The Serpentine-Group 

Minerals

GEOLOGICAL SURVEY PROFESSIONAL PAPER 384-A
The Serpentine-Group 

Minerals

By GEORGE T. FAUST and JOSEPH J. FAHEY

STUDIES OF THE NATURAL PHASES IN THE SYSTEM 

MgO-SiO2 -H2O AND THE SYSTEMS CONTAINING THE 

CONGENERS OF MAGNESIUM

GEOLOGICAL SURVEY PROFESSIONAL PAPER 384-A

Correlation of the physical and chemical properties 

in terms of crystal chemistry, and the application 

of geo chemical data to thepetrogenesis of serpentine 

and ultrabasic rocks

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1962
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

REPRINTED 

1964

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

Washington, D.C., 20402 - Price 65 cents (paper cover)
CONTENTS

Abstract-..________________________________________

Introduction _______________________________________

Acknowledgments_____. _____________________________

The term "serpentine"- ___--___-____-______--_-_____

Mineral names used in this study.______________ _____

Geological occurrence of the specimens studied-________

Description of the minerals._________________________

Preparation of the samples for study._________________

Chemical studies of serpentine and related minerals.

Methods of chemical analysis.___________________

Analyses studied for this report__________________

Analyses taken from the literature_________________

Location and description of 219 specimens. ____

Analyses of 219 specimens. ________________ _

Interpretation of the chemical analysis.___________

Interpretation of the calculated structural formulas 

of the samples reported in this study.____-____-.

Interpretation of the structural formulas calculated

from analyses obtained from the literature._ 

Thermal-analysis studies. ____________________ ______

Static (dehydration) method.____________________

Dynamic (differential-thermal-analysis) method-___.

Previous DTA studies on serpentine-group

minerals._ _______________________________

Present DTA studies._________ _____________

Interpretation of the DTA curves__ _ ________________

A typical clinochrysotile curve______--_____-___..

The collection of chrysotile and lizardite curves..---

Detailed analysis of the curves in the tempera

ture range 85° to 200°C. _-_-___-___-_-____

Detailed analysis of the curves in the temperature range 200° to 600°C__________________

Detailed analysis of the curves in the temperature range 600° to 750°C__ ________________

1

1

3

3

4

7

8

18

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18

18

19

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27

27

37

40

48

48

51

52

53

53

53

55

55

59

Interpretation of the DTA curves Continued

The collection of chrysotile and lizardite curves Con.

Detailed analysis of the chrysotile and lizardite

curves in the temperature range 750° to

A typical antigorite curve____ _ ___________________

The collection of antigorite curves. _______-_-_.___

Detailed analysis of the antigorite curves in the

temperature range 25° to 700°C ..---__--_..

Detailed analysis of the antigorite curves in the

temperature range 700° to 800°C ___________

Detailed analysis of the antigorite curves in the

temperature range 800° to 1,100°C ___ _--__

Effect of some admixed minerals on the DTA patterns

of serpentine. ________________________________

Application of the DTA studies on the serpentinegroup minerals to problems of identification. _____

X-ray studies. ____-___--_--____--_________--_--_-__

X-ray classification of the serpentine-group minerals. 

X- ray powder diffraction studies. . ________________

Status of deweylite_ ________________________________

Geochemical studies. _______________________________

Distribution of minor elements in magnesium-rich 

minerals and rocks and in some contrasted rock 

types... _.___-------_-_-------------------..-

Minor elements present in the serpentine minerals 

studied- _____________________________________

Some theories on the origin of serpentine and serpentine-rich rocks____ _ ___-_-_--__-____--__-___

Minor elements in serpentine minerals as petrological 

indicators _ _ __-___-__-_-__.___-____----_--_-

Literature cited. ___________________________________

Page

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77

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79

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81

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85

87

ILLUSTRATIONS

FIGURE 1. The mathematical curve named serpentine________________________________________________

2. Clinochrysotile (Globe-type), Gila County, Ariz___________________________________________

3. Clinochrysotile (deweylite), near Moa, Cuba._____________________________________________

4. Clinoehrysotile (iron-bearing serpentine), Stillwater County, Mont_________________________

5. Clinochrysotile and lizardite (deweylite) Forest Hill, Harford County, Md____________________

,6. Clinochrysotile and lizardite, Morris County, N.J____________________--__-____--------___

7. Clinochrysotile and lizardite, variant form, Morris County, N.J.____________________________

8. Lizardite plus clinochrysotile, Snarum, Norway__________________________________________

9. Lizardite plus clinochrysotile, Snarum, Norway, another part of the thin section___________-___

10. Lizardite (deweylite), Delaware County, Pa__-___________-_____________-_---__---__--_--

11. Lizardite, Staten Island, Richmond County, N.Y___-_____---_______-___------------_--_-_-

12. Antigorite and chrysotile (baltimorite), Baltimore County, Md______________________________

13. Antigorite with minor amounts of chrysotile (Yu-Yen Shi stone), Liaoning Province, Manchuria14. Antigorite (williamsite), Low's mine, Lancaster County, Pa_________________________________

15. Antigorite (from the type locality), Val Antigorio, Italy.__________________-_-----_-----____

16. Antigorite, similar to figure 15, but a platy form__________-__-__-_______---_--___-------_

17. Antigorite, vicinity of Caracas, Venezuela_____________________----____-----------------_

Page

4

14

14

14

14

15

15

15

15

16

16

16

16

17

17

17

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IV CONTENTS

Page 

FIGURE 18. The relation between the ions in octahedral coordination and the ions in tetrahedral coordination calculated from

the analyses reported in this study_____________________-.____-_-_-_--__-_-___--_-_-___-___-_________ 38

19. The relation between the ions in octahedral coordination and the ions in tetrahedral coordination calculated from 

the chemical analyses of samples called deweylite and reported in this study. Section along the tieline 

theoretical serpentine to theoretical ste vensite. _______________________________________________________ 39

20. The relation between the ions in octahedral coordination and the ions in tetrahedral coordination calculated from

the chemical analyses taken from the literature-._____________________________________________________ 42

21. The relation between the ions in octahedral coordination and the ions in tetrahedral coordination calculated from 

the chemical analyses taken from the literature. Section along the tieline theoretical serpentine to theoretical 

stevensite__ _ _______________-_--________________________-_--___________--__--__-____-_--_-_____-- 43

22. Natural phases in the ternary system MgO-SiO2-H2 0___________________________________________________ 44

23. Graphs of the relation 2-j versus ^ for serpentine of class A__-_--_-_-___-_-_--__-_--__-___-_-_--__-_-_ 46

^-\ ^-\

24. Graphs of the relation ^-J versus -f-r' for serpentine of class B______-______-_______________-____-___-__-_ 47 ^ oct tet ^

25. Thermal-analysis curves of serpentine-group minerals obtained by the static method. _____-__--_-_--_-______ 49

26. Thermal-analysis curves of serpentine-group minerals obtained by the static method________________________ 50

27. Thermal-analysis curve of lizardite__________________________________-_____-_____________.:_____________ 52

28. Differential-thermal-analysis curves of clinochrysotile from Pennsylvania, New Jersey, and Arkansas and from

	a synthetic preparation._____-___-___-___________________-_____-_-__-__-_-_-_--_-__-____--___-___-- 56

29. Differential-thermal-analysis curves of clinochrysotile from Cuba, California, and Quebec-___________________ 57

30. Differential-thermal-analysis curves of clinochrysotile (Globe-type) from Arizona, New Jersey, and Nevada. _ _ _ _ _ 58

31. Differential-thermal-analysis curves of clinochrysotile (Globe-type) from Pennsylvania.____________________ 59

32. Differential-thermal-analysis curves of clinochrysotile plus orthochrysotile_________________________________ 60

33. Differential-thermal-analysis curves of chrysotile plus lizardite, C>L, from New York, Cuba, and California..---- 61

34. Differential-thermal-analysis curve of chrysotile plus lizardite, C>L, from New Jersey______________________ 62

35. Differential-thermal-analysis curves of lizardite plus clinochrysotile, L> C _________________________________ 63

36. Differential-thermal-analysis curves of lizardite from Vermont, Austria, and New York._____________________ 64

37. Differential-thermal-analysis curves of lizardite from Hungary, Tennessee, and Pennsylvania_________________ 65

38. Schematic diagram showing the method of designating the angular relationships in an endothermie trough_____ 67

39. Differential-thermal-analysis curve of the type lizardite-..________________________________________________ 69

40. Differential-thermal-analysis curves of antigorite______________________________________________________ 73

41. Differential-thermal-analysis curves of serpentine-group minerals admixed with paragenetically associated miner- 

	als.,-.. ___..._________________________.______-_____-_---_-____________-______ 76

42. Graphical representation of the concentration of some minor elements in the serpentine-group minerals..______ 81

TABLES

Page 

TABLE 1. Mineral names used in this paper with interpretation of the pertinent data_____-_--_--____----------_---__- 5

2. Chemical analyses of serpentine minerals formed by the reaction of hydrothermal solutions with ultrabasic rocks,

class A_____-___-_-_-----_-__----___--________-______-___-------__,.--_---_----_-___--_____-_-____ 18

3. Chemical analyses of serpentine minerals formed in calcareous or dolomitie rocks by the replacement of ferromagnesian minerals by hydrothermal solutions or by deposition by hydrothermal solutions, class B__-_________ 19

4. Chemical analysis of a partially serpentinized phlogopite (eastonite)______________________________________ 19

5. Chemical analyses of serpentine and related minerals taken from the literature_____________________________ 28

6. Equivalent weights used in the calculations_______--___---__--_-----------*-----------------_-_--------- 32

7. Relationship of the ions in octahedral and tetrahedral coordination as calculated from the chemical analyses of

the specimens studied and listed in tables 2 and 3__---_----_--------------------------------------_-- 33

8. Relationship of the ions in octahedral and tetrahedral coordination as calculated from the chemical analyses of

serpentine group minerals taken from the literature and listed in table 5_ __________________________ _____ 34

9. Relationship of the ions in octahedral and tetrahedral coordination as calculated from the chemical analyses of

jenkinsite, hydrophite, and zineian serpentines. ________-____-__---_-_------------_________-______--_- 36

10. Relationship of the ions in octahedral and tetrahedral coordination as calculated from the chemical analyses of

antigorites studied and listed in tables 2 and 3_____----------_------------------------------_-------- 41

11. Thermal-analysis data obtained by the static method on minerals of the serpentine group.____________________ 51

12. Correspondence between H2O reported in chemical analysis and that found by dehydration studies. __________ 51

13. Observations of the differential-thermal-analysis curves of chrysotiles and lizardites__-_-_______________--_-_ 54

14. Relation between H2O in chrysotiles and lizardites and their behavior in differential thermal analysis___--_ 62

15. Comparison of FeO and FeaOs in chrysotiles and lizardites with their thermal behavior in differential thermal

analysis, and with their paragenesis and mineralogy..___________--__-_------------____________-_______ 66

16. Angular relationships of the high temperature endothermie trough of the chrysotiles and lizardite_____-_______ 68
CONTENTS V

Page 

TABLE 17. Phases identified by X-ray methods in the chrysotile and lizardite specimens heated to about 1,000°C in the

DTA studies._____-------_-_____--_-_-____________-_-_________-_-________----------------------__ 70

18. Summary and relations of the thermal data in the temperature range of 600° to 1050°C of chrysotile and lizardite__ _ 71

19. Comparison of the high-temperature thermal data of the chrysotiles and lizardites- _________________________ 71

20. Observations of the differential-thermal-analysis curves of antigorite and samples composed chiefly of antigorite_ 72

21. Angular relationships of the principal endotherm of the antigorites________________________________________ 74

22. Phases identified by X-ray diffraction methods in specimens of antigorite heated to about 1,000°C in DTA studies. - 74

23. Classification of the serpentine specimens studied by X-ray powder diffraction methods_____________________ 78

24. Chemical, differential-thermal-analysis, and X-ray data on some minerals called deweylite___________________ 79

25. Minor elements in serpentines..____--__--_______-__-__-_--________-___-____--______ _________________ 82

26. Basic data on the serpentine-group minerals studied geochemically____________________________ ____________ 83

27. Geographic finding list for description of specimens used in this study _____________________________________ 86

28. Geographic finding list for chemical analyses taken from the literature____________________________________ 87

STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-Si02-H20 AND OF THE SYSTEMS CONTAINING THE

CONGENERS OF MAGNESIUM

THE SERPENTINE-GROUP MINERALS

By GEORGE T. FAUST and JOSEPH J. FAHEY

ABSTRACT

Twenty-eight chemically analyzed specimens for 19 of which 

the analyses have not been published previously and many 

unanalyzed specimens of serpentine-groups minerals were 

studied by various techniques, including chemical, optical, 

static dehydration, and differential-thermal-analysis (DTA), and 

X-ray powder diffraction methods. The various data were 

correlated and used to interpret the mineralogy of the serpentine 

group. This study demonstrates once again the necessity of 

using many experimental techniques in the identification of 

these fine-grained minerals. The admixture of small amounts 

of foreign phases in serpentine must always be suspected, and 

each of the various techniques has its special field of application 

in disclosing their presence. Admixtures of the polymorphous 

members of the serpentine group amongst themselves, when they 

are present to the extent of 25 percent or more, can usually be 

identified by X-ray powder diffraction methods, commonly by 

differential-thermal-analyses, and almost always by a combination of these methods and the use of the solution technique of 

Nagy and Bates (1952). The problem of identification of these 

admixtures becomes more difficult when the amount of a second 

polymorph is 10 percent or less of the sample. In such specimens 

the solution technique and electron microscopy may prove very 

valuable and may yield an unequivocal answer.

The calculation of the chemical analyses of selected and carefully purified members of the serpentine group to the structural 

formula XeY4Oio(OH) 8 reveals the closeness of the agreement 

between the analyses and the structural formula. X ranges 

from 6.04 to 5.81, and Y ranges from 4.00 to 4.09.

A compilation of 219 analyses from the literature is given.

The chemical uniqueness of antigorite in the serpentine group 

is affirmed. An examination of the data shows that with one 

exception, sample F-53, all the specimens that show a deficiency 

of 0.19 to 0.16 ion in octahedral coordination are antigorites. 

This compositional difference sets apart the antigorites from the 

chrysotiles and lizardite.

Considering the possibility of analytical error, the close agreement of the structural formulas calculated from analyses of the 

chrysotiles and lizardite with the theoretical formula is remarkable and is evidence of the constancy in composition. The 

numerical expressions in the structural formula are admirably 

suited as cartesian coordinates, and a plot of the sum of the 

ions in tetrahedral sites versus the sum of the ions in octahedral 

sites is very informative. Plotting the formula of stevensite in 

terms of the serpentine formula and connecting it with a tieline 

to the theoretical formula of serpentine brings to light the true 

nature of the analyses of those deweylites which lie astride or 

near the tieline. These are admixtures of serpentine and stevensite, a disclosure confirmed by DTA (see below) and X-ray 

studies.

From the information revealed by the study of the analyses 

of these specially selected and purified samples, it is possible to 

interpret the analyses of the serpentine group minerals taken from 

the literature. That the material called deweylite is an admixture of serpentine and stevensite is again confirmed.

A critique of the differential-thermal-analysis (DTA) method 

as applied to a group of minerals shows the limitations that must 

be placed on the interpretation of the significance of the temperature of endothermic and exothermic reactions, of the differences 

in temperature between such reactions, and of the angular relations of the endotherms. The DTA method is very valuable for 

differentiating between antigorite and the pair chrysotilelizardite. It is very helpful in detecting and estimating the 

amounts of many common admixtures of other minerals with 

serpentines.

According to the paragenetic and the spectrographic data 

given in this paper and the geochemical and petrological data 

from the literature, the geochemistry of the serpentine group 

minerals is related to their mode of origin and to the genesis of 

ultrabasic rocks. Geochemical studies show that there is a relation between the minor-element content of serpentines and their 

geologic origin. Serpentines derived from ultrabasic rocks 

through deuteric or subsequent hydrothermal replacements are 

rich in the suite of minor elements consisting of niekel, chromium, cobalt, and scandium, whereas serpentines derived from 

various types of metamorphic limestones and dolomites, from 

contact metamorphic deposits and from hydrothermal replacements and hydrothermal veins in these rocks, are notably poor 

in this suite of minor elements. From these observations and 

data from various petrologic and geochemical studies in the 

literature it is concluded that minor-element studies lend no 

support to the proponents of the theory that ultrabasic rocks 

are produced by metamorphism from magnesian limestones, 

dolomites, or other magnesian sedimentary rocks.

INTRODUCTION

The minerals of the serpentine group are layer structures, phyllosilicates, having the general formula 

X6Y4Oio(OH)8), where X stands for the atoms in octahedral coordination chiefly magnesium but -also 

nickel, cobalt, manganese, ferrous iron, zinc, and generally lesser amounts of aluminum, ferric iron, chromium and titanium and Y stands chiefly for silicon 

and in part for aluminum and ferric iron. Because 

the number of atoms in octahedral coordination for the 

ideal composition of the serpentine group is equal to 

3 for half the unit cell, these minerals are considered

l
STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

structually as trioctahedral. The crystal structure of 

the chrysotiles is based on a cylindrical lattice (Whittaker, 1954; 1955a, b, c; and Waser, 1955), and their 

tubular character has been established by electron 

microscopy (Turkevich and Hillier, 1949; and Bates, 

1951). Noll, Kircher and Sybertz (1958) have introduced the name " solensilicates" to be applied to these 

structures and have suggested its addition to the subgroup of the phyllosilicates in the Strunz (1938, 1957) 

classification of silicate structures. The prefix "solen", 

from the Greek, means "pipe." The most abundant 

serpentine minerals are hydrous magnesium silicates. 

T?he classification followed in this. paper is that of 

Whittaker and Zussman (1956) given herewith:

Serpentine.

(Chrysotile- 

. < Lizardite 

^Antigorite

fOrthochrysotile 

._< Clinochrysotile 

l^Parachrysotile

In addition, we use* the term clinochrysotile (Globe 

type) to describe a group of specimens made up chiefly 

.of clinochrysotile and probably admixed with orthochrysotile and best illustrated by the X-ray powder 

diffraction pattern of the silky chrysotile from the 

''Globe" district of Arizona,

,The minerals of the serpentine group have been defined chemically as having a formula of the general 

type X6Y4Oio(OH)8 . This of course permits substitutions not only in the X and Y positions, but also in the 

positions allocated to (OH) where F and Cl may enter. 

Phase-rule theory also requires that any phase considered tof be a polymorph of the serpentine-group minerals must adhere to the general formula.

Although we follow the established usage of considering antigorite as a member of the serpentine group, 

we do so with reservations, as will be explained later 

in the text. (See p. 37 and 40.)

Crystal chemical and structural relationships require 

that the ions entering into the octahedral and tetrahedral positions should have ionic radii similar in size 

to those of magnesium and silicon, respectively. In 

octahedral coordination occur Mg with an ionic radius, 

according to Ahrens (1952); of 0.67 A, Fe2+ with 0.74 A, 

Co with 0.73 A, Ni with 0.69 A, Mn2+ with 0.80 A, and 

Zn with 0.74 A. In addition Cr3+ with 0.63 A, Ti*+ 

with 0.68 A, Cu2+ with 0.72 A; Mn3+ with 0.66 A, and 

some or all of Fe3+ with 0.64 A, and Al with 0.51 A are 

assigned to octahedral positions. The assignment of 

Na with 0.94 A, Ca with 0.99 A and K with 1.33 A is 

provisional because we do not know (1) whether they 

actually belong in the serpentine structure, (2) whether 

they have been accidentally introduced during the 

analysis, and (3) whether they arise from impurities 

in the sample. The size of these ions is not compatible

with that of ions known to be in octahedral coordination. It should be noted that lithium may be misidentified as sodium and reported as such in an analysis. 

Lithium with an ionic radius of 0.68 A can replace 

magnesium in octahedral coordination.

The chief ion entering into tetrahedral coordination 

is silicon with a radius of 0.42 A. Silicon is replaced 

in part by aluminum with 0.51 A and ferric iron with 

0.64 A.

Within the serpentine group of minerals there is a 

wide range of substitutional solid solutions involving the 

aforementioned atoms. Most of these substitutional 

solid solutions involve the atoms in octahedral coordination. To specify such solid solutions use may be 

made of the hypothetical end-member formulas given 

below:

Mg9Si4010 (OH)8

FeeSi4010 (OH) 8

NieSi4O10 (OH) 8

Co6Si4O10 (OH)8

Mn6Si4O10 (OH) 8

ZneSi4Oio(OH) 8

Some of these end-member compositions have been 

demonstrated to exist as synthetic compounds. Bowen 

and Tuttle (1949) synthesized chrysotile with the 

formula Mg6Si4O10 (OII)8 ; Noll, Kircher and Sybertz 

(1958) synthesized cobalt chrysotile; Noll and Kircher 

(1952) synthesized nickel chrysotile, as did several 

others including Roy and Roy (1954). In addition Roy 

and Roy succeeded in making serpentines of the composition Mg6Ge4O10 (OH)8 and Ni6Ge4O10 (OH) 8 .

Natural serpentines are rarely, if ever, composed of a 

single pure end-member but rather belong to multicomponent systems. Thus a serpentine represented by 

the formula [Mgg.oNio. gFe2+o. g ]S4O10 (OH) 8 is actually a 

phase in the quinary system MgO-NiO-FeO-SiO2-H2O.

Much smaller quantities of calcium, sodium, potassium, and copper have been recorded in analyses, but 

just where these atoms fit into the structure is not 

known. Extremely small amounts no doubt are 

entrapped in sites in the structure. Significant amounts 

of calcium, sodium, and potassium usually indicate the 

presence of impurities, such as associated carbonates 

and silicates.

The hydrous nickel-magnesium silicates are, in part, 

members of the serpentine-group, and some of these 

materials resembling or called deweylite exhibit identical relationships. Because this group of minerals is an 

entity all in itself, it will be described in detail in a later 

paper. Brief comments on this work are given on 

page 48.

The relation of the serpentine-group minerals to that 

of the chlorites was first proposed by Tschermak (1890,
THE SERPENTINE-GROUP MINERALS

1891) who defined the chlorites in terms of the endmembers "serpentine," (H4Mg3Si2O9) and ^ amesite 

(H4Mg2Al2SiO9 ). Petrologists, such as Thorolf Vogt 

(1927), found these theoretical molecules of Tschermak 

to be useful in the interpretation of the reactions 

involving chlorite in metamorphic rock facies. Winchell 

and Winchell (1951) also follow Tschermak's concept 

and claim that serpentine is chlorite with no trivalent 

element. We shall not discuss this relationship of the 

serpentines to the chlorites in this study but will consider it separately in a later paper on the chlorites. 

The differentiation of chlqrites from serpentine may be 

made by X-ray methods (Brindley, 1951; Shirozu, 

1958a, b) by optical studies (Winchell and Winchell, 

1951); by solution studies (Clarke and Schneider, 1890); 

by differential-thermal-analysis (MacKenzie 1957); and 

by a combination of these techniques. The optical 

properties of lizardite, which may be confused with 

antigorite, and chlorite are given by Midgely (1951).

ACKNOWLEDGMENTS

We are indebted to many colleagues for specimens of 

serpentine for study, and we particularly wish to acknowledge the following: the late Norman L. Bowen 

and O. F. Juttle and H. S. Yoder, Jr., all of the Geophysical Laboratory, Carnegie Institution of Washington, for various synthetic products from the quaternary 

system MgO-Al2O3-SiO2-H2O; Paul F. Kerr and 

George C. Self ridge, Columbia University; Clarence S. 

Ross and Waldemar T. Schaller, U.S. Geological Survey; 

A. E. J. Engel, California Institute of Technology; and 

the late William F. Foshag, formerly curator of minerals 

in the U.S. National Museum..

Norman L. Bowen kindly furnished us with determinations of water content on the synthetic clinochrysotiles. Thermal-analyses (static method) of several serpentines were furnished by the late Perley G. 

Nutting. Harry H. Hess, A. E. J. Engel, Clarence S. 

Ross, Edward Bailey, and Donald L. Everhart kindly 

allowed us to use some of their unpublished chemical 

analyses.

We also wish to acknowledge the assistance of pur 

colleagues in the U.S. Geological Survey. John P. 

Marble, Richard C. Erd, Donald H. Richter, Geraldine 

Windham Werdig, and Joseph R. Houston prepared 

most of the X-ray powder diffraction patterns. Daniel 

E. Appleman, using the known constants for the unit 

cell of lizardite, prepared on the digital computer 

the calculated d-spacings for this mineral. Michael 

Fleischer furnished us with pertinent references to the 

literature and we have benefited by discussion of the 

problems with him. Some of the chemical analyses 

were by John G. Fairehild, Margaret D. Foster, Marie 

L. Lindberg, Charles Milton, and Rollin E. Stevens.

Some of the spectrographic analyses were made by 

Harry Bastron and Harry J. Rose. To these scientists 

and to all others mentioned in this report we are deeply 

indebted.

To our colleague K. Jack Murata we are under deep 

obligation. His transfer to the Hawaiian Volcano Observatory of the U.S. Geological Survey has not permitted him to cooperate in this work as was originally 

planned. He has kindly turned over to us four unpublished chemical analyses and spectrographic data.

THE TERM "SERPENTINE"

The mineral of the serpentine group and the rocks 

composed of serpentine minerals are common substances and have been known to man for a long time. 

Hintze (1897) and others believe our name serpentine 

applies in part to the substances called Xi0os CH^ITT/S by 

Dioscorides (A.D. 50) and ophites by Pliny (A.D. 77). 

The Greek term "o<£is" means serpent. Many fanciful 

interpretations have arisen as to the selection of this 

term for the name of the mineral or rock. It has been 

suggested that o<£« refers to the speckled color pattern 

of serpents; others believed it was so called because of 

its use against snake poison and Dioscorides recommended it for the prevention of snake bite.

Agricola in 1546 latinized the name to serpentaria 

and this form was widely accepted. Our English word 

"serpentine," derived from the Latin form, is common to 

many languages. In those languages which employ 

the Latin alphabet, the word "serpentine" or one of its 

variants is part of the vocabulary. In the languages of 

the Teutonic countries, Austria, Denmark, Germany, 

Norway, Sweden, and Switzerland, it is "serpentin"; of 

the Low Countries it is "serpentine" in Belgium and 

"serpentijn" in Holland; of the slavic countries it is 

"serpentin" in Czechoslovakia, "serpentinu" in Hungary 

and Yugoslavia (Croatian), "serpentina" in Rumania, 

and "serpentyn" in Poland. In the languages of the 

Romanqe countries it is "serpentine" in France, and! 

"serpentine" in Italy, Portugal, and Spain.

Today the word "serpentine" has (diverse meanings 

depending upon the interests of the user. In literary 

works it conveys the idea* of winding, of turning first 

one way and then another. To the mathematician 

(Larsen, 1954) it signifies a curve which was defined 

by Sir Isaac Newton by the equation (a2 -\-x2 )y= 

abx where x a cot <£ and y=b sin 4> cos <f>, as illustrated 

in figure 1. To the sculptor it designates a green rock 

usually coming from Italy or Germany, commonly 

with a mottled appearance and suitable for small 

statuary, vases, and mantlepieces. Pliny observes 

that the use of serpentine by sculptors extends to 

ancient times.
STUDIES OP THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

X

FIGURE 1. The mathematical curve named serpentine and 

discovered by Sir Isaac Newton. Modified from Larsen 

(1954) and published by permission of Rinehard & Co., Inc.

To the architect the term "serpentine" denotes a 

rock, the classic example being the "verde antico" of 

the ancients; one serpentine was quarried on the island 

of Tinos in Greece (Kieslinger, 1951). Other serpentine rocks familiar to the architect are the verde di 

Polceverra, verde del Mare, verde de Genoa, and the 

verde di Pegli from the vicinity of Genoa, the verde 

di Prato from the quarries at Monteferrato near Prato, 

in Tuscany, Italy (Kieslinger, 1951), and the serpentine of Zoblitz (Zeblich) and Waldheim in Saxony 

(Agricola, 1546). Some of these rocks are actually 

serpentine marbles (ophicalcites) such as the verde di 

Prato. The so-called Irish green or Connemara marble 

from Galway County, Ireland, which has been popular 

with architects, is also an ophicalcite (Watson, 1916). 

According to Dana (1892, p. 671) "Any serpentine 

rock cut into slabs and polished is called serpentine 

marble."

To the soil scientist and to some farmers the word 

"serpentine" immediately suggests the infertile soils 

known as the "serpentine barrens" (Johannsen, 1928). 

The bastite locality, Todtmoos in the Wehra Tal, 

Schwarzwald, is described by Baedeker (1886) thus 

"The bold pine-crowned cliffs enclosing the valley are 

clothed with luxuriant vegetation broken here and 

there by imposing masses of barren rocks."

On August 29, 1960, Faust visited the bastite locality at Todtmoos in the Schwarzwald with W. W. 

Wimmenauer, geologist with the Geologisches Landesamt in Baden-Wurttemburg (Freiburg im Breisgau). 

At the time of the examination of this occurrence, huge 

blocks and the associated train of smaller fragments 

were exposed as part of a landslide. This landslide, 

apparently confined to the serpentine, took place during 

1959. The description given by Baedeker (1886) 

possibly refers to the Wehra Tal. It is also possible 

that the creep of the soil mantle over the serpentines 

during the past 75 years has covered some of the 

barren exposures observed by the authors of Baedeker 

(1886). (See also Egller, 1955, p. 27-72.)

In the Alps, barren outcrops (bosses) of serpentine 

are known as "monts morts" to the farmers and dairymen. In a written communication dated April 20,

1959, Dr. J. V. Howell, Petroleum Geologist of Tulsa, 

Okla., wrote regarding this term:

Actually this is a geographic or ecologic term and probably can 

be found much more readily in the literature of those disciplines. 

Dr. Schaetti states that the term is applied by the farmers and 

dairymen who pasture their cattle in the upper valleys of the 

Alps where the pasturage is excellent. On the serpentine bosses 

only a sparse growth of vegetation is found, whose contrast is 

so marked as compared with the lush growth of the valleys that 

they are termed "monts morts" or "dead mountains." So far 

as he is aware, the term has no geological connotation and 

possibly the term might be applied to similar "dead" areas 

underlain by rocks other than serpentine.

In a written communication dated January 5, 1961, 

Dr. Armin von Moos, of the Eidgenossischen Technischen Hochschule, Zurich, wrote:

... I can tell you that on the so-called "todtalp" exist areas 

which carry no vegetation whatsoever. Underlying outcropping rock is serpentine either in place or as dry cone and debris 

of the above mentioned rock. The todtalp is about 2,500 m 

above sea level and is situated near the famous resort place 

Davos in the Grisons, Switzerland. This serpentine is also 

referred to as todtalp-serpentine. (Geologischer Fiihrer der 

Schweiz, Fasc. XIV, 996. 1934. J. Cadisch: Weissfluhgruppe. 

Beitrage Geol. Karte der Schweiz, N. F. 49, I, 1921.)

In areas of weathered serpentines the forester and 

lumberman know serpentine to be characterized by 

stunted oaks, scrub pine, and mountain laurel. The 

botanist thinks of serpentine areas as the natural 

habitat of moss phlox (Phlox subulata L.), and of 

certain ferns (Wherry, 1932; Eberle, 1957; Rune, 

1953).

Mineralogists and petrologists have used the word 

"serpentine" in two senses, generally with reference to 

the serpentine minerals and to a lesser extent for rocks. 

Haiiy (1822) was one who considered serpentine to refer 

to a rock. Its more common use has been to the serpentine minerals and such is its usage today; rocks 

composed chiefly of serpentine minerals are commonly 

called serpentinites. This usage of serpentinite introduced by Lodo&iikow (1936, p. 29 and 728) is gaining 

much favor. Lodocnikow defined it thus: 1 "! designate as serpentinite those rocks which are composed 

chiefly of serpentine group minerals." The older usage 

of the term by von Leonhard (1823-24, p. 131) as a 

synonym for gabbro has long since been forgotten.

MINERAL NAMES USED IN THIS STUDY

The serpentine group of minerals has associated with 

it an .abundance of mineral names. In making this 

study of the minerals of the serpentine group it was 

necessary to investigate some of these materials and to 

consult the work of others for additional data. Table 1 

summarizes these data and gives our observations and 

interpretations of them.

J Literal translation from the German abstract, by George T. Faust.
THE SEKPENTINE-GKOUP MINEEALS 

TABLE 1. Mineral names used in this paper with interpretation of the pertinent data

Varietal name

Alumino-chrysotile _ 

Antillite-_________

Aquacreptite __-__- 

Baltimorite. _______

Barettite. _________

Bastite_ _.

Bowenite.

Dermatine. 

Deweylite_.

Hydrophite.

Jenkinsite_

Karachaite.

Lithomarge

Marmolite.

Proposed by 

D. P. Serdyuchenko (1945). 

C. U. Shepard (1872)_____

C. U. Shepard (1868)__.__ 

T. Thomson (1843) _______

L. Bombicci (1868)_______

W. Haidinger (1845).

J. D. Dana (1850).

A. Breithaupt (1830). 

E. Emmons (1826)__

L. F. Svanberg (1839).

C. U. Shepard (1853); Winchell (1927, p. 378) considered jenkinsite a ferriferous antigorite.

N. E. Efremov (1936)___

T. Nuttall (1822).

Analysis No. 

From this study From the literature

F-19-

F-8.

F-3, F-26, F40, F-42, 

F-43, F-48, 

F-49, F-50, 

F-52.

3

214

177, 179

31

255, 256, 257

83, 126, 150,

163, 208,

209, 211,

218.

13

124, 131, 140,

154, 159,

165, 170,

171,

176,

193,

174,

181,

237

235, 236

175

151

125, 220

Observations and interpretations

See footnotes at end of table, p. 7.

Serdyuchenko's data suggest aluminian chrysotile. Data in figure 21 suggest an impure 

sample.

Based on the data of Nagy and Faust (1956) 

this is probably a mixture of lizardite and 

chrysotile.

Data in figure 21 suggest that although these 

samples are somewhat impure they are 

chiefly stevensite and chrysotile.

F-19 is antigorite and chrysotile. Data in 

figure 5 suggest a mixture of antigorite and 

chrysotile.

The original sample analysed by Prof. Sestini 

contains gross impurities. Koufimsky and 

Satava (1954) believe it to be antigorite. 

Their DTA curve is a complicated curve 

and shows that the material is impure. 

D'Ambrosio (1924) reanalyzed this mineral 

and stated that it consists ot serpentine and 

brucite. Recomputation of his analyses 

gives [Mg5 .55 Fe2+ . 19 A1.23] [Si3 .87 A1. 13]O10 (OH) 8 

and [Mg5 .26 Fe2+ . 26 A1. 32] [Si3 .99 A1.01 ]O10 (OH) 8 

which fall within the limits of composition 

of serpentine-group minerals.

Some of the analyses obtained from the literature may refer to this variety. Whittaker 

and Zussman (1956) studied three bastites 

and found that two specimens from the type 

locality are mainly lizardite as is also a 

specimen from Scotland.

F-8 is antigorite. The data in figure 21 suggest that the samples used for analyses 126 

and 150, are representative; that Nos. 83, 

208, 209, 211, and 218 are probably contaminated with a little carbonate; and that 

No. 163 is rather impure. DTA curves 

obtained by Caillere (1936) suggest that her 

samples are antigorite.

The data obtained by Caillere (1936) suggest 

that this mineral is antigorite.

The results of this study show that most of 

the material called deweylite is a mixture 

of chrysotile or lizardite with stevensite. 

See figure 21.

Analysis 237 suggests that hydrophite is an 

iron-rich serpentine. The DTA, and optical data of Koufimsky and Satava (1954) 

suggest that similar material is chrysotile 

and magnetite. Dana (1892) notes that 

hydrophite is decomposed by HC1.

The data in figure 21 suggest that the sample 

used for analysis 236 may be an admixture 

of chrysotile and stevensite. Dana (1892) 

notes that jenkinsite is decomposed by HC1.

The position of the analysis in figure 21 suggest that the sample is a mixture of chrysotile and stevensite.

The data in figure 21 suggest that the sample 

consists of chrysotile (or lizardite) and some 

stevensite.

The physical appearance, the studies of Nagy 

and Faust (1956), and the chemical data in 

figure 21 suggest that this mineral is chiefly 

lizardite with some chrysotile. Whittaker 

and Zussman find that two specimens of 

marmolite from Hoboken, N.J., are different: one is chiefly chrysotile, the other 

chiefly lizardite. The data of Koufimsky 

and Satava (1954) suggest similar conclusions. Brush and Penfield (1898) state it to 

be "readily decomposed by acids."
6 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

TABLE 1. Mineral names used in this paper with interpretation of the pertinent data Continued

Varietal name

Meerschaum 2 . 

