater than the increase in 

Al(IY). The fact that the excess of R+2 (YI) decrease 

over Si decrease is almost identical with the excess of 

R+3 (YI) increase over Al(IY) increase strongly suggests oxidation in these samples.

TABLE 6. A1(IV)R+3 (VI) replacement of SiR+2 (VI) in high potassium-high charge celadonites and glauconites

Decrease Decrease Decrease in Increase Increase Increase in Negative

Si in Si R+* (VI) inR+2(VI) Si+R+2 (VI) Al(IV) inAl(IV) R« (VI) inR«(VI) Al(IV) la-rer

+R+s(VI) charge

Theoretical end-member. 4.00 1.00 0.00 0.00 1.00 0.00 1.00

Celadonites

Analysis:

01 -

2_ 

3 -_ -

4 

5 -----

6 -----

7--- - -----

8- --------

9 -.- -

Analysis:

Gl 

2---. -----

3 -

4

5 -

6- --------

7 

8-- - -----

9. -- 

10 

 4.00

---------- 4.00

--.-.- 3.90

__.._.-- 3.88

___ .-- 3.88

 .. 3.86

-------- 3.83

 3.79

-_ .. - 3.76

___ 3.73

-_ . -. 3.70

--- .-. 3.67

_. ---. 3.67

-..- --. 3.64

------ 3.63

-_-- -. 3.62

 . ... 3.58

 ...... . 3.55

. .. 3.43

0.00

.00

.10

.12

.12

.14

.17

.21

.24

0.27

.30

.33

.33

.36

.37

.38

.42

.45

.57

1.02

.76

.79

.85

.88

.80

.84

.78

.83

0.71

.63

.69

.43

.53

.54

.59

.63

.56

.39

0. 02 (1)

.24

.21

.15

.12

.20

.16

.22

.17

Glanconites

0.29

.37

.31

.57

.47

.46

.41

.37

.44

.61

0.24

.31

.27

.24

.34

.33

.43

.41

0.56

.67

.64

.90

.83

.83

.79

.79

.89

1.18

0.00

.00

.10

.12

.12

.14

2.17

.21

.24

0.27

.30

.33

.33

.36

.37

.38

.42

.45

.57

0.00

.00

.10

.12

.12

.14

.17

.21

.24

0.27

.30

.33

.33

.36

.37

.38

.42

.45

.57

1.00

1.19

1.21

1.15

1.10

1.20

1.18

1.22

1.19

1.29

1.39

1.30

1.48

1.47

1.46

1.41

1.37

1.46

1.61

0.00

.19

.21

.15

.10

.20

.18

.22

.19

0.29

.39

.30

.48

.47

.46

.41

.37

.46

.61

0.00

.19

.31

.27

.22

.34

.35

.43

.43

0.56

.69

.63

.81

.83

.83

.79

.79

.91

1.18

0.96

.91

.89

.97

1.06

.94

.95

.99

1.01

0.98

.87

1.04

1.03

.89

.91

.97

1.05

.94

.96

1 Increase 0.02.

2 Includes 0.03 atomic ratio Fe+3 .

In the high potassium-high charge celadonites and 

glauconites, therefore, the relations between decrease in 

Si and R+2 (YI) and increase in Al(IY) and R+3 (YI) 

indicate that these celadonites and glauconites belong to 

a Al(IY)R+3 (YI)-»SiR+2 (YI) replacement series, 

which starts with tetrasilicic mica, and which continues 

to about halfway between the tetrasilicic and trisilicic 

end-members, or to a replacement of about 0.5 Si and 

0.5 R+2 (YDby 0.5 Al(IY) and 0.5 R+3 (YI). The discrepancies in some of the samples between R+2 (YI) decrease 

and Si decrease, and between R+3 (YI) increase and Al 

(IY) increase indicate oxidation of R+2 (YI) to R+3 

(YI). In the most divergent samples, C2 and G4, octahedral occupancy is low, only 1.95 and 1.91 positions, 

respectively. This low octahedral occupancy may indicate faulty analysis or analysis of impure samples, 

which may account for the fact that the SiR+2 (YI) and 

A1(IY)R+3 (YI) data for these analyses do not correlate 

with such data for the other high potassuim-high charge 

celadonites and glauconites.

The data for SiR+2 (YI) and A1(IV)R+3 (YI) relations in high potassium glauconites having interlayer 

charges less than +0.89 per half cell are given in tab^e 7. 

In all these glauconites there is good agreement between 

Si+R+2 (YI) and Al(IY) +R+3 (YI). However, in these 

glauconites, R+2 (YI) decrease is significantly greater 

than Si decrease, and R+3 (YI) increase is greater than 

Al(IY) increase. The amount that the decrease in R+2 

(YI) exceeds the decrease in Si agrees closely with the 

amount that the increase in R+3 (YI) exceeds the increase in Al(IY). Thus, there is evidence of oxidation 

in all these glauconites, and this oxidation of bivalent 

to trivalent iron may account for the lower interlayer 

charge of these glauconites as compared with those 

having comparable contents of potassium but higher 

interlayer charges.

Data on Al(IY) and R+3 (VI) replacement of Si and 

R+2 (yi) in celadonites and glauconites having less than 

0.66 potassium ion per half cell, given in table 8, also 

show close agreement between Si+R+2 (YI) decrease 

and Al(IY) +R+3 (YI) increasa In the low potassium
F12 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 7. A1(IV)R+3 (VI) replacement of SiR+2 (VT) in high potassium C>0.66)-low charge «-f0.S£) glauconites

Decrease Decrease Decrease in Increase Increase Increase in Negative

Si in Si R« (VI) in R« (VI) Si+R« (VI) Al(IV) in Al(IV) R« (VI) in R+s (VI) Al(IV) layer

+R«(VI) charge

Theoretical end-member. 4.00 1.00 0.00 0.00 1.00 0.00 1.00

Analysis: 

Gil 

12 

13 

14 . 

16 

16.. . 

17 

18 

19 

 . 3.79

 . . 3.74

 3.72

 3.69

 ... . 3.66

 3.64

... .... ... ... 3.63

 .- . 3.62

 ... . 3.56

0.21

.26

.28

.31

.34

.36

.37

.38

.44

0 64

.60

.56

.57

.57

.49

.49

.43

0.36

.40

.44

.43

.43

40

.51

.51

.57

0.57

.66

.72

.74

.77

.85

.88

.89

1.01

0.21

.26

.28

.31

.34

.36

.37

.38

.44

a 01

.26

.28

.31

.34

.36

.37

.38

1.36

1.40

1.44

1.45

1 40

1.62

1.51

1.59

0.36

.40

.44

.45

.45

.49

.62

.51

.59

0.57

.66

.72

.76

.79

.85

.89

.89

1.03

0.85

.86

.84

.82

.85

.87

.83

.87

.81

celadonites and glauconites that have interlayer charges 

greater than +0.85, the decrease in R+2 (VI) agrees 

fairly well with the decrease in Si, and the increase in 

R+3 (VI) with the increase in Al(IV), but in the low 

potassium-low charge glauconites the discrepancy between these values is considerably greater. Again, the 

close agreement between the amount that the decrease 

in R+2 (VI) exceeds the decrease in Si and the amount 

that the increase in R+3 (VI) exceeds the increase in 

Al(IV) suggests oxidation of bivalent to trivalent iron 

by the amount of the excess.

The data on decrease in Si and R+2 (VI) and increase 

in Al(IV) and R*3 (VI) indicate that the low potassium 

celadonites and glauconites belong to the same isomorphous replacement series as the high potassium celadonites and glauconites. However, the amount by which

the decrease in R+2 (VI) exceeds the decrease in Si, and 

the amount by which the increase in R+3 (VI) exceeds 

the increase in Al(IV) are greater in them, and therefore indicate greater degrees of oxidation.

As shown in figure 5, there is a close agreement between the excess of R+2 (VI) decrease over Si decrease 

and layer charge excess or deficiency compared with 

 1.00, the layer charge of the theoretical end-member, 

regardless of the amount of excess or the charge excess 

or deficiency. As excess of R+2 (VI) decrease over Si decrease suggests oxidation, and as oxidation reduces the 

layer charge by the number of ferrous ions oxidized, 

this close relationship implies that most of these celadonites and glauconites, whether high or lov in potassium, originally had layer charges very close to the 

theoretical 1.00.

TABLE 8. A1(IV)R+3 (VI) replacement of SiR+2 (VI) in low potassium «0.66 per half cell) celadonites and glauconites

Decrease Decrease Decrease in Increase Increase Increase in Negative

Si in Si R« (VI) in R+s (VI) Si+R+» (VI) Al(IV) in Al(IV) R« (VI) in R« (VI) A1(IV) layer

+R«(VI) charge

Theoretical end-member. 4.00 1.00 0.00 0.00 1.00 0.00 1.00

Celadonites

Analysis: 

CIO.....- .. ..