Metaxite_____.

Neolite.

Picrolite.

PicrosminePorcellophite.

Pykno trope.

RetinaliteSchweizerite.

Steatoid.

Proposed byA. Breithaupt (1832).

Scheerer (1847).

J. F. L. Hausmann (1808)__

W. Haidinger (1824).

J. D. Dana (1868).

A. Breithaupt (1832).

T. Thomson (1836).

T. Scheerer (1847).

E. F. Glocker (1829).

Analysis No 

From this study From the literature

F-46, F-47, 

F-66

F-22, F-25.___

F-23-

166

1, 6, 17, 61

186

14, 43, 136,

139, 153,

162, 190,

191

11, 40, 44, 185

123, 155

206

96, 133, 199,

207

47

Observations and interpretations

The data in figure 21 suggest that this material 

is a mixture of chrysotile (or lizardite) and 

stevensite.

From the data in figure 20 it appears that this 

substance is chiefly serpentine-group minerals. Analysis 1 is an impure mixture. 

Whittaker and Zussman (1956) find metaxite 

from type locality to be chiefly chrysotile.

Analysis 186 yields a formula suggestive of 

stevensite. This material from Pennsylvania is described as colloidal. Dana (1892) 

questions the homogeneity of the original 

materials described as neolite.

F-46 and F-47 are lizardite; F-66 is antigorite. 

The data in figure 21 suggest that analyses 

No. 14, 43, 136, and 153 are chiefly serpentine-group minerals; analyses 190 and 191 are 

probably contaminated with olivine (or brucite); analyses 139 and 162 may contain stevensite. The data for four specimens of 

picrolite given by Nagy and Faust (1956) 

show it to consist chiefly of antigorite with 

various amounts of chrysotile. Whittaker 

and Zussman (1956) find a picrolite from 

Taberg, Sweden, to be antigorite.

The description by Dana (1892) includes columnar habit, suggestive of the varieties picrolite 

and baltimorite. The data in figure 20 show 

that these samples are serpentine-group minerals. Analysis 185 indicates that this sample is 'chiefly stevensite. Whittaker and 

Zussman (1956) show that a specimen from 

the Tyrol is antigorite. Koufimsky and Satava (1954) found one specimen to be a mixture of antigorite and chrysotile and another 

to be antigorite.

The data in figure 4 show that the analyses are 

typical of the serpentine-group minerals. 

The optical and solution data in Nagy and 

Faust (1956) suggest that their specimen is 

a mixture of chrysotile and lizardite.

Analysis 2 of material from the type locality by 

Fikenscher is obviously erroneous (see fig. 

21) Koufimsky and Satava (1954) studied 

material from the type locality and found it 

to be a mixture of antigorite and chrysotile. 

Their DTA curves suggest a very impure 

substance.

Specimen F-22 is clinochrysotile; F-25 is chrysotile and lizardite where C>L. Analysis 

206 appears to have been made on slightly 

impure material.

Specimen F-23 is lizardite. Analyses 96, 133, 

199, and 207 all fall within the general composition field of serpentine-group minerals. 

Whittaker and Zussman (1956) found schweizerite from Zermatt, Switzerland, to be pure 

clonochrysotile.

The original usage for this term applied to the 

serpentine pseudomorphs from Snarum, 

Norway. Analysis 47 is typical of a serpentine-group mineral. Sample F-71 on probably similar material is lizardite and clinochrysotile where L>C. Whittaker and 

Zussman (1956) studies on the "serpentine 

mineral" from Snarum, Norway, showed it 

to be mainly lizardite with very little 

clinochrysotile.

See footnotes at end of table, p. 7.
THE SERPENTINE-GROUP MINERALS

TABLE 1. Mineral names used in this paper with interpretation of the pertinent data Continued

Varietal name

£1 i" P v P n Q i f P

Thermophyllite_

6-layer orthoserpentine.

Proposed by 

A. R. Leeds (1873) _..__-__

A. E. Nordenskiold (1855) __

A. Kenngott (1857) -____-

Zussman, Brindley, and 

Comer (1957). 

R. Brauns (1887) ._.. ______

C. U. Shepard (1848) ______

Analysis No. 

From this study

F-l__________

From the literature

99. 113, 128 

137

33, 112 

172, 182

34, 85, 156, 

173, 183, 201

Observations and interpretations

Shown by Faust and Murata (1953) to be the 

magnesium end member of the montmorillonite group. 

Analyses 99 and 113 suggest that this is a 

typical serpentine-group mineral. 

Analysis 137 is that of a typical serpentinegroup mineral. Koufimsky and Satava 

(1954) identified as chrysotile a sample of 

this mineral from the Val di Fiemme. 

A serpentine-group mineral having a six-layer 

orthohexagonal cell. 

Analyses 172 and 182 appear to be impure 

mixtures of a serpentine-group^mineral and 

stevensite. KouHmsky and Satava believe 

this mineral to be a mixture of chrysotile and 

antigorite. Their DTA curve suggests a 

mixture of a chrysotile (or lizardite) and 

stevensite. 

F-l is antigorite. Analyses 34, 85, and 201 

probably represent antigorite. Analyses 156, 

173, and 183 are probably admixtures of a 

serpentine-group ^mineral and stevensite. 

Koufimsky and Satava (1954) found williamsite from the original locality to be. 

chiefly antigorite with a little chrysotile.

1 The usage of this name for a hydrous magnesium silicate is not in accord with the original definition.

2 This usage is a misnomer.

Although we have made much use of Dana (1915), 

Doelter (1921-31), Hintze (1897), Hey (1955), and 

Strunz (1957), we have also checked almost all the literature references.

Many hydrous magnesium silicates having a composition approximating that of serpentine were described 

as new minerals, but many were soon discredited and by 

the time of the sixth edition of James D. Dana's "A 

System of Mineralogy" (1892) their number had been 

reduced. Weinschenk (1912, p. 313) stated the case 

very clearly with respect to serpentine.

New names cannot be given to these dense aggregates simply 

because they have different habit as has been done in the antigorite varieties, picrosmine, metaxite, picrolite, etc., and likewise 

the microscopic forms of aggregation, e.g., the radial, which has 

lately given use to the name radiotine, cannot be recognized as 

sufficient ground for evolving a new name.

Of those that remained only two of the serpentine-group 

minerals have met the requirements for a good mineral 

species and these are chrysotile and antigorite.

The original description of chrysotile by von Kobell 

(1834) established this species. It was so named by 

combining the greek words for golden, XPV&OS, and 

fibrous, nXos.

Antigorite likewise was well established at an early 

date by Schweizer (1840) and named for its occurrence 

in the Val Antigorio, Italy, by Bonney (1908).

Lizardite was first described by Midgley (1951) as the 

"magnesium analogue of kaolinite" and "probably a 

variety of antigorite with very little iron substitution." 

It was later redefined by Whittaker and Zussman 

(1956).

GEOLOGICAL OCCURRENCE OF THE SPECIMENS 

STUDIED

Data on the geological occurrence of the specimens 

studied were obtained through reference to the literature, personal communications from the collectors and 

donors of specimens, examination of the hand specimens, and examination in the field for many of the 

specimens. Faust, over a period of 25 years, has 

examined occurrences of serpentine in the eastern 

United States from Troup County, Ga., to Lamoille 

County, Vt. He has also examined the occurrence of 

deweylite in the mica-peridotite in Arkansas; the deweylite at Currant Creek, Nev.; and serpentine at several 

localities in California. Faust examined the famous 

serpentine quarries at Kemmelton bei fiospenthal, 

Canton Uri, Switzerland, as well as other Alpine serpentine localities in 1959, and in 1960 he examined the 

once much disputed occurrence at Snarum, Modum 

Canton, Parish of Buskerud, Norway, and the important locality for bastite in the Todtmoos, Schwarzwald,.
8 STUDIES OF THE NATURAL PHASES IN THE SYSTEM

Germany. Fahey has examined occurrences of serpentine in Pennsylvania and Maryland.

The serpentine minerals reported on in this paper 

have been referred to two distinct types of paragenesis 

here designated classes A and B.

Serpentine minerals formed in ultrabasic rocks are 

referred to class A. We use the term ultrabasic rock 

in its widest sense, but it is recognized that this usage 

includes igneous rocks derived from several different 

lines of magmatic descent. Hess (1955) has emphasized 

this difference and he divides the ultrabasic igneous 

rocks into two suites: the ultramafic rock suite characteristic of the alpine-type mountain systems, which 

includes dunites, pyroxenites, peridotites, and related 

rocks, and the suite composed of alnoites, kimberlites, 

mica-peridotites, and related rocks which differ from 

the ultramafic suite not only in chemical and mineralogic composition, but also in their tectonic setting. 

Two of the specimens (F-40 and F-42) examined by us 

belong to the alnoite, kimberlite, mica-peridotite suite.

Serpentine-bearing rocks of various types of metamorphic origins are referred to class B. Class B 

includes metamorphosed limestones and dolomites, 

contact metamorphic deposits, and hydrothermal veins. 

Metamorphosed limestones contain ferromagnesian and 

magnesian minerals such as olivine, pyroxene, and 

amphibole, and these are commonly replaced by minerals of the serpentine group.

The process of serpentinization is usually defined 

as the formation of serpentine from preexisting ferromagnesian or magnesian minerals by hydrothermal 

solutions. Chlorite, talc, stevensite, saponite, and 

other hydrous magnesium silicates commonly occur 

with serpentine.

The description of the geological occurrence of the 

, serpentine specimens studied by us is given for each 

specimen in the-following section on the description of 

the minerals.

DESCRIPTION OF THE MINERALS

A given hand specimen of serpentine may be completely homogeneous composed of a single serpentine 

mineral. Another hand specimen of serpentine may 

consist of several serpentine minerals in variable proportions in different parts of its mass. The amount of 

heterogeneity of a given specimen may be detected by 

a combination of the various methods described in this 

report.

Except for the silky luster and fibrous habit of 

chrysotile and the platy character and dark-green color 

of some antigorites, it is almost impossible to name 

serpentine minerals by sight identification alone.

Locality, likewise, is generally an unreliable means 

of identifying the serpentine minerals, although there

are some exceptions. Varietal names such as deweylite and retinalite are also of little value, for they are 

not all referable to the same mineral of the serpentine 

group and quite commonly are mixtures. Even elaborate physical and chemical techniques are not always 

sufficiently sensitive in quantitative studies. The identifications given in the descriptions that follow represent 

the predominant mineral of the serpentine group found 

in the particular sample studied and apply only to this 

material. Thus a specimen characterized as antigorite 

consists entirely or almost entirely of antigorite (90 

percent or more); one characterized as chiefly antigorite 

contains antigorite as the predominant phase (70 

percent or more).

To facilitate the use of the data and the information 

on localities, two geographic finding lists are given at 

the end of this report. Table 27 gives the information 

for specimens used in this study and table 28 for the 

chemical analyses taken from the literature.

F-l

Name: Antigorite (labeled williamsite). Green, translucent, massive; associated with chromite (fig. 14). 

This is the type of serpentine commonly used as a 

gem material. It is cut as stones for rings and 

pendants, and as beads.

Locality. State Line Pits (Low's mine), Lancaster 

County, Pa. approximately 1.2 miles west-northwest 

of Rock Springs, Cecil County, Md.

Geological occurrence: Class A. Hydrothermal alteration of ultrabasic rocks.

Furnished by: Clarence S. Ross.

Reference: Gordon, 1921, W. T. Schaller, oral communication, 1954.

F-3

Name: Lizardite and clinochrysotile, labeled deweylite 

(fig. 5). Cream colored, earthy, massive; adheres 

to the tongue.

Locality: Near Forest Hill, Harford County, Md.

Geological occurrence: Class A. Hydrothermal alteration of ultrabasic rocks.

Furnished by: Oliver Bowles and Clarence S. Ross.

Reference: Johannsen, 1928.

F-8

Name: Antigorite (labeled bowenite). Pale greenish

gray, translucent, massive. 

Locality: Smithfield, Providence County, R.I. 

Geological occurence: Class B. Hydrothermal alterartion of ferromagnesian minerals in metamorphosed

limestone beds.

Furnished by: Professor Paul F. Kerr, Kerr No. R-19. 

Reference: Bowen, 1822, Emerson, 1917.
THE SERPENTINE-GROUP MINERALS

F-13

Name: Chiefly antigorite (labeled "pseudomorphic" 

serpentine). Grayish green, cuboidal masses.

Locality: Tilly Foster iron mine, near Brewster Station, 

Putnam County, N.Y.

Geological occurrence: Class B. Hydrothermal alteration of ferromagnesian minerals in a contact metamorphic deposit.

Furnished by: U.S. National Museum, USNM 82509.

Reference: Koerberlin, 1909; Brendler, 1912; Dana, 

1915; Manchester, 1931.

F-14

Name: Chiefly antigorite (labeled "Hsiu-yen stone" 

known as "Yu-Yen Shi stone" in the jewelry trade). 

Pale greenish gray, translucent, massive; resembles 

jade in appearance, (fig. 13.) This material is commonly cut as an ornamental stone, as vases and table 

weights. It sometimes is cut as chopsticks.

Locality: Pei-wa-kou (and Lao-yeh-ling), Hsiu-yen 

Hsien, Liaoning Province, Manchuria.

Geological occurrence: Class B. Hydrothermal replacement of ferromagnesian minerals in metamorphosed 

dolomite of Precambrian age.

Furnished by: U.S. National Museum. The specimen 

is designated as a standard "Yu Yen Stone" and 

bears the number USNM 94356.

Reference: Merrill, 1922, p. 96; E. P. Henderson, oral 

communication 1954; S. Yabe, 1930 and written 

communication 1954.

F-15

Name: Antigorite. Grayish green, massive, breaks 

to form gently folded plates, (fig. 15; an oriented 

specimen from the same locality is shown in fig. 16.)

Locality: North of Domodossola in Val Antigorio, 

Novara Province, Piedmont region, Italy. According to Bonney (1908, p. 158), "But its occurrence 

in situ in the Val Antigorio itself is very doubtful. 

Thus the original specimen may have been obtained, 

either from an erratic in the lower part of that valley, 

or from an actual outcrop in a tributary one (such 

as the Val Devero or the Val Bognanco), to which 

the name of the main valley has been rather inaccurately attached."

Geological occurrence: Class A. . Hydrothermal alteration of an ultrabasic -rock (augite-olivine rock).

Furnished by: Professor Paul F. Kerr, Kerr No. R-18.

Reference: Schweizer 1840; Bonney, 1908; Brendler, 

1912.

F-19

Name: Antigorite and chrysotile (labelled baltimorite). 

Grayish green, tight bundles of fibers up to 6 inches 

in length (fig. 12). Baltimorite is a synonym for 

picrolite.

Locality: Bare Hills, Baltimore County, Md.

Geological occurrence: Class A. Hydrothermal alteration of ultrabasic rocks.

Furnished by: U.S. National Museum, USNM 80500.

Reference: Knopf and Jonas, 1929.

F-20

Name: Clinochrysotile (Globe-type). Light golden

brown, fawn, silky fibers of 2% inches in length. 

Locality: Asbestos deposits, Gila County, Ariz. The

label on this specimen bears a reference to Globe,

but this is a town from which asbestos is shipped.

Many deposits are scattered through 25 townships

in Gila County. 

Geological occurrence: Class B. Hydrothermal vein

deposits in limestone. 

Furnished by: Clarence S. Ross. 

Reference: Bateman, 1923, Stewart and Haury, 1947,

Bromfield and Shride, 1956.

F-20A

Name: Clinochrysotile (Globe-type). The chrypotile

is intimately associated with very fine grained calcite.

Color flesh pink, massive, pyrognomic (fig. 2). 

Locality: Asbestos deposits, Gila County, Ariz. The

label on this specimen bears a reference to Globe,

but this is a town from which asbestos is shipped.

Many deposits are scattered through 25 townships

in Gila County. 

Geological occurrence: Class B. Hydrothermal vein

deposits in limestone. 

Furnished by: Clarence S. Ross. 

Reference: Bateman, 1923, Stewart and Haury, 1947.

Bromfield and Shride, 1956.

F-22

Name: Clinochrysotile (labeled "serpentine"; this appears to be the variety retinalite).

Locality: Turkey Mountain, near Montville, Morris 

County, N.J.

Geological occurrence: Class B. Hydrothermal alteration of diopside in metamorphosed limestones.

Furnished by: Dr. George C. Self ridge, Jr., Self ridge 

No. 1.

Reference: Merrill, 1888, Shannon, 1927.
10 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

F-23

Name: Lizardite (labeled schweizerite). Greenish yellow, opaque, massive.

Locality: Dognacska, 10 kilometers west from Reschitza, Severin Province, Hungary, now Dognecea, 

Rumania.

Geological occurrence: Class B. Hydro thermal alteration of ferromagnesian minerals in a contact metamorphosed limestone.

Furnished by: Dr. George C. Selfridge, Jr., Selfridge 

No. 4.

Reference: Beck, 1905, p. 592.

F-24

Name: Clinochrysotile (Globe-type). Amber, silky

fibers % inch in length. 

Locality: Turkey Mountain, near Montville, Morris

County, N.J. 

Geological occurrence: Class B. Hydro thermal vein

deposits in metamorphosed limestone. 

Furnished by: Dr. George C. Selfridge, Jr., Selfridge

No. 75. 

"Reference: Merrill, 1888, Shannon, 1927.

F-25

Name: Chrysotile and lizardite, C>L (labeled retinalite). Light yellow, translucent, massive. Figures 

6 and 7 are photomicrographs of similar material.

Locality: Turkey Mountain, near Montville, Morris 

County, N.J.

Geological occurrence: Class B. Hydro thermal alteration of diopside in metamorphosed limestone.

Furnished by: Dr. George C. Selfridge, Jr., Selfridge No. 

77.

Reference: Merrill, 1888, Shannon, 1927.

F-26

Name: Clinochrysotile (Globe-type). Intimately mixed 

with stevensite (labeled deweylite). Amber, massive.

Locality: Texas, Lyles P. O., Fulton Township, Lancaster County, Pa.

Geological occurrence: Class A. Hydrothermal alteration of ultrabasic rocks.

Furnished by: Dr. George C. Selfridge, Jr., Selfridge No. 

35.

Reference: Gordon, 1922.

F-40

Name: Clinochrysotile (labeled deweylite). White, 

shining luster, massive, small-chonchoidal fracture, 

adheres to the tongue.

Locality: Prairie Creek area of peridotite in T. 8 S., R. 

25 W., 2% miles south-southeast of Murfreesboro, 

Pike County, Ark.

Geological occurrence: Class A. Narrow seams in the 

altered peridotite. Hydrothermal alteration of ultrabasic rocks.

Furnished by: Collected by George T. Faust in 1943.

Reference: Miser and Ross, 1922; Faust, unpublished 

data.

F-41

Name: Clinochrysotile (Globe-type). (Labeled deweylite.) White to buff, granular, massive, adheres to 

the tongue.

Locality: Windous deposit, Currant Creek magnesite 

deposits, White Pine County, Nev.

Geological occurrence: Class B. Hydrothermal replacement of calcareous tuffs.

Furnished by: Eugene Callaghan and Charles J. Vitaliano.

Reference: Faust and Callaghan, 1948.

F-42

Name: Lizardite (labeled deweylite). Light-greenish 

brown, waxy luster, massive, pyrognomic.

Locality: Clark hallow on the southeast side of Lone 

Mountain, near Norris, Union County, Tenn.

Geological occurrence: Class A. Hydrothermal alteration of a mica-peridotite.

Furnished by: George M. Hall and Clarence S. Ross.

Reference: Hall and Amick, 1944.

F-43

Name: Lizardite (labeled deweylite). Greenish gray to 

brownish gray, shining luster, massive, small-conchoidal fracture, adheres to the tongue (fig. 10).

Locality: Crump's quarry, Mineral Hill, % mile north of 

State Roads, about 1 mile west of Media, Middletown Township, Delaware County, Pa.

Geological occurrence: Class A. Hydrothermal alteration of ultrabasic rocks.

Furnished by: Collected by George T. Faust in 1924.

Reference: Gordon, 1922.

F-45

Name: Clinochrysotile (Globe-type). Intimately admixed with stevensite and dolomite (labeled deweylite). Amber colored, botryoidal, friable, massive. 

Resembles gum arabic.

Locality: Wood's chrome mine, Open Quarry, Little 

Britain Township, Lancaster County, Pa.

Geological occurrence: Class A. Hydrothermal alteration of ultrabasic rocks.

Furnished by: W. H. Tomlinson and W. T. Schaller.

Reference: Gordon, 1921.
THE SERPENTINE-GROUP MINERALS 11

F-46

Name: Lizardite (labeled picrolite). The label on this 

specimen bears the statement "lithomarge(?)," a serpentine of the picrolite type. Only the powdered 

material of the original tube sample was available.

Locality: Near Bellows Falls, Windham County, Vt.

Geological occurrence: Class A. Hydro thermal alteration of ultrabasic rocks.

Furnished by: Clarence S. Ross.

Reference: Wells, 1937.

Note: The possibility that samples F-46 and F-47 are 

identical is suggested by (1) the similarity of the 

chemical and physical data of these two samples 

(2), the presence of sample F-47 in the collection of the 

U.S. National Museum, (3) the observation of our 

colleague, Alfred H. Chidester, U.S. Geological Survey, who knows of no such occurrence of serpentine 

near Bellows Falls, Vt.

F-47

Name: Lizardite (labeled picrolite). The label bears 

the statement "Carnat," a serpentine of the picrolite 

type. Only the powdered material of the original tube 

sample was available.

Locality: Tyrol, Austria.

Geological occurrence: Class A. No description available. Picrolites are, however, formed in hydro thermally altered ultrabasic rocks.

Furnished by: Clarence S. Ross; USNM R-4687.

Reference: Wells, 1937.

F-48

Name: Stevensite plus chrysotile (labeled deweylite).

Amber, translucent, massive. 

Locality: Mine Creek, Bakersville, Mitchell County,

N.C. 

Geological occurrence: Class A. Probably a hydrothermal alteration product of dunite. 

Furnished by: Clarence S. Ross. 

Reference: Ross, oral communication; Faust, Hathaway,

and Millot (1959).

F-49

Name: Chrysotile (labeled deweylite, "white serpentine"). White, opaque, massive.

Locality: Wood's chrome mine, Open quarry, Little 

Britain Township, Lancaster County, Pa.

Geological occurrence: Class A. Hydrothermal alteration of ultrabasic rocks.

Furnished by: Collected by Wallace R. Griffitts.

Reference: Gordon. 1921.

F-50

Name: Clinochrysotile (labeled deweylite). Pale greenish gray, opaque, massive, adheres to the tongue. 

(Fig. 3).

Locality: Chrome mine near Moa, Oriente Province, 

Cuba.

Geological occurrence: Class A. Hydrothermal alteration product of ultrabasic rocks.

Furnished by: Collected by Clarence S. Ross.

Reference: Clarence S. Ross, oral communication.

F-51

Name: Clinochrysotile and Lizardite (labeled Serpentine). Dark green, resinous.

Locality: Nicaro, Oriente Province, Cuba.

Geological occurrence: Class A. Hydrothermal alteration of ultrabasic rocks.

Furnished by: Collected by Clarence S. Ross.

Reference: Clarence S. Ross, oral communication.

F-52

Name: Clinochrysotile (labeled deweylite). Brown, 

subtranslucent, massive with conchoidal fracture, 

adheres to the tongue.

Locality: Spar quarries, approximately 2 miles northwest of Sylmar, West Nottingham Township, Chester 

County, Pa.

Geological occurrence: Related to Class A. Hydrothermal replacement of albite in desilicated granitic pegmatites occurring within ultrabasic rocks, Gordon, 

1922.

Furnished by: Samuel G. Gordon.

Reference: Gordon, 1922.

F-53

Name: Clinochrysotile (Globe-type). Golden brown 

fawn, silky fibers of 3 inches in length.

Locality: Asbestos deposits, beneath Grand View, about 

11 miles southeast of El Tovar Hotel, Grand Canyon, 

Coconino County, Ariz.

Geological occurrence: Class B. Hydrothermal vein deposits in limestone.

Furnished by: Roger C. Wells, Wells sample 335, collected by J. S. Diller.

Reference: Diller, 1911, Laboratory notes of Roger C. 

Wells, 1913, Bateman, 1923, Stewart and Haury, 1947 

Bromfield and Shride, 1956.

F-54

Name: Clinochrysotile. White, powder.

Locality: Synthetic product T-2-29C formed at 400°C 

and 1,000 atmospheres pressure.

Furnished by: Synthesized at the Geophysical Laboratory, Carnegie Institution, by Drs. N. L. Bowen and 

O. F. Tuttle.

Reference: Bowen and Tuttle, 1949.

F-56

Name: Clinochrysotile and orthochrysotile (labeled serpentine). Pale greenish gray, translucent, massive.
12 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

Locality: Fifth level, at the shaft, Gouverneur Talc Co., 

«2,000 feet north of Balmat Corners, St. Lawrence 

County, N.Y.

Geological occurrence: Class B. ''Se-2 (F-56) is serpentine replacing diopside in a diopsidic, calcitic marble. 

The diopside formed as the highest grade mineral in 

the marble, by reaction of sedimentary quartz and 

dolomite. Retrograde processes have removed the 

Mg (calcified the marble) and produced the stepwise 

assemblage anthophyllite ^serpentine »talc."

Furnished by: Collected by Dr. Albert E. J. Engel.

Rejerence: A. E. J. Engel, written communication; 

Brown and Engel, 1956.

F-57

Name: Clinochrysotile and Lizardite (labeled serpentine). Yellow brown, opaque, massive.

Locality: Some 8 miles northeast of Se-2 (F-56) at the 

International (Freeman) Talc mine. The specimen 

came from the 2% mine, 5th level, 1,600 feet westsouthwest of shaft. Talcville, St. Lawrence County, 

N.Y.

Geological occurrence: Class B. "2^-5-16 (F-57) has 

an analogous origin to F-56."

Furnished by: Dr. Albert E. J. Engel, Engel No. 2#-5- 

16.

Rejerence: A. E. J. Engel, written communication; 

Brown and Engel, 1956.

F-58

Name: Clinochrysotile (labeled serpentine). Green, 

shining luster, subtranslucent, massive.

Locality: Canyon of Clear Creek, New Idria quadrangle, NK sec. 12, T. 18 S., R. 11 E., San Benito 

County, Calif.

Geological occurrence: Class A. Highly sheared, and 

brecciated, lenticular masses of serpentine.

Furnished by: Dr. H. S. Yoder, Yoder No. J-33-1.

Rejerence: Yoder and Chesterman, 1951.

F-60

Name: Clinochrysotile. Artifically disaggregated bundles of white fibers.

Locality: Near Thetford, Megantic County, Quebec, 

Canada.

Geological occurrence: Class A. Hydro thermal replacement of ultrabasic rocks.

Furnished by: Dr. Bartholomew Nagy, Sample 1.

Rejerence: Cirkel, 1910; Dresser, 1913; Poitevin and 

Graham, 1918; Ross, J. G., 1931.

F-61

Name: Clinochrysotile. Part of specimen F-60, treated 

with IN HC1.

Locality: Near Thetford, Megantic County, Quebec,

Canada. 

Furnished by: Dr. Bartholomew Nagy, Sample 1.

F-63

Name: Lizardite (labeled serpentine). Light green, 

opaque, massive but having a columnar aspect which 

causes the material to break as slablike fragments. 

(Fig. 11)

Locality: Staten Island, Richmond County, N.Y.

Geological occurrence: Class A. Hydro thermal alteration of ultrabasic rocks.

Furnished by: Professor Paul F. Kerr, Kerr No. 32.

Rejerence: Newland, 1901, Pougji, 1938, Behm, 1954.

F-64

Name: Clinochrysotile and orthochrysotile (labeled 

"serpentine"). Amber, translucent, massive.

Locality: Turkey Mountain, Montville, Morris County, 

N.J.

Geological occurrence: Class B. Hydro thermal vein 

deposits in metamorphosed limestone.

Furnished by: Professor Paul F. Kerr.

Reference: Merrill, 1888, Shannon, 1927.

F-65

Name: Lizardite (labeled serpentine). Microscopic

grains in a pencatite. 

Locality: South end of the Organ Mountains, N. Mex.,

about 18 miles north of the Texas border. 

Geological occurrence: Class B. Hydrothermal alteration

of olivine in a pencatite (brucite-marble). 

Furnished by: Professor Walter F. Hunt. 

Reference: Hunt and Faust, 1937.

F-66

Name: Antigorite (labeled picrolite). Leek green, 

opaque, coarsely fibrous to lath shaped masses, some 

laths up to 1 inch in length.

Locality: Cyclops Mountains, Hollandia, Tanah Merah 

Bay, Dutch New Guinea.

Geological occurrence: Class A. Hydrothermal alteration of ultyabasic rocks.

Furnished by; Collected by Richard C. Erd.

Reference: van Bemmelen. 1949, p. 710.

F-67 

Name: Antigorite.

Locality: North of Domodossola in Val Antigorio, Novara Province, Piedmont region, Italy. According to Bonney (p. 158) 

But its occurrence in situ in the Val Antigorio itself is very 

doubtful. Thus the original specimen may have been obtained, 

either from an erratic in the lower part of the valley, or from 

an actual outcrop in a tributary one (such as the Val Devero 

or the Val Bognanco), to which the name of the main valley has 

been rather inaccurately attached.
THE SERPENTINE-GROUP MINERALS 13

Geological occurrence: Class A. Hydro thermal alteration of an ultrabasic rock (augite-olivine rock). 

Furnished by: Dr. Bartholomew Nagy, Sample 2. 

Reference: Schweizer, 1840; Bonney, 1908; Brendler, 

1912.

F-68

Name: Serpentinized phlogopite. Phlogopite with a 

small amount of chrysotile.

Locality: Verdolite quarry, River Road, 1 mile north of 

Easton, Forks Township, Northampton County, Pa.

Geological occurrence: Class B. Hydrothermal alteration of magnesian silicate minerals in metamorphosed limestone.

Furnished by: Collected by Professor W. S. Bayley.

Reference: Gordon, 1922; Bayley, 1941; Montgomery, 

1955.

F-69

Name: Chrysotile and some lizardite (?) (labeled serpentine). Fresh, homogeneous, yellowish green, 

massive.

Locality: Nickel mine, Webster, Jackson County, N.C.

Geological occurrence: Class A. Hydrothermal alteration of ultrabasic rocks (dunite).

Furnished by: Clarence S. Ross.

Reference: Nutting, 1928; Ross, Shannon, and Gonyer, 

1928.

F-70

Name: Clinochrysotile (labeled serpentine). Green,

picrolite type. 

Locality: Near Thetford, Megantic County, Quebec,

Canada. 

Geological occurrence: Class A. Hydrothermal alteration

of ultrabasic rocks. 

Furnished by: Dr. W. E. Richmond and Dr. P. G.

Nutting. 

Reference: Cirkel, 1910; Dresser, 1913; Poitevin and

Graham, 1918; Ross, J. G., 1931.

F-71

Name: Lizardite plus clinochrysotile, L>C. Lemon

yellow, translucent, massive (figs. 8, 9). 

Locality: Snarum, Modum Canton, Parish of Buskerud,

Norway. 

Geological occurrence: Class A. A lenticular mass of

serpentinized ultrabasic rock contained within gneissic rocks.

Furnished by: George T. Faust. 

Reference: Bobert, 1838; Rose, 1851; Helland, 1873;

Haraldsen, 1928 (Haraldsen's sample is referred to in

this paper as H-l).

F-72

Name: Chrysotile plus lizardite C^>L. Grayish green, 

opaque, massive.

Locality: Underground workings, New Almaden mine, 

Santa Clara County, Calif.

Geological occurrence: Class A. Completely serpentinized Iherzolite, unsheared and completely fresh. 

Bailey, written communication, found 20 percent 

bastite, much microscopic chrysotile(?), and a few 

rather amorphous veins.

Furnished by: Edgar H. Bailey (NA-32).

Reference: Bailey, 1957, written communication.

F-73

Name: Chrysotile plus lizardite OL. Greenish gray, 

opaque, massive.

Locality: Underground workings, New Almaden mine, 

Santa Clara County, Calif.

Geological occurrence: Class A. Completely serpentinized Iherzolite, unsheared and completely fresh.

Furnished by: Edgar H. Bailey (NA-39).

Reference: Bailey, 1957, written communication.

F-74

Name: Clinochrysotile plus orthochrysotile. Grayish 

green, opaque, massive.

Locality: Underground workings, New Almaden mine, 

Santa Clara County, Calif.

Geological occurrence: Class A. Highly sheared serpentine, original nature cannot be stated, but probably 

is also a Iherzolite. This rock is fresh in appearance.

Furnished by: Edgar H. Bailey (NA-33).

Reference: Bailey, 1957, written communication.

F-75

Name: Lizardite plus clinochrysotile, L>C. Opaque, 

massive. Locality: Campus of the Stevens Institute 

of Technology, Castle Point, Hoboken, Hudson 

County, N.J.

Geological occurrence: Class A. Serpentinization of 

ultrabasic rocks.

Furnished by: Collected by George T. Faust in 1947.

Reference: Newland, 1901.

F-76

Name: Lizardite plus clinochrysotile, L^>C. Part of 

specimen F-75 treated at 20°C for 1 hour with cold 

dilute HC1 (1:1).

Locality: Campus of the Stevens Institute of Technology, Castle Point, Hoboken, Hudson County, N.J.

Furnished by: Collected by George T. Faust in 1947.
14 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

FIGURE 2. Clinochrysotile (Globe-type), F-20A, asbestos deposits, Gila County, 

Ariz. Photomicrograph shows a pattern of closely mingled fibers, interrupted by 

bands of cllnoclirysotile in another orientation. Crossed polars.

FIGURE 3. Clinochrysotile (deweylite), F-50, near Moa, Cuba, Pale greenish gray 

material, massive in aspect but showing a pronounced fibration. Photomicrograph 

shows a pattern of closely mingled fibers crossed by crenulating bands. Crossed 

polars.

FIGURE 4. Clinochrysotile (iron-bearing serpentine), 145, Stillwater County, Mont. 

Massive greenish material showing the character of a metacolloidal aggregate with 

numerous polarization crosses. Crossed polars.-

FIGURE 5. Clinochrysotile and lizardite (deweylite), F-3, Forest Hill, Harford 

County, Md. Massive cream-colored material shows under the microscope a mass 

composed of plates of lizardite embedded in a matrix of Clinochrysotile and platelets 

of lizardite. Crossed polars.
THE SERPENTINE-GEOUP MINERALS 15

FIGURE 6. Clinochrysotile and llzardite, similar to F-25, Turkey Mountain, near 

Montvllle, Morris County, N.J. Photomicrograph shows flamboyant extinction in lizardite that was formed by the replacement of diopside. The 

associated grains showing a marked relief are diopside. Crossed polare.

FIGURE 7. Clinochrysotile. and lizardite. Same as figure 6. This specimen shows 

a variant form with shadowy extinction in the lizardite pseudomorphs after diopside. The pseudomorphs are embedded in a matrix of fine-grained Clinochrysotile 

and lizardite. Crossed polars.

FIGUEE 8. Lizardite plus Clinochrysotile, F-71, Snarum, Norway. Lemon-yellow 

translucent masses sho\v in thin section a mesh structure resulting from the replacement of ollvine and also platy masses of lizardite. The platy lizardite shows 

anomalous brown polarization tints. Crossed polars.

FIGUEE 9. Lizardite plus Clinochrysotile, F-71, another part of the thin section 

shown in figure 8. Typical mesh structure of the serpentine made up of an admixture of these minerals. Crossed polars.
16 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

FIGURE 10. Lizardite (deweylite), F-43, Mineral Hill, Delaware County, Pa 

Photomicropgraph has a fabriclike aspect showing an apparent mat structure. 

Crossed polars.

FIGURE 11. Lizardite, F-63, Staten Island, Richmond County, N.Y. Green slablike fragments traversed by veins of white chrysotile fibers. Thin section shows 

cleavage traces, in lizardite, ostensibly basal {OOl}, and chrysotile bands cutting 

across the cleavage. Crossed polars.

FIGURE 12. Antigorite and chrysotile (baltimorite), F-19, Bare Hills, Baltimore 

County, Md. Photomicrograph shows fibrous habit which, in part, gives rise to 

a spindly pattern. Dark spots are small accumulations of iron oxides. Crossed 

polars.

FIGURE 13. Antigorite with minor amounts of chrysotile (Yu-Yen Shi stone), F-14, 

Liaoning Province, Manchuria. Photomicrograph shows fine scaly aggregates in 

several orientations but with a prevailing orientation. Crossed polars.
THE SERPENTINE-GROUP MINERALS 17

FIGURE 14. Antigorite (williamsite), F-l, Low's mine, Lancaster County, Pa. 

Photomicrograph shows fine scaly aggregates, in part lamellar, in part divergent 

with a plumose character in the extinction relations. Crossed polars.

FIGURE 15. Antigorite (from the type locality), F-15, north of Domodossola in Val 

Antigorio, Novara Province, Piedmont region, Italy. A typical schistose specimen 

which shows in thin section scaly laminar plates. Crossed polars.

FIGURE 16. Antigorite (from the type locality), similar to F-15 but a platy form. 

Photomicrograph shows several sets of oriented lamellae. Crossed polars.

FIGURE 17. Antigorite, 120, vicinity of Caracas, Venezuela, a portion of the material 

studied by Hess, Smith, and Dengo (1952). Basal cleavage {OOIJ plates well 

developed and forming a confused aggregate. Crossed polars.
18 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

PREPARATION OF THE SAMPLES FOR STUDY

Most of the samples used in this study were prepared 

by carefully crushing large fragments down to the size 

where the serpentine-group mineral became unlocked 

from associated minerals. These grains were then 

handpicked under a binocular microscope or jeweller's 

loupe, and the purified samples crushed to a still finer 

size and reexamined. After the sample thus obtained 

was crushed to pass through a 100-mesh sieve, it was 

reexamined for impurities under the petrographic 

microscope. Almost all the samples thus prepared 

contained no detectable impurities, but in a few samples 

small specks of chromite so finely divided as to preclude 

further purification were present. In only one specimen 

did the Cr2O3 amount to as much as 0.22 percent. If we 

assume that all this Cr2O3 is present in chromite, and 

there are valid reasons to doubt this, then the maximum 

chromite content would have amounted to only 0.32 

percent.

A few samples purified by the donors were studied by 

us without further purification so as to keep the samples 

intact. Almost all these samples were studied by DTA 

and X-ray methods, and this afforded additional checks 

on the purity of the samples. These techniques are 

particularly informative on the purity of very fine 

grained mixtures.

CHEMICAL STUDIES OF SERPENTINE AND RELATED 

MINERALS

METHODS OF CHEMICAL ANALYSIS

The chemical analyses were made on samples prepared from carefully hand-picked crushed material that

was then ground to pass a 100-mesh sieve. The 

standard methods of rock analysis as outlined in "Applied Inorganic Analysis" by Hillebrand and Lundell 

(1929) were used. The SiO2 , R2O3 , CaO, and MgO were 

determined on a 1-gram sample after fusion with 

Na2CO3 . Total water was determined on half a gram 

by the Penfield method using one gram of anhydrous 

sodium tungstate as a flux. The alkalies when present 

were determined by the J. Lawrence Smith procedure.

ANALYSES STUDIED FOB THIS REPORT

Twenty-eight chemical analyses are given in tables 2, 

3, and 4 of serpentine minerals that were studied by 

various techniques and are reported upon in this contribution. Some of them have been published previously in other studies. Analyses F-l, F-14, F-19, F-20 

and F-40 are given in a paper by Nagy and Faust 

(1956); analyses F-46, F-47, and F-53 by Wells (1937), 

analysis F-68 by Bayley (1941) and analysis F-69 by 

Ross, Shannon, and Gonyer (1928). Unpublished analyses F-56 and F-57 are given with the kind permission 

of A. E. J. Engel; F-72, F-73, F-74 by our colleagues 

Edgar H. Bailey and Donald L. Everhart. Several of 

the analyses included here were made in connection 

with other studies for Clarence S. Ross, who generously 

made them available to us.

The analyses are divided into groups class A and 

class B based on their mode of origin, defined previously in the section dealing with the geological occurrence of the specimen studied.

Table 4 contains the analysis of a partially serpentinized phlogopite (eastonite) which is compared

TABLE 2. Chemical analyses of serpentine minerals formed by the reaction of hydrothermal solutions with ultrabasic rocks, Class A

SiOj -_~ ..

AhOs -

FeO.. _ __ __

MgO . - 

CaO. __ - _ ...........

Na2O-. _ _- - 

KjO 

H2O- . 

HtO+....... ... ............

TiO2 . _ - ...

CO2 - 

SO3 - 

F.._.. .__._-_ ............

NiO - - 

CoO. __ .. 

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

S.... .................

F-l

44.50

1.41

.35

41.56

.02

12.36

.06

.095

None

100.36

F-43

43.31

.30

1 40

.17

41.46

.02

.80

12.92

100.40

F-42

41.66

1.47

.87

40.92

} 14.57

99.49

F-47

40.97

5.55

Tr.

40.43

/ n. d.

I 13.80

100.75

F-46

39.92

.44

5.68

Tr.

39.10

13.80

98.94

F-40

44.25

.24

1 34

.60

39.02

.02

2.06

12.54

.07

.02

100.16

F-3

41.74

1.02

87

.17

37.90

4.85

13.16

nfi

01

99.78

F-19

43.53

1.89

.49

4.21

37.52

None

.55

11.69

0)

.01

.20

.04

100.13

F-15

41.50

3.18

1.81

4.10

35.44

.10

.80

12.60

None

.28

.16

.09

100.06

F-26

46.20

.14

.04

35.25

None

} .04

4.82

13.20

None

.04

99.73

F-48

47.0

5.5

29.7

.2 { -

} 17.7

100.1

F-72

35.98

3.19

6.36

1.72

37.60

None

14.16

.84

.29

.09

2100.27

F-73

35.98

3.36

5.49

2.29

36.99

None

15.00

.54

.32

.09

3100.20

F-74

37.36

4.31

4.42

.71

38.54

None

1C. OU

.88

.07

.25

.09

* 100. 13

F-51

36.62

.54

3.81

2.96

39.02

.02

/ 1.28

I 15.80

.22

.08

100.35

F-69

35.56

2.46

4.62

2.02

39.88

.10

.88

15.04

.22

100.78

' Very weak test. 

2 No PsOj; S=0.04.

"NoP2O6 :S=0.14. 

* No PsOs.

Sample and locality

F-l. State Line Pits, Low's mine, Pa____ Joseph J. Fahey. 

F-43. Mineral Hill, Delaware County, Pa___________ Joseph J. Fahey. 

F-42. Near Norris, Tenn_____________________ Charles Milton. 

F-47. Tyrol, Austria..-.______________________ John G. Fairchild 

F-46. Near BeUows Falls, Vt____________________ John O. Fairchild 

F-40. Murfreesboro, Ark. __________________. Joseph J. Fahey. 

F-3. Near Forest Hill, Md_____.______._ .. K. J. Murata. 

F-19. Bare Hills, Baltimore County, Md__ K. J. Murata.

DESCRIPTION OF SAMPLES 

Analyst Sample and locality Analyst 

F-15. Val Antigorio, Piedmont, Italy______________ K. J. Murata. 

F-26. Texas, Pa_______.__.__._ . _ Joseph J. Fahey. 

F-48. Mine Greek, Bakersville, N.C____._ _.....__ Charles Milton. 

F-72. New Almaden mine, Santa Clara County, Calif.. Forest A. Oonyer. 

F-73. New Almaden mine, Santa Clara County, Calif- Forest A. Oonyer. 

F-74. New Almaden mine, Santa Clara County, Calif.. Forest A. Oonyer. 

F-51. Nicaro, Oriente Province, Cuba....-.- _ -- Marie L. Lindberg. 

F-69. Nickel mine, Webster, N. C_____ ._ ... Forest A. Oonyer.
THE SERPENTINE-GROUP MINERALS 19

TABLE 3. Chemical analyses of serpentine minerals formed in calcareous or dolomitic rocks by the replacement of ferromagnesian minerals

by hydrothermal solutions or by deposition by hydrothermal solutions, Class B

[BaO was found to be absent In F-41]

SiOj...... . . . .

AljOi.... ......... . . . ...... ........

FejOs-- - . ~

FeO-..- -- . ......

MgO... . 

CaO.. ..... __ .... _ . ... 

NajO

KjO. ....... ... . 

HiO-...- ..... _

UiO+.. ................................ ....

TiOj. .......................................

COi - .... 

F...... - _ . . 

CrjOa-. - ..

NiO.. ........ ....... ...

MnO...... _ ... _. . 

2.-..-. .. ..... . 

2(cor.)-- - 

F-25

42.44

.64

.19

.03

42.76

.06

.08

.50

13.58

None

.03

100. 31

F-24

41.90

.34

42.58

.99

13.92

.04

99.77

F-22

41.88

.66

.26

no

42.18

.14

None

.70

13.98

.09

99.98

F-14

44.70

.50

.07

.29

42.05

.12

.06

12.43

100.22

F-8

44.52

.12

.07

41.88

.64

.06

12.64

.31

.002

m*>/i

.13

100.11

F-23

41.64

.72

1.96

IS

41.55

.10

NoGG

.36

13.74

None

.03

100.28

F-20

* 42.02

.52

.19

.11

41.44

1.64

14.04

.03

99.99

F-53

43.68

.34

.51

40.64

.09

.14

.11

1.18

13.12

.17

99.98

F-56

43.04

0

.87

.16

40.64

.85

.07

.01

.41

13.76

.02

.74

.10

.05

100.77

F-13

42.76

.96

.23

2.44

39.31

.02

.24

.93

13.30

None

.005

.002

.07

100.26

F-41

41.79

.09

.07

38.33

1.62

2.92

12.53

.01

2.87

.003

100.23

1-57

42.03

.35

.26

f\A

^0 Qf\

1 VI

1 04

19 OS

.16

1

1O

.55

.01

.49

fU

99.83

Sample and locality 

F-25. Montville, N.J. .........

F-24. Montville, N.J. ... . 

F-22. Turkey Mountain, Montville, N.J. 

F-14. Manchuria -.- _._______ 

F-8. Smithfleld, R.I.... 

F-23. Dognacska, Hungary_. 

Description of samples

Analyst Sample and locality

Joseph J. Fahey. F-20. Gila County, Ariz........ ...

K. J. Murata. F-53. Grand Canyon, Ariz... ......

Joseph J. Fahey. F-56. Balmat Corners, N.Y..______.

Joseph J. Fahey. F-13. Near Brewster Station, N.Y..__.

K. J. Murata. F-41. White Pine County, Nev._ .

Joseph J. Fahey. F-57. Talcville, N.Y...... ..-.-.....

Analyst

Joseph J. Fahey. 

Roger C. Wells. 

Margaret D. Foster. 

Joseph J. Fahey. 

Rollin E. Stevens. 

Eileen K. Oslund.

with the calculated composition of a mixture of 50 percent phlogopite and 50 percent serpentine (Bayley, 

1941).

ANALYSES TAKEN FROM THE LITERATURE

The collection of analyses of serpentine-group minerals from the literature is a sizable task, for they were 

amongst the earliest minerals to be analyzed. In 

order to bound the selection of analyses it was decided 

to take them as follows: For the older literature, the 

sources Dana (1892) and Gordon (1922); and for the 

recent literature, the papers by Jakob (1931), Selfridge 

(1936), Caillere (1936) Koufimsk£ and Satava (1954), 

Pundsack (1955), Kalousek and Muttart (1957), and 

Brindley and Zussman (1957) were consulted. In so

TABLE 4. Chemical analysis of a partially serpentinized 

phlogopite (eastonite)

[Sample F-68. Easton, Pa., John G. Fairchild, analyst. Calculated mixture 

Calculated composition of a mixture of 50 percent unaltered phlogopite and 50 

percent pure serpentine. Calculated by W. S. Bayley]

SiO2 ._. 

A12O3 - 

Fe2O3 - 

MgCLCaO_. 

Na2OK2O 

H2O-. 

H2 0+. 

C02

F-68

46.20

5. 59

1.06

33. 95

None

.25

4.54

.24

5. 72

Present

.60

98. 15

Mixture 

42.8 

5. 5 

.3 

36. 5 

None 

. 15 

4.9 

0 

7.5

.55

98.20

doing all duplications were eliminated and further 

analyses were found and a representative number of 

these are included herein. Asbestos is an important 

industrial mineral and it was more than desirable to 

include analyses of typical specimens. Merrill (1895), 

Becker and Haag (1928), Hall (1930), Ross (1931), 

Golding and Phaup (1936), Bowles (1955), Sinclair 

(1955), and Kalousek and Muttart (1957) were the 

chief sources. Sinclair's collection, obtained chiefly 

from the above references, was used as a check for 

coverage. It contains in addition some averaged 

analyses, prepared by averaging the data for different 

samples and some analyses from which minor constituents have been omitted. The collection in the 1928 

edition of Becker and Haag likewise contains averaged 

analyses. Almost all the averaged analyses from the 

various sources have been excluded, and those which 

were known to be incomplete were verified and corrected.

A brief statement pertinent to each analysis includes, 

insofar as known, the name, variety, color, locality, 

analyst, source for the chemical analysis, and notes. 

In preparing the data on topographic mineralogy, free 

use was made of Brendler (1912), the Columbia Lippincott Gazetteer of the World (Seltzer, 1952), and Dana 

(1892).

LOCATION AND DESCRIPTION OF 219 SPECIMENS

[For analyses of these specimens, see table 5]

1. Metaxite. Reichenstein, Silesia. Robert B. Hare, 

1879, analyst. Source: Caillere, 1936.
20 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

2. Pyknotrope. Waldheim, Saxony. Fikenscher, analyst. Source: Kourlmsk^ and Satava, 1954.

3. Alumino-chrysotile. Hard, flattened, fibers. In the 

contact zone of granite and serpentinite. Markoopidj river basin, northern Caucasus, U.S.S.R. 

Dimitri Serdyuchenko, 1945, analyst. Source: 

Serdyuchenko, 1945.

4. Altered serpentine. Verdolite quarry, Easton, 

Northampton County, Pa. John Eyerman, 1911, 

analyst. Source: Gordon, 1922.

5. Serpentine. Ambindavato, Madagascar. S. Caillere, 1936, analyst. Source: Caillere, 1936.

6. Metaxite. Moncaup, Dept. Haute-Garonne, 

France. S. Caillere, 1936, analyst. Source: 

Caillere, 1936.

10. Antigorite. Sterzing, Tyrol, (Vipiteno) Bolzano 

Province, Italy. S. Caillere, 1936, analyst. 

Source: Caillere, 1936.

11. Picrosmine. Windisch-Matrei, East Tyrol, Austria. S. Caillere, 1936, analyst. Source: Caillere, 1936.

12. Antigorite. Zermatt, Canton Wallis, Switzerland. 

S. Caillere, 1936, analyst. Source: Caillere, 

1936.

13. Dermatine. Waldheim, Saxony, Germany. S. 

Caillere, 1936, analyst. Source: Caillere, 1936.

14. Picrolite. North quarry, "Orphan's Luck Claims," 

Belingwe District, Southern Rhodesia. Ernest 

Golding, 1936, analyst. Source: Golding and 

Phaup, 1936, p. 96.

15. Antigorite. Rossa, Val Antigorio, Piedmont, Italy. 

USNM R-96917. William E. Smith, 1957, 

analyst. Source: Kalousek and Muttart, 1957.

16. Serpentine. Dense, gray "mother rock" of serpentine sample 121. Kaapsche Hoop, Barberton District, Transavaal, Union of South Africa. 

Johann Jakob, 1931, analyst. Source: Jakob, 

1931.

17. Metaxite. Vallee de Comberousse near Saint 

Colomban-des-Villards, Savoy, France. S. Caillere, 1936, analyst. Source: Caillere, 1936.

18. Serpentine, green; adhering to chrysotile. Northern Joubertsdal, Barberton District, Transvaal, 

Union of South Africa. J. McCrae, 1930, analyst. 

Source: Hall, 1930, p. 113.

19. Serpentine, green. Northern Joubertsdal, Barberton District, Transvaal, Union of South 

Africa. J. McCrae, 1930, analyst. Source: Hall, 

1930, p. 113.

20. Antigorite. North of Domodossola in Val Antigorio, Novara Province, Piedmont region, Italy. 

Sylvia Hillebrand, 1906, analyst. Source: Caillere, 1936.

21. Serpentine, green; containing stichtite. New Aniianthus mine, Northern Joubertsdal, Barberton 

District, Transvaal, Union of South Africa. 

J. McCrae, 1930, analyst. Source: Hall, 1930, 

p. 113.

25. Antigorite. North of Domodossola in Val Antigorio, Novara Province, Piedmont region, Italy. 

S. Caillere, 1936, analyst. Source: Caillere, 

1936.

26. Serpentine, precious. Easton, Northampton County, Pa. Thomas Thomson, 1828, analyst. 

Source: Gordon, 1922.

27. Serpentine, green. Altered gray pyroxene. Montville, Morris County, N.J. Charles Catlett, 

1881, analyst. Source: Merrill, 1888.

28. Chrysotile. Slip fiber. Biltong Mine, Vukwe 

Mountains, Belingwe District, Southern Rhodesia. 

Ernest Golding, 1936, analyst. Source: Golding and Phaup, 1936, p. 96.

29. Antigorite. Villa Rosa, on the Po, Italy. Achille 

E. O. J. Delesse, 1848, analyst. Source: Delesse, 

1848.

30. Antigorite. North of Domodossola, in Val Antigorio, Novara Province, Piedmont region, Italy. 

George J. Brush, 1857, analyst. Source: Brush, 

1857.

31. Baltimorite. Bare Hills, Baltimore County, Md. 

Thomas Thomson, 1843, analyst. Source: Selfridge, 1936.

32. Serpentine, red-brown. Porthalla, Lizard, Cornwall, England. J. H. Collins, 1884, analyst. 

Source: Dana, 1892.

33. 6-layer orthoserpentine. No. 1 Massive. Nikka Vord chromite quarries, north of Baltasound, 

Unst, Shetland Islands. Oleg von Knorring, 

1954, analyst. Source: Brindley and von Knorring, 1954.

34. Williamsite. Texas, Lancaster County, Pa. 

James Lawrence Smith and George J. Brush, 

1853, analysts. Caillere, 1936.

35. Chrysotile. Shabani asbestos mine, Southern 

Rhodesia. Government Chemical Laboratory, 

Johannesburg, analyst not known. Source: 

Hall, 1930, p. 31.

36. Serpentine. Port Henry, Essex County, N.Y. 

Charles Catlett, 1889, analyst. Source: Dana, 

1892.

37. Chrysotile. Fiber. Ethel mine, Lomagundi District, Southern Rhodesia. Ernest Golding, 1936, 

analyst. Source: Golding and Phaup, 1936, p. 

94.

38. Serpentine, light. Sulphur Bank, on Clear Lake, 

Lake County, Calif. W. H. Melville, 1888, analyst. Source: Dana, 1892.
THE SERPENTINE-GROUP MINERALS 21

39. Antigorite. Tilly Foster mine, near Brew^ter Station, N.Y. George W. Hawes, 1874, analyst. 

Source: Caillere, 1936.

40. Picrosmine. Pressnitz, Czechoslovakia. S. Caillere, 1936, analyst. Source: Caillere, 1936.

41. Serpentine. New Idria, San Benito County, Calif. 

W. H. Melville, 1888, analyst. Source: Dana, 

1892.

42. Chrysotile. Province of Quebec, Canada. S. Caillere, 1936, analyst. Source: Caillere, 1936.

43. Picrolite. Val d'Aosta, Italy. S. Caillere, 1936, 

analyst. Source: Caillere, 1936.

44. Picrosmine. Greiner, Zemin Tal, Ziller-Tal, Austria. Schweizer, 1844, analyst. Source: Schweizer, 1844. Koufimsk^ and Satava, 1954, find 

it to be antigorite.

45. Chrysotile. Silky. Transvaal, Union of South 

Africa. William A. Deer, 1957, analyst. Source: 

Brindley and Zussman, 1957.

46. Serpentine, precious. William's Bushkill quarry, 

Easton, Northampton County, Pa. John Eyerman, 1911, analyst. Source: Gordon, 1922.

47. Serpentine, variety steatoid. Dybingdale, north of 

a small lake called Dybingin, in the "Walde des 

Hofes Uhlen," Snarum, Modum Canton, Parish 

of Buskerud, Norway. Candidate Hartwall, in 

Prot. Berzelius' laboratory, 1838, analyst. 

Source: Bobert, 1838.

48. Serpentine, yellow. Altered white pyroxene. 

Montville, Morris County, N.J. Charles Catlett, 

1888, analyst. Source: Merrill, 1888.

49. Antigorite, platy. Mikonui, New Zealand. Robert 

A. Howie, 1954, analyst. Source: Zussman, 1954.

50. Antigorite, green; from a kluft in dense serpentine, 

outermost zone of peridotite in contact with 

amphibolite. Valle di Capolo, left bank of the 

river Centovalli in Tessin (Ticino), Switzerland. 

Johann Jakob, 1931, analyst. Source: Jakob, 

1931.

51. Chrysotile. About 8 miles from Tinaquillo, State 

of Cojedes; approximately 145 miles from Caracas, Venezuela. Analysis turnished by "Raybestos Manhattan" of New York. Source: Davey, 

1947, confirmed by Donald O. Kennedy, U.S. 

Bur. Mines, written communication, April 24, 

1959.

52. Chrysotile. Yellowish-white fibers with a silky 

luster. Montville, Morris County, N.J. Edwin 

L. Reakirt, 1854, analyst. Source: Dana, 1892.

53. Chrysotile, yellow1. Ship ton, Richmond County, 

Quebec Province, Canada. E., G. Smith, 1885, 

analyst. Source: Dana, 1892.

54. Chrysotile, light-green. Australia(?). Johann 

Jakob, 1931, analyst. Source: Jakob, 1931.

60. Serpentine, oil-green. Porthalla, Lizard, Cornwall, 

England. J. H. Collins, 1884, analyst. Source: 

Dana, 1892.

61. Metaxite. Reichenstein, Silesia. S. Caillere, 1936 

analyst. Source: Caillere, 1936.

62. Serpentine. Snarum, Modum Canton, Parish of 

Buskerud, Norway. D. Fogy, 1906, analyst. 

Source: Selfridge, 1936.

63. Antigorite, green. Sils im Oberengadin, Grisons 

Canton, Switzerland. Johann Jakob, 1931, analyst. Source: Jakob,1931.

64. Chrysotile. Fibers. Montville, Morris County, 

N.J, USNM R-4656. William E. Smith, 1957, 

analyst. Source: Kalousek and Muttart, 1957.

65. Chrysotile. Fibers. Middletown Township. Delaware County, Pa. USNM R-4658. William E. 

Smith, 1957, analyst. Source: Kalousek and 

Muttart, 1957.

66. Serpentine, .dense, light-gray. Premier diamond 

pit, fhillinan, South-central Transvaal, Union of 

South Africa. Johann Jakob, 1931, analyst. 

Source: Jakob, 1931.

67. Chrysotile. Slip fiber. Biltong mine, Vukwe 

Mountains, Belingwe District, Southern Rhodesia. Ernest Golding, 1936, analyst. Source: 

Golding and Phaup, 1936, p. 96.

68. Serpentine. Matrix. Montville, Morris County, 

N.J. USNM R-4656. William E. Smith, 1957, 

analyst. Source: Kalousek and Muttart, 1957.

69. Serpentine. Matrix. Middletown Township, Delaware County, Pa. USNM R-4658. William E. 

Smith, 1957, analyst. Source: Kalousek and 

Muttart, 1957.

70. Chrysotile. Montville, Morris County, N.J. Sylvia 

Hillebrand, 1906, analyst. Source: Caillere, 1936.

71. Chrysotile, light-green. Reichenstein, Silesia. 

Johann Jakob,, 1931, analyst. Source: Jakob, 

1931.

72. Serpentine, precious. Niddister, Hillswick Ness, 

Shetland Island. Matthew F. Heddle, 1924, 

analyst. Source: Brindley and von Knorring, 

1954.

73. Serpentine, gray. Tilly Foster mine, near Brewster Station, N.Y. C. A. Burt, 1873, analyst. 

Source: Dana, 1892.

75. Chrysotile. Long fiber, "Ribbon Line," New Amianthus mine, Barberton District, Transvaal, 

Union of South Africa. Government Chemical 

Laboratory, Johannesburg, analyst not known. 

Source: Hall, 1930, p. 31.

76. Chrysotile, pale-green. From the ancient mines 

on the southeast of Mount Troodos, Island of 

Cyprus, Mediterranean Sea. G. S. Blake, 1906, 

analyst. Source: Evans, 1906.
22 STUDIES OP THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

77. Serpentine, black. Cadgwith, Lizard, Cornwall, 

England. W. H. Hudleston, 1877, analyst. 

Source: Dana, 1892.

78. Antigorite. North of Domodossola, in Val Antigorio, Novara Province, Piedmont region, Italy. 

Bergrath Stokar-Escher 1856, analyst. Source: 

Kenngott, 1856-57.

79. Black chrysotile. Bazhenovo, Ural Mountains, 

south of Sverdlovsk Oblast', U.S.S.R. A. V. 

Benevopenskoi, 1956, analyst. Source: Vertushkov and Yarosh, 1956.

80. Chrysotile. Fibrous serpentine, amianthus. 

Victoria, Province of British Columbia, Canada. 

George P. Merrill, 1895, analyst. Source: Merrill, 1895.

81. Pseudo-cubic serpentine. Tilly Foster mine, near 

Brewster Station, N.Y. Georges Friedel, 1891, 

analyst. Source: Dana, 1892.

82. Serpentine, dark-red. Lizard, Cornwall, England. 

J. A. Phillips, 1871, analyst. Source: Dana, 

1892.

83. Bowenite. Kuttenberg, Bohemia; Kutna Hora, 

Czechoslovakia. A. Bukowsky, 1908, analyst. 

Source: Caillere, 1936.

84. Serpentine, fibrous; "Williamsite." 100 feet 

from road between Ethel mine and the Matoroshanga Pass, 1.8 miles south from south-center, 

beacon of the Umvukwe Ranch Extension, 

Umvukne Ranch, Southern Rhodesia. Ernest 

Golding, 1930, analyst. Source: Keep, 1930, 

p. 83.

85. Williamsite. Texas, Lancaster County, Pa. S. 

Caillere, 1936, analyst. Source: Caillere, 1936.

86. Chrysotile. Long fiber, "Grade IXL." From No. 

4, main workings, Munnik-Mybirgh Asbestos 

Ltd., near Kaapsche Hoop deposits, Barberton 

District, Transvaal, Union of South Africa. 

H. G. Weall, 1930, analyst. Source: Hall, 1930, 

p. 31.

87. Serpentine. Matrix. Templeton Township, Papineau County, Quebec, Canada. Specimen from 

Prof. Charles U. Shepard, 1881. USNM 18879. 

William E. Smith, 1957, analyst. Source: 

Kalousek and Muttart, 1957.

88. Serpentine. Matrix. Aboutville, New York. 

Specimen from Prof. George J. Brush, 1874. 

USNM 9143. William E. Smith, 1957, analyst. 

Source: Kalousek and Muttart, 1957.

89. Chrysotile. Thetford, Megantic County, Quebec, 

Canada. J. T. Donald, Montreal, 1910, analyst. 

Source: Cirkel, 1910, p. 31.

90. Serpentine. Snarum, Modum Canton, Parish of 

Buskerud, Norway. Theodor Scheerer, 1846, 

analyst. Source: Rose, 1851.

91. Chrysotile. Fibers. Aboutville, N.Y. Specimen 

from George J. Brush, 1874. USNM 9143. 

William E. Smith, 1957, analyst. Source: 

Kalousek and Muttart, 1957.

92. Serpentine, dark. Sulphur Bank, Clear Lake, 

Lake County, Calif. W. H. Melville, 1888, 

analyst. Source: Dana, 1892.

93. White serpentine. Tilly Foster mine, near Brewster Station, Putnam County, N.Y. E. S. 

Breidenbaugh, 1873, analyst. Source: Dana, 

1892.

94. Chrysotile. Southwark mine, Black Lake, 5 miles 

southwest of Thetford mines, Megantic County, 

Quebec, Canada. J. T. Donald, Montreal, 1910, 

analyst. Source: Cirkel, 1910, p. 31.

95. Serpentine, precious. Leslie's farm, Newlin, 

Chester Count}^, Pa. John Eyerman, 1911, 

analyst. Source: Gordon, 1922.

96. Schweizerite. Zermatt, Canton Wallis, Switzerland. S. Caillere, 1936, analyst. Source: 

Caillere, 1936.

97. Chrysotile. Average of 11 analyses of typical and 

representative samples of chrysotile from the 

Province of Quebec, Canada. Primary data in 

Cirkel, 1910. Computed by Hall, 1930. Source: 

Hall, 1930, p. 31.

98. Serpentine, precious. Newburyport, Essex County, 

Mass. Th. Petersen, 1866, analyst. Source: 

Dana, 1892.

99. Thermophyllite. Delaware River quarry, Easton, 

Northampton County, Pa. John Eyerman, 

1911, analyst. Source: Gordon, 1922.

100. Chrysotile. From the nickel mines at Petsamo, 

Finland. G. Bastien and A. Dikenstein, 1954, 

analysts. Source: Thoreau, 1954, p. 110.

101. Chrysotile. Templeton Township, Papineau 

County, Quebec, Canada. J. T. Donald, 1891, 

analyst. Source: Dana, 1892.

102. Antigorite. Tilly Foster mine, near Brewster 

Station, N.Y. S. Caillere, 1936, analyst. 

Source: Caillere, 1936.

110. Serpentine, green to grayish-black. Edward's 

quarry, Willistown, Chester County, Pa. John 

Eyerman, 1911, analyst. Source: Gordon, 

1922.

111. Chrysotile. Fort Victoria, Southern Rhodesia. 

Government Chemical Laboratory, Johannesburg, analyst not known. Source: Hall, 1930, 

p. 31.

112. Orthoserpentine, 6-layer. No. 2, Nikka Vord 

chromite quarries, North of Baltasound, Unst, 

Shetland Islands. Oleg von Knorring, 1954, 

analyst. Source: Brindley and von Knorring, 

1954.
THE SERPENTINE-GROUP MINERALS 23

113. Thermophyllite. Hoponsuo, near Pitkaranta, 

Finland. Augustus B. Northcote, 1858, 

analyst. Source: Dana, 1892.

114. Precious serpentine. Dense. Snarum, Modum 

Canton, Parish of Buskerud, Norway. Johann 

Jakob, 1931, analyst. Source: Jakob, 1931.

115. Chrysotile. Amalgamated Asbestos Corp. B. C. 

quarries, Black Lake, 5 miles southwest of 

Tbetford mines, Megantic County, Quebec, 

Canada. Milton Hershey, Montreal, 1910, 

analyst. Source: Cirkel, 1910, p. 31.

116. Serpentine. Snarum, Modum Canton, Parish of 

Buskerud, Norway. Haakon Haraldsen, 1928, 

analyst. Source: Haraldsen, 1928.

120. Antigorite (fig. 17). Vicinity of Caracas, Federal 

District, Venezuela. Lee C. Peck, 1952, analyst. Source: Hess, Smith, and Dengo, 1952.

121. Chrysotile, light-green. Kaapsche Hoop, Barberton District, Transvaal, Union of South Africa. 

Johann Jakob, 1931, analyst. Source: Jakob, 

1931.

122. Serpentine, white. Easton, Northampton County, 

Pa. John Eyerman, 1911, analyst. Source: 

Gordon, 1922.

123. Porcellophite. Delaware River quarry, Easton, 

Northampton County, Pa. John Eyerman, 

1911, analyst. Source: Gordon, 1922.

124. Deweylite, white. Optically pseudo-isotropic. 

Mladotice, near Ronow, (eastern Bohemia), 

Czechoslovakia. Jiri Konta, 1953, analyst. 

Source: Konta, 1953.

125. Marmolite. Hoboken, Hudson County, N.J. 

Franz von Kobell, 1874, analyst. Source: 

Selfridge, 1936.

126. Bowenite. Khotan, near the Yarkand, Chinese 

Turkestan, China. S. Caillere, 1936, analyst. 

Source: CaillSre, 1936.

127. Antigorite. Muruhattan, Northern Sweden. 

Ragnar Blix, 1935, analyst. Source: Du Rietz, 

1935.

128. Thermophyllite. Hoponsuo, near Pitkaranta, 

Finland. R. Hermann, 1858, analyst. Source: 

Selfridge, 1936.

129. Chrysotile. Gath Asbestos mines, Gath, Victoria 

Province, vSouthern Rhodesia. Government 

Chemical Laboratory, Johannesburg, analyst 

not known. Source: Hall, 1930, p. 31.

130. Serpentine. Corundum Hill, near Franklin on the 

Little Tennessee River, Macon County, N.C. 

Edward A. Schneider, 1890, analyst. Source: 

Dana, 1892.

131. Deweylite, grayish-green. Optically pseudo-isotropic. Mladotice, near Ronow, (Eastern Bohemia), Czechoslovakia. Jiri Konta, 1953, analyst. Source: Konta, 1953.

132. Antigorite. Zermatt, Canton Wallis, Switzerland. F. von Kobell, 1876, analyst. Source: 

Dana, 1892.

133. Schweizerite. Zermatt, Canton Wallis, Switzerland. Eduard Schweizer, 1884, analyst. 

Source: Selfridge, 1936.

134. Serpentine. Coleraine, southeast of Thetford, 

Megantic County, Quebec, Canada. B. J. 

Harrington, 1890, analyst. Source: Dana, 1892.

135. Serpentine, light-green. Cornwall, Lebanon 

County, Pa. John Eyerman, 1911, analyst. 

Source: Gordon, 1922.

136. Picrolite. Taberg, 12 km south of J6nk6ping, Lan 

J6nk6ping, Smalands, south Sweden. Nils W. 

Almroth, 1818, analyst. Source: Almroth, 1818. 

Kouflmsky and Satava, 1954, find it to be "sort 

of antigorite."

137. Serpentine, variety vorhauserite. Fassa-Tal, (Val 

di Fassa) Tyrol, Italy. Joseph Oellacher, 1857, 

analyst. Source: Kenngott, 1857. Not included in the analysis 0.96 percent apatite.

138. Chrysotile. Amelose bei Biedenkopf an der Lahn, 

Hesse-Nassau, Germany. R. Brauns, 1887, analyst. Source: Dana, 1892.

139. Picrolite. Florida, Berkshire County, Mass. 

W. H. Melville, 1879, analyst. Source: Dana, 

1892.

140. Deweylite. The Hunt, Delaware County, Pa. 

John Eyerman, 1911, analyst. Source: Gordon, 

1922.

145. Serpentine, iron-bearing (fig. 4). Stillwater 

Complex, Stillwater County, Montana. 

Alexander H. Phillips, analyst. Source: Harry 

H. Hess, written communication, 1957.

146. Lizardite. Kennack Cove, Lizard, England. L.J. 

Larner, 1951, analyst. Source: Midgley, 1951, 

p. 527.

147. Chrysotile. Radiated. Franklin, Hardyston 

Township, Sussex County, N.J. William F. 

Foshag, 1926, analyst. Source: Foshag, 1926.

148. Chrysotile. MSdous, 2 kilometers from Bagn&resde-Bigorre, Hautes-Pyren6es, France. S. Cail13re, 1936, analyst. Source: CaillSre, 1936.

149. Chrysotile. Ambindavato, Madagascar. S. 

Caillere, 1936, analyst. Source: CaillSre, 1936.

150. Bowenite. Bh6ra, Shahpur district, Afghanistan. 

G. T. Prior, 1890,analyst. Source: Dana, 1892.

151. Porcellanous, resembling compact lithomarge. 

Middletown, Delaware County, Pa. Beverly S. 

Burton, 1868, analyst. Source: Gordon, 1922.
24 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

152. Chrysotile. .Typematerial. Reichenstein, Silesia. 

Franz von Kobell, 1834, analyst. Source: von 

Kobell, 1834.

153. Picrolite. Wood's mine, Lancaster County, Pa. 

W. H. Brewer, 1850, analyst. Source: Gordon, 

1922.

154. Deweylite, brownish-red. Distinctly fibrous.

Mladotice, near Ronow, (Eastern Bohemia),

Czechoslovakia. Jiri Konta, 1953, analyst.

Source: Konta, 1953. 