11.. .. .. ..

12.. .

13..-...-- .

.... . 3.89

.-..-- . 3.88

.- .. .. 3.79

..- . . 3.76

0.11

.12

.21

.24

0.66

.74

.75

.73

0.34

.26

.25

.27

0.45

.38

.46

.51

0.11

.12

>.21

.24

0.11

.12

.21

.24

1.34

1.26

1.25

1.27

0.34

.26

.25

.27

0.45

.38

.46

.51

0.77

.84

.95

.97

High charge glauconites O+0.88)

Analysis: 

G20 . .... - 

21 . . 

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

23 

24. 

. . _ 3.68

. .. 3.62

 ..-.. 3.60

3.57

. ... 3.49

0.32

.38

.40

.43

.51

0.68

.51

.53

.54

.44

0.32

.49

.47

.46

.56

0.64

.87

.87

.89

1.07

0.32

.38

.40

.43

.51

0.32

.38

.40

.43

.51

1.34

1.49

1.47

1.46

1.56

0.34

.49

.47

.46

.56

0.66 0

.87

.87

.89

1.07

(VI

89

93

07

96

Low charge glauconites «+0.89)

Analysis: 

G25 .......... ....

26 . 

27 

28 

29 

30...... .......

31 

32 

 . 3.85

.... .... ... .. 3.79

.... .. 3.75

 ..... 3.66

 - 3.66

 ....... 3.65

 3.63

..... 3.62

0.15

.21

.25

.34

.34

.35

.37

.38

0.61

.47

.53

.48

.57

.52

10

.48

0.39

.53

.47

.52

.49

.48

.61

.52

0.56

.74

.72

.86

.83

.83

.98

.90

0.15

.21

.25

.34

.34

.35

.37

.38

0.15

.21

.25

.34

.34

.35

.37

.38

1.39

1.51

1.47

1.54

1.49

1.48

1.61

1.53

0.39

.51

.47

.54

.49

.48

.61

.53

0.56

79

.72

.88

.83

.83

no

.91

0.76

.74

.78

.76

.85

.87

.75

.83

' Includes 0.06 atomic ratio Fe^.
STUDIES OF CELADONITE AND GLAUCONITE F13

-i-U.28 

+0.24 

+0.20 

+0.16 

+0.12 

+0.08

+0.04. 

0.00

-0.04 

-0.08 /

>cG4

'//

x'

 X

C2

/

X

/%

s

X

X

/

'XX

=XPLf

 Ce

* X Gla

/

WATI 

adonite 

uconite

/

DN 

+0.08 +0.04 0,00 -0.04 -0.08 -0.12 -0.16 -0.20 -0.24 -0.28 

LAYER CHARGE EXCESS OR DEFICIENCY

FIGURE 5. Relation between excess of R+2 (VI) decrease over 

Si decrease and layer charge excess or deficiency.

INTERPRETATION OF GLAUCONITE COMPOSITION

RELATION BETWEEN TRIVALENT IRON AND 

OCTAHEDRAL ALUMINUM

In the first part of this study it was shown that except 

for deficiency in potassium content, potassium-deficient 

glauconites are very similar in composition to the high 

potassium glauconites. Aside from potassium content, 

the most variable constituents in these glauconites are 

the trivalent octahedral cations, iron and aluminum, 

which bear a reciprocal relation to each other (fig. 6). 

These relations, especially when found in high potassium-high charge glauconites, suggest that a high content of octahedral aluminum in a glauconite may not 

necessarily indicate degradation or admixture, but 

might be indicative of the environment in which the 

glauconite developed specifically with reference to the 

concentration of iron.

Because many glauconites are high in iron, it has been 

generally postulated that glauconite is developed in environments rich in iron. Even in such environments, 

however, iron concentration differs greatly, and these 

differences are reflected in the iron content of the 

glauconite.