1'55. Porcellophite. Middletown, Delaware County,

Pa. Beverly S. Burton, 1868, analyst. Source:

Selfridge, 1936.

156. Williamsite. Texas, Lancaster County, Pa. R. 

Hermann, 1851, analyst. Source: Selfridge, 

1936.

157. Serpentine, yellowish. East Goshen, Chester 

County, Pa. S. B. Sharpies, 1866, analyst. 

Source: Gordon, 1922.

158. Serpentine, slaty. Low's mine, Lancaster County, 

Pa. Benjamin Silliman, Jr., 1849, analyst. 

Source: Gordon, 1922.

159. Deweylite. Bare Hills, Baltimore County, Md. 

Thomas Thomson, 1843, analyst. Source: Selfridge, 1936.

160. Serpentine, light-green. Delaware River quarry, 

Easton, Northampton County, Pa. John Eyerman, 1911, analyst. Source: Gordon, 1922.

161. Chrysotile. Near New Havefi, New Haven 

County, Conn. George J. Brush, 1854, analyst. 

Source: Dana, 1892.

162. Picrolite. Taberg, 12 km south of Jonkoping, 

Lan Jonkoping, Smalands, south Sweden. L. 

P. Lyehnell, 1826, analyst. Source: Lychnell, 

1826.

163. Bowenite. New Zealand. F. Berwerth, 1879, 

analyst. Source: Dana, 1892.

164. Chrysotile. "High-grade fiber," occurring in 

dolomite. Diepgezet east of Carolina, Transvaal, Union of South Africa. C. Gardthausen, 

1930, analyst. Source: Hall, 1930, p. 31.

165. Deweylite. Baie d'Ouie, near la Peak, New Caledonia, Pacific Ocean. Auguste Terreil, 

analyst. Source: Lacroix, 1942-1943, p. 30.

166. "Meerschaum," serpentine. Middletown, Delaware County, Pa. John Eyerman, 1911, 

analyst. Source: Gordon, 1922.

170. Deweylite. Ruth's mine, Berks County, Pa. D. 

B. Brunner and Edgar F. Smith, 1883, analysts. 

Source: Gordon, 1922.

171. Deweylite. .Baie d'Ouie, near la Peak, New Caledonia, Pacific Ocean. S. Caill&re, 1936, analyst. 

Source: CaiMre, 1936.

172. Webskyite. Between Mornshausen an der 

Dautphe and Amelose "in Hessische Hinterland," not far from Bindenkopf an der Lahn, 

Hesse-Nassau, Germany. Rheinhard Brauns, 

1887, analyst. Source: Brauns, 1887. Kourimsky and Satava, 1954, find it to be a mixture 

of antigorite and chrysotile where antigorite ^> 

chrysotile.

173. Williamsite. Texas, Lancaster County, Pa. 

Adolf Lindner, 1896, analyst. Source: Caillere, 

1936.

174. Deweylite. Brownish, resinous botryoidal masses. 

Wood's mine, Lancaster County, Pa. George 

J. Brush, 1854, analyst. Source: Selfridge, 

1936.

175. Serpentine, variety Karachaite. Yellow fibers, 

silky luster, hard. Asbestos deposits of ShamanBeklegen, Karachi, northwest Caucasus, 

U.S.S.R. V. Krylova, 1936, analyst. Source: 

Efremov, 1936.

176. Deweylite. Baie d'Ouie, near la Peak, New Caledonia, Pacific Ocean. Stoyanoff, analyst. 

Source: Lacroix, 1942-1943, p. 30.

177. Aquacreptite. Yellowish-brown, amorphous 

masses, with conchoidal fracture. Strode's 

Mill, East Bradford, Chester County, Pa. J. 

H. Eaton, 1868, analyst. Source: Gordon, 

1922.

178. Serpentine. Ambindavato, Madagascar. S. Caillere, 1936, analyst. Source: Caillere, 1936.

179. Aquacreptite. Strode's Mill, East Bradford, 

Chester County, Pa. C. U. Shepard, 1868, 

analyst. Source: Gordon, 1922.

180. Serpentine, blue-black. Northern Joubertsdal, 

Barberton District, Transvaal, Union of South 

Africa. J. McCrae, 1930, analyst. Source: 

Hall, 1930, p. 113. "Finely fibrous talcose or 

serpentine mineral replaced pale or colorless 

mineral."

181. Deweylite. Whitish and brownish resinous coatings with aragonite and serpentine. Ruth's 

mine, Berks County, Pa. D. B. Brunner and 

Edgar F. Smith, 1883, analysts. Source: 

Gordon, 1922.

182. Webskyite. Bottenhorn, 15 km northeast of 

Dillenburg, Hesse-Nassau, Germany. Rheinhard Brauns, 1887, analyst. Source: Brauns, 

1887.

183. Williamsite. Low's mine, Lancaster County, Pa. 

George J. Brush, 1850, analyst. Source: Gordon, 1922.

185. Picrosmine. Pressnitz, Czechoslovakia. Guster 

Magnus, 1826, analyst. Source: Caillere, 1936.
THE SERPENTINE-GROUP MINERALS 25

186. Neolite, green or yellow; massive or silky, fibrous. 

Rose's quarry, Lower Merion, Montgomery 

County, Pa. Harry W. Jayrie, 1875, analyst. 

Source: Gordon, 1922.

187. Picrosmine. Zwickau, Saxony, Germany. August Frenzel, 1880, analyst. Source: Cailleire, 

1936.

190. Picrolite. Val d'Aosta, Italy. Alfonso Cossa, 

1878, analyst. Source: Caillere, 1936.

191. Picrolite. Val d'Aosta, Italy. Alfonso Cossa, 

1878, analyst. Source: Caillere, 1936.

192. Serpentine. Dense "mother rock" associated with 

the chrysotile No. 202. Templeton, Temple ton 

Township, Papineau County, Quebec, Canada. 

Johann Jakob, 1931, analyst. Source: Jakob, 

1931.

193. Deweylite. Ruth's mine, Berks County, Pa. H. F. 

Keller, 1885, analyst. Source: Gordon, 1922.

194. Chrysotile. Montville, Morris County, N.J. S. 

Caillere, 1936, analyst. Source: Caillere, 1936.

195. Serpentine, dark oil green. Delaware River quarry, Easton, Northampton County, Pa. John 

Eyerman, 1911, analyst. Source: Gordon, 1922.

196. Chrysotile. Bell Asbestos mine, depth 130 ft., 

north side, Thetford, Megantic County, Quebec, 

Canada. E. A. Thompson, 1931, analyst. 

Source: Ross, 1931, p. 20.

197. Chrysotile, green. Wurlitz, 8 km southeast of 

Hof, Fichtelgebirge, Germany. Johann Jakob, 

1931, analyst. Source: Jakob, 1931.

198. Serpentine. Wheatfield mine, Berks County, Pa. 

H. F. Keller, 1885, analyst. Source: Dana, 

1892.

199. Schweizerite. Zermatt, Canton, Wallis, Switzerland. Viktor Merz, 1861, analyst. Source: 

Caillere, 1936.

200. Serpentine, fibrous, amianthus. Province of Quebec, Canada. James T. Donald, 1891, analyst. 

Source: Merrill, 1895.

201. Williamsite. Low's mine, Lancaster County, Pa. 

James Lawrence Smith and George J. Brush, 

1853, analysts. Source: Gordon, 1922.

202. Chrysotile, light-yellow; almost colorless. Templeton, Templeton Township, Papineau County, 

Quebec, Canada. Johann Jakob, 1931, analyst. 

Source: Jakob, 1931.

203. Chrysotile, dark-green. Ship ton, Richmond 

County, Quebec, Canada. E. G. Smith, 1885 

analyst. Source: Dana, 1892.

204. Chrysotile. Goujot, Vosges, France. AchilleE. J. 

Delesse, 1897, analyst. Source: Selfridge, 1936.

205. Chrysotile. Serpentine, fibrous, amianthus. "Alpine beds," Italy. J. T. Donald, Montreal, 

1891, analyst. Source: Cirkel, 1910, p. 31.

206. Retinalite, pale wax-yellow. Calumet Islands on 

the Ottawa River, southwest Quebec, Canada. 

T. Sterry Hunt, 1883, analyst. Source: Dana, 

1892.

207. Schweizerite. Zermatt, Canton Wallis, Switzerland. Adolf Lindner, 1896, analyst. Source: 

Caillere, 1936.

208. Bowenite. Smithfield, Providence County, R. I. 

James Lawrence Smith and George J. Brush, 

1853, analysts. Source: Selfridge, 1936.

209. Bowenite. Smithfield, Providence County, R.I. 

James Lawrence Smith and George J. Brush, 

1853, analysts. Source: Selfridge, 1936.

210. Serpentine. Light-green fibers. Shabani mine, 

Shabani, Southern Rhodesia. Johann Jakob, 

1931, analyst. Source: Jakob, 1931.

211. Bowenite, yellow. Smithfield, Providence County, R.I. James Lawrence Smith and George J. 

Brush, 1853, analysts. Source: Dana, 1892.

212. Chrysotile. Broughton, Beauce County, Quebec, 

Canada. J. T. Donald, 1891, analyst. Source: 

Dana, 1892.

213. Serpentine, green. Tilly Foster mine, near Brewster Station, N.Y. C. A. Burt, 1873, analyst. 

Source: Dana, 1892.

214. Antillite. Havana, Havana Province, Cuba, West 

Indies. Charles U. Shepard, 1872, analyst. 

Source: Shepard, 1872.

215. Serpentine. Buckwheat mine, Franklin, Hardyston Township, Sussex County, N.J. Henry E. 

Merwin, 1937, analyst. Source: Palache, 1937. 

Note. Analysis recalculated to 100 percent after eliminating 3.63 percent carbonates.

216. Serpentine, dark oil-green. William's Delaware 

quarry, Easton, Northampton County, Pa. 

John Eyerman, 1911, analyst. Source: Gordon, 1922.

217. Chrysotile. Danville area, Richmond County, 

Quebec, Canada. Thomas Sopoci and Richard 

Wiley, 1955, analysts. Source: Pundsack, 

1955.

218. Bowenite. Shigar, Ladakh District, East Kashmir, Kashmir State. C. A. McMahon, 1901, 

analyst. Source: Selfridge, 1936.

219. Serpentine. Ruth's mine, Berks County, Pa. H. 

F. Keller, 1885, analyst. Source: Dana, 1892.

220. Marmolite. Hoboken, Hudson County, N.J. 

Thomas H. Garrett, 1850, analyst. Source: 

Dana, 1892.

221. Serpentine. Snarum, Modum Canton, Parish of 

Buskerud, Norway. Amund Helland, 1873, 

analyst. Source: Dana, 1892.

222. Chrysotile. Fibers. Templeton Township, Papineau County, Quebec, Canada. Specimen
26 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

from Prof. Charles U. Shepard, 1881. USNM. 

18879. William E. Smith, 1957, analyst. 

Source: Kalousek and Muttart, 1957.

225. Chrysotile. Province of Quebec, Canada. S. 

Caillere, 1936, analyst. Source: Caillere, 1936.

226. Antigorite, ferriferous. From the nickel mines at 

Petsamo, Finland. G. Bastien and A. Dikenstein, 1954, analysts. Source: Thoreau, 1954, 

p. 110.

227. Serpentine, precious. Dense. Snarum, Modum 

Canton, Parish of Buskerud, Norway. Johann 

Jakob, 1931, analyst. Source: Jakob, 1931.

228. Chrysotile. Canada. Auguste Terreil, 1885, analyst. Source: Dana, 189?.

229. Chrysotile. Robertsonville, Thetford Township, 

Megantic County, Quebec, Canada. Analyst, 

not known. Source: Bryant, 1928 p. 10-14.

235. Jenkinsite. O'Neil mine Monroe, Orange County, 

N.Y. J. Lawrence Smith and George J. Brush, 

1853, analysts. Source: Smith and Brush, 1853.

236. Jenkinsite. O'Neil mine, Monroe, Orange County, 

N.Y. J. Lawrence Smith and George J. Brush, 

1853, analysts. Source: Smith and Brush, 1853.

237. Hydrophite. Taberg, Jtfnkoping County, Smalands, south Sweden. Lars 2. Svanberg, 1839, 

analyst. Source: Svanberg, 1839.

238. Zincian serpentine. Occurs in dolomites. Almal'ik 

deposit, Uzbek, U.S.S.R. E. F. Kas'yanova, 

1958, analyst. Source: Badalov, 1958.

239. Zincian serpentine. Occurs in dolomites. Almal'ik 

deposit, Uzbek, U.S.S.R. E. F. Kas'yanova, 

1958, analyst. Source: Badalov, 1958.

240. Serpentine. Franklin, Hardyston Township, Sussex County, N.J. David Jenkins and Lawson 

H. Bauer, 1926, analysts. Source: Palache, 

1937.

241. Serpentine. Franklin, Hardyston Township, Susse^x County,- N.J. George A. Koenig, 1886, 

analyst. Source: Palache, 1937. Note: Analysis corrected for 4.08 percent franklinite equivalent to the Fe2O3 found in the analysis.

242. Serpentine, manganiferous. Franklin, Hardyston 

Township, Sussex County, N.J. Earl V. Shannon, 1926, analyst. Source: Shannon and Larsen, 1926.

243. Antigorite. Blocklike masses. Snarum, Modum 

Canton, Parish of Buskerud, Norway. Ragner 

Blix, 1947, analyst. Source: B0ggild, 1947.

244. Serpentine. Valli dell Idice e del Sillaro, Italy. 

P. Gazzi, 1956, analyst. Source: Gazzi, 1956. 

Note: CaO is present as calcite so 0.39 percent 

CO2 is deducted from ignition loss.

245. Serpentine with very little carbonates. Valli dell 

Idice e del Sillaro, Italy. P. Gazzi, 1956, analyst. Source: Gazzi, 1956. Note: CaO=5.41 

percent is present as calcite so 4.24 percent COa 

is subtracted from the ignition loss.

246. Chrysotile. Fibers. Globe, Gila County Ariz. 

USNM R-4654. William E. Smith, 1957, analyst. Source: Kalousek and Muttart, 1957, 

Note: The CaO represents calcite and is not 

used in the calculation.

247. Serpentine. Matrix, contains impurities. Globe, 

Gila County, Ariz. USNM R-4654. William 

E. Smith, 1957, analyst. Source: Kalousek and 

and Muttart, 1957. Note: The 21.00 percent 

CaO is probably present as calcite, so this constituent is not used in the calculation.

248. Chrysotile asbestos. Classified as soft fiber. Ash 

Creek mine, Ash Creek, Globe field, Ariz. R. E. 

Zimmerman, 1918, analyst. Source: Diller, 

1922, p. 302.

249. Chrysotile. Harsh fiber. Ash Creek mine, Globe 

field, Gila County, Ariz. R. E. Zimmerman, 

1918, analyst. Source: Diller, 1922.

250. Chrysotile. Soft fiber. Near the summit of Coon 

Creek Butte at the south end of the Sierra 

Ancha, Gila County, Ariz. R. E. Zimmerman, 

1918, analyst. Source: Diller, 1922.

251. Chrysotile. Harsh fiber. Near the summit of 

Coon Creek Butte at the south end of the 

Sierra Ancha, Gila County, Ariz. R. E. Zimmerman, 1918, analyst. Source: Diller, 1922.

255. Bastite. Todtmoos im Wehra-Tal, Schwarzwald, 

Baden, Germany. W. Hetzer, analyst, in Weiss, 

1863. Source: Dana, 1892.

256. Bastite. Massive material. Baste, Radau-Tal, 

near Harzburg, Harz, Germany. Friedrich 

Kohler, 1827, analyst. Source: Dana, 1892.

257. Bastite. Crystalline material. Baste, RadauTal, near Harzburg, Harz, Germany. Friedrich 

Kohler, 1827, analyst. Source: Dana, 1892.

258. Serpentine, dull-green. Formed by the alteration 

of pyroxene. Montville, Morris County, N.J. 

Edward A. Schneider, 1890, analyst. Source: 

Clarke and Schneider, 1890.

259. Serpentine, dark-green. Newburyport, Essex 

County, Mass. Edward A. Schneider, 1890, 

analyst. Source: Clarke and Schneider, 1890.

260. Chrysotile, silky, fibrous. Montville, Morris 

County, N.J. Edward A. Schneider, 1890, 

analyst. Source: Clarke and Schneider, 1890.

261. Deweylite(?), grayish-green. Corundum Hill, 

Macon County, N.G. Edward A. Schneider, 

1890, analyst. Source: Clarke and Schneider, 

1890.
THE SERPENTINE-GROUP MINERALS 27

ANALYSIS OF 219 SPECIMENS

The collection of analyses, table 5, comprises 219 

analyses of serpentine-group minerals and 42 analyses 

of specimens consisting chiefly of serpentine.

Harry H. Hess, Princeton University, kindly furnished us a copy of analysis 145 and material suitable 

for DTA and X-ray studies. (Fig. 4.) See Hess 

(1960).

INTERPRETATION OF THE CHEMICAL ANALYSIS

The structural formula for the minerals of the serpentine group is

[Mg6SiAo(OH)8],

which represents the contents of the unit cell. It 

is assumed that the structural water in serpentine 

is that represented by the (OH) groups. The lowtemperature water is ignored and considered to be 

either adsorbed or, in mixtures containing stevensite, 

to belong to that admixed species. The analytical 

determination of water in a mineral requires great skiU 

and good judgment on the part of the chemist and the 

excellent agreement shown with the data of static 

thermal-analysis studies, table 12, is a testimony to 

their skill. Thermal-analysis studies, however, show 

conclusively that the determination of H2O-f- and 

H2O based on 100° or 110°C as fiducial points, no 

matter how accurately they are done, do not reveal the 

respective amounts of hydroxyl and adsorbed water. 

It is argued here that the uncertainty introduced by 

using total water (adsorbed water and hydroxyl water) 

in the calculation far outweighs the supposed advantage 

gained by including it (Bates, 1959). Moreover, from 

the results of thermal-analysis studies and other considerations it is concluded that its use leads (1) to a false 

sense of precision, (2) to the postulate that significant 

defects exist in the structuraUy equivalent positions of 

the large anions, a fact which has not been unequivocally demonstrated, and (3) to the assumption that the 

nonreporting of fluorine and chlorine by the chemist 

means that they are absent.

An examination of the analyses shows many in which 

H2O-f- and H2O have not been separated and some 

in which the water determination is in error. AU these 

would be excluded, if a rigorous insistence on an 

"accurate" determination of H2O-f- and H2O were 

made as a provision" for the acceptance of an analysis.

The method of calculation is similar to that given 

by Hendricks and Ross (1941). For purposes of calculation it is not necessary to recompute the analyses to 

100 percent, or to a so-called dry basis, for the ratios 

of the constituents are maintained in the method. 

Table 6 gives the equivalent weights used in the calculations. In general, where the pairs of constituents

K2O and Na2O, Fe2O3 and A12O3 , and FeO and Fe2O3 

were reported together in an analysis, the equivalent 

weight used in the computation was the calculated 

mean of the two constituents; thus for Fe2O3 -f- A12O3 , 

the mean of 21.80 was used.

The procedure for calculation (see table below) is 

as follows:

1. It is assumed that the total negative valency is 

contributed by the 10 oxygen ions and the 8 

hydroxyl groups giving a total negative valency 

of 28.

2. The analytically determined values of the metallic 

oxides are divided by their respective equivalent 

weights, and the quotients are labeled e.

3. The sum obtained by adding the various values of 

e in item 2 above is divided into 28 to yield a 

quotient called the factor F. This factor is used 

to adjust the total positive valency to 28 by 

multiplying each quotient in e the column labeled 

by F. The sum of these products (e'} should be 

exactly 28 and if it does not total 28 it should be 

adjusted to do so.

4. Each value of e' in item 3 is divided by the valence 

of the metal to give the data in column 4 from 

which the formula is written. The method of 

calculation is illustrated in the table below.

Sample F-l. Antigorite (labeled williamsite), State Line Pits

S\03 .. ...........................

AisQi - .- - .-

FeaOi...... ..................... .

FeO-.. . . 

MgO_ - 

CaO. .._.- .-_._- - 

H2 0+- 

NiO.. 

Analysis 

(percent)

. -44.50

1.41

.35

41.56

.02

12.36

.06

.095

100.36

e

2.964

.083

.010

2.062

.002

.010

5.131

e' (= e X F)

16. 117

.453

.054

11.250

.011

.055

OQ nftA

Atomic 

ratios

4.044

.151

.027

5.625

.003

.028

Calculation:

J-.glj-5.4H8

[Mg6 .MFe»+MNi.wAl.,d[Si4.oJO,o(OH)8 

oct=5.83 tet=4.04

The collection of structural formulas computed from 

the chemical analyses is shown in tables 7, 8, and 9. 

The results bear out the precept given by Genth (1875, 

p. 120B) in reference to the montmorillonite mineral 

sauconite, to wit:

Like all similar minerals, the composition is somewhat variable, 

owing in part to accidental admixture and a replacement of one 

isomorphous substance by another.

Genth's interpretation is just as valid today. It is 

the hope of the chemist that he is analyzing a pure 

sample free from "accidental admixture." It is the 

responsibility of the mineralogist and petrologist that 

the admixed substances are removed by one or several
28 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

TABLE 5. Chemical analyses of 219 specimens of serpentine and related minerals 

[Analyses from the literature. For location and description of specimens, see p. 19-26]

Si02 . ..............

AhOs 

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

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

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

K2 0_-. ............

Ti02 .......... 

Cr203 ._ ... 

NiO-._ ...... 

MnO._ ............

ZnO. _ ..... _ ...

CuO .... 

H.20-. .............

H20+...... ........

C02 ---.. ....

S03 . _ .

2.. 

Spgr... ... .....

Si02 --. 

AliOj.... ...- 

FejOj..... ...... 

FeO. . .... ....

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

CaO. . . . ......

Na2O 

KjOTiOs .... __ .

NiO.. .............

MnO 

ZnO. _ ...........

CuO .............

H2 0-... . .......

HjO+.. .........

C02 ._ .. ...........

SO8 . 

8p gr.. ....... .....

SlOs.... ... .... .

AljOs.. .........

FeO_..... ......

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

CaO_.... .......

NasO ... .. 

KjO-. ... .

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

CrjOs 

NiO.. .............

MnO-.. .. ...

ZnO.... ... ...

CuO.... ....... .

H2 0-. ............

H2 0+. ........

CO2--. . .......

SO3 ..... .... .

2. _ ... _ .

Spgr.. .......

1

43.87

23.44

5.37

1 K 10

1.24

10.86

99.96

21

37.15

3.20

7.70

36.20

1.40

i

[ 15. 10

100. 75

41

41.54

2.48

1.37

40.42

.04

} 14.17

100. 02

2

45.02

29.31

.21

12.60

4.43

7.03

98.60

25

40.75

2.51

3.47

a 19

36.94

1.62

.06

{

11 .Jl

11.74

100.52

2. 550

42

32.45

2.57

17.61

1.30

33.59

.40

( .83

I 11.34

3

42.54

5.68

1.06

.74

35.57

.13

J .38 

1 13.26

99.36

26

41. 55

S on

40.15

i

> 13.70

99.30

3.39

43

40.60

.30

3.63

.54

39.79

.98

13.05

99.68

4

41.68

11.33

3.47

.33

37.75

Tr.

.80

4.55

QQ Q1

27

40.23

2

1 Q

4.02

Tr.

39.46

14.24

noo. 13

44

41.69

1.56

2.07

40.33

} 12. 82

98.47

5

39.72

3.06

6.20

.91

34 44

.63

Tr.

J 1.51 

1 13. 28

99.75

28

38.23

1 4Q

6.53

37.33

.031

J 1.10 

1 12.30

* 100. 63

45

41.33

80

1.29

.08

41.39

Tr.

.02

.04

( 1.57

I 13. 66

100.18

6

40.82

2.07

6.10

1.00

35.88

.50

.35

13.26

29

41.34

3.22

K KA

37.61

Tr.

Tr.

i

i 12.06

99.77

2.644

46

42.44

1.13

.26

1.69

41.45

.23

} 12. 70

99.90

2

7QO

10

41.73

3.84

3.58

35.79

.73

Tr.

i 1

[ 12.93J

99.76

30

41.58

2 60

7.22

36.80

12.67

100.87

47

42.97

.87

2.48

41.66

12.02

100 00

11

42.86

1.48

3.96

2.03

Q7 K.-7

.46

Tr.

.31

11.56

100. 23

2. 645

31

40.95

i en

10.05

34.70

12.60

99.80

48

42.38

.07

.97

.17

42.14

14.12

3 QQ OK

12

42.75

1.95

2.49

3.07

37.32

.63

.39

11.88

100.48

32

39.50

5.08

i 8.12

34.65

}. 

12.55

100. 00

2.545

49

43.45

.81

.88

.69

41.90

.04

.05

.02

.02

{

(14

12.29

inn 10

13

42.53

.35

3.80

.72

38.44

.98

.86

12.50

100. 18

33

41. 65

.10

f 2.88

1 .16

41.06

.05

f 1.12

1 13. 10

100. 12

50

41.76

.65

2.71

.39

40.36

.41

.24

.03

.02

.33

13.17

100.07

14

38.87

7.91

2.95

.43

36.17

Nil

.29

.15

.23

.04

1.26

11.68

.42

i 100. 40

34

42.10

2.43

41.50

.45

i

\ 12. 70

99.18

51

41.70

1.10

3.50

38.95

.14

1.07

13.89

100.35

15

41.30

1.59

3.61

4.51

36.30

.43

.04

.02

.If

.30

.26

.11

n.d.

11.19

.03

.06

99.90

35

40.96

1.70

9 4d

38.73

.10

J 2.70

1 13. 37

100.00

52

42.62

.38

.27

42.67

} 14. 25

100.19

16

41.20

1.26

2.80

,11

38.60

.06

.13

.18

.21

1.39

14.14

100. 08

36

42.17

.30

1.57

RA

41.33 !"-"

13.72

99.73

53

42.04

3.66

39.54

. ol

99.55

2.29

17

43.00

.62

3.03

2.45

QQ 7/1

.69

.01

11.97

37

42.15

.58

1.45

40.76

.17

.10

f .92

1 13. 11

100.20

54

42.15

3.57

40.41

.03

f 1.24

I 12. 65

100.05

18

41.15

1.95

2.35

or

3S.05

05

.25

.10

.30

i

[ 16.05

2100.90

38

41.86

.69

4.15

38.63

.24

Tr.

.20

i

| 14. 16

99.93

60

37.15

5.60

1.10

8.80

32.80

.10

I 29 / "*

} 14.16

100.00

2.56

19

40 15

2.35

3 OK

QQ Af\

.40

.25

.10

.30

14.35

100. 60

39

41.80

.95

4.65

38. 55 .

13 95

99.90

61

39.78

.47

2.61

.53

35.73

6.77

,.__

f .17

I 14. 21

100. 27

20

41 40

1.45

3.06

Q QA

37.01

.72

13.27

100.75

40

41.55

.63

3.35

*>9

40.77

.13

{

40 

'

12.33

99.76

62

41.59

2.43

42.32

} 13.55

99.89

See footnotes at end of table, p. 32.
THE SERPENTINE-GROUP MINERALS

TABLE 5. Chemical analyses of 219 specimens of serpentine and related minerals Continued

29

SiOj ~ 

A12O3 

Fe2 O3 

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

MgO ... .. ...

CaO- .... . _ ..

NasO.. .... ......

KjO .

TiOj.. . 

CrjOs - _

NiO 

MnO ... ...

ZnO 

CuO.-- ........

H2OH2 0+. ... .... ...

COj -

SOa -- 

2.... ____ ..

Sp gr.. . .... ..

SiO2 

AhOs 

FesOa - 

FeO... . _ ..

MgO.- .... .

CaO 

Na2O ... ...

KjO-- 

TiO2 - .....

NiOMnO _ ..

ZnO 

CuO 

H2O-. 

H2 0+ ...... ...

CO2 .....

SOz..... ...........

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

Sp gr .... ... .....

SiO» ~ 

AbOs 

FejOa ----- 

FeO- - 

MgO.. 

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

Na2O . _ ...

KjOTiOn ...

CriOa 

NiO. ...

MnO.. ..

ZnO- .... .....

CuO------ _ .....

HjO-. 

HiO+. 

COj--- 

SO3 

J^. ...........

Spgr ..... ... 

80

41.95

2.81

41.62

} 14.85

101.23

97

40.49

1.27

| 2.53

41.41

} 14.06

99.76

63

41.91

.49

1.90

.16

41.36

.43

.19

.02

.33

13.26

100.05

81

41.98

2.87

41.38

13.78

100.01

2 48

98

41.76

Tr.

I 4.06

41.40

13.40

100.62

2 on*

64

41.88

.19

.81

.05

41.38

.47

.06

.023

.036

.005

0

.05

.60

14.22

.02

.31

100.10

82

38.86

2.95

1.86

5.04

34.61

\ 1.10

.08

.28

15.52

100.30

99

39.83

6.39

1.71

39.92

.07

1.11

10.43

99.46

2.718

65

42.50

.32

.50

.010

42.50

.04

.04

.02

.021

.004

0

.02

.01

.65

13.46

.14

100.23

83

40.06

2.36

1.99

40.49

,.. ....

/ 1.78

114.53

101.21

100

40.08

.15

2.82

7.68

36.64

1.31

Tr.

.33

Tr.

11. 35

'100.36

66

42.74

.21

1.22

.43

41.20

.44

.25

.11

.22

13.25

100.07

84

41.33

2.11

1.75

1.41

40.01

nil

.34

.40

.08

.05

.55

12.35

100.38

2.29

101

40.52

2.10

1.97

42.05

13.46

100. 10

67

38.49

1.32

3.29

.57

37.80

1.41

.49

.70

11.20

4.54

« 99. 87

85

41.96

.59

.93

.54

42.01

1.15

Tr.

Tr.

.17

12.30

99.65

102

39.13

2.49

1.74

40.58

.50

( 2.80

I 13. 19

100.43

68

42.02

.49

1.50

.057

42.05

.26

.02

.014

.073

.001

.002

.024

.32

13.74

.06

.07

100.70

86

40.75

.90

1.30

.60

41.00

.35

Tr.

1.90

13.45

100.25

110

36.59

Tr.

8.84

1.05

38.85

1.46

} 13. 41

100.20

69

42.40

.74

.48

.043

42.70

.01

.03

.02

.070

.008

0

.02

.05

.26

13.52

.11

100.46

87

41.52

.57

.36

.06

42.80

.11

.03

.02

.06

.01

0

.04

.05

.60

14.36

.02

100. 61

111

38.58

3.21

2.53

38.87

2.90

14.10

100.19

70

42.72

.20

.68

43.38

} 13.40

100. 38

88

41.80

.19

.93

.06

42.67

.19

.02

.01

.10

.003

0

.04

.24

13.88

.04

.08

100.25

112

38.40

.10

3.42

41.91

.05

/ 1.26

I 15.03

100.17

71

42.17

3.33

40.54

.09

/ 2.53

111.40

100.06

89

39.05

3.67

} 2.41

40.07

n.d.

14.48

99.68

113

41.48

5.49

1.59

37.42

2.84

±U. oo

99.70

2.61

72

41.46

.01

2.42

1.16

41.76

.23

} 12.43

99.47

90

40.71

2.39

{ 2.43

41.48

I/, ol

99.62

114

38.62

.20

3.21

41.88

.30

.42

.04

/ .29

I 15. 09

100.05

73

39.38

1.56

13.87

32.25

[ - 17

11.90

99.13

2.4

91

41.80

.11

.68

.05

42.82

.10

.03

.01

.05

.003

0

.04

f .28

I 14.04

.01

.09

100.11

115

39.36

O. OJ.

42.15

n.d.

14.50

99.32

75

40.05

1.90

1.60

.40

38.35

.15

/ .25

\ .15

16.60

99.45

92

39.64

1.30

7.76

37.13

.29

.33

.12

1O. Ol

100.38

116

37.39

2.66

f 2.63

\ 1.96

40.77

.62

} 14.08

100.11

76

40.54

1.09

4.87

39.02

f 1.13

I 13. 47

100.12

93

42.28

.86

2.57

40.29

1.35

.48

L&. o&

100.35

120

43.60

1.03

.90

.81

41.00

.05

.01

.03

 .01

.02

.16

.04

f .08

I 12.18

99.92

77

38.50

1.02

4.66

3.31

36.40

1 07

.59

}l2. 35

8 100 58

2.587

94

39.22

3.64

} 2.26

40.27

/ n.d.

1 14.37

99.76

121

42.25

1.70

41.40

.02

.68

14.05

100.10

78

40.83

3.20

5.84

36.62

12.37

QD Oft

95

40.23

1.01

f 2.43

I 3.50

41.10

} 11.54

99.81

122

44.21

2.72

.52

40.55

.26

100.69

2.363

79

« 99

.28

1.07TO

41 98

.12

.08

14.80

00 OJ.

2.48

96

40.70

.22

1.57

.31

42.05

.82

f .38

I 13.63

99.68

123

42.87

.26

2.35

40.40

1.04

L£i. aO

99.90

2.510

See footnotes at end of table, p. 32.
30 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O 

TABLE 5. Chemical analyses of 219 specimens of serpentine and related minerals Continued

SiO2 .. __ --..

AhOa ... -_____-

FejOs ~- ~

FeO.-. ___________

MgO. ----.--______

CaO .-_ 

NajO 

K.O--.- 

TiOj. -----

Cr2Oa -------

NiO. __- -- 

MnO _ .. 

ZnO- _ 

CuO..__-_- .-. 

H.O-. .. _________

HsO+_._ . 

CO_.__._ . 

SOs --------

S -__ _ -_

Spgr--._ 

SiOz-. --------

AhO3 -------

Fe 2O3 .

FeOMgO. --.____-. -___

CaO___ 

NajO. ...

ZiO. ..............

TtO2 ._.__ 

Cr2O3 -------

NiO.-.- 

MnO. . - _-

ZnO._-_ 

CuO - 

H.O-. .. --------

H2 0+- - 

CO8 ._.-_ . 

SOs _

s

Spgr. ...-__----_

BIO.. . -

Al.Os -

Kc2Os

FeO -

MgO.. ... 

CaO. 

NajO ..

K.O. 

TiO.-. 

Cr2O3 NiOMnO 

ZnO 

CuO-. .... ...

HiO- .

H20+ -

COs... .

S03 -

____ 

Spgr... 

124

41.13

.55

.51

no

39.59

91

3d

4.13

13.81

100. 36

145

42.30

.59

A. U

1.97

35.88

0

.03

1.30

13.12

99.78

162

40.98

7Q

8.72

33.44

1.54

12.86

1 73

100. 00

125

42.00

.26

on

41.00

} 15.00

99.16

146

44.49

2.26

48

40.27

.03

.03

} 12.80

100. 36

163

M, 77

3.35

39.17

} 12.94

100. 23

2.61

126

43.60

.03

40

42.58

.55

{

on

19 (19

100.08

147

.10

on

38.40

.83

.42

.71

f 2.31

X 14. 51

99.65

164

« oft

36.30

Kf\

2 71

18.00

99.41

127

42.94

.46

1.56

3

1 Q

38.92

Tr.

.08

.07

on

12.56

148

.SO

3.60

34.52

1.27

4.70

11.55

99 71

165

1.36

37.38

20.39

100. 94

128

43.12

4.91

1.99

34.87

1.33

| 13.13

99.35

149

43.30

.35

2.62

.40

38.58

.72

Tr.

Tr.

1.66

12.91

Iftfl 14.

166

Tr.

2.13

39.55

12.91

99.17

129

1 EQ

1.76

38.70

1 l«

f - 16

{

1 84

13.75

100.00

150

AA 7Q

.32

.33

42.64

Tr.

} 12.21

100. 23

O CQ

170

42.34

1 30

36.77

Tr.

19.03

99.53

130

« Qfi

.71

.91

n.d.

40.16

/

\

.10

} 16.16

99.94

151

44 08

qfl

1.17

40.87

Q7

13.70

inn 4.Q

2

AQ

171

43.16

.47

.41

.10

37.69

.20

{

A. CU

13.58

100. 55

131

41.23

19

.31

.53

OQ ylO

24

.16

/ 4.06

\ 13. 62

99.76

152

A*3 Kfi

At)

2.08

40 00

13.80

QQ 7ft

172

34.96

49

9.13

3.03

21.97

21.20

9.84

100. 62

132

42.73

1.33

7.20

36.51

Tr.

Tr.

} 11.66

99.43

153

AA OK

4.90

3.67

34.00

.69

12.32

99.83

173

.30

} 7.28

34.62

91

\ 11.70

99.82

133

43.66

64

1.96

41.12

13.57

100. 95

154

4fl 9Q

.12

.86

no

37.08

.20

.31

f 7.02

X 14. 23

100.20

174

43.15

Tr.

I ..

35.95

20.25

99.35

134

43.13

.37

42.05

Tr.

Tr.

13.88

99.43

2.514

155

44.08

.30

1.17

40.87

.37

| 13. 70

100.49

175

47.12

2.82

2.58

30.90

3.20

f .76

\ 13. 48

100.86

2.20

135

42.11

5 4.7

37.80

.68

14.13

100. 19

2.559

156

44.50

.75

1.39

39.70

.90 -

12.75

99.93

176

44.56

.50

36.30

' 1O. UU

99.36

136

38.80

9.08

4.70

100.90

157

43.89

1.38

40.48

13. 45

99.20

177

43.03

12.30

19.58

17.40

97.87

2.05-

2.08

137

41.21

1.72

39.24

.30

f .41

X 16. 16

99.04

158

44.58

3.03

6.15

34.51

Tr.

12.38

100.65

178

44.85

1.31

9.83

.51

26.70

.75

Tr.

f 5.78

10.61

100. 34

138

42.54

3.78

4.75

30.48

} 13.13

100.25

2.604

159

40.16

Tr.

1.16

36.00

.80

21.60

99.72

179

41.00

4.00

13.30

17.60

 ^o. uu

98.90

2.05-

2.08

139

44.22

CO

6.61

f .36

I 11.26

100.52

160

45.23

3.61

39.59

11.60

100.03

2.517

180

50.75

3.40

1.25

7.40

28.80

.75

.50

.15

99.75

140

42.29

1.92

39.90

\ 16.16

100.27

161

44.05

2.53

39.24

13.49

99.31

2.49

181

45.65

.20

34.38

Tr.

iy. tu

99.72

2.3
THE SEEPENTINE-GEOUP MINERALS 

TABLE 5. Chemical analyses of 219 specimens of serpentine and related minerals Continued

31

8102 

AljOa 

FeO 

MgO 

CaO. 

Na8 0 

K2 0. 

Ti02 . 

NiO 

MnO 

ZnO. ..............

CuO.. - 

H2 0- 

H2 0+ 

COs 

80s -

Spgr. 

AhOs 

FeO_ 

MgO 

CaO 

Na2 0 _ 

K2 0_ 

TiOa 

NiO_ .

MnO 

ZnO. . _ 

CuO_ 

S. S 0-. ............

H2 0+. ... 

COi... 

SOs - 

S. ............

Spgr-_ 

SiO2 

AliO}.. ............

FeO 

MgO.... 

C*Q n

NajO . 

K»0 

Ti02 -

NiO...... ... 

MnO 

ZnO. ..............

CuO.. ... 

H2 0-.._ .... 

H2 0+ 

C02 .__ 

S03 

2.. ....... 

Spgr. 

182

36.74

11.52

3.06

17.38

t O£. \j£t

100.72

202

41.32

.58

42.16

.04

1.40

14.57

100.07

219

42.14

2.06

41.61

} 14.20

100. 01

183

45.02

3.35

37.75

13.01

99.13

203

41.84

2.23

41.99

} 14.28

100.34

2 14

220

42.32

.66

1.28

42.23

13.80

100. 29

185

54.89

.79

1.40

33.55

.42

7.30

98.35

204

41.58

.42

1.69

42.61

13.70

100.00

221

42.72

2.25

42.52

io. oy

9 100. 94

2.53

186

61.70

/ 6. 85

27.95

} 5.00

101. 50

2.77

205

40.30

2 27

.87

43.37

L&. t &

99.53

222

41.70

.24

.30

.05

42.85

.05

.07

.01

.03

.005

0

.02

.02

/ .83

\ 14.23

.07

.02

100.50

187

60.45

f .50

6.34

26.01

1.25

5.05

99.60

206

41.20

| .,

43.52

15.40

100. 92

2.381

225

28.76

.88

5.37

2.02

44.34

.41

.88

16.86

99.52

190

40.90

Tr.

4.70

41.31

.02

.03

.08

100. 44

207

41.66

t

\ 3.84

40.50

13.19

899.82

226

23.28

3.01

28.00

23.68

1.00

.39

.52

.38

4.66

.11

} 10. 55

1° 104. 64

191

40.86

Tr.

4.59

41.37

.03

.02

.09

13.08

100.04

208

42.20

Tr.

1.56

42.50

Tr.

J.O. £<J

99.54

227

35.31

.38

3.08

.22

45.07

.38

.20

.04

f .25

1 15. 13

100.06

192

40.83

1.02

42.94

.04

? .70

\ 14.49

100. 02

209

42.56

Tr.

.95

43.15

Tr.

99.50

228

37.10

Tr.

5.73

39.94

1

99.62

2.56

193

39.32

.51

41.14

} 18.41

99.38

210

41.97

2.14

41.90

.02

f .73

X 13. 33

100.09

229

30.18

1.41

f 5. 81

45.80

15.70

98.90

194

41.07

1.05

42.33

.58

f .77

\ 13. 92

99.72

2.498

211

42.29

Tr.

1.21

42.29

.63

\.£t, yu

99.38

2.57

235

37.42

.98

{ 20.60

22.75

4.05

13.48

99.28

195

44.77

.51

4.77

45.09

} 4.96

100.10

2.417

212

40.57

.90

2.81

41.50

99.33

236

38.97

.53

19.30

22.87

4.36

99.39

196

40.36

.21

1.35

.66

43.86

/ n.d.

\ 13.45

99.89

2.55

213

41.43

2.16

40.18

.95

J.O. Ol

98.47

237

36.19

2.90

22.73

21.08

1.17

" 100. 26

2.65

197

41.28

1.93

42.00

.04

.82

14.00

100. 07

214

39.30

6.79

36.12

Tr.

Tr.

Tr.

16.79

99.00

238

40.88

2.40

1.64

38.01

.08

1.64

.80

99.97

198

41.46

.99

44.68

} 14. 07

101.20

215

42.58

43.48

±o. y±

100.00

239

41.38

1.94

39.93

.08

2.60

1O. OO

none

99.78

199

42.27

1.88

43.10

13.59

100.84

216

43.28

2.50

42.55

.23

11.44

100.00

2.487

240

39.62

1.30

2.39

33.60

.37

3.42

4.14

/ 1.18

I 14.06

100.08

200

M K7

on

2.81

13.55

99.33

217

41 97

.10

.38

1.57

42.50

.08

13.56

100. 16

241

43.65

30.92

7.12

3.62

[ 14.69

100. 00

201

41.60

Tr.

3 9J.

41.11

.50

12.70

99 15

218

41.13

1.23

1 49

43.65

.17

} 12. 46J

100.13

242

41.32

.65

1.57

32.58

.96

7.57

.14

f .94

I 12.44

98.17

See footnotes at end of table, p. 32.
32 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O 

TABLE 5. Chemical analyses of 219 specimens of serpentine and related minerals Continued

SiO!-.---- ----------

AlaOs- ----------------

FeO -----------------

MgO. --------------------

CaO... -----------------

Na2 O

 K.tQ..... ....................

TiO2 --- -------------

NiO ------------ -----

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

ZnO ---------- --------

CuO. -------------------

H2 O-__ ------------

HsO+.. -

CO2

SO3 -------------------

s

Sp gr . --

243

42.12

1.26

.49

40.39

.85

Tr.

.79

12.51

1.55

99.96

244

37.39

5.34

7.12

3.53

30.91

.50

.51

.37

.09

.08

| 14. 25

.39

100.48

245

35.45

4.56

5.09

2.03

27.96

5.41

.46

.17

.35

.05

4.24

99.59

246

43.00

.27

1.08

.17

40.00

1.43

.03

.02

.020

.005

0

.16

.03

f .53

\ 13. 17

.78

.01

100.71

247

26.80

.42

1.13

.22

25.00

21.00

.03

.03

.006

0

.12

.05

.16

14.85

9.98

99.82

248

41.56

1.27

.64

42.05

1.39

12.92

99.83

249

41.35

.91

.69

41.85

.07

1.38

11.96

98.21

250

40.75

1,82

.74

40.69

1.86

12.65

98.51

251

42.28

1.07

.88

41.41

.10

1.33

12.23

99.30

255

43.77

6.10

7.14

30.92

1.17

Tr.

Tr.

8.51

1.67

12 100. 40

256

42.36

2.18

13.27

28.90

.63

.85

100.26

257

43.90

1.50

10.79

26.00

2.70

2.37

.55

12.43

100.24

258

42.05

.30

.10

42.57

.05

f .96

\ 13.70

99.73

259

41.47

1. to

.09

41.70

1.20

13.86

100.05

260

42.42

/ .63

41.01

Tr.

.23

2.04

13.60

100.55

261

41.90

.71

n.d.

40.16

.10

2.26

13.90

99.94

i Cl = trace.

* S includes CoO = 0.40.

a Total H2O reported as ignition loss.

* S includes CoO = 0.08. 

» S includes P2 O5 = 0.06. 

« S includes FeS2 (insoluble) = 1.78.

methods of purification and that the final purity has 

been confirmed by examination under the polarizing 

microscope. For samples ranging from coarse grained 

to fine grained, it is usually possible to effect a purification. For fine-grained or stained samples it may not 

be possible to purify the sample or to detect the impurity by microscope methods alone, and resort to 

electron microscopy, DTA, and X-ray may be required. 

Faust (1951) demonstrated the hitherto unsuspected 

presence of halloysite in some very fine grained sauconites by several of the aforementioned techniques. 

The analyses of serpentine taken from the literature 

show clearly the validity of Genth's observation.

The calculated data for the analyzed samples studied 

in this research (table 7) are arranged first according 

to their geologic origin and then in the order in which 

they appear in tables 2 and 3. It will be observed 

that all the analyses when calculated on the basis of 

the structural formula show a full complement of ions 

in tetrahedral sites. Five analyses show a decided 

excess of ions in tetrahedral sites and a corresponding 

deficiency in octahedral sites; these are so-called 

deweylites, mixtures of serpentine-group minerals and 

stevensite. Ten of the analyses show only silicon 

atoms in tetrahedral coordination, six of them silicon

TABLE 6. Equivalent weights used in the calculations

Equivalent 

Oxide weight

-------------- 15.02

-------------- 16.99

-------------- 26.62

FeO. ---------------- 35.92

MgO---.------------ 20.16

CaO. ._. ----------- 28.04

NajO-___ --------- 30.99

K2 O_---_----_------- 47. 10

Equivalent

Oxide weight

-_ ------ 19.98

CrjOj---- --- 25.34

NiO- - - 37.36

MnO.- 35.47

ZnO -------------- 40.69

CoO------ ------ 37.47

ViO5 ------------ 18. 19

' No sulfur present.

8 S includes 0.63 undetermined.

6 S includes Mn2 Os = 0.06.

10 S includes S = 9.06. Correction O for S = 4.53; corrected S = 100.11.

11 S includes V2 O5 = 0.11.

12 S includes organic substance = 1.12.

and aluminum, four have silicon, aluminum, and trivalent iron, and two have silicon and trivalent iron in 

tetrahedral coordination. Samples F-72, F-73, and 

F-74 were derived from rocks known to contain magnetite, and the material analyzed probably contained 

some magnetite. Comparison of the data for these 

three samples with that calculated for a mixture of 90 

percent serpentine and 10 percent magnetite indicates 

from the values for Fe2+ and Fe3+ that the contamination should not be great. The very low value for 

the number of silicon atoms in tetrahedral coordination is distinctly abnormal. These three samples, 

however, are not pure and they cannot be directly 

compared with the other samples studied by us. All 

analyses showing Fe3+ in tetrahedral coordination 

must be viewed with caution until the absence of 

significant amounts of magnetite are confirmed or a 

quantitative estimate of its abundance is determined. 

The analyses in table 8 have been arranged, in 

general, first according to the number of ions in tetrahedral coordination, and then according to an increasing number of ions in octahedral coordination. 

Analyses 1 through 116, with the exception of analyses 80 and 81, all have exactly four calculated atoms 

in tetrahedral coordination and a range of ions in 

octahedral coordination from 4.76 to 6.19. Analyses 

120 through 187 are arranged in order of increasing 

number of ions in tetrahedral coordination from 4.01 

to 5.06. Analyses 190 through 222 are, with two 

exceptions (Nos. 198 and 218), arranged in order of 

ions in tetrahedral coordination from 3.89 to 3.99. 

Analyses 225 through 229, 243 through 251, and 255 

through 261 represent special or regional collections 

and are grouped together. Table 9 contains the data
THE SERPENTINE-GROUP MINERALS 33

TABLE 7. Relationship of the ions in octahedral and tetrahedral coordination as calculated from the chemical analyses of the specimens

studied and listed in tables 2 and 3

Sample Locality

Ions in octahedral coordination

Mg Fe2+ Fe3+ Al Mn Ni Or Ti Zn Ca Na K S 

oct

Ions in tetrahedral 

coordination

Si Al Fes+ 2

tet

Class A

F-l-. 

F-43- 

F-42 . __ .

F-47--.. .

F-46 .......

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

F-19. 

F-15- 

F-26.. ......

F-48- -

F-72.. 

F-73. ...... .

F-74..- .

F-51- 

F-69- 

Near Bellows Falls, Vt._ _ 

Near Forest Hill, Md ............... .......

Bare Hills, Md........ .... .... . .

 .do.-. ...

Webster N C

5.63

5.74

5.78

5.68

5.61

5.45

5.53

5.20

5.01

5.06

4.33

6. SO

5.45

5.57

5.84

5.85

0.03

.01

.07

.05

.02

.38

.33

.45

.14

.19

.06

.25

.17

0.10

.27

.31

no

.07

.03

.13

.37

.36

.32

.03

.14

0.15

.03

.12

.03

.12

.21

.30

.02

.08

0.01

.01

.01

.01

.01

.01

0.01

.01

.01

.01

.02

.02

0.01

.02

.02

.03

.02

0.01

0.01

.02

.01

0.01

5.83

5.88

5.97

5.95

5.92

5.63

5.75

5.84

5.82

5.10

4.80

6.04

6.04

6.06

6.14

6.19

4.05

4.02

3.95

3.87

3.85

4.15

4.09

4.05

3.94

4.45

4.60

3.53

3.56

3.59

3.68

3.51

0.05

.05

.06

.37

.39

.41

.06

.29

0.13

.10

.10

.05

.26

.20

4,0

4 0

4,0

40

4.0

4 1

4,0

4 0

40

4 4

4 6

40

4,0

4,0

40

4 0

Class B

F-25- 

F-24 ......

F-22- -

F-14- 

F-8- - 

F-23- 

F-20.. 

F-53.. 

F

Ka

F-13- 

F-41.. 

F-57- 

Montvffle, N.J 

 .do 

 do. 

Balmat, N.Y... 

Talcville ' N Y

5.94

6.01

5.93

5.72

5.73

5.82

5.88

5.67

S

en

5.53

5.54

5

7K

0.01

.01

.02

.01

.02

.01

.01

.19

.01

0.01

.02

.01

.01

.14

.01

.04

.06

n9

.01

po

0.03

.02

.05

.06

.04

.11

.01

nd.

0.01

.01

.01

.01

.04 0.01

0.01

.06

.01

.08

0.01

.03

.02

.03

.01

0.01

.01

.03

6.01

6.01

6.02

5.81

5.81

6.00

5.96

5.81

5.86

5.89

5.56

5.87

3.96

3.97

3.95

4.08

4.09

3.92

4.00

4.09

4.05

4.04

4.22

4.05

0.04

.05

.08

0.03

4 0

4,0

4,0

4 0

4 0

40

4 0

4 0

4 0

4 0

4 ?

4.0

for two special collections, the manganese-rich and 

zinc-rich species.

Serpentine-group minerals theoretically should have 

6.00 ions in octahedral coordination and 4.00 ions in 

tetrahedral coordination. Assuming the material prepared for analysis to be 100 percent pure, the accuracy 

of the formula calculated for the mineral in expressing 

its true composition will depend chiefly on (1) the 

analytical skill of the chemist, (2) the quality of the 

methods used in the determinations, (3) the purity of 

the reagents, and (4) the completeness of the analysis.

The chemical analyses gathered from the literature 

were made over a long span of years, by various 

analysts, using many different procedures. There also 

has been some variation within this span of years in 

the values assigned to the atomic weights used in 

calculating the analysis. Lange (1952) gives a table 

showing the changes in atomic weights over the period 

1894 to 1951. Indirect determinations that require 

that a factor be used to calculate the percentage of a 

constituent are affected by significant changes in the 

value of the atomic weight. For example, magnesium 

is commonly determined as magnesium pyrophosphate 

and calculated by means of a factor to MgO. Less 

obvious, but nonetheless frequently important, are 

those determinations that may be direct in themselves 

but are subject to correction because other constituents 

are present. Thus alumina is calculated from the value

for the R2O3 group by subtracting from it the Fe2O3 , 

TiO2 , or other oxide included in it. As the determination of iron involves the use of a conversion factor, 

calculation of Fe2O3 could introduce error.

Incompleteness of an analysis can introduce serious 

error into calculations of formulas. Washington (1919) 

has discussed such errors. He points out that failure 

to determine Fe2O3 , Cr2O3 , V2O3 , TiO2 , ZrO2 , P2O6 , 

MnO, and a little SiO2 , if they are present in significant 

amounts in the R2O3 precipitate, yields a figure for 

alumina which is too high. On the other hand, the 

nondetermination of those constituents which are precipitated and weighed with others and not otherwise 

determined leads to a low summation for the analysis. 

For the serpentines this includes chiefly NiO, MnO, 

and CO2 . NiO + MnO may be partially caught in 

the R2O3 precipitate.

Considering the calculation of the structural formula, 

it follows that the nondetermination of other constituents in the R2O3 group precipitate may result in a high 

value for aluminum ions. If considerable amounts of 

other constituents are present this may raise the total 

for the ions in octahedral coordination beyond S = 6.00.

The charge relationships for the octahedral and tetrahedral layers in the crystal structure of the minerals of 

the serpentine group will be discussed by Faust in a 

subsequent report on these minerals. Suffice it to say 

that most of the analyses reported on in this paper
34 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

TABLE 8. Relationship of the ions in octahedral and tetrahedral coordination as calculated from the chemical analyses of serpentine-group

minerals taken from the literature and listed in table 5

Sample

1 

2 

3

4 

5 

6 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

50 

51 

52 

53 

54 

60 

61 

62 

63 

64 

65 

66 

67 

68 

69 

70 

71 

72 

73 

75 

76 

77 

78 

79 

80 

81 

82 

83 

84 

85 

86 

87 

88 

89 

90 

91 

92 

93 

94 

95 

96 

97 

98 

99 

100 

101 

102 

110 

111 

112 

113 

114

Locality

Waldheim. -...__...._________ ... ._

U.S.S.R-...----. ... _ ... ______________

Easton, Pa . _____

Transvaal, Union of South Africa. ._____.______._

Transvaal, Union of South Africa. .__-__-____--__ 

. .do _ . .-..-..-..-_.-.._.._.__________

Montville, N.J...--_--___-_____. __._.._... ......

Villa Rosa, Italy.... ____________ .................

Bare Hills, Md..._. ..__.._.______..._.___________

Port Henry, N.Y. .....-......______.____._._____

Southern Rhodesia _ ._..._..._______ _ _________ 

Sulphur Bank, Calif.. ...._...__.________________

Montville, N.J.... _____________.___-_-.___._----_

Lizard, England. --___---___ __ ............_._..

IVtontville N" J

Transvaal, Union of South Africa .. . ...-...

Delaware County, Pa ________________

Shetland Island ___________________

Urals, U.S.S.R- _ . ___ ... . . __ . ...

HPpYQQ T-*Q

Transvaal, Union of South Africa.. ________

Aboutville, N.Y... _ ...........................

Aboutville, N.Y-.- ..... ....

California ______________ ............. 

Brewster Station, N. Y..._ .......................

Brewster Station, N.Y....... . .... ... 

Snarum. Norway. .. ___ 

Ions in octahedral coordination

Mg

1.98

1.61

4.94

4.79 

4.96

5.09

5.01

5.19

5.16

5.38

5.03 

5.09 

5.51 

5.34

5.42 

5.42 

5.21

5.24

5.16

5.69

5.57

5.30 

5.26

5.16

5.00

4.93 

5.78

5.80

5.58

5.72 

5.50 

5.48

5

CQ

5.66

4.97

5.66

5.68

5.86

5.74

5.73 Son

5.73

5.66

5.50

5.94

5.71

4.82 

5.16

5 GO

5.78

5.86

e AQ

5.74 

5.55

S ftfi

5.92 

5.98

5.73

5.84 

4.76

5.58

5.60

5.29 

5.20

5.95

5.85

5.83

5.08

5.77

5.57

5.82

5.84

5.98

5.71

5.79

6.01 

5.37 

5.60

5.76

5 Q4

5.87

5

ft1

5.40

5.22

5.89

5.89

5.65

5.55

6.10

6.05

F62+

0.02

.06

.02 

.07

.08

.28

.16

.24

.06

.03 

.36 

.01 

.19

.02 

.04 

.30

.25

.12 

.43

.81

.65 

.02

.20 

.05

.08 

.33 

.37

.04

.11

.04

.17

.01

.13

.19 

.01

.05

04

.38

.02

.40

Oft

!04

.01

.01

.03 

.05

.01

.01

97

.09 

1.15

.03

.39

.27 

.47

.03

.22

.23

.41

.16

.11

.04

.05 

.01

.01

19

.01 

.63 

.20

OR

.24

.03

.20

.26

.13

.61

.16

.14

.09

.20

.12

Fe«+

0.36

.07

.22

.45

.44

.08

.28

.17

.27

.21 

.26 

.20 

.21

.17 

.28 

.22

.54

.24

99

.29

.47

.15

.12

.15 

.11

.10

.21

.84

.17

no

.02

.07

.06

in

.08 

.10

Aft

.11

.06

.04

.09 

.19

AQ

.04 

.03

.07

.18

.21

.03

.14

.12

.04

.09

.02

......

.07

.05

.23

.01

.01

Al

2 9ft

.59

.69 

.19

1 9

.36

.13

.18

.03

.50 

.06 

.09 

.05

.16 

.07 

.07

.10

.06

.04 

.25

.21

.13

.35

.04 

.08 

.10

19

.12

09

.06

Aft

Aft

Aft

.03

.31

.02

.02

.03

AQ

.13

.03

.26

.17

.11

00

......

.15

.07

"."oT

.13

.34

.04

.06

40

Mn

0.06

.01 

.02

~~."02~

......

.01 

.04

......

.01

.02

.01

......

.01

Ni

0.02 

.02

.02 

.02

.03

.01

......

......

......

......

.05

.02

.01

......

.03

Or

6^62"

.02

.11

~".~02~

______

......

......

......

......

.02

Ti

0.01 

.01

______

__....

......

......

.01

......

.01

......

......

Zn

-_.-..

......

......

......

......

......

 ...

Ca

0.14

.02

.08

.06

.09

.06

.08

19

0.4 ~".'6if

.01

.16

------

.02

.05

.10

.03

.01

.01 

.70

.05

"riff

.03

......

.02

.21

.01

.14

.02

.02

.10

.01 

.16

.07

.30

Na

0.05 

.01 

.01

.06 

.06

.02

.02

------

.01

.07

.03

.05

.08 

.02

.01

.08

.01

.01

-----

.08

.21

.14

.06 

.01

.01

.01

"."6ff

.20

.14

.51

.05

K

0.48

.02

.02

______

______

.03

__._._

.02

.03

......

......

......

......

.04

.06

2 

oct

4.76

4.92

5.68

5.78

5.75

5.79 

5.82

5.82

5.83

5.86

5.86 

5.88 

5.87 

5.87

5.88 

5.89 

5.89

5.89 

5.91

5.91

5.92 

5.93

5.94

5.94 

5.94

5.95

5.95 

5.95

5.95 

5.95

5.95 

5.95 

5.95 

5.96 

5.96 

5.97 

5.97 

5.97

5.98 

5.98

5.98

5.98

5.94

5.99

5.99

5.99

5.99

5.99

6.00 

6.00 

6.00

6.00 

6.00 

6.00

6.00 

6.01 

6.01 

6.01 

6.01 

6.01

6.02 

6.02 

6.02 

6.02

6.03 

5.93

6.03 

6.07

6.06

6.04

6.04

6.04

6.04 

6.04 

6.04 

6.04 

6.05 

6.05

6.05 

6.06 

6.06 

6.07

6.07 

6.07 

6.07

6.07

6.08

6.08 

6.09 

6.10

6.11

6.11

6.11 

6.15

6.17

Ions in tetrahedral 

coordination

Si

3 OK

3.85

3.97

3.55

3.84

3.89 

3.93

3.97

3.97

3.99

3.63 

3.89 

3.95 

3.98

3.94 

3.81 

3.91

3.61 

3.82

3.94

3.82 

3.65

3.89

3.92 

3.96

3.78

3.94 

3.95

3.96 

3.97

3.98 

4.00 

4.00 

3.90 

3.91 

3.22 

3.88 

3.95

3.93 

3.94

3.97

3.99

3.99

3.93

3.96

3.99

4.00

4.00

3.66 

3.86 

3.91

3.93 

3.98

3 Oft

4.00 

3.79 

3.93 

3.95 

3.96 

4.00

3.90 

3.90 

3.91 

3.91

3.75 

3.90

3.92 

3.96

3.97

3.83

3.84

3.86

3.90 

3.90 

3.91 

3.93 

3.74 

3.81

3.94 

3.85 

3.94 

3.72

3.79 

3.86 

3.86

3.94

3.65

3.83 

3.81 

3.82

3.58

3.70

3.75 

3.81

3.75

Al

0.15

.03

.45

.16

.11 

.07

.03

.03

.01

.37 

.11 

.05

09

.06 

.19 

.09

.37 

.18

.18 

.35

.11

.08 

.04

.22

.01

.04 

.03

.02

.07 

.09 

.30 

.03 

.05

.07 

.06

.03

.01

.01

.07

.04

.01

.34 

.05

.05 

.02 

.02

.15 

.05 

.05 

.02

"""16" 

.09 

.09

.12 

.10

.03

.17

.16

.14

.07 

.10 

.06 

.02 

.26 

.19

.01

.15 

.06 

.28

.11 

.03 

.14

.35

.02 

.19

.30

.01 

.19

.02

.»

.,...-

0.02

.06

.05 

.05

_...__

.03

.48 

.09

~".~6<r

.09 

.02

.06 

.02

"."62"

.10

.13

.05

.03

ios

.05

.10 

.11

.06

.15 "."Is"

.42

.24

.23

2 

tet

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4 00

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

3.96 

3.97 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00 

4.00
THE SERPENTINE-GROUP MINERALS 35

TABLE 8. Relationship of the ions in octahedral and tetrahedral coordination as calculated from the chemical analyses of serpentine-group

minerals taken from the literature and listed in table 5 Continued

Sample

115 

116 

120 

121 

122 

123 

124 

125 

126 

127 

128 

129 

130 

131 

132 

133 

134 

135 

136 

137 

138 

139 

140 

145 

146 

147 

148 

149 

150 

151 

152 

153 

154 

155 

156 

157 

158 

159 

160 

161 

162 

163 

164 

165 

166 

170 

171 

172 

173 

174 

175 

176 

177 

178 

179 

180 

181 

182 

183 

185 

186 

187 

190 

191 

192 

193 

194 

195 

1% 

197 

198 

199 

200 

201 

202 

203 

204 

205 

206 

207 

208 

209 

210 

211 

212 

213 

214 

215 

216 

217 

218 

219 

220 

221 

222

Locality

Thetford, Canada. __ . _________ . ___ .

 do... 

Hoboken, N.J....... .............................

China...... - ...... .....................

Czechoslovakia __ __ ______________

.....do ... - . .........................

T'vrnl Ttfllv

Franklin, N.J. ............. _ . _ . _ . _ ......

Silesia

Bare Hills, Md._- . .. __ ..... _ ............

 do... ........ __ ... _ ..... ....... ... ...

U.S.S.R. ....... ....... ....... .... .......

Italy. _ _ . .. 

..... do ............. ......, . 

Montville, N.J...................................

 -do... .... 

Italy. _. _._ ._. _.__ ..._

 -do.... _ . .................. 

Hoboken, N.J........... .. . 

Quebec, Canada... __ .. .... . ..

Ions in octahedral coordination

Mg

6.09

5.84

5.62

5.85

5.48

5.63

5.76

5.85

5.85

5.44

4.85

5.51

5.74

5.76 

5.14

5.67

5.88

5.40

5.20

5.74

4.32

5.69

5.13

5.47

5.59 

5.07

5 4ft

5.78

5.64

5.60

4.68

5.62

5 fid.

5.47

5.66

4.76 

5.52

5.41

5.50

4.81

5.42

5.36

5.55

5.50

5.44

3.94

4.85

4.23

5.27

2.94

3.86

2.82

3.76

5.02

3.15

4.21 

4.29

3.34

3.24

5.84

5 Oft

6.11

6.11

6.10 

5.83

6.16

5 Q7

6.20 

5.98 

5.91

5.81

6.02 

5.91

5.97

6.09

6 12

5.75

5

QC

6.00

5.90

5.89

 5.76

6.05 

5.83

5.94

6.03

5.83

5.92

5.88

6.03

Fea+

.10

.16

.06

.14

.04

.18

.01

.07

.03

.25

.16

.14

.04 

.57

.15

.03

.44

.70

.14

.44

.16

.07 

.30

.03

.02

.09

.16

.28

.01

.09

.11

.11

.48

.28

.20

.74

.26

.11

.17

.01

.30

.04

.04

.54

.31

.45

.37

.37

.08

.04

.08 

.35

.05 

.15

.08 

.15 

.22

.26

.05 

.18

.13

.07

.30

.12

.07

.17

.10

.22

.17

.58

10

.12

.11

.16

.10

.12

.01

Fe«+

.09

.06

.04

.11

.07

.02

.34

.46

.14

.33

.04

.18

.07

.07

.10

.03

.83

.57

.18

.93

.72

1.08

.08

.02

1.05

.09

Al

.11

9Q

.03

.06

.03

.01

.18

AO

.02 

.15

.07

.42

.06

.07

.24

.01 

.10

(\A

(\A

.03

.05

.53

.01

.03

.08

.33

no

.06

.07

.04

.31

.66

.16

.51

.35

dn

.08

.50

.05

Mn

.03

.01

.01

.02

.06

.03

.03

Ni

.01

......

ft*

.07

.07

.01

.01

.04

Cr

.01

 

......

Ti

.01

......

......

Zn

......

......

Ca

.06

.01

.03

.13

.03

.07

.03

.09

.01

.11 

.13

.09

.04

.03

.02

.11

...07

.03

.38

.10

.09

.11

.07

.06

.10

.03

.02

.01

Na

.24

.02

......

.08

.52

.11

.01

K

......

......

.01

s

oct

6.19

6.15

5.88

5.99

5.84 

5.97 

5.93

5.95

5.96 

5.82

5.25

5.85

5.89

5.88 

5.86

5.89

5.91

5.93

5.90

5.90

5.52 

5.64

5.83

5.70 

5.75 

5.92 

5.74

5.74

5.84

5.80

5.81

5.54

5.77

5.78

5.73 

5.77

5.57

5.70

5.69

5.70

5.64

5.68

5.95

5.66

5.67

5.54 

5.58

5.14

5.53 

5.40 

5.10 

5.31

4.53

4.88

4.41 

4.93

5.04

4.51

4.61

4.49

3.84

3.85

6.22

6.24 

6.19

6.15

6.16 

6.18 

6.21 

6.12 

6.28

6.13

6.13

6.11

6.07 

6.09

6.10

6.16

6.12 

6.05 

6.07 

6.07

6.07

6.07

6.11

6.03

6.04

6.05

6.05

6.07 

6.16

5.99

6.02

6.00 

6.06

Ions in tetrahedral 

coordination

Si

3.82

3.60 

4.01

4.01

4.01 

4.01 

4.02

4.02

4.02 

4.03

4.93

4.03

4.02

4.04 

4.04

4.04

4.04

4.04

4.05

4.05

4.05 

4.05

4.05

4.06 

4.06 

4.06 

4.07

4.07

4.07

4.09

4.09

4.09

4.10

4.10

4.12 

4.12

4.13

4.14

4.15

4.15

4.16

4.16

4.16

4.17

4.17

4.20 

4.20

4.20

4.23 

4.32 

4.33 

4.34

4.34 

4.35

4.41 

4.45

4.48

4.48

4.59

4.71

4.96

5.06

3.89

3.88 

3.90

3.92

3.92 

3.89 

3.81 

3.94 

3.86

3.94

3.88

3.95

3.96 

3.96

3.91

3.80

3.90 

3.97 

3.97 

3.97

3.97

3.97

3.87

3.98

3.98

3.98

3.98

3.94 

3.82

3.99

3.98

3.97 

3.94

Al

.30

......

.02

.05

.10

.01 

.13

.01

"."6§"

Fes+

.18 

.10

......

.03 

.10

.07

.16 

.06

.03

.01

.02

S 

tet

4.00 

4.00 

4.01 

4.01 

4.01 

4.01 

4.02 

4.02 

4.02 

4.03 

4.03 

4.03 

4.02 

4.04 

4.04 

4.04 

4.04 

4.04 

4.05 

4.05 

4.05 

4.05 

4.05 

4.06 

4.06 

4.06 

4.07 

4.07 

4.07 

4.09 

4.09 

4.09 

4.10 

4.10 

4.12 

4.12 

4.13 

4.14 

4.15 

4.15 

4.16 

4.16 

4.16 

4.17 

4.17 

4.20 

4.20 

4.20 

4.23 

4.32 

4.33 

4.34 

4.34 

4.35 

4.41 

4.45 

4.48 

4.48 

4.59 

4.71 

4.96 

5.06 

3.89 

3.88 

3.90 

3.92 

3.92 

3.92 

3.93 

3.94 

3.86 

3.94 

3.95 

3.95 

3.96 

3.96 

3.96 

3.96 

3.96 

3.97 

3.97 

3.97 

3.97 

3.97 

3.97 

3.98 

3.98 

3.98 

3.98 

3.98 

3.95 

3.99 

3.99 

3.98 

3.90
36 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

TABLE 8. Relationship of the ions in octahedral and tetrahedral coordination as calculated from the chemical analyses of serpentine group

minerals taken from the literature artd listed in table 5 Continued

Sample

225 

226 

227 

228 

229 

243 

244 

245 

246 

247 

248 

249 

250 

251 

255 

256 

257 

258 

259 

260 

261

Locality

Finland ________________________

 do 

Italy .- 

__ do 

Globe, Ariz.. _________ __ ______

 . .do 

 -do ... ....... ..... ... 

... ..do ..... ....... ...... ... ...... ... ....

 do . -

Baste. Harz

 do 

Montville, NJ... ... 

Montville,N.J ................................

Ions in octahedral coordination

Mg

6.93

4.74

6.59

6.01

7.03

5.69

4.53

4.51 

5.65

5.59

5.90

5.92

5.81

5.80

4.29 

4.18

3.76

6.00

5.89

5.78

5.74

Fe2+

.18

1.93

.02

.50

0.04

.29

.19 

.01

.03

.05

.05

.06

.07

.56 

1.08

.87

.01

Fea+

0.09

.53

.41 

.08

.13

.01

.09

.06

.07

Al

.30

.42 

.03

ns

.06

.03

12

no

.67

.25

.17

.07

.08

Mn

0.01 ~"6i"

.01

.07

.04

Ni

------

.02

.01

Cr

......

Ti

.08

0.01

.03

Zn

......

Ca

.06

.17

......

0.01

.01

.06

.28

Na

.10

.02

0.10

.10 

.01

.01

K

.09

.07

0.07

.03

S 

oct

7.17 

7.11

6.70 

6.51

7.03 

5.82

5.84

5.69 

5.79

5.85

6.01

6.01

5.99 

5.97

5.52

5.64

5.30

6.01

5.99

5.93

5.90

Ions in tetrahertral 

coordination

Si

3.02 

3.13

3.47 

3.75

3.11 

4.06

3.68

3.84 

4.07

4.03

3.92

3.93

3.91 

3.97

4.08

4.12

4.25

3.98

3.94

4.02

4.02

Al

.11 

.48

.04

.17

0.32

.16

.08

.07

.09 

.03

Fe^

.42

.23

.50

......