THE Pe+3:Fe+2 RATIO

Theoretically, the relation between bivalent and trivalent iron in a glauconite is determined by the oxidation 

potential in the environment of its development. With 

change of environment, however, a glauconite may un0.90 

0.80 

0.70 

0.60 

0.50 

0.40 

0.30 

0.20

0.10 

0.00

X*

<

 X

E 

More tt 

Fewer 1

X

XPLAI 

ian 0.65 

ban 0.6

 

x *

x»

X 

X

MATIO 

Kionp 

>KJon

x

x

N 

erhalfc 

ier half

x

XX

en

cell -

X

0.50 0.60 0.70 0.80 0.90 1.00 1.10 .1.20 

TRIVALENT (VI) IRON-ATOMIC RATIO

1.30 1.40

FIGURE 6. Relation between Fe*8 and Al(VI) in glauconiter*

dergo oxidation; this appears to have happened to many 

of the glauconites under review. As has been pointed 

out, oxidation is strongly suggested when the decrease 

in R+2 (VI) is greater than the decrease in Si, and tie 

increase in R+8 (VI) is greater than the increase in 

Al(IV) compared with the theoretical tetrasilicic endmember, and when the amount by which the decrease in 

R*2 (VI) exceeds the decrease in Si agrees closely with 

the amount by which the increase in R+3 (VI) exceeds 

the increase in Al (IV).

The only glauconites included in this study in which 

R+2 (VI) decrease agreed closely with Si decrease, and 

R+3 (VI) increase agreed closely with Al(IV) increase, 

indicating little or no oxidation, are those high potassium glauconites that also have layer charges close to 

-I.00i0.05, Gl, G3, G4, G7, and G9. In all the other,-', 

the relations between R+2 (VI) and Si and between 

R+3 (VI) and Al(IV) indicate that some oxidation hrs 

taken place, and that Fe+3 : Fe+2 ratios calculated from 

the analytical results do not reflect the true oxidationpotential of the respective environments of development 

For glauconites that have undergone only a minor 

degree of oxidation, the calculated Fe+3 : Fe+2 approximates the Fe+3 : Fe+2 relation in the original glauconit?-. 

If, however, two-thirds or more of the original bivalert 

iron has been oxidized, as in G26, G28, and G31, such 

calculated ratios would be very misleading, unless tl ^ 

amount of oxidation, as indicated by the amount 

by which the decrease in B+2 (VT) exceeds the decrease
F14 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

in Si and the amount by which the increase in 

R+? (VI) exceeds the increase in Al(IV), is taken into 

consideration.

RELATION BETWEEN IRON AND POTASSIUM

As is obvious from figure 7, there is no correlation 

between potassium and iron in glauconites. Glauconites 

high in potassium may be high, medium, or low in iron, 

and others low in potassium may be high, medium, or 

low in potassium. This is contrary to Hower's (1961) 

conclusion that in glauconites, potassium and iron 

should be directly proportional to each other. However, 

these constituents are incorporated into the structure 

by different processes, and any proportionality between 

them is coincidental.

After a study of glauconite formation in modern 

foraminiferal sediments of the southeastern coast of 

the United States, Ehlmann, Hulings, and Glover, 

(1963, p. 95) concluded that "the earliest stage material 

having an FesOs content of 20 percent may be regarded 

as a potassium-deficient prototype of glauconite with 

iron already incorporated into the structure." This conclusion supports the present hypothesis that glauconitization consists of two separate, unrelated processes, 

incorporation of iron into the crystal structure and fixation of potassium in interlayer positions, with incorporation of iron and development of negative layer charge

0.84 

0.80

Q 0.76

I 

0°-?2

^0.68

5 

o

8 0.64

g£L

0.60 

0.56 

0.52 

0.48

X

EXPLANATION 

More than 0.65 K ion per half c 

Fewer than 0.66 K ion per half

X X

X

X

ell

cell

»

X

XX

X

x :

: :

0.60 0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 

(Fe+2+Fe+3)-ATOMIC RATIO

FIGURE 7. Relation between total iron and potassium in 

glauconites.

preceding complete fixation of potassium. Thus, there is 

not necessarily a relation between iron and potassium 

in a glauconite, as has been postulated by some 

investigators.

FIXATION OE POTASSIUM

Fixation of potassium may begin to take place relatively early in the development of a glauconite, especially if the parent material is a stripped and degraded 

layer silicate, with potassium first being taken into 

exchange positions before becoming fixed. As the potassium gradually settles into fixed positions and thus 

changes the relative proportions of the exchangeable 

cations present, continual readjustment is required between the exchangeable cations present and tlie cations 

of the surrounding water, usually sea water. Eventually, 

if the process is not interrupted, most of the negative 

layer charge is neutralized by potassium. As more and 

more potassium becomes fixed, the sheets become more 

and more tightly bound together, and further entry of 

potassium becomes increasingly difficult. Thu^, it may 

be that fixation never proceeds to completion in a glauconite, and that most glauconites contain some exchangeable cations. An occupancy of about 85 percent 

of the possible interlayer positions, as in G3, G4, G15 

and G18, may be the maximum to be expected in glauconites, even though their negative layer charges are 

equivalent, as in G3 and G4, to those of true micas.

DEFICIENCY IN POTASSIUM CONTENT

Deficiency in potassium content may be due to failure 

to attain maximum fixation because of change of environment, burial, uplift, or dilution, or to oxidation, 

with accompanying decrease in layer charge and loss 

of some potassium that had been fixed. Failure to attain maximum fixation of potassium is exemplified by 

glauconites G20-G24. These five glauconites all have 

high layer charges, ranging from 0.89 to 0.97, per 

half cell, but they contain only from 0.48 to 0.62 ions of 

potassium, with exchangeable cations neutralizing the 

remainder of the layer charge. Although a slight excess 

of K+2 (VI) decrease over Si decrease and excess of K+8 

(VI) increase over Al(IV) increase indicate some 

oxidation in those with layer charges less than 0.95, 

their very high content of exchangeable cation? averaging 0.39 positive charge per half cell, and particularly 

their content of exchangeable sodium, averaging 0.19 

ion per half cell, is very suggestive of immaturity. The 

fact that the R+2 (VI) and Si and the K+3 (VI) and Al 

(IV) relations in these glauconites indicate that they 

have undergone little oxidation also suggests immaturity as the cause of the low content of potassium.
STUDIES OF CELADONITE AND GLAUCONITE F15

Many of the glauconites that have undergone oxidation are characterized by relatively lower contents of 

bivalent iron, lower layer and interlayer charges, lower 

exchangeable cation content, and a somewhat lower 

potassium content. For example, the relations between 

decrease in E+2 (VI) and in Si, and between increase in 

E+3 (VI) and in Al (IV) in seven high potassium glauconites having layer charges of 0.95 or more, Gl, G3, 

G4, and GT-G10, indicate that these glauconites have 

undergone no oxidation; whereas in six other high potassium glauconites, Gil, G13-G15, GIT, and G19, the 

relations between decrease in E+2 (VI) and in Si and 

between increase in E+3 (VI) and in Al(IV) indicate 

that from 0.10-0.16 ion of bivalent iron has been oxidized to trivalent iron. As a result of this oxidation 

these glauconites have not only lower layer charges, 

averaging 0.83 compared with an average of 1.00 

in the seven unoxidized glauconites, but an average of 

0.13 fewer bivalent iron cations, and only about half 

as many exchangeable cation charges, averaging +0.10 

as compared with 0.21. Although there is also a slight 

decrease in average potassium content, from 0.77- 

0.73, most of the loss in negative layer charge has 

been offset by the release of exchangeable cations, not of 

fixed potassium.

In some of the low potassium glauconites it is difficult to determine whether potassium deficiency is due 

to oxidation or immaturity. The relations between decrease in E+2 (VI) and in Si and between E+3 (VI) and 

Al (IV) in these glauconites indicate that they have lost 

an average of 0.24 cation of bivalent iron by oxidation. 

In terms of the individual glauconites this means that 

one-half (for G25 and G27), two-thirds (for G26 and 

G28), and three-fourths (for G31) of the bivalent iron 

originally present has been converted to trivalent iron. 

It also means that there has been a loss in negative layer 

charge corresponding to the loss in bivalent iron content, as these glauconites have an average layer charge 

of 0.76. With an average exchangeable cation charge 

only + 0.05 less than that in the unoxidized high chargehigh potassium glauconites, Gl, G3, G4, and G7-G10, 

it is difficult at this stage to resolve the reason for the 

deficiency in potassium in these glauconites, which 

averages only 0.61 ion per half cell whether it is due 

to release because of oxidation, or to immaturity, failure 

to attain maximum fixation, as in G20-G24, or to a combination of the two.