.02 

.06

S 

tet

3.55 

3.61 

3.74 

3.75

3.78 

4.06 

4.00 

4.00 

4.07 

4.03 

4.00 

4.00 

4.00 

4.00 

4.08 

4.12 

4.25 

4.00 

4.00 

4.02 

4.02

yield formulas which are either neutral or have a 

charge excess or deficiency of ±0.02. This value is 

well within the limit of analytical error plus the error 

of rounding off to the second decimal place.

To assess the effect for any particular ion, it is 

necessary to take into consideration the equivalent 

weights for the ions concerned. In one of the analyses 

0.29 percent Cr2O3 was accidentally included with the 

A12O3 . This leads to the formula

[Ma.w F^SNi.o,Mn.o,AI.08][Si,.w Al. 1 ,]0,o(OH) 8

S 6.09 ions S = 4.00 ions 

oct tet

Recalculations on the basis of the determined value of 

Cr2O3 gives

= 6.06 ions

oct tet

= 4.00 ions

In another analysis a similarly small amount, 0.24 

percent O2O3 , was included with the A12O3 and computed as A12O3 to give

[Ma.49FeSMn.o,Al.H][Si4.oo]010 (OH) 8

S = 5.95 ions

oct

With correction for Cr2O3 there results

[Mg5 .5oFe^Mn.o2Cr.o2Al.o8][Si4 .oo]010 (OH) 8

S = 5.95 ions 

oct

An error in the analytically determined value of silica 

and alumina may lead to one of several conditions. If 

some alumina is reported as silica, the value of silicon 

in tetrahedral coordination may appear too high, or 

failing to exceed S=4.00 ions it will mask the fact that a 

small but definite number of aluminum ions is in 

tetrahedral coordination. If some silica is reported as 

alumina, a deficiency of silicon ions in tetrahedral 

coordination may be reported.

From studies of the micas, montmorillonites, and 

other layer lattice minerals, it now appears to be established that ferric iron may replace silica to a limited 

extent in sites in tetrahedral coordination. This

TABLE 9. Relationship of the ions in octahedral and tetrahedral coordination as calculated from the chemical analyses of Jenkinsite

hydrophite, and zincian serpentine

Sample Locality

Ions in octahedral coordination

Mg FC2+ F63+ Al Mn Zn Oa S 

oct

Ions in tetrahedral coordination

Si Al Fe»+ S 

tet

Jenkinsite and hydrophite

235

236

237

Orange County, N.Y __ . _

__ .do _______ .

Sweden, _ __ .. ___

3.62

3.59

3.41

1.84

1 70

0.12

30

0

07

on

.11

5.95

5.75

5.88

4.00

4.11

3.93 0.07

4.<X

4.1

4.0

Zincian serpentine

238

239

240

241

242

Uzbek, U.S. S.R. ............

 ..do -... .

Franklin, NJ....... ..

 .do... ... .

 do ........

5

AA

5.00

4

KA

4.81

.20

1*1

10

0.20

.11

.08

0.01

.01

29

60

0 12

1Q

.31

.26

.01

6.05

1 Q

5.98

5.96

5.40

5 7Q

3.93

3.96

3.96

4.30

4.09

0.07

.04

0.04

4.00

4.00

4.00

4.30

4.09
THE SERPENTINE-GEOUP MINERALS 37

appears to be true in the serpentines. It is therefore 

particularly desirable, if iron is present in significant 

amounts, to determine both Fe2O3 and FeO. Failure 

to do so may introduce error into the calculated formula. 

Thus considering all iron to be bivalent could lead to a 

deficiency in the number of ions in tetrahedral coordination. It will be noted in table 8 that some of the 

analyses of serpentines deficient in ions in tetrahedral 

positions report only bivalent iron, whereas some of it 

is probably trivalent and if it were reported as such, a 

sufficient amount could be assigned to tetrahedral 

sites. The absence of magnetite, usually easily proven 

by running a strong hand magnet over the crushed 

powder should, however, be demonstrated.

Nickel, cobalt, zinc, and manganese, referred to as 

the zinc group, are precipitated together with ammonium sulfide after the iron, aluminum, and other ions 

have been removed as hydroxides by ammonium -hydroxide. If they are present in significant amounts in 

the sample being analyzed, but are not determined, 

they will cause the analysis to have a low summation 

and the structural formula to show deficiency in octahedral sites filled.

INTERPRETATION OP THE CALCULATED STRUCTURAL FORMULAS OF THE SAMPLES REPORTED 

IN THIS STUDY

A graphical method was used to evaluate our chemical analyses* A plot was made using the sum of the 

ions in tetrahedral coordination (£) and the sum of the

tet

ions in octahedral coordination (£) as coordinate axes

oct

(figs. 18 and 19). It was found that most of the 

analyses fall within a rectangle having the coordinates 

(2=4.00-4.10) and (S = 5.80-6.04). Two of the analytet oct

ses which fall outside this rectangle have their full 

complement of tetrahedral sites but show some excess 

of ions in octahedral coordination. These chemical 

analyses F-51, a specimen from Nicaro, Cuba; and 

F-69, from Webster, N.C. represent serpentinized 

ultrabasic rocks. Ross, Shannon, and Gonyer (1928), 

commenting on anaysis F-69, imply the presence of 

unaltered olivine, an observation which is in accord 

with our graphical study. A similar interpretation 

is suggested for sample F-51.

Five other specimens have calculated formulas that 

lie outside the rectangle defined above. These samples 

have all been called deweylite. Only one specimen 

whose calculated formula lies within the rectangle, 

F-43, has been described as a deweylite. It had been 

observed in the DTA and X-ray studies that these 

same deweylite specimens were natural mixtures of 

serpentine and the magnesium end-member of the 

montmorillonite group, stevensite. In earlier studies

such as that of Self ridge (1936), stevensite had been 

regarded as a member of the serpentine group. In 

order to check the experimentally determined mixedphase concept of deweylite by the graphical relation 

outlined above, the chemical analysis of theoretical 

stevensite was treated as a serpentine, calculated to 

yield the postulated formula below,

[Mg3.82 ][Sis.o.l010 [OH]8

and plotted as such on the diagram (fig. 19). A straight 

line connecting the positions of theoretical serpentine 

and theoretical stevensite (calculated as a serpentinegroup mineral) shows that the five analyses F-3, 

F-40, F-41, F-26, and F-48 all lie astride it or close 

to it. Sample F-40 is known to contain some carbonate 

mineral as an impurity.

Twenty samples are included within the rectangle 

and even though this is a small number of analyses, 

there does appear to be a tendency for the antigorites 

to be set apart from the chrysotiles and lizardites. 

Only one sample, F-13,*from the Tilly Foster mine, 

Brewster Station, N.Y., considered to be a mixture by 

other studies, is not associated with its congeners. 

The antigorites lie within a subrectangle with the 

coordinates S=5.80 to 5.84 and S=4.00 to 4.10. This

oct tet

compositional difference between the antigorites and 

the chrysotiles and lizardite is in accord with the 

crystal structure relationships. Zussman (1954, p. 510) 

describes it as follows:

The Crystal structure proposed involves 8>£ repeats of the subcel^ 

in the tetrahedral layer, i.e. 34 Si atoms per cell. It may also 

be noted that the "rectified wave" model clearly implies a 

deficiency of Mg and (OH) ions, since at the junction of neighbouring "arches" there is insufficient room for an extra half 

subcell in the octahedral layer. Moreover, the two (OH) 

ions at the top of the tetrahedral layer in positions marked 

A (fig. 4) would be unduly close to one another and would 

probably also be omitted. Allowing for these deficiencies, the 

numbers of atoms in successive planes would be as follows: 

51(O), 34Si, 34(O) and 15(OH), 48 Mg, 48(OH). The structural 

model is thus in accord with the chemical data and with the 

observed density, within the limits of experimental error.

Kunze (1956, 1958) has made a comprehensive study 

of the crystal structure of antigorite and his results 

show (1956, p. 82) that,

The chemical formula of chrysotile, Mg3(OH)4 Si2 O5, is not valid 

for antigorite, the reason is a so-called "coincidence" deficiency 

of electroneutral atom groups. This deficiency is repeated 

along the crystallographical a axis with exactly defined (superperiod) distance. In the resulting superstructure of antigorite 

(which is a so-called "double half-wave" structure), we find two 

"half-waves" alternately connected by means /of Mg-bridges. 

In contrast to the monoclinic chrysotile, here we find a larger 

interaction in the form of hydrogen bonds between two layers 

along the direction of the layer period c.

and (1958, p. 319)
38 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

6.25 1 1

 F-69

 F-51

 F-74

 F-72,F-73 

_ _^

F-<

1

F-22 

fF-24,F-25 F-23

 F-42 

 F-20 

 F-47

F-46

 F-13 

^3« 

 F-57 

 F-56

 F-19

F-15 ' "' 

F-I4- -F

1

-8,F-53

3.90

6.20

6.10

 o

0>

JZ

6.00 |

O

5.90

5.80

5.75

4.00 4.10 4.15

2 tetrahedral

FIGURE 18. The relation between the ions in octahedral coordination! * ) and the ions in tetrabedral coordination ( ),

Voet/ \tet/

calculated from the analyses reported in this study. Rectangle outlines compositions of typical serpentine-group minerals.
THE SERPENTINE-GROUP MINERALS 39

|f|etical serpentine

A3

\

 F-3

Deweylite of Strunz

 F-r 40 

F-41 Deweylite of Dana

 F-26

F-48

Theoretical stevensite

6.10

6.00

5.80

5.60

5.40

5.20

5.00

4..80

4.60

4.40

4.20

4.00

3.80

3.80 4.00 4.20 4.40 4.60 4.80

S tetrahedral

5.00 5.15

FIGURE 19. The relation between the ions in octahedral coordination ( ^ J and the ions in tetrahedral coordination ( ^ ), calculated

Voot/ \tet/

from the chemical analyses of samples called deweylite and reported in this study. Section along the tieline theoretical serpentine 

to theoretical stevensite. Shaded area outlines compositions of typical serpentine-group minerals, as in figure 18.
40 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

To be sure the chemical formula of antigorite [Mg2 .8i3][Si2 ]O5 - 

(OH)3 «47 has less MgO and H2 O than chrysotile [Mg3 ][Si2 ]OB - 

(OH)4 . . . .

Antigorite and chrysotile have (1) different but related crystal structures, (2) different but related 

chemical composition, and (3) different densities, so 

that we are posed with a dilemma. According to 

the phase rule we can regard them as separate phases. 

Furthermore, they appear to differ enough so that, 

strictly speaking they are not polymorphs. However, 

for the purpose of this study we have included them in 

the general term "serpentine group."

The structural formulas of the antigorites reported 

on in this study, tables 2 and 3, have been computed 

to the requirements of the crystal-structure data for 

Zussman (1954) and Kunze (1956, 1958) and are given 

in table 10.

Calculation of the analysis of the so-called serpentinized phlogopite F-68, and of the theoretical composition of the mixture, into the structural formula used 

in this paper gives the following: for the natural mixture F-68

2 = 4.12

tet

2 = 5.73 

oct

for Bayley's (1941) theoretical mixture of 50 percent 

phlogopite + 50 percent serpentine

2=6.09 

oct

2=4.00

tet

These formulas suggest that sample F-68 is a natural 

admixture of serpentine, stevensite, and phlogopite. 

This observation is concordant with the interpretation 

of the analyses of other serpentine group minerals from 

Easton, Pa., taken from the literature (fig. 24).

INTERPRETATION OF THE STRUCTURAL FORMULAS 

CALCULATED FROM ANALYSES OBTAINED FROM 

THE LITERATURE

The data obtained from the chemical analyses of the 

serpentine group minerals taken from the literature are 

plotted in figures 20 and 21. Because some of these 

samples obviously are impure, it is desirable to know 

just how certain impurities (fig. 22) will affect the calculated structural formulas. In order to bring this out 

clearly, it is useful to treat the various admixed phases 

as if they were serpentine and calculate their formula 

in terms of the formula X6Y4Oi0 (OH)8 . This yields the 

following postulated structural formulas.

MINERALS

Forsterite.. _ _____________ [Mg7.0o][Si3.5o]Oio (OH)8

Fayalite.----- ------- [Fe7.oo][Si3.5o]O10 (OH)8

Diopside - --------

Tremolite -__

Enstatite. ______________

Stevensite--.------------ [Mg3.82 ][Si5 .09 ]Oio(OH)8

Sepiolite (Dana)---- -.- [Mg3.5o][Si5 . 25 ]O10 (OH)8

Sepiolite (Strunz)___------ [Mg3.82 ][Si5 .o9]O10 (OH)8

Spadaite (Dana)___-_ .__ [Mg4.ro Fe20+7 Al.o7 ][Si4 .91 ]O10 (OH)8

Talc-..---,------------- [Mg3 .82 ][Si5 .o9 ]010 (OH)8

Deweylite (Dana)------- [Mg5 .60 ][Si4 .2o]O1 o(OH)8

Deweylite (Strunz) ____ [Mg5 .70 ][Si4.i5 ]O10 (OH)8

MIXTURES

80 percent serpentine _ . 

20 percent brucite. _______

95 percent serpentine ._ 

5 percent quartz....______

90 percent serpentine 

10 percent quartz - 

90 percent serpentine.. ._ 

10 percent Fe2 O3 ________

95 percent serpentine. _ 

5 percent Fe2 Oj___ _-_ --_

90 percent serpentine.. . _ 

10 percent calcite (aragonite). 

90 percent serpentine______ 1

10 percent magnesite -J 

90 percent serpentine_...1 

10 percent dolomite. __j 

90 percent serpentine.....-!

10 percent magnetite. -J

[Mg7. 1S ][Si3.42 ]010 (OH)8

[Mg5.M ][Si4._jQio(OH)g 

[Mg5 .22 ][Si4.38 ]010 (OH)8 

[MgB .M Fe?7+1 ][Sil .»]QIo(OH)g

[Mg5 .77Fe32+5 ][Si3 .85 ]010 (OH)8

[Mg8 .39][Si3.8o]010 (OH)8

[Mge.o4Ca.31 ][Si3 .82 ]01 o(OH)8

[MgB .w Fe?__Fe»a+1 ][Sil.M Fe?£] 

010 (OH)8

These postulated formulas are plotted on figures 20 

and 21 and allow interpretation of the data to be made. 

It would be desirable to be able to check the suspected 

impurities in the samples studied, but this cannot be 

done and we have to base our interpretations on such 

other data as are available.

The mixtures of the carbonate mineral and serpentine 

are calculated on the assumption that an analyst did 

not determine carbon dioxide directly and the carbon 

dioxide percentage is included with the "loss on ignition" 

or as part of the H2O+.

The following calculated formulas illustrate the 

magnitude of the change in the calculated formula for 

a sample containing 5.33 percent dolomite and 0.64 

percent magnesite. 

No allowance made for the carbonates:

[Mg5 .6oFe?otAl.oiCa.17][Si4.io]01 o(OH) 8

2=5.79 ions 2=4.10 ions 

oct tet

Analysis corrected for 5.33 percent dolomite and 0.64 

percent magnesite based on the determined amount of 

CO2 and on mineralogical data:

[Mg5 .64Fe3otAl.01][Si4.22]010 (OH) 8

2=5.56 2=4.22 

oct tet

It will be observed that the second corrected formula 

clearly shows that this sample is a deweylite.
TABLE 10. Relationship of the ions in octahedral and tetrahedral coordination as calculated from the chemical analyses of antigorites studi

Calculated formula 

for sample 

F-l

F-8 ___ -_-_ __

F-13_-__ .____--

F-14 _--.-.-__

F-15.. ._-._.__..

F-19 ___________

According to Zussman (1954)

Ions in lattice

Mg,. MSi40,o(OH) 7 . 41 .... ______ __.. - _.

[Mg,.,1Fe«_Al.,1Ni.oi][Si,.,,Al.o4]0,o(OH) 7 .«_ _____._-_

[Mg6.6_Fe5SFeffiCa.o6]_8i4.oo]O.0 (OH) 7 .4i-__ ___ ________

[Mg8 ^F^F^SAl.o6 Mn.oiK.o8][Si8 .»6Al.o.lO,o(OH)7.«-_-

[Mgs.eoFe&Feft Al.05Ca.oi][Si4 .oo]0 10 (OH) 7 .«_ -------

[Mg4.9oFe23+2Fe31tAl. 21 Cr.o2Ni.01 Mn.oiCa.oi]

[Sis.B.Al.ulOwCOHh.W

[Mg5 . 09Fe23+2Fe36H3Al. 16Ni.oi][Si3.96Al.o4]01o(OH) 7 .«- ______

2 

oct

5.65

5.66

5.69

5.72

5.69

5.61

5.61

2 

tet

4.00

4.00

4.00

4.00

4.00

4.00

4.00

According to Kunze (195

Ions in lattice

Mg5 . 626Si4 010 (OH) 7.294- _.__-_-_-_-_____

[Mg5.49FeS_Al.IONi.o,][Sis.»6Al .o5]O10 (OH) 7 . 2

[Mg8 .,.Fe!!ftCa .06][Si,.MFe!S]01 o(OH) ,.».__ 

[Mg5 .39Fe21tFe3o+2 A].o4 Mn.o1 K.o3][Si3.93Al.o7]0

[Mgs.s.Fe^Fe^ Al.o3Ca.o1 ][&i3.98Al.o2]01 o(O

[ Mg4 . ssFe^FeS Al . 19Cr .MNi .01 Mn M Ca M]

[Si3.84Al. 16]010 (OH) 7 . 29 

[MgB.o7Fe23.Fe3o-3Al. 15Ni.o,][Si3.95Al.o5]O10 (OH
42 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

7.30

6.90

6.50

6.25

6.15

6.05

5.95

5.85

5.75

 225

60% serpentine,... 

 20% brucite * 226

Forsterite, 

fayalite

 229

 227

 226

90% serpentine, 

/If\ 0% dolomite

90% serpentine, / 

I 0% magnesite ... ,. ^j°% serpentine,

10% calcite r 198

90 % serpentine, 

10 % hematite >I9I 

 190

 196

192

195

194

193

95% serpentine, 

5% hematite

29

199- «200 

I97« -206 

201- «2I2

 204

 203 

206-2IL 

60,202* -217

61.

 113,116

 110-112

.102

>IOI

 99-100

42-44,251 

40-41,240 

32-39,235 

-31 .Borettite 

26,76

130,26 

19-21,236 

15,237

Barettite 

244

45-49,239 

**23 .:. : ' 

 125

 260

 I24*|3S 

27 I4t» 

25-26 *'34

13-14 .132

.140

-M .127

serpentine, 

J0%magnetite 

249,256 

,250

-137

 152 

 .151 

246- *242

 155 

I54« -157

 146 '236

3.40 3.80 3.90 4.00 

S tetrahedral

4.10 4.20

FIGURE 20. The relation between the ions in octahedral coordination( ^ Jand the ions in tetrahedral coordination! ^ ) calculated from

\oct/ Vtet/

the chemical analyses taken from the literature; large rectangle encloses serpentine analyses. Shaded rectangle is the same as figure IS.
THE SERPENTINE-GROUP MINERALS 43

5.70

5.50

5.30

5.10

o 4.90

4.70

4.50

4.30

4.10

3.90

 I54A.I57

 5 -146 -236 

148-149 «I56

* 4 ° f strun2 - 161

16S \ 95% serpentine, 

5%Si02

 Deweylite of Dona

.153 170 

138* "255

\"

"176

\ 90% serpentine,

' 10% Si02

TalcSerpentine of Strunz\ 

Stevensite- I87« 186

3.60 3.80 4.00 4.20 4.40 

2 tetrahedral

4.60 4.80 5.00

FIQUBE 21 . The relation between the ions in octahedral coordination ( ) and the ions in tetrahedral coordination ( ) calculated from the chemical analyses taken

\oot/ Vtet/

from the literature. Section along the tieline theoretical serpentine to theoretical stevensite.
44 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

SiO_

0 \Anthophyllite, Mg Si 0 (OH)

Enstatite, MgSiO-j

Forsterite, Mg SiO

MgO (periclase)

FIGTIKE 22. Natural phases in the ternary system MgO-SiOj-HaO.

Some of the minerals of the chlorite group have 

compositions closely similar, if not identical, with the 

minerals of the serpentine group so that it will be very 

difficult if not impossible to detect them by this 

graphical treatment. They are easily detected by 

experimental techniques and consequently are not 

likely to be present as contaminants.

The rectangle outlined by the coordinates S =3.92,

oct

S =5.82; S =3.92, S =6.20; S =4.05, S =5.82;

tet oct tet oct tet

and S =4.05, S =6.20 contains most of the analyses

oct tet

of substances reported to be serpentine-group minerals. 

With the aid of the postulated formulas for possible 

admixed substances, the likely impurities may be 

disclosed. Olivine (forsterite and fayalite), brucite, 

calcite, magnesite, or dolomite as admixtures with

serpentine will displace the calculated formula towards 

a higher value of ions in octahedral coordination. 

Analyses 225, 226, 227, 228, and 229 may be suspected 

of such admixtures. Small amounts of enstatite, 

diopside, or tremolite will displace the formula towards 

the corner of the rectangle with coordinates S =4.05

oct

and S =5.82.

tet

Mixtures of 5 or 10 percent of hematite with serpentine will displace the formula away from the 

theoretical composition toward the corner with coordinates S =3.92 and S =6.20 but with a much

oct tet

lower slope than the admixtures of olivine and other 

admixtures mentioned above.

The tieline (fig. 21) connecting the composition of 

theoretical serpentine with theoretical stevensite, cal-
THE SERPENTINE-GROUP MINERALS 45

culated on the basis of the serpentine formula, contains 

quite a number of analyses. Many, if not air; of these 

points represent analyses of admixtures of stevensite 

and serpentine. The deweylites of Dana and Strunz 

lie along this tieline, together with the various deweylite analyses from the literature. The composition of 

spadaite lies on this tieline and it has been found by 

other studies to consist chiefly of stevensite.

Analyses 1 and 2 are definitely not serpentine-group 

minerals, although they may contain some admixed 

serpentine. They probably represent altered minerals.

Analyses 177 and 179 have been called acquacreptite; 

Nos. 172 and 182, webskyite; and these together with 

No. 178 are characterized by a considerable quantity of 

Fe2O3 in their analyses. The values of Fe2O3 are as 

follows: Analysis 177, 12.30 percent; No. 179, 13.30 

percent; No. 172, 9.13 percent; No. 182, 11.52 percent; 

and No. 178, 9.83 percent. They are probably mixtures of a montmorillonite-group mineral and serpentine. A mixture similar to these has been found to 

consist of serpentine and a montmorillonite-group 

mineral and does not contain any free iron oxide 

mineral.

The heavy concentration of points along the coordinate axis 2 4.00 is at once apparent. This arises,

tet

in part, from the method of calculation wherein S

tet

is adjusted to 4.00. The deviation of a point from 

2 =6.00 represents either (a) deficiency of ions in the

oct 

structure in octahedral coordination, as in the antigorites, (b) analytical error, (c) a small amount of 

contamination by admixed impurities, or (d) a combination chiefly of (b) and (c). The effect of an inaccurate 

analytical value for silica will, in general, shift 2 

to values less than 6.00 ions. oct

The areal trends for a given type of occurrence are 

given in figures 23 and 24. Serpentines of class A are 

represented by analyses from Texas, Pa.; Quebec, 

Canada; Transvaal, Union of South Africa; Southern 

Rhodesia; Val Antigorio, Italy; Lizard, England; and 

Snarum, Norway. Serpentines of class B are represented by analyses from Easton, Pa.; Gila County, 

Ariz.; Montville, N.J.; and Tilly Foster mine, Brewster 

Station, N.Y.

The samples from Texa§, Pa., all lie on or near the 

tieline theoretical serpentine to theoretical stevensite. 

Most of them are so-called deweylites. The plot of 

the analyses of the serpentines from Quebec suggests 

that some of them contain admixed brucite or olivine. 

Mineralogical studies suggest that the most likely 

admixed phase is brucite. The analyses of the samples 

from the Transvaal, Union of South Africa, indicate 

that most of the samples are nearly pure. One of the 

specimens is a so-called deweylite. The analyses of

the specimens from southern Rhodesia cluster about 

theoretical serpentine. The analyses of samples from 

Val Antigorio, Italy, cluster about and slightly above 

the theoretical value for antigorites, namely S =5.88

oct

and S =4.00. The analyses of the specimens from the

tet

Lizard, England, cluster about theoretical serpentine. 

One analysis is a so-called deweylite. The analyses of 

the specimens from Snarum, Norway, in general, cluster 

about theoretical serpentine. One analysis suggests 

admixture with olivine.

The analyses of the specimens from Easton, Pa., 

range over a fairly large interval for S namely, from

oct

S =5.78 to S =6.08. One specimen appears to be

oct oct

contaminated with an iron oxide mineral. The analyses 

of the chrysotiles from Gila County, Ariz., show a 

tendency to group around theoretical serpentine. Two 

of the analyses depart from this and each is known, from 

the literature, to contain impurities. The analyses of 

the samples from Montville, N.J., are, with one exception, close to theoretical serpentine in composition. 

The analysis with S =6.16 and S =3.92 is probably

oct tet

contaminated with the pyroxene from which the serpentine is derived. The analyses of specimens from 

Tilly Foster mine, Brewster Station, N.Y., suggest 

that they are antigorites contaminated with chrysotile.

Manganoan serpentine minerals have been known for 

a long time. Kenngott (1856-57) reported 0.30 percent MnO in the serpentine from the Fleimstal, Monzoni, in the Italian Tyrol, which he named vorhauserite 

(analysis 137). Serpentine-group minerals containing 

sufficient MnO to appear in the structural formulas in 

table 7 are as follows: F-13, F-15, F-19, F-22, F-26, 

F-53, F-56, F-57, F-72, F-73, and F-74. In 10 of 

these formulas, Mn amounts to 0.01 ions in octahedral 

coordination, and in only one (F-57) does it reach 0.04 

ions. In table 8, which contains a wide selection of 

data from the literature, serpentine samples reported to 

have sufficient MnO to appear in the structural formulas are as follows: analyses 15, 66, 71, 79, 92, 127, 

131, 244, 246, and 247 show 0.01 ions in octahedral 

coordination; analyses 16, 38, 72, and 137 show 0.02 

ions; analyses 124, 154, and 185 show 0.03 ions; analyses 

67 and 257 show 0.04 ions; and analyses 4 and 147 show 

0.06 ions; analysis 256 shows 0.07 ions in octahedral 

coordination. Spectrographic studies of serpentines 

suggest that bivalent manganese is very commonly 

present in small amounts.

Although the quantity of bivalent manganese is low 

in most serpentine minerals and generally of no importance in the crystal structure, its presence is significant 

because of the common occurrence of these minerals.
46 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

Texas, Pa. Quebec

I ' 

 85

 153

 225

4.20 

2J tetrohedral

Transvaal

 66

 75

.-.19,21 I8 i| 6

3.50

5.60 '

4.00 4.20 4.40

South Rhodesia 2 tetrahedral 

620

4.90

Lizard

 210

 64

 67

.37 35

 28

.14 129

Val Antigorio

6.40

6.20

 196 

 192 .115

203« AIOI 

202« '94,97

222-X*' 89 222 .87

 53 

. >42

I .134

6.30

5.90

3.70 3.90 

2) tetrahedral

390 4.10 

S tetrahedral

5.60 390« 4.10 3.90 4.10 

2, tetrahedral y ........j..,

5.60

I '

 114

 116

22I« .62 

 47

tetrahedral

3.90 4.10 

Z tetrahedral

FIGUEE 23. Graphs of the relation 2 versus 2 for serpentines of Glass A from Texas, Pa.; Quebec, Canada; Transvaal, Union of South

oct tet 

Africa; Southern Rbodesla; Val Antigorio, Italy; Lizard, England; and Snarum, Norway.
THE SERPENTINE-GROUP MINERALS

Easton, Pa.

47

Gila County,Ariz.

3.1

.195 1

 99 

 216

.46 123

 26

 122

 4

~ I60~

1

30 4.10

6.00

o

 o 

a>

.c 

o

 t 

0

o

5.80 

3.'

1

 248,249 

 250 

 251

 247

~ 246-~~

1

30 4. 

2 tetrahedral

o.w w

o

k. o 

a>

5.80 o

o 

o

10

5.60

2 tetrahedral

Montville, N. J.

O.IU

lly Foster mine, New York

1

 »I02 

81* «93 

2I3 ° «73

 39

I

0

k. o 

a>

6.00 1 I 59 ° 

^ S

O r ^, 

 *- ^}

0 ^

o

R 7O

1

_ -258 _

 194 

 260

 

_ 64 ;68,70 _

 27

i

3.90 4.10 

2 tetrahedral

39.0 4.10 

2 tetrahedral

FIGURE 24. Graphs of the relation S versus S for serpentines of Class B from Easton, Pa.; Gila County, Ariz.; Montville, N.J.; 

oct tet

and Tilly Foster mine, Brewster Station, N.Y.
48 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

The cobaltian wads (asbolan, asbolite) of New Caledonia, described by La Croix (1942-43) show that the 

content of manganese may be significantly concentrated in the decomposition and weathering of serpentine minerals.

Larger amounts of bivalent manganese appear in the 

iron-rich serpentine minerals jenkinsite and hydrophite, 

which contain 0.37-0.39 ions and 0.11 ions, respectively, in octahedral coordination (table 9). The 

zincian serpentine minerals (table 9) commonly contain 

large amounts of manganese, the three specimens from 

Franklin, N.J., showing 0.29, 0.60, and 0.63 ions in 

octahedral coordination. Manganoan serpentine minerals are probaly more abundant than the reported data 

show. They should be looked for at pyrometasomatic 

zinc deposits where the pyroxenes johannsenite 

CaMnSi2O6 and its solid solutions with diopside and 

hedenbergite occur and have been altered by later 

hydrothermal solutions.

Zincian serpentine minerals were observed in the 

mineral assemblage at Franklin, N.J., by Koeing (1886) 

Shannon and Larsen (1926), and David Jenkins and 

Lawson H. Bauer, 1926, quoted in Plaache (1937). 

(See table 9, specimens 240, 241, and 242.) Recently 

Badalov (1958) has described zincian serpentine minerals from Uzbek, U.S.S.R. (See table 9, specimens 

238 and 239.)

The hydrous nickel-magnesium silicates (the garnierite group), including genthite, nickeloan stevensite, 

pimelite (nickeloan saponite), nickeloan deweylites, 

and nickeloan serpentines have also been studied and 

the results of this work will be published later. The 

observation is significant that a plot of the data for 

more than 50 analyses of these minerals gathered from 

the literature shows many of them to be admixtures of 

the nickeloan serpentine minerals and nickeloan stevensite and to lie along the tieline connecting these two 

phases, so that the plot is similar in appearance to 

figure 21.

THERMAL-ANALYSIS STUDIES

STATIC (DEHYDRATION) METHOD

The static method of thermal-analysis consists of 

heating a sample at a given temperature until it attains 

"constancy" in weight. This operation is repeated 

at successively higher temperatures until the sample 

has lost all its water. The system is commonly investigated from room temperature up to 1,000°C. The 

graph resulting from a plot of the data showing the loss 

in weight of the sample as a function of the temperature 

is called a dehydration curve. There are various experimental methods for obtaining the data. The methods 

used in this study have been described by Nutting 

(1943). The crucible containing the sample is suspended from the bottom of the pan of an analytical 

balance by means of a platinum wire and hangs in the 

"hot-spot" of the furnace. The sample is always in the 

furnace and the heating process is continuous. The 

water is lost from the specimen; therefore, the process 

is irreversible and the system investigated is not in 

equilibrium.

Dehydration curves are very useful because a given 

mineral species gives a characteristic curve, which, 

when taken together with other data, permits indentifications to be made. These curves also show the 

manner in which the water is lost from the mineral in 

the particular heating process used in the experiment.

Many dehydration studies have been made on minerals of the serpentine group. Some of these studies 

have been made an pure minerals, but very few of the 

dehydration studies have been accompanied by chemical 

analyses of the purified minerals.

Rammelsberg (1869) was probably the first to make 

dehydration studies on serpentine He studied a 

light-green serpentine from Texas, Lancaster County, 

Pa. Clarke and Schneider (1890) made dehydration 

studies at 105°, 250°, 383°-412°, and 498°-527°C, and 

redi heat and white heat on five analyzed serpentine 

minerals. These were:

A. Dull-green serpentine from Montville, N.J. (altered 

pyroxene), analysis 258.

B. Dark-green serpentine from Newburyport, Massachusetts, analysis 259.

C. Silky fibrous chrysotile from Montville, N.J., analysis 260.

D. Grayish-green picrolite from Buck Creek, N.C., 

analysis 130.

E. Massive serpentine (deweylite) from Corundum 

Hill, N.C., analysis 261.

On the basis of the data in their paper and results on 

similar material in this paper, it is suggested that 

sample A is chiefly chrysotile with possibly some 

lizardite; sample C is chiefly clinochrysotile; and 

sample D is chiefly antigorite with some chrysotile. 

Zambonini (1910, referred in some publications as 

1908, the date of oral presentation) included three 

serpentine minerals in his studies on dehydration 

phenomenon: chrysotile from the type locality at 

Reichenstein, Province of Silesia, analysis 152; noble 

serpentine from the Peninsula of Eyre, South Australia; and bowenite from New Zealand. The chrysotile from Reichenstein is probably chiefly clinochrysotile. Kurnakov and Chernykh (1926), and Chernykh 

(1933) in connection with their studies of magnesium 

carbonates and silicates made automatic recordings 

of the dehydration curves of various members of the 

serpentine group. Bianchi and Carpanese (1928) made
THE SERPENTINE-GKOUP MINERALS 49

dehydration studies on ''precious serpentine" from 

Snarum, Norway, and antigorite from Valsavaranche, 

Aosta, Italy.

Thermal dehydration data for six analyzed specimens 

and two unanalyzed specimens are given in table 11 

and the graphs in figures 25 and 26. Joseph J. Fahey 

made the dehydration studies on F-1 and F-13 and 

the others were studied by Perley G. Nutting. The 

shapes of these curves fall into two groups. In one 

class F-1, F-13, F-14, F-19, and F-70 each sample 

shows a single "shoulder" in the temperature range of 

550° to 650 °C; in the other class F-41a, F-43, and 

F-69 each sample shows in addition a "shoulder" 

corresponding to the loss of "low-temperature" water.

The correspondence between the water, H2O-f- and

H2O , as determined in the chemical analysis and as 

obtained at similar temperatures in the thermal-dehydration studies, is given in table 12. The agreement 

between these two methods is excellent. Those 

samples having significant amounts of ferrous iron 

need to be corrected for the small increase in weight 

in the dehydration experiments arising from the oxidation to Fe2O3 . Specimen F 41, on which the chemical 

analysis was made, and F-41a, used in the dehydration study, were not from the same specimen; F-41a 

apparently contains a greater proportion of finegrained carbonate minerals.

The curves for three of these serpentine specimens 

show an additional "shoulder" at low temperatures. 

Such a relationship is to be expected for specimens

UJ 10

5

F-43

300 400 500 600

TEMPERATURE 

F-70

300 400 5OO 600

TEMPERATURE

F-69

300 400 500 600

TEMPERATURE

ioo 500

TEMPERATURE

FIGURE 25. Thermal-analysis curves of serpentine-group minerals obtained by the static method. Temperature expressed in degrees Centigrade. F-43, lizardlte, 

Mineral Hill, Delaware County, Pa.; F-69, chrysotile and some lizardite(?), Webster, N.C.; F-70, clinochrysotile, Thetford, Quebec; F-1, antigorite, State Line 

Pits, Low's mine, Lancaster County, Pa.
50

o

to *

to

o

STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

F-13

" F-14

fc «-

200 300 400 500 600 700

TEMPERATURE

900 ioooioso X) 1050 300 400 500 600

TEMPERATURE

800 900

. 

o

V) a

</)

O

F-19

100 200 300 400 500 6OO 700 COO 900

TEMPERATURE

100 200 300 400 500 600 700 800 900 IOOO

FIGTJBE 26. Thermal-analysis curves of serpentine-group minerals obtained by the static method. Temperature expressed in degrees Centigrade. F-13, chiefly antigorite, Tilly Foster iron mine, near Brewster Station, N.Y.; F-14, chiefly antigorite, "Yu-Yen stone", Manchuria; F-19, antigorite, and some chrysotile, Bare Hills, 

Baltimore County, Md.; F-41a clinochrysotile (Globe-type), Currant Creek, Nev.

F-41a and F-43, which are typical of the variety 

deweylite. Chemical-solution studies by Nutting 

(1928) suggest that specimen F-69 consists of chrysotile and some lizardite. Nutting (1928) studied the 

absorption of water vapor by specimen F-69 at 26°, 

36°, and 46 °C and at humidities ranging from 0 to 100 

percent saturation. Specimen F-69 was placed in a 

desiccator at a humidity of 80 percent saturation at 

26 °C before thermal analyses. Under these conditions 

a gram of this material could adsorb as much as 1.59 

percent of its weight in water. This pretreafcment

accounts for the anomalous behavior of specimen F-69. 

It should be noted that insufficiently dried specimens 

of the related mineral kaolinite will behave similarly. 

A graphical study (figs. 25 and 26) of these data 

shows that the high-temperature "shoulder" in curves 

for the specimens composed entirely or chiefly of 

antigorite F-l, F-13, F-14, and F-19 is found at a 

higher temperature than the corresponding shoulder in 

curves for specimens consisting entirely or chiefly of 

clinochrysotile, F-41a and F-70, or lizardite, F-43, or 

of the inferred mixture, F-69. This trend is to be
THE SERPENTINE-GROUP MINERALS 51

TABLE 11. Thermal-analysis data obtained by the static method on minerals of the serpentine group 

[Specimen numbers in the table are described in section on the description of the minerals]

F-l

Antigorite

Temperature (°C)

30

110

380

480

628

630

637

645

690

760

830

850

860

1000

Loss in 

weight

(percent)

None

None

0.08

.13

.18

.52

10.93

11.32

11.62

11.82

11.83

11.97

11.99

12.22

F-13

Chiefly antigorite

Temperature (°C)

26

70

106

140

175

200

275

340

420

442

477

494

504

539

562

576

583

588

590

593

598

610

623

630

666

678

683

688

700

717

760

800

900

940

1050

Loss in 

weight

(percent)

0.63

.93

1.05

1.15

1.23

1.33

1.41

1.57

1.66

1.82

1.89

2.08

2.30

2.43

2.55

2.65

4.12

10.98

10.98

11.15

11.30

11.44

11.84

12.00

12.19

12.25

12.38

12.50

12.63

12.87

13.01

13.39

13.68

14.11

F-14

Chiefly antigorite

Temperature (°C)

28

95

125

145

245

310

375

420

470

555

610

655

700

760

765

860

Loss in 

weight

(percent)

0.11

.12

.12

.18

.26

.29

.33

.38

.51

6.32

10.40

11.61

12.01

12.06

12.31

"

'

F-19

Antigorite and 

some chrysotile

Temperature (°C)

27

65

102

160

220

325

370

460

485

515

585

655

695

760

Loss in 

weight

(percent)

0.38

.54

.62

.84

1.05

1.14

1.26

1.36

1.48

1.83

11.13

11.70

11.97

F-41a

Clinochrysotile 

(Globe-type) 

(labeled

deweylite)

Temperature (°C)

28

95

145

190

235

270

285

345

395

440

480

545

565

620

655

710

750

815

880

950

Loss in 

weight

(percent)

2.80

3.23

3.47

3.75

3.96

4.06

4.44

4.66

4.97

5.39

8.65

13.17

18.06

18.68

18.98

19.16

19.54

19.66

19.70

F-43

Lizardite 

(labeled 

deweylite)

Temperature (°C)

30

91

118

181

230

262

305

350

395

450

478

517

565

630

650

705

790

885

925

960

Loss in 

weight

(percent)

None

1.14

1.32

1.64

1.80

2.21

2.30

2.48

2.63

2.96

3.38

3.80

10.55

13.08

13.31

13.60

14.10

14.58

14.62

14.62

F-69

Chrysotile and 

some lizardite(?)

Temperature (°C)

26

50

75

100

150

200

300

400

500

550

600

650

700

750

800

900

Loss in 

weight

(percent)

0.70

1.19

1.57

2.16

2.58

3.30

4.16

5.33

6.21

7.61

11.16

11.45

15.50

15.83

16.17

F-70

Clinochrysotile

Temperature (°C)

28

100

155

195

260

305

338

405

432

480

532

585

626

657

712

777

795

837

Loss in 

weight

(percent)

0.54

.74

.84

1.00

1.06

1.41

2.07

2.31

2.55

3.40

11.93

13.39

13.54

13.86

14.09

14.34

14.34

H-l

Lizardite (?) 

Data of Haraldsen 

(1928)

Temperature (°C)

20

110

500

600

700

800

1000

1200

1300

Loss in 

weight

(percent)

0

.60

4.18

12.26

13.30

13.52

13.77

13.94

13.86

found also in the data of others, in particular, Bianchi 

and Carpanese (1928) and Epprecht (1947). It is also 

in agreement with the results of DTA studies on 

serpentines.

The results of thermal dehydration studies of minerals of the serpentine-group show that these minerals 

give characteristic curves which are very similar to 

those of kaolinite and halloysite. Specimens of antigorite tend to give curves which have a relatively welldeveloped "flat" shoulder, and these shoulders occur at 

slightly higher temperatures than those in curves for 

chrysotile or lizardite.

Curve H-l (fig. 27) is taken from the work of

Haraldsen (1928) and represents a study of the behavior 

of serpentine from Snarum, Norway probably dominant lizardite with some Clinochrysotile at temperatures up to 1,300°C and demonstrates the mono tonic 

character of the curve after dehydration has taken 

place.

DYNAMIC (DIFFERENTIAL-THERMAL-ANALYSIS) 

METHOD

The apparatus for differential thermal analysis (DTA) 

as used in this study is a modification of that described 

by Alexander, Hendricks, and Nelson (1939). The 

technique used is given in two papers by Faust (1948,

TABLE 12. Correspondence between H^O reported in chemical analysis and that found by dehydration studies

From chemical 

analysis %

From dehydration

F-l 

Antigorite

H2O0 

0 (110°C)

H2 0+

12.36 

12.22

F-13

Chiefly antigorite

H2O0.93 

. 93 (106°C)

H2O+

13.30 

13.18

F-14 

Chiefly antigorite

H2O0.06 

. 11 (95°C)

H2O+

12.43 

12.20

F-19

Antigorite and some 

chrysotile

H2O0.55 

. 54 (102° C)

H2 0+

11.69 

11.43

F-41 F-41a i

Clinochrysotile 

(Globe-type 

labeled deweylite)

H2O2.92 

2. 80 (95° C)

H2 0+

12.53 

16.90

F-13

Lizardite (labeled 

deweylite)

H2O0.80

1. 32 (118° 

C)

H2 0+

12.92 

13.30

F-69

Chrysotile and some 

lizardite

H2O0.88 

1.57

H2 0+

15.04 

14.60

Chemical analysis and dehydration study were not made on the same tube sample. 

Water determined in chemical analysis is stated as H2O+ and H2O referred to 110°C.
52 STUDIES OF THE NATUEAL PHASES IN THE SYSTEM MgO-SiO2-H2O

H-l

CD 

UJ

16 i 

14 -

12 

10

Q __

6 

UJ 

O

cr

UJ 4

100 200 300 400 500 600 700 800 900 1000 MOO 1200 1300 

TEMPERATURE, IN DEGREES CENTIGRADE

FIGURE 27. Thermal-analysis curve of sample H-l, lizardite, Snarum, Norway, obtained by the static method. Data of Haraldsen, 1928.

1950). The samples were heated at the rate of 12 °C per 

minute. The records were obtained as photographs.

PREVIOUS DTA STUDIES ON SERPENTINE-GROUP* 

MINERALS

Caillere (1933) divided the serpentine-group minerals 

into two subgroups on the basis of DTA studies. Group 

I (p. 135) includes those minerals whose curve is characterized by an endothermic inflection corresponding to 

a sudden loss of water at 650 °C and prolonged up to 

750 °C; and by an exothermic peak, which follows immediately, at 750 ° to 825 CC. The minerals of Group II 

(p. 137) yield a curve presenting only an endothermic 

inflection at 650 °C which corresponds to a sudden dehydration of the substance. CaillSre (1934a) introduced 

the names a-antigorites for Group I and /8-antigorites 

for Group II. In her comprehensive paper (Caillere, 

1936) covering the serpentine minerals, she has followed 

this nomenclature and states (p. 224) that the /3-antigorite is the most abundant and that, in general, the 

bowenites, williamsites, and chrysotiles are /8-antigorites. She further concludes 2 that, in general, all 

specimens of altered serpentines friable, bright green,

* Caillere, 1936, p. 232-233. Literal translation by George T. Faust.

rich in adsorbed water belong to the group of aantigorites, whereas the dark-green rocks, poor in 

hygroscopic water, are made up of /8-antigorites. It 

appears that the a variety most generally arises by the 

superficial alteration .of the $ form. This hypothesis she finds to be in accord with her observation that 

intimate mixtures of these two antigorites in the same 

rock are extremely rare.

Efremov (1939, 1940) characterized the DTA curves 

of the serpentine-group minerals as an endothermic 

reaction in the range 600° to 700 °C followed by an 

exothermic effect.

Caillere and Henin (1945) observed that bowenite 

from Khotan, Chinese Turkestan, a /8-antigorite treated 

with solutions of sodium, magnesium, or calcium salts 

behaved as an a-antigorite in DTA tests. Faust, in 

Bowen and Tuttle, 1949, identified by DTA methods 

their synthetic mineral as chrysotile. A summary of 

the unpublished DTA studies by Faust of nickel-bearing 

serpentine and related minerals found in garnierite is 

given in the paper by Pecora, Hobbs, and Murata 

(1949, p. 20, 22). Kauffman and Dilling (1950) included DTA curves for five serpentine specimens in
THE SERPENTINE-GROUP MINERALS 53

their study of the DTA method. Midgley (1951) presented a DTA curve for an unusual serpentine mineral 

from Kennack Cove, Lizard, Cornwall, England. This 

mineral he considered to be a polymorph of normal 

antigorite.

Kiefer (1950-51, 1951) made DTA studies on three 

serpentines. In addition he ground three different 

serpentines in water, or solutions of acids or alkalies, 

for 40 hours, obtained DTA curves, and noted in each 

experiment that he had converted the /3-antigorite to 

a-antigorite. He concluded that his results, indicating 

that the a-antigorites were more stable than the (3- 

antigorites, were at variance with those of Simonne 

Caillere but preferred to use the same designations for 

the "antigorites" rather than introduce confusion into 

the literature. Kiefer also observed that the endothermic trough occurs at higher temperatures for (3- 

antigorite than a-antigorite.

Hess, Smith, and Dengo (1952) published a DTA 

curve for antigorite from Caracas, Venezuela. Sudo 

and others (1952) published two curves of serpentine 

minerals from Japan. Faust and Murata (1953) published DTA curves for the synthetic chrysotile made by 

Bowen and Tuttle and for antigorite from the type 

locality, Antigorio Valley, Italy. Nagy (1953) published portions of his DTA curves for acid-heated antigorite and chrysotile. Schmidt and Heystek (1953) 

published DTA curves for antigorite and chrysotile 

specimens from South Africa. Vermaas (1953) published DTA curves for antigorite specimens from the 

Transvaal, the type antigorite from Antigorio, Italy, 

and chrysotile specimens from the Transvaal. Kalousek 

and Mui (1954) made DTA studies on reaction products 

in the system H2O-MgO-SiO2 , synthesized in the temperature range of 75° to 350°C, and they identified by 

the DTA curves a substance they called "chrysotilelike." Pundsack (1955) published a DTA curve of 

chrysotile from the Danville area, Quebec, Canada (No. 

1 crude grade of fiber). Eckhardt (1956) gives DTA 

curves for chrysotile from Yugoslavia and schweizerite 

from Findelengletscher, near Zermatt, Wallis, Switzerland. Nagy and Faust (1956) give DTA curves for 

natural and synthetic chrysotile, natural antigorite, and 

a natural mixture of chrysotile and antigorite.

A detailed study of the minerals o£ the serpentinegroup was made by Kourimsk^ and Satava (1954) in 

which DTA methods were extensively used in identifying the minerals.

The work cited above is not all of equal quality. This 

arises in part from the scope of the study and from the 

experimental details. Those scientists interested in 

the bulk of the specimens are content to use impure 

materials, and this has its field of application in economic geology.

PRESENT DTA STUDIES

The DTA curves for the serpentine group of minerals 

given in this paper were all made over the temperature 

range 25° to 1,100°C. A word should be said about 

the accuracy of the temperature measurements. No 

attempt at accurate thermometry is implied in the 

temperature data ascribed to a particular point on a 

DTA curve. The curves were calibrated using quartz 

as a standard (Faust, 1948) and corrections were made 

for the cold junctions. Maxima and minima for sharp 

curves are easy to measure and are at least within 

±2°C of their true values. Gently curved or rounded 

peaks and troughs are measured by erecting a tangent 

line to the curve parallel to the baseline and passing a 

perpendicular line through the point of tangency. Such 

curves have a wide latitude of error, sometimes as much 

as ±4°C. The precision of the measurements is much 

more uncertain, because the dissociation of serpentine, 

minerals, in DTA, is an inequilibrium process. The 

data for the synthetic clinochrysotile (specimen F-54, 

curves C-488 and C-489 in table 13) represent a very 

favorable comparison. The DTA patterns of the chrysotiles and lizardites are so similar in morphology and 

temperature of the various peaks and troughs that they 

are grouped together. These have been divided into 

six subgroups: A, clinochrysotile; B, clinochrysotile of 

the Globe type; C, clinochrysotile plus orthochrysotile; 

D, chrysotile plus lizardite, where C^>L; E, lizardite 

plus clinochrysotile, where L>(7; and F, lizardite. The 

basis for the classification is chiefly from the X-ray 

powder diffraction studies but DTA, solution studies, 

and other techniques have also been used in the placement of a given specimen in a given subgroup. The 

data are given in table 13.

INTERPRETATION OF THE DTA CURVES 

A TYPICAL CUNOCHRYSOTILE CURVE

The synthetic preparation, specimen F-54, of Bowen 

and Tuttle (1949) yields a simple clinochrysotile type 

pattern which is shown in curves C-488 and C-489 in 

figure 28. These curves show a very shallow endothermic trough in the temperature range 100° to 175°C 

which arises from the loss of adsorbed water. On 

record C-488, between 175°C and approximately 

525°C, the curve has a very slight upward bow. At 

approximately 525 °C the curve begins its descent into 

the trough and reaches a minimum at 665°C. This 

endothermic trough is unsymmetrical and is wider than 

it is deep. Broad troughs of this type are characteristic of very fine grained substances. After the expulsion of the water from this clinochrysotile, the 

curve returns to the baseline at about 700°C and 

continues along until approximately 785°C where an 

exothermic reaction begins and reaches a maximum
54 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2~H2O

TABLE 13. Observations of the differential-thermal-analysis curves of chrysotiles and lizardites 

[Principal endotherms marked (EN); principal exotherms marked (EX)]

Specimen Curve

Temperature (°C) of thermal phenomena for indicated range

85°-200°C 200°-400°C 400°-600°C 600°-700°C 700°-800°C 800°-900°C 900°-1000°C

A. Clinochrysotile

F-54_ _________

F-54 __________

F-52.__---_---_

F-22-------_--_

F-40___-___--_-

F-50___--_-___.

F-58_-_-_------

F-70__--.--__-_

F-60____._ _____

F-61 3 __-___--_.

C-488______

C-489-. -.

C-501-___.

C-122- _.

C-Q1

C-470______

C-655------

C-746___.._

C-680_____-

C-681- _.

0)

0)

104

135 (EN)

130

121

117

131

120

160

57

87

393

384

426

665 (EN)

670 (EN)

676 (EN)

692 (EN)

696 (EN)

690

790

796

701 (EN)

788 (?)

710 (EN)

2 706 (EN)

2 721 (EN)

705 (EN)

803 (EX)

805 (EX)

801 (EX)

820 (EX)

817 (EX)

805 (EX)

807 (EX)

806 (EX)

814 (EX)

819

900

B. Clinochrysotile (Globe- type)

F-20___---___--

F-20A____-_____

F-53__-__--_-_-

F-24______--.--

F-41 ___._.____

F-45-----------

F-45-----------

F-26_------_--_

C-84 _.__

C-817______

C-731______

C-125__-._

C-133______

C-92_.._.__

C-Q4

C-93_._.__.

94

137 

110

8 138 

6 155

292 (') 

(l)

357 

351

382

433

410 

590

492

690 (EN) 

647

640

681 (EN) 

697 (EN)

8 654 (EN)

8 645

678 (EN)

710 (EN)

712 (EN) 

8 789 (EX) 

705 (EN)

824 (EX) 

825 (EX) 

5 802 (EX) 

833 

823 (EX) 

815 (EX) 

820 (EX) 

851 

884 

817 (EX) 

866 

804 (EX) 

872

4 923

C. Clinochrysotile plus orthochrysotile

F-56____--_____

F-64_______..__

F-74_____-_____

C-650 -_.

C-728_.__--

C-805 --

134 

109

(>)

394

229 

380

689 (EN) 

687 (EN)

799 (EX)

708 (EN)

816 (EX) 

859 

890 

804 (EX)

D. Chrysotile plus lizardite, C > L

F-57. __-._.--_.

F-51----.------

F-73._______.--

F-72_---_-_____

F-25--- ~~-

C-562_____.

C-478___ 

O-809 _

C-803 _._

C-115__._..

89

117

88

128

(l)

0)

213

250

224

387

408

660

692 (EN)

671 (EN)

690 (EN)

698 (EN)

615

698 (EN)

782

798 (EX)

784 (EX)

803 (EX)

805 (EX)

825 (EX) 916

E. Lizardite plus Clinochrysotile, L > C

F-71_______.___

F-75. __-______-

F-76__. ________

F-3___-____ __

C-804._____

C-849 _-.

C-850_.-__

C-135 _ -.

0)

106

133

139

286

308

311

202

687 (EN)

623

637 (EN)

676

602 (EN)

627

671 (EN)

729 (EX)

720

732 (EX)

811 (EX)

816 (EX)

See footnotes at end of table, p. 55.
THE SERPENTINE-GROUP MINERALS

TABLE 13. Observations of the differential-thermal-analysis curves of chrysotiles and lizardites Continued

55

Specimen Curve

Temperature (°C) of thermal phenomena for indicated range

85°-200°C 200°-400°C 400°-600°C 600°-700°C 700°-800°C 800°-900°C 900°-1000°C

F. Lizardite

F-46. __________

F-47-__________

F-63-_____---_-

F-63-___-----_-

F-23-----------

F-42__. ________

F-43-__-----.._-

Type lizardite 8 __

C-104_.____

C-98.___.-_

C-727____-_

C-818______

C-117____-.

C-729__..__

C-105- __

115

135

113

63

107

365

0)

379

250

(330?)

264

372

303

7 686

7 689

681 (EN)

687 (EN)

7 661

698 (EN)

700 (EN)

702 (EN)

700 (EN)

707 (EN)

714 (EN)

807 (EX)

812 (EX)

815 (EX)

824 (EX)

819 (EX)

800 (EX)

813

824 (EX)

854

883

818 (EX)

1 Present but not measured.

2 Doublet (706° and 721°C). 

a Sample treated with HC1. 

4 Specimen contains much calcite.

 Doublet (789° and 802°C).

 Specimen contains much stevensitc.

7 Inflection.

s Temperatures estimated from Midgley (1951).

peak temperature at 803 °C. Subsequently the curve 

drops steeply to the baseline and remains essentially 

straight until the conclusion of the run. This flat 

portion of the curve following the exothermic peak is 

offset above the flat portion which precedes the peak. 

This offset arises from the difference in the specific 

heat and conductivity of the phase assemblages existing before and after the exothermic reactions.

An examination of the DTA curves of the clinochrysotile samples (figs. 28 and 29) shows the parallel 

correspondence of the synthetic and natural materials. 

In most natural clinochrysotiles the endothermic peak 

is narrower and deeper than that of the synthetic 

chrysotile, a consequence of the great difference in 

grain size. It is of interest that the synthetic chrysotile made by Noll (1950) gave a dehydration curve 

closely parallel to that of a natural chrysotile from 

Australia.

THE COLLECTION OF CHRYSOTILE AND LIZARDITE 

CURVES

A collection of 36 DTA curves (figs. 28 to 37) of 

specimens consisting of chrysotile or lizardite or of 

mixtures of chrysotile and lizardite were studied. The 

thermal-analysis data are gathered together in table 

13. A detailed analysis of these curves is given for 

four somewhat arbitrary temperature ranges.

DETAILED ANALYSIS OP THE CURVES IN THE TEMPERATURE RANGE 85° TO 200°C

Twenty-one of 36 DTA curves of chrysotile and 

lizardite showed a decided shallow trough which extends 

over a span of temperatures and indicates a generally

constant loss of water. Seven of the curves show faint 

but definite depressions and eight showed no evidence 

of a break. A study of the chemical analyses of 10 of 

these samples shows the H2O to range from 0.36 to 

1.64 percent with an average value of 0.86 percent (table 

14). A correlation of the column "Area of the trough" 

against the product of the weight of the sample used 

in the experiment and the analytically determined percentage of H2O should be linear.

For those samples whose H2O was determined by 

chemical analysis, there does not seem to be any correlation of this value with the various data in the table. 

This probably is due to the experimental technique. 

Since the DTA studies on the different samples were 

not made at the same time, but over a period of about 

10 years and in two different laboratories, humidity 

probably played an important role in changing the 

H2O content of a given sample while it was being 

prepared for DTA. The analytical values of H2O 

used for comparison are not the true ones at the time 

of the experiment. A plot of the column "Area of 

the trougn" against the column "Weight of sample" 

examined (table 14) shows only the expected general 

trend.

The data for the column "Area of the trough" in 

table 14 show that the specimens consisting chiefly of 

lizardite have much lower amounts of adsorbed water. 

This is probably not a true relationship because the 

DTA of Midgley's type lizardite (fig. 39) shows a welldeveloped trough with two minima.

This adsorbed water, which fine-grained materials 

and fibers tend to pick up rather readily, may compli-
56 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

803

C-488

LU 

Q

(D

(J

CD 

LU 

LU 

Ct 

(D 

LU 

Q

LU

LU 

Q_ 

^

LU

LU

696

INCREASING TEMPERATURE. IN DEGREES CENTIGRADE

FIGUEE 28. Diflerential-thermal-analysis curves of clinochrysotile, table 13A. C-488, F-54, synthetic; C-489, F-54, synthetic; C-501. 

F-52, Sylmar, Chester County, Pa.; C-122, F-22, MontviUe, Morris County, N.J.; C-91, F-40, Murfreesboro, Pike County, Ark. 

All curves, except C-489, were obtained with a resistance of 600 ohms in the galvanometer circuit. Curve C-489 was obtained with 

999.9 ohms.
THE SERPENTINE-GROUP MINERALS 57

805

C-470

Ul 

Q

1- 

Z 

Ul

o

CD 

Ul 

Ul

Ul 

Q

Ul

a:

Ul 

Q_

^

Ul 1-

1- 

z:

Ul

a: ui 

u. 

u.

706

C-680 384

160

705

819

INCREASING TEMPERATURE, IN DEGREES CENTIGRADE

FIGURE 29. Diflerentlal-thermal-analysis curves of clinochrysotile, table 13A. C-470, F-50, near Moa, Oriente Province, Cuba; 

C-655, F-68, Canyon of Clear Creek, San Benito County, Calif.; C-746, F-70, near Thetford, Megantic County, Quebec; 

C-680, F-60, near Tnetford, Megantic County, Quebec; C-681, F-61, part of the preceding sample F-60, treated with 1 N 

HC1. 'All curves obtained with a resistance of 600 ohms in the galvanometer circuit.
58 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

Ul 

Q 

<

cc

CD

UJ 

U

cn

UJ

ui 

cc

CD 

UI 

Q

292 433 824

C-84

C 731

923

798 802 940

833

681

INCREASING TEMPERATURE. IN DEGREES CENTIGRADE

FIGUBE 30. Differential-thermal-analysis curves o£ clinochrysotile (Globe-type), table 13B. C-84, F-20, Gila County, Ariz.; C-817, F-20A, 

Gila County, Ariz., contains much calcite; C-731, F-53, Grand Canyon, Ariz.; C-125, F-24, Montville, Morris County, N.J.; C-133, F-41, 

Currant Creek, Nev. All curves obtained with a resistance of 600 ohms in the galvanometer circuit.
THE SERPENTINE-GROUP MINERALS 59

LU 

Q

(D

LU 

O

cn

LU 

LUCE

CD 

LU 

Q

C-92 820

884

697

LU

LU 

QS

LU

C-94 382 817

866

138

LU 

C£ 

LU 

Lu

492 804

C-93

872

645

INCREASING TEMPERATURE. IN DEGREES CENTIGRADE

FIGURE 31. Diflerential-thermal-analysis curves of clinochrysotile table 13B (Globe-type). C-92, F-45, Wood's chrome mine, Lancaster County, Pa.; C-94, F-45, Wood's 

chrome mine, Lancaster County, Pa., contains much stevenslte; C-93, F-26, Texas, Lancaster County, Pa., contains much stevensite. All curves obtained with a 

resistance of 600 ohms in the galvanometer circuit.

cate the "low-temperature" portion of the DTA curve. 

As mentioned previously under the static method of 

thermal-analysis, Nutting (1943) has shown that water 

adsorbed on serpentine minerals will affect the "lowtemperature" portion of a dehydration curve. The 

DTA curves (figs. 28-31) show in a similar manner how 

this adsorbed water modifies the chrysotile curve. If 

a sample of the related mineral kaolinite is washed and 

partially dried it will show correspondingly an additional 

low-temperature endothermic trough.

The low-temperature endotherm of the curves for the

serpentine-group minerals may be further complicated 

by the presence of stevensite in the sample. Stevensite 

(Faust and Murata, 1953) loses much of its water in the 

same temperature range (curves C-93 and C-94, fig. 31),

DETAILED ANALYSIS OP THE CURVES IN THE TEMPERATURE KANQE 200° TO 600°C

Almost all the 36 DTA curves show a definite, long 

range, upward bowing of the curve in the temperature 

range of 200° to about 550°C. On many of the DTA 

curves the accidental recording of the polymorphic 

transformation in the nickel block at 354°C, as recog-
DIFFERENTIAL TEMPERATURE, IN DEGREES CENTIGRA

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THE SERPENTINE-GROUP MINERALS 61

798

Ld 

Q 

< 

01

Id 

O

C-562

89 117

692

764

698

INCREASING TEMPERATURE. IN DEGREES CENTIGRADE

FIGURE 33. Differential-thermal-analysis curves of chrysotile plus lizardite, C>L, table 13D. C-562, F-57, Talcville, St. Lawrence 

County, N.Y.; C-478, F-51, Nicaro, Oriente Province, Cuba; C-809, F-73, New Almaden mine, Santa Clara, County, Calif; 

C-803, F-72, New Almaden mine, Santa Clara County, Calif. All curves obtained with a resistance of 600 ohms in the galvanometer circuit.
62 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

825 916

698

INCREASING TEMPERATURE, IN DEGREES CENTIGRADE

Q

FIGURE 34. Differential-thermal-analysis curve of chrysotile plus lizardite, C>L, table 13D. C-115, F-25, Montville, Morris County, N.J. Curve obtained with a

resistance of 600 ohms in the galvanometer circuit.

nized by Faust (1948), may complicate the phenomena. 

The magnitude of this extraneous bow or peak may be

TABLE 14. Relation between H2O in chrysotiles and lizardites 

and their behavior in differential thermal analysis

Sample

H2 0-by 

chemical 

analysis 

(percent)

Temperature 

of endothermic trough (°C)

Area of the 

trough 

(square millimeters)

Weight of 

sample 

(grams)

A. Clinochry so tiles

F-54

F-22 

F-58 

F-60.... .................

il.2 

.70

.54

(2) 

130 

131 

120 

160

10.1 

17.0 

5.1 

16.0

0. 2349 

.6231 

.4391 

.2931 

.1519

B. Clinochrysotiles (Globe-type)

F-20.-- ..............

F-53.. ....

F-24..... ................

1.64

1.18 

.99

3 Not observed 

94 

« Not observed

5.4

0. 2342

.2813 

.2610

C. Clinochrysotile plus orthochrysotile

F-56 

F-64............ .........

0.41 134 

109

7.1 0.4650 

.5180

D. Chrysotile plus lizardite, C > L

F-57 - ...........

F-25.. . . . ....

1.04 

.50

89 

117 (2)

31.8

20.3

0.5260

.6383

F. Lizardite

F-46.. .... .........

F-47-- - -- 

F-63. .... . ..

F-23.... .................

n.d. 

n.d.

0.36

(2) 

Not 

observed 

115 (2)

3.0 

1.0

3.0

0. 2078 

.3157

.3605 

.4353

1 Determined by Dr. Norman L. Bowen. 

2 Temperature not measured. 

8 Although not observed the endotherm may be masked, see curves C-84 and C-125 

in figure 30.

assessed by comparing the DTA curve of these minerals 

with that of the curves for quartz or other substances 

which have no exothermic reactions between 200° and 

500°C and which were analyzed at about the same time 

and under the same experimental conditions. After 

taking this into consideration, it is observed that a genuine upward bow in the curve is present, and it is concluded that this arises from the occurrence of some 

phenomena taking place in chrysotile and lizardite in 

this temperature span. On records C-650, C-731, 

O478, C-488, and C-489 (figs. 28, 30, 32, and 33), the 

upward bowing of the curve is very gentle. On records 

C-562, C-104, C-746, C-98, C-655, C-115, C-680, and 

C-117 (figs. 29, 33, 34, 36, and 37), the bow in the curve 

becomes increasingly larger and the development of a 

gently rounded peak becomes clear. On records C-727, 

C-84, C-125, C-728, and C-122 (figs. 28, 30, 32, and 

36), there is a distinct peak which is sharp enough so 

that a maximum can be assigned for measurement.

The occurrence of a gentle bowing in the curve or the 

more well developed peaks cannot be ascribed to the 

burning of organic matter, which may produce a similar 

phenomenon. Nor can it be traced to the oxidation of 

ferrous iron to ferric iron, as an examination of the 

values for these constituents or their ratio in table 15 

shows.

Koufimsk^ and Satava (1954) used a ceramic block 

as the reaction cell and used only platinum: platinumrhodium thermocouples for thermometry. Nine of 

their 18 curves show a pronounced peak in the temperature range of 278° to 366°C, with an average of 340°C. 

The specimens showing this phenomenon appear to be
THE SERPENTINE-GROUP MINERALS 63

LU 

Q 

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cr 

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hz:

LU

o

CO 

LU 

LU

cr 

o

LU 

Q

LU

cr

286

C-804

623

637

cr LU

Q_

^.

LUILU

cr

LU

Q

732

C-850

139

671

INCREASING TEMPERATURE, IN DEGREES CENTIGRADE

FIGURE 35. Differential-thermal-analysis curves of lizardite plus clinochrysotile, L>0, table 13E. 0-804, F-71, Snarum, Norway; 0-849, F-75, 

Hoboken, Hudson County, N.T.; 0-860, F-76, part of the preceding sample, F-75, treated with cold dilute HCI (1:1); 0-135, F-3,near Forest 

Hill, Harford County, Md. All curves obtained with a resistance of 600 ohms in the galvanometer circuit.
DIFFERENTIAL TEMPERATURE, IN DEGREES CENTIGRA

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THE SERPENTINE-GROUP MINERALS 65

819

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CJ

CO 

LU 

LU 

C£ 

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LU 

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C-117

LU 

Q_ 681

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LU 

C£ 

LU

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C-105

854

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INCREASING TEMPERATURE, IN DEGREES CENTIGRADE

FIGURE 37. Differential-thermal-analysis curves of lizardite, table 13F. C-117, F-23, Dognacska, Severin Province, Hungary; C-729, IM2, near Norris, Union County, 

Term.; C-105, F-i3, Crump's quarry, Mineral Hill, Delaware County, Pa. All curves obtained with a resistance of 600 ohms in the galvanometer circuit.
66 STUDIES OP THE NATURAL PHASES IN THE SYSTEM MgO-SiO2~H2O

TABLE 15. Comparison of FeO and Fe2O3 in chrysotiles and lizardites with their thermal behavior in differential-thermal-analysis, and

with their paragenesis and mineralogy

F-56_-_-____

F-53-__-.-._

F-51 _ ---_.

F-54'__ -.

F-57._ ------

F-46-__-__-

F-47__-.--_-

F-25-------

F-23____--__

F-20-------

F-24.. ------

F-22 _ -----

C-650

C-731

C-478

C-488

C-562

C-104

C-98

C-115

C-117

C-84

C-125

C-122

Intensity of thermal effect in temperature range 200° to 600° C

_._-_do._-__-_. _. -------

-__-_do-_---__-_---_-___

_____do._ ---__-__---

_._--do-----_.--------_-

-__-_do-------___ .___--

-__--do--__-_--_--_---__

___-_do___-_-_-__-_-_-._

_----do._---_.. -.----_._

-. ...do.--... .._._._._..

do

FeO

(percent)

0. 16

2. 96

None

.06

Tr.

Tr.

.03

. 18

. 11

.09

FezOs

(percent)

0. 87

. 51

3. 81

.26

5.68

5. 55

. 19

1.96

. 19

.34

.26

Fe3 03

FeO

5.44

(All Fe2O3)

1. 29

4.33

(All Fe2 03)

(All Fe2 03)

6.33

10.89

1. 72

(All Fe2O3)

2.89

Paragenetic

class

B

B

A

B

A

A

B

B

B

B

B

thochrysotile. 

Clinochrysotile (Globetype) . 

Chrysotile plus lizardite, C>L.

Chrysotile plus

lizardite, C>L. 

Lizardite.

Do.

lizardite, C>L. 

Lizardite.

Clinochrysotile

(Globe-type). 

Do.

Clinochrysotile.

1 Synthetic material.

chrysotile, lizardite, or mixtures of chrysotile and 

lizardite.

No other relation between the intensity of this thermal effect and chemical composition was noted. The 

possibility that this peak could be associated with the 

oxidation of magnetite to maghemite (Gheith, 1952), 

which takes place in this temperature range was also 

considered. The optical, chemical, and X-ray data do 

not show magnetite to be present in these samples. If 

it is assumed that all the iron oxides are present as magnetite, there is still no correlation between the amount 

of "assumed magnetite" and the intensity of the thermal effect. Nor, as can be seen from table 15, is there 

any relation to paragenesis or mineralogic composition. 

Accordingly, it becomes necessary to look for some 

other factor.

In blowpipe analysis, reference is made to the phenomen of "glowing" or becoming incandescent when 

heated before the blowpipe. This is an exothermic reaction. A number of minerals such as calcite and brucite possess this property. Scheerer (1840) coined the 

word "pyrognomic" for this behavior of substances, and 

it is also called thermoluminescence. Pabst (1952) gives 

an excellent summary of some previous work on this 

phenomenon.

Incandescence or "glowing" of some specimens of 

serpentine minerals has been noted by mineralogists in 

blowpipe examinations. Simonne Caillere (1934b), 

who has correlated her DTA studies with the phenomenon of incandescence in serpentine, believes that this 

phenonenon is related to the exothermic peak at 720°C. 

Caillere (1935) further points out that the luminescence 

can be observed at dull-red heat.

In our studies we have noted this "glowing" effect 

for a few of the chrysotile specimens. The flesh-pink

massive form of chrysotile, F-20A, associated with the 

fibrous form F-20 from Arizona, is particularly pyrognomic and glows at temperatures considerably below a 

dull-red heat. It is admixed with calcite and the effect 

may be totally unrelated to the Clinochrysotile (see 

DTA curve C-817, fig. 30).

We plan to investigate -the pyrognomic behavior of 

the serpentines to see if there is any relationship to the 

exothermic phenomena in the range of 200° to 400°C of 

these chrysotiles and lizardites. The maximum peak 

temperature ranges from 264° to 394°C.

DETAILED ANALYSIS OF THE CURVES IN THE 

TEMPERATURE RANGE 6OO° TO 75O°C

The major thermal effect in the DTA study of chrysotile and lizardite takes place in the temperature range 

600° to 750°C and is expressed as an endothermic 

trough. At the temperature of the beginning of the 

trough, the phase present is chrysotile or lizardite. As 

soon as the chrysotile or lizardite starts to decompose 

and lose water, a mixture of the dissociated material and 

chrysotile or lizardite is present and the amounts of 

chrysotile or lizardite decreases as the temperature rises 

until the temperature of the end of the trough is reached 

when no more chrysotile or lizardite remains.

The endothermic trough is thus the record of the heat 

effect accompanying the destruction of the crystal structure and its area is proportional to the weight of the 

chrysotile or lizardite which is dissociated.