RELATION BETWEEN GLAUCONITE COMPOSITION 

AND GEOLOGIC AGE

Attempts to correlate glauconite composition with 

geologic age have not been altogether successful; too 

few analyses of glauconites can be reliably referred to

definite geologic periods to furnish adequate information as to trends in composition over the eons of geologic time. Smulikowski (1954) based a correlation on 

average values of the principal constituents of the gk.uconites assigned to various geologic periods. He concluded (p. 77) that "the older the geological formation, 

the smaller in its glauconite the prevalence of ferric 

iron over aluminum in the octahedral layer and the 

greater in its glauconite the total amount of interlayer 

cations." He based these broad conclusions on six analyses for the Quaternary Period, 18 for the Tertiary, 13 

for the Cretaceous, none for the Triassic, Permian, 

Carboniferous, and Devonian, two for the Silurian, f ve 

for the Ordovician, and three for the Cambrian. Smrlikowski excluded from consideration five analyses of 

Jurassic glauconites because all were by the same r,nalyst, and represented glauconites from only two Iocs Uties, both in Eussia. However, four of his five Ordovician analyses were from limestone in Sweden, and 

these he did include. All in all, he had no data for the 

long period of time between the end of the Silurian and 

the beginning of the Cretaceous, and only scanty data 

(10 analyses) for the Silurian, Ordovician, and Cambrian, which he grouped together as early Paleozoic, 

a peribd of almost 200 million years.

Smulikowski's average values for octahedral aluminum in Tertiary, Cretaceous, and early Paleozoic glp-uconites, 0.399, 0.426, and 0.501 ion per half cell, respectively, differ by only 0.102 ion for a length of time of 

more than 500 millions of years. This is a very small 

difference in amount of octahedral aluminum and very 

scant data upon which to base the broad conclusions he 

came to, particularly in view of the great variations in 

the compositions of the Tertiary and Cretaceous glauconites upon which his averages for these periods are 

based. Thus, his average value of octahedral aluminum 

in Tertiary glauconites is based on values that rarge 

from 0.121 to 0.686 ion per half cell, and in Cretaceous 

glauconites from 0.135 to 0.942 ion. The variation in 

content of octahedral aluminum in glauconites referred 

to each of these periods is more than six and nine times 

greater than the average difference between octahedral 

aluminum in the Tertiary and early Paleozoic 

glauconites.

The great variety of composition to be found in glauconites from the Cretaceous and Tertiary, the periods 

best represented in the glauconites included in this 

study, is indicated in figure 8. The range in content of 

octahedral aluminum, bivalent and trivalent iron, potassium and interlayer charge among the eight Cretaceous glauconites is almost as great as among the entire 

suite of analyses studied. They range from the highly 

ferruginous, as illustrated by Gil, in figure 8, to the
F16 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

CRETACEOUS TERTIARY

Table 2, No. Gil 

-0.64 -0.21

Average 

-'0.55 -0.30

Table 2, No. Gl 

-0.71 -0.27

Table 3, No. G25 

0.61 -0.17

Average 

-0.55-0.33.

Table 2, No. G16 

-0.51 -0.36

Si K Exchangeable 

cations

FIGURE 8. Extreme and average compositions of Cretaceous and Tertiary glauconites. Figures above the first and second 

Columns of each diagram indicate the positive-charge deficiencies of the octahedral and tetrahedral layers; fig ires above 

the third column indicate the positive interlayer charge.

highly aluminous, as illustrated by Gl, in figure 8. They 

are equally variable in potassium content and in interlayer charge, ranging from 0.84 to 0.57 ion of potassium per half cell, and + 0.97 to + 0.76 interlayer charge 

per half cell. Some of the Tertiary glauconites studied 

are as ferruginous as any of the Cretaceous glauconites, 

but none of the Tertiary glauconites were as high in 

octahedral aluminum as Gl, the highest octahedral 

aluminum content occupying only 30.0 percent of the 

octahedral layer. The range in potassium content in 

the Tertiary glauconites, from 0.88 to 0.58 ion per half 

cell, is very similar to that in Cretaceous glauconites,

as is also the range in interlayer charge, from +1.03 

to 0.77.

The variety of compositions found among both the 

Cretaceous and Tertiary glauconites suggests that geologic age has little to do with the compositior of glauconites. Other factors, such as the specific environment 

in which the glauconite is formed particular^ its degree of iron concentration and its oxidation-reduction 

and opportunities for potassium fixation and for oxidation, are of far greater importance in determining the 

composition of a glauconite than the geologic age in 

which it was formed.
STUDIES OF CELADONITB AND GLAUCONITE F17

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