The values of the temperature for the minimum of 

this trough for each sample are given in table 18. As 

these minima represent temperatures of an irreversible 

reaction, no significance can be placed on the absolute 

values. It is desirable, however, to determine whether 

or not a correlation of those factors, such as grain size, 

or habit, which normally influence the temperature of
THE SERPENTINE-GROUP MINERALS 67

irreversible reactions can be made. The data were 

divided into three groups: (a) the fine-grained specimens which include the translucent varieties called 

retinalite, schweizerite, and deweylite; (b) the characteristic fibers of chrysotile as "chrysotile" was originally used by von Kobell (1834); and (c) the more coarsely fibrous variety, sometimes called picrolite. The 

DTA curves for 23 fine-grained specimens have temperatures for the minimum in the range 637° to 714°C, 

with an average value of 688°C, the curves for 4 samples 

of fibrous chrysotile in the range 705° to 712°C, with an 

average value of 708°C, and the curves for 3 so-called 

"picrolites" in the range 700° to 715°C, with an average 

value of 708°C. These data suggest that the particles 

of finer grain size tend to dissociate at somewhat lower 

temperatures than the coarser material. The synthetic clinochrysotile, having an exceedingly fine grain 

size bears out this suggestion, for the temperature of 

its minimum is at 670°_C.

There is no apparent correlation between the mineralojgic composition and temperature of the minimum of 

the trough in the DTA curves for these samples. The 

values for the range in the temperature of the minimum 

for the subgroups is as follows: (A) clinochrysotile, 670° 

to 715°C; (B) clinochrysotile (Globe-type), 679° to 

712°C; (C) clinochrysotile plus orthochrysotile, 687° to 

708°C; (D) chrysotile plus lizardite, C>L, 671° to 

698°C; (E) lizardite plus clinochrysotile, L>C, 637° 

to 687°C; and (F) lizardite, 681° to 714°C.

Angular relationships of the high-temperature endothermic trough of the DTA curves of related minerals 

of the kaolin group kaolinite, endellite, and halloysite were studied by Dean (1947) and more extensively by Bramao, Cady, Hendricks, and Swerdlow 

(1952). The angles a and ft are defined according to 

the procedure of Dean as shown in figure 38, where the 

two sides of the angles determined by the DTA curve 

are formed by the extension of the straight portions of 

the trough. For most of the DTA curves the whole 

angle 7 was measured. The data are given in table 16.

The whole angle 7 of the various subgroups ranges 

as follows: (A) clinochrysotile 10.5° to 33.5°; (B) 

clinochrysotile (Globe type) 7.5° to 40°; (C) clinochrysotile plus orthochrysotile 17° to 24°; (D) chrysotile plus lizardite, C>L, 13° to 31°; (E) lizardite plus 

clinochrysotile, L>C, 21° to 58°; (F) lizardite, 9° to 

13°. Midgley's (1951) type lizardite has an estimated 

angle 7 of 21°. Admittedly, all these mineralogical 

subgroups have values of 7 which overlap, so that a 

measure of -y itself is not diagnostic of its subgroup 

mineralogic composition. The appearance of an inflection on the DTA curves of some samples containing 

lizardite is noteworthy. The shoulder appears on the 

DTA curves of specimen F-57 of subgroup D, specimen

FIGUBE 38. Schematic diagram showing the method of designating the angular relationships in an endothermic trough. 

Modified from Dean (1952).

F-75 of subgroup E, and on the DTA curves of specimens F-46 and F-47 of subgroup F. It also appears on 

the DTA curve of the type lizardite (fig. 39) given by 

Midgley (1951). The whole angle 7 is always greater for 

the inflection than for the "normal" part of the endotherm. Data for curve C-850 are not included, because 

the results were obtained on an acid-treated specimen. 

Likewise, the data for curve C-488 are omitted because this curve was obtained with a greater amount 

of resistance in the galvanometer cicuit and is therefore 

not comparable with the other curves. It does, however, serve to emphasize the necessity for comparing 

curves obtained under similar experimental conditions. 

The use of a relationship involving the angles a and 

ft has also been advocated and a study was therefore 

made on a number of the specimens hi this collection. 

From the measured angles a and 0 the ratio of the tangents of a and ft was computed. The data in table 16 

show that in curves for subgroup A, clinochrysotile, the 

value of this ratio ranges from 1.63 to 5.47; in a single 

curve in subgroup B, clinochrysotile (Globe-type) it
68 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

TABLE 16. Angular relationships of the high temperature endothermic trough of the chrysotiles and lizardite

Specimen Curve Angle 7 

(degrees)

tan a

tan /3

Specimen Curve Angle 7 

(degrees)

tan a

tan /3

A. Clinochrysotile

F-54.......

F-54_.__.._

F-52 .....

F-22.......

F-40.......

C-488 

C-489 

C-501 

C-122 

C-91

149.5 

230 

32 

10.5 

17

2.86 

3.46 

2.68 

1.63 

1.85

F-50.. ......

F-58. . ...

F-70.-_.--..

F-60-_..__.

C-470 

C-655 

C-746 

C-680

16 

23 

33 

32.5

5.47 

2.11 

2.81 

1.99

B. Clinochrysotile (Globe- type)

F-20.......

F-20A .. 

F-53._.__..

F-24. ......

C-84 

C-817 

C-731 

C-125

28 

36 

40 

30

2.40

F-41.......

F-45 -

F-45 -

F-26-, ...

C-133 

C-92 

C-94 

C-93

29

7.5 378 

328

C. Clinochrysotile plus orthochrysotile

F-56.......

F-64.......

C-650 

C-728

18 

24

F-74. ...... . C-805 17 2.43

D. Chrysotile plus lizardite, C>L

F-57 ....

F-51... ....

F-73.......

C-562

C-478 

C-809

445 

27 

31 

29.5

4.59 

2.40

2.18

F-72.. 

F-25 - 

C-803 

C-115

25 

13

2.65

E. Lizardite plus Clinochrysotile, L>C

F-71.......

F-75 ....

C-804 

C-849

22 

429 

28

1.32 

3.29 

2.37

F-76 -

F-3 ...

C-850 

C-135

58 444

21

1.00 

2.07

F. Lizardite

F-46_-.--_.

F-47- _

F-63.......

F-63....___

C-104 

C-98

C-727 

C-818

«23 

13 425 

10.5 

16.5 

13

2.33 

2.27

F-23 -

F-42.. - .

F-43........

Type 

lizardite

C-117 

C-729 

C-105 

Estimated 

from 

Midgley

13 

14 

9 <25 

21

5.49 

4.37

1 Resistance in galvanometer circuit was 999.9 ohms.

2 Resistance in galvanometer circuit was 600 ohms. 

> Measured on a curve containing Clinochrysotile and stevensite. 

-4 Inflection on endotherm.

was 2.40; similarly, a sample of subgroup C, clinochrysotile plus orthochrysotile yielded the value of 

2.43; three curves of subgroup D, chrysotile plus 

lizardite with C>L, ranged from 2.18 to 2.65 with the 

value for the inflection on curve F-57 of 4,59; subgroup 

E, curves for lizardite plus Clinochrysotile, L>C, 

yielded values of the ratio ranging from 1.00 to 2.37, 

with the value for the inflection on curve C-489 of 

3.29; curves for subgroup F, lizardite, show ratios obtained on two different samples from the same specimen 

with values of the ratio of 2.27 and 2.33. Data derived 

from Midgley's (1951) DTA record give the ratio of 

4.37 and the value for the inflection of 5.49.

The ratio tan a/tan {3 is an expression of the symmetry 

of the DTA endotherm. For the case a=/3, (curve 

C-850, fig. 35), the ratio is unity and the curve is 

symmetrical. As the angle a becomes progressively 

larger than the angle /3, the ratio increases and the 

endotherm becomes asymmetrical, with respect to the

normal to the baseline. Physically, this means that 

most of the chyrsotile or lizardite has dissociated before 

the temperature of the minimum has been reached. 

The angular relationships of the endothermic trough 

are a function of a number of variables including mineralogic composition, particle shape, particle size, and 

experimental conditions. The data in table 16 do not 

yield any unambiguous correlation between the various 

angular relationships and mineralogic composition or 

estimated particle size. The consistently smaller 

value of the angle 7 for the lizardites is suggestive, but 

there are overlaps with some of the chrysotiles.

DETAILED ANALYSIS OF THE CHRYSOTILE AND LIZARDITE 

CURVES IN THE TEMPERATURE RANGE 750° TO 1,OOO°C

After the chrysotile or lizardite has been dissociated, 

the trace of the DTA returns to the base line and 

continues monotonously as a straight line until an 

exothermic peak is observed. The exothermic peak 

corresponds to the heat effect accompanying the recrystallization of some of the dehydrated chrysotile (or 

lizardite) into a new phase assemblage. The area of 

this peak and its height do not seem to bear any simple 

relationship to the weight of the sample used in the experiment. Such discordant areal relationships are to 

be expected in rate processes such as a recrystallization 

into more stable phases.

Some of the curves also show additional minor peaks 

which may be sharp or gently rounded and which 

occur at lower or higher temperatures than that of the 

principal exothermic peak. The exothermic peaks are 

probably to be associated with the recrystallization of 

the dissociated materials. The gently rounded endothermic troughs may represent high-temperature phase 

transitions.

Chemical, microscope, X-ray and other studies of the 

products formed by the dissociation and recrystallization of serpentine were made by a number of workers. 

Haraldsen (1928) fired the serpentine from Snarum, 

probably dominant lizardite with some Clinochrysotile, 

as judged by his X-ray data, for (a) a period of 24 hours 

at 500°C; (b) 24 hours at 700°C; (c) 24 hours at 800°C; 

(d) 24 hours at 1,000°C; (e) 5 hours at 1,200°C, and 5 

hours at 1,300°C and studied the products. At 500°C 

the X-ray pattern is identical with that of the original 

serpentine, the lines are a bit more diffuse, and some of 

the weakest lines are not recognizable. At 600°C a 

single line, apparently belonging to the olivine pattern, 

is present with those of serpentine. At 700°C the pattern is clearly that of olivine; the lines are not as intense 

as those of natural olivine, but this probably is due to 

the small size and low concentration of olivine. The 

pattern at 800°C is still stronger and the number of 

lines has increased representing a growth in the amount 

of olivine.
THE SERPENTINE-GROUP MINERALS 69

LU

L±J

CL hS F, 

LU LU

H<->

_j in L±J

10

10

LU CD 

LU

100 200 300 400 500 600 700 800 900

INCREASING TEMPERATURE, IN DEGREES CENTIGRADE

1000

FIGURE 39. Differential-thermal-analysis curve of the type lizardite from Cornwall, England. Enlarged by pantograph from the original drawing of Midgley (1951).

At 1,000°C the X-ray pattern shows from the sharpness, intensity, and abundance of lines, that the olivine 

crystals have grown, and in addition a line appears 

which is due to the presence of "enstatite." At 1,200°C 

the "enstatite" crystals, as judged from the X-ray pattern are still small in size and present in limited 

amounts. At 1,300°C the amount of "enstatite" has 

increased.

Treatment of the material, heated at 800°C and 

1,200°C with sodium hydroxide solution, shows the 

presence of silica; treatment with hydrochloric acid 

removes the olivine and leaves the "enstatite."

Haraldsen concludes from his studies that the amount 

of amorphous silica decreases as the temperature is 

increased, because it is consumed in a reaction of olivine 

and silica to form "enstatite." The phase "enstatite" 

is placed in quotation marks here because an examination of Haraldsen's data in terms of the X-ray powder 

diffraction data for protoenstatite, clinoenstatite, and 

enstatite of Clark (1946) does not lead to a simple 

coincidence with enstatite, but suggests the presence of 

protoenstatite.

Hargreaves and Taylor (1946) found that a sample of 

chrysotile from Canada heated in excess of 750° 

". . . showed an extreamly faint wide band in a position corresponding to the strongest line of the enstatite 

pattern. ..." They did not find any evidence of 

low-temperature formation of enstatite.

Brindley and Zussman (1957) made a very detailed 

X-ray structural study of the transformation, upon 

heating, of serpentine into forsterite. They observed 

a transitional product which for two-layer serpentine

shows a spacing at 14.5 A which is nearly constant; for 

one-layer serpentine the spacing diminishes from about 

14 to 10 A. Six-layer serpentine behaved like twolayer serpentine.

The fired products obtained from the DTA studies 

had been prepared by heating the charges to a temperature of about 1,000°C in 80 minutes and then allowing 

the charge to cool in the furnace. The heating schedule 

used in the DTA studies is not the equivalent of the 

longer heat treatments used by Haraldsen (1928) and 

Hargreaves and Taylor (1946) and it is less likely that 

the reactions observed by Haraldsen will occur.

Thirty-five of the specimens on which DTA studies 

were made for this research were examined by X-ray 

powder diffraction methods. In all but specimen F-45 

the olivine (forsterite) pattern was clearly developed. 

The patterns contain an abundance of lines and many 

of these lines are quite dark and somewhat broadened. 

Table 17 contains the data for these specimens. A 

collection of eight other serpentine specimens, not 

related to this study, on which DTA studies had been 

made were examined by X-ray powder methods and 

they also yielded similar patterns of olivine. All but 

one of the samples showed, in addition to the lines of 

the olivine pattern, two other lines in their powder 

pattern corresponding to two of the principal lines of a 

polymorph of enstatite. These lines appear on the 

pattern at 3.17± A and 2.87± A. On the basis of the 

relative intensities of these two lines in which 72 .87±A 

> /a.i2±A it is suggested that this polymorph is 

clinoenstatite.
70 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

TABLE 17. Phases identified by X-ray methods in the chrysotile 

and lizardite specimens heated to about 1,000°C in the DTA 

studies

Specimen Chief phase Minor phase '

Intensity of two 

principal lines of 

enstatite pattern

Remarks

A. Clinochrysotile

F-54 ...

F-54 

F-52 

F-22 

F-40. 

F-50 

F-58 

F-70 

F-60 

 do .

 do 

..... do... ..... . 

 do 

..... do 

..... do 

 do .... 

.... .do 

Enstatite 

.... .do ....

 .do ..... 

..... do 

.... .do.. 

 .do... ......

 do ....

 do 

Absent (?)

Weak ___ . .... 

 .. do .......

Very weak. .....

Medium weak 

Weak. .. ...

Curve C-488. 

Curve C-489.

The two enstatite 

lines are sharp.

Extra lines at 2.70, 

2.20, 1.84, and 

1.69 A.

A very faint line at 

2.87± A suggests 

enstatite.

B. Clinochrysotile (Globe-type)

F-20 

F-63. 

F-24 

F-41 ...

F-45. 

F-45 

F-26. 

 do 

 do _ .

 do 

.....do 

Absent(?) _ ..

.... .do ... ...

.. do. .....

..... do ...

Very very weak. 

Weak. ___ ....

Weak...... .....

Fiber pattern.

Do. 

Based on C-72. 

Extra lines at 

4.15 A, strong; 

2.11 A, medium. 

Curve C-92. 

Curve C-94.

C. Clinochrysotile plus orthochrysotile

F-56 

.F-64 ... . 

F-74 

.... . do ....

 .do ...

Enstatite . 

.... .do 

..... do . 

Weak. .... 

..... do... ... ... ..

Weak line at 2.10 A.

D. Chrysotile plus lizardite, C>L

F-57 ....

F-51. 

F-73 

F-72 

F-25. ...

 do ...

 do 

 _ do ... 

 do... ... ...

.... .do ....

 . ..do 

 do .... 

 do... ......

Medium weak 

Very very weak.

Weak. .... ... 

Very very weakEnstatite line just 

visible. 

Weak line at 2.70 

and 2.10 A. 

Do.

E. Lizardite plus Clinochrysotile, L>C

F-71 

F-75 

F-76- 

F-3 ... -

 .do... 

..... do 

 -do 

 do 

..... do .

..... do ....

Weak ...........

Medium weak 

.....do ......

F. Lizardite

F-46 

F-47 

F-63 

F-63 .

F-23 

F-42 

F-43 

 -do 

 .do .....

.... .do 

 do .... .

..... do ...... 

 doEnstatite . 

... -do - 

 .do 

 .do 

 do 

 do 

 do 

Medium weak.. 

Weak ....

 do -

Medium weakVery very weak1 Enstatite has been used as the name of the phase having the composition MgSiOs. 

Reasons for believing that the polymorph of MgSiOa formed in these fired charges is 

elinoenstatlte are given in the discussion of the results in this table.

The phases olivine and clinoenstatite are those which 

should appear when serpentine is dissociated and 

recrystallized. These fired charges do not represent 

equilibrium conditions and this accounts for the 

relatively poor development of the clinoenstatite.

Sample F-45 is a mixture of Clinochrysotile, stevensite, and a small amount of dolomite, and it appears to 

be converted into clinoenstatite as the chief phase.

The danger of concluding that enstatite or its polymorphs is not present in the fired products, such as 

F-20 and F-60, table 17, is clearly indicated by Haraldsen's examination of his sample of serpentine 

heated to 800 °C. X-ray powder photographs, containing an abundance of lines, showed only olivine to 

be present. The treatment of the material with a 

solution of sodium hydroxide disclosed the presence of 

amorphous silica. The further treatment with hydrochloric acid removed the abundant olivine and left an 

insoluble residue. This residue gave an X-ray pattern 

which contained seven lines equivalent to "enstatite". 

A comparison of this partially complete pattern with 

that which he obtained from the residue heated to 

1,200°C confirmed the existence of the "enstatite" 

phase in the charge heated to 800°C.

The possibility that the different polymorphs of 

chrysotile and lizardite might show a difference in their 

thermal behavior after the dissociation was investigated 

by comparing (1) the temperature of the peak of the 

exothermic reaction and (2) the difference in temperature A(EX-EN) between the temperature of the exothermic peak and the endothermic trough as given in 

table 18. The average values of these data and their 

range are given in table 19. The data for the 31 specimens examined in this study, including Midgley's data 

on the type lizardite, do not show any systematic correlation of the data with the mineralogic composition.

Further study of the form of the DTA curve in the 

temperature range from the termination of the endothermic trough, at the close of the dissociation process, 

to the end of the DTA experiment was made, as had 

been suggested, to see if any correlation of form and 

mineralogy could be found. The following observations 

were made: (a) the offset of the base line before and 

after the high-temperature exotherm, and (b) the 

approximate distance from the termination of the endothermic trough to the onset of the exothermic peak. 

In making such. observations it is necessary to bear in 

mind that (1) the phenomena being observed are nonequilibium in nature and (2) that possible instrumental 

errors may interfere with the recording. In general, 

the Clinochrysotile curves show an offset of the baseline 

after the high-temperature exotherm of about 0.3 cm. 

The lizardites on the other hand appear to have no, or 

exceedingly small, offset. The observations on the 

various mixtures are, however, very inconsistent.

The approximate distance from the termination of 

the endothermic trough to the onset of the exothermic 

peak ranges from about 0.5 to about 2.5 centimeters in 

the curves for the clinochrysotiles, and from about 1.5 

to about 2.7 centimeters in the curves for the lizardites. 

The range in the curves for the mixtures is again inconsistent. Although no clear-cut difference exists between
THE SERPENTINE-GROUP MINERALS 71

TABLE 18. Summary and relations of the thermal data in the 

temperature range of 600° to 1,050°C of chrysotile and 

lizardite

Specimen Curve

Temperature of the 

minimum 

(EN° C)

Temperature of the 

maximum 

(EX° C)

A (EX-EN) (°C) Remarks

A. Clinochrysotile

F-54.-.--

F-22---.-

F_cfl

F-58-.----

F-70------

F-60------

C-489 

C-501 

C-122

C-91 

C-470

C-655 

C-746

C-680

670 

676 

692

696 

701

710 

715

705

805 

801 

820

817 

805

807 

806

814

135 

125

128

121 

104

97 

91

109

Minor (EN) at 790°. 

Minor (EX) at 696°. 

Minor (EX) at 863°. 

Minor (EN) precedes 

major (EX). 

Minor (EN) precedes 

major (EX) at 788°.

Doublet on (EN) at 

706° and 721°. Minor 

(EN) precedes major 

(EX).

B. Clinochrysotile (Globe-type)

F-20-..---

F-53------

F-24_--_-

F-45___--

C-84 

C-731

C-125 

C-133 

C-92

710 

712

705 

681 

697

824 

795

823 

815 

820

114

83

118 

134 

123

Doublet on (EX) at 

789° and 802°.

Minor (EN) at 851°.

C. Clinochrysotile plus orthochrysotile

F-56......

F-64---.--

F-74-_-.._

C-650 

C-728 

C-805

689 

687 

708

799 

816 

804

110 

129 

96

Minor (EN) at 859°. 

Major (EX) has an 

inflection above 804°.

D. Chrysotile plus lizardite, C>L

F-57--. 

F-51------

F-73..-.-

F-72--.-~

F-25------

C-562 

C-478 

C-809 

C-803 

C-115

692 

671 

690 

698 

698

798 

784 

803 

805 

825

106 

113 

113 

107 

127

Minor (EN) at 782°.

Minor (EN) after 

major (EX).

E. Lizardite plus clinochrysotile, L>C

F-71------

F-75------

F-3--.- 

C-804 

C-849 

C-135

687 

637 

671

811 

729 

816

124 

92 

145

Minor (EN) at 715°. 

Minor (EN) precedes 

major (EX).

F. Lizardite

F-46-----

F-47....-

F-63-----

F-63_-._-

F-23--..-

F-42......

F-43----

Type 

C-104 

C-98 

C-727 

C-818 

C-117 

C-729

C-105 

Midgley 

(1951)

700 

702 

700 

707 

714 

681

687 

698

807 

812 

815 

824 

819 

800

824 

818

107 

110 

115 

117 

105 

119

137 

120

Major (EX) is a doublet 800° and 803°. 

Minor (EN) at 854°. 

Estimated.

the form of the curve and the mineralogic composition 

for this portion of the DTA curve, such suggested differences combined with other observations might prove 

useful in identification. 

The occurrence of minor endothermic troughs just 

before, or following, the high-temperature exotherm has 

been mentioned. The following were observed: The 

curves for three of the clinochrysotiles, group A, had 

small endothermic troughs preceding the major exotherm; those for three of the clinochrysotiles (Globetype), group B, had endothermic troughs following the 

major exotherm; those for the mixtures of clinochrysotile arid orthochrysotile, group C, contained only one 

curve with a small endothermic trough following the 

major exotherm; the curve for the chrysotiles plus 

lizardite, where C>L, group D, contained two DTA 

curves with endothermic troughs before the major exotherm, and one curve showed it following the major 

exotherm; the DTA curves of lizardite plus chrysotile, 

where L>C, group E, contained three curves which 

showed small endothermic troughs before the major 

exotherm; only one curve of the lizardite specimens, 

group F, showed a small endothermic effect and this 

followed the major exotherm. Some of the DTA curves 

showed a gentle slope upward from the base line and 

merging with the major exotherm. This was observed 

on one curve in group A, two in group C, two in group 

D, and three in group F. No real criterion for the 

differentiation of chrysotiles from lizardite is apparent 

in these observations, and this is in agreement with the 

common behavior of substances in nonequilibrium

systems.

A TYPICAL ANTIQOBITE CURVE

A typical antigorite is the green translucent gem 

material williamsite from the famous mineral locality 

at the State Line Pits, specimen F-l. This specimen is 

noteworthy because of its low content of ferrous and 

ferric iron oxides (table 2). The DTA curve is given 

in figure 40, as curve C-124. The curve is relatively 

simple. Over the temperature range 25° to 700°C the 

curve is essentially monotonic save for a slight bowing 

which has a maximum at 344 °C. Owing to the low 

intensity of this bow it appears as a broad trough. Its 

closeness to the temperature at which nickel undergoes 

its magnetic transition at 353°C strongly suggests that 

this bow represents a subdued manifestation of the 

nickel transition. At approximately 675°C the antigorite begins to dissociate and the curve descends into 

a well-formed endothermic trough with the temperature 

of the minimum at 796 °C. The curve then returns to 

the base*line at about 830°C. Subsequently a minor 

endothermic trough appears with a minimum at 874°C. 

The significance of this trough is not known. Such

TABLE 19. Comparison of the high-temperature thermal data 

of the chrysotiles and lizardites

Serpentine-group minerals

A. 

B. 

C. 

D. 

E. 

F.

Clinochrysotile plus orthochrysotile- .

Lizardite plus clinochrysotile, L>C_.

Temperature (°C) 

of the maximum 

(EX)

Average

809 

815 

806 

803 

785 

815

Range

801-820 

795-824 

799-816 

784-825 

729-816 

800-824

AEX-EN (°C)

Average

114 

114 

112 

113 

120 

116

Range

91-135 

83-134 

96-129 

106-127 

92-145 

105-137
72 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

high-temperature troughs are generally suggestive of a 

phase transformation of some type. After this minor 

endotherm the curve becomes straight.

THE COLLECTION OF ANTIGORITE CURVES

A collection of six chemically analyzed specimens of 

antigorite, or of samples made up chiefly of antigorite, 

were studied by DTA methods. In addition, a number 

of DTA curves of unanalyzed specimens of antigorite 

were examined to check the consistency of the data. 

The thermal-analysis data for the analyzed specimens 

of antigorite are given in table 20, and their DTA 

curves are shown in figure 40.

DETAILED ANALYSIS OF THE ANTIGORITE CURVES IN THE 

TEMPERATURE RANGE 25° TO 700°C

Four of the six curves of antigorite show a very 

slight downward bowing in the range of 85° to about 

125°C. This bow arises from the loss of the absorbed 

water. Two of the DTA curves, C-121 (F-13) and 

C-116 (F-19), exhibited sufficient area under the curve, 

associated with the loss of adsorbed water, to be 

measured. Sample F-13 contains 0.93 percent H2O , 

and 0.4025 grams of this mineral yielded an area under 

the curve of 12.7 square millimeters. Sample F-19 

contains 0.55 percent H2O , and 0.2285 grams of this 

sample yielded an area under the curve of 1.7 square 

millimeters. The reduction of the data, that is, the 

weight of the sample used in the DTA experiment and 

the analytically determined percentage of H2O , to an 

equivalent basis for specimens F-13 and F-19 shows 

that the area under curve for specimen F-13 should be 

about three times greater than that for specimen F-19. 

The considerable discrepancy, cited above, is to be 

attributed to the drying out of sample F-19 in the 

balance case previous to the DTA study.

The gentle upward bow which appeared in the DTA 

curves of chrysotile and lizardite in the temperature 

range of 300° to 400°C apparently does not occur in

antigorite. One record of antigorite, C-124, specimen 

F-l, does in fact show a slight bow, but as has been 

pointed out previously this bow is probably to be 

attributed to the magnetic transition in nickel. The 

curve for specimen F-13, likewise shows an upward 

bow, and it is more pronounced than that shown by 

specimen F-l. As sample F-13 contains chrysotile 

the upward bow in the curve C-121 may be due in 

part to the nickel transition and in part arises from the 

chrysotile in the sample.

In the temperature range 25° to 700°C antigorite 

gives a DTA pattern which is nearly a straight line.

DETAILED ANALYSIS OF THE ANTIGORITE CURVES IN THE 

TEMPERATURE RANGE 7OO° TO 8OO°C

All the antigorites undergo the major decomposition 

in this temperature range. The shape of the endotherm varies from the simple trough in the curves for 

specimens F-l (C-124) and F-14 (C-120) to the 

slightly inflected form of the curve for specimen F-8 

(C-126), to the more highly inflected forms shown by 

the curves for specimens F-15 (C-64) and F-13 (C-121). 

The inflections on the low-temperature side of the endotherm may arise from (1) the presence of some chrysotile 

in the sample, (2) heterogeneity within the specimen 

itself, such as the presence of some iron-rich portions 

of serpentine within the specimen, or (3) nonequilibrium 

factors.

Actual resolution of this inflection to form two separate troughs is shown by the specimen F-19, curve 

C-116 (fig. 40). This specimen is the variety baltimorite and consists of both antigorite and chrysotile. 

Nagy and Faust (1956) reported the sample to contain 

about 50 percent of antigorite and 50 percent chrysotile 

on the basis of the Nagy and Bates (1952) solution 

test.

A study of the angular relationships of the principal 

endotherm was made to-aid in the detection of possible 

admixtures with chrysotile (table 21). The convenTABLE 20. Observations of the differential-thermal-analysis curves of antigorite and samples composed chiefly of antigorite

[These curves were all obtained with a resistance of 600 ohms in the galvanometer circuit. Principal endotherms marked (EN), principal exotherms marked (EX)]

Specimen

F-15-. ... --------

F-l________-__ 

F-8 .- -.

F-14. ____________

F-13---.. ______ _.

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

Curve

C-64..._.

C-124_.._

C-126___-

0-120... _ 

C-121____ 

C-116....

Temperature of thermal phenomena for indicated range

85°-200°C

(2)

(2) 

(2) 

(2)

200°-400°C

344

(2)

400°-700°C 700°-800°C

'762

796 (EN)

790 (EN) 

760 (EN) 

739 (EN) 

733 (EN) 

763 (EN)

800°-900°C

802 (EN) 

872 

874 

828 (EX)

829 (EX) 

811 (EX) 

815 (EX)

900°-1000°C

939

1000°-1100°C

1023

1039 (EX)

1 Inflection

2 Present but not measured.
THE SERPENTINE-GROUP MINERALS 73

C-64

INCREASING TEMPERATURE, IN DEGREES CENTIGRADE

FIGURE 40. Diflerential-thermal-analysis curves of antigorites. C-64, F-15, Val Antigorio, Italy; C-124, F-1, State Line Pits, Lancaster County 

Pa.; C-126, F-8, Smithfield, Providence County, R.I.; C-120, F-14, "Yu-Yen Stone," Manchuria; C-121, F-13, Tilly Foster iron mine, near 

Brewster Station, N.Y.; C-116, F-19, Bare Hills, Baltimore County, Md. All curves obtained with a resistance of 600 ohms in the galvanometer circuit.
74 STUDIES OF THE NATUKAL PHASES IN THE SYSTEM MgO~Si02-H2O

tions for measurement are the same as those used in 

describing the chrysotiles. The only observation that 

may be made is that concerning the low-temperature 

inflection on the principal endotherm, which has a larger 

angle 7 and a higher value for the ratio of tan a/tan /3. 

In curve C-116, for specimen F-19, where the inflection 

is resolved as two seperate troughs only the angle a 

could be measured for the endotherm at 733°C, but 

from this it is obvious that the angle 7 will be larger for 

it than the angle 7 for the endotherm at 763°C.

Curves for samples which are pure or practically pure 

specimens of antigorite specimens F-15, F-l, and F-8 

(table 20) have a temperature for the minimum of the 

trough of 790° to 802°C; whereas those for specimens 

known to contain another phase, chrysotile, have lower 

temperatures for the minimum of 739° to 760°C. The 

curve for a mixture of approximately 50 percent antigorite and 50 percent chrysotile has minima at 733° and 

763 °C. These data suggest that curves for an admixture of chrysotile and antigorite may show a lower 

temperature for the minimum of the endothermic trough 

than that of a pure specimen of antigorite.

DETAILED ANALYSIS OP THE ANTIGORITE CURVES IN THE 

TEMPERATURE RANGE 80O° TO 1,10O°C

After the end of the dissociation there appears in the 

curves for some of the antigorites a small, rather round 

to bow-shaped endotherm of minor proportions. It is 

best developed in curve C-64. It is much smaller in 

curve C-124 and practically negligible in curves C-126, 

C-120, and C-116. Curve C-121 does not exhibit any 

trace of an endotherm following the main endotherm. 

Very commonly the area "under the curve" for these 

endotherms is small so that the identity of the phase 

or mechanism responsible for them may be difficult 

to determine.

The existence of such endotherms has generally been 

attributed to a possible phase transformation. They 

may also be due to the presence of compositional zoning 

or to the presence of a few larger particles amongst a 

fine matrix. More recently, studies of diffusion in 

heated phases undergoing dissociation in a nonequilibrium process have suggested that some swapping of 

sites by atoms or groups of atoms to form slightly more

TABLE 21. Angular relationships of the principal endotherm of

antigorite

Specimen

F-l--... .................

F-15................ .......

F-l 3 (Inflection) ..._.. 

F-19 EN at 763°C ____ .... .

F-19 EN at 733°C. ..... ...

Curve

C-124 C-64

C-126

C-120

C-121

C-116

Angle y 

(degrees)

22

26

wt

44M

47 

46

Angle a 

(degrees)

15M

16M

14

16 

10

33

61

Angle ft 

(degrees)

6KQTZ

514

gl

14

tan a 

tan ft

2.43

1.77

9 10

2.98 

1.34

9 <*fi

2.60 

1.41

stable configurations or metastable phases might occur. 

Just what this mechanism may be has not been 

determined. The following suggest themselves: (1) The 

dissociation of a disordered (or defect) structure followed by annealing with the production of domains of 

less ordered (or defective) configuration. Diffusion of 

water vapor through this may permit the formation of 

the more stable form of the original phase. This will 

decompose at somewhat higher temperatures than the 

original phase. (2) The production of a new, less hydrous phase. Hedvall (1938) has indicated the ease 

of synthesizing phase in such assemblages, and Stubican (1959) has investigated relationships of this kind 

with ordered and disordered kaolinites and halloysites.

The DTA curve for the pure or nearly pure antigorites after the principal endotherm, save for the presence of a minor endotherm, is essentially a straight line.

The crystalline phases present in the specimens of 

antigorite after they have been heated to about 1,000°C 

in the DTA studies were indentified by X-ray diffraction 

techniques and the data are given in table 22. The 

chief phase is olivine and its powder pattern dominates 

the X-ray film. Minor amounts of enstatite constitute 

the second crystalline phase. Enstatite is most abundant in the pseudocubic serpentine from Brewster 

Station, N.Y. (F-13) and the baltimorite from Bare 

Hills, Md. (F-19).

EFFECT OF SOME ADMIXED MINERALS ON THE 

DTA PATTERNS OF SERPENTINE

In the general application of the DTA method to the 

study of serpentine-group minerals, it is necessary to 

consider the probable effects of any mineral with which 

they are admixed. Such mixtures may consist of the 

minerals they replaced, were replaced by, or which 

were introduced at a later stage in the paragenesis. AdTABLB 22. Phases identified by X-ray diffraction methods in 

specimens of antigorite heated to about] 1,000°C in DTA studies.

Specimen Chief phase Minor phase '

Intensity of two 

principal lines of 

enstatite pattern

Remarks

Antigorite

F-15- 

F-l 

F-8 

... _do.._...._ .

 .do..--. 

Enstatite- 

 do... ......

 do..... 

Very very weak _

Antigorite plus chrysotile

F-14. 

F-13- 

F-19-. 

 do...... 

 do--..- 

Enstatite- - 

 do..... do.-.--........

This specimen is 

richest in enstatite. 

X-ray pattern almost the same 

as F-13, above.

> The presence of enstatite in all these samples is based on the presence of the two 

principal lines of enstatite with spacings at d=3.15 A and d=2.85 A. The intensity of 

the two lines is nearly the same but the line at d=2.85 A seems to be somewhat the 

stronger of the two.
THE SERPENTINE-GROUP MINERALS 75

mixture of minerals which yield thermal effects in the 

range where the serpentine minerals are thermally active 

may modify the DTA patterns of. serpentines to a notable extent. Some of the common associates of serpentine minerals which are capable of modifying the DTA 

curves are magnetite, chromite, talc, chlorite, pholgopite, 

stevensite, calcite, dolomite, magnesite, brucite, hydrous magnesium carbonates such as artinite and hydromagnesite, and the silica minerals opal and quartz.

Talc generally does not complicate the DTA record 

of serpentine group minerals because it usually shows 

an endothermic trough at 950° to about 1,050°C. Confusion may result, however, if serpentine specimens 

which exhibit a minor high-temperature endotherm are 

contaminated with talc. A DTA curve of a sample of 

what at one time was considered to be a hydrous talc 

(Foshag and Wherry, 1922) is shown in figure 41 as 

curve C-540. This specimen from the Atwater serpentine quarry of the Westfield Marble Company, Russell 

Mass., is seen to consist of talc, "chrysotile," and probably a very small amount of calcite. Fahey found 

about 0.1 percent of CO2 in Foshag's tube sample indicating the presence of approximately 0.25 percent 

calcite.

The chlorites, when present as a major constituent 

with serpentine minerals in a DTA sample, can modify 

the curve to such an extent as to make it difficult to 

interpret. In fact DTA curves of some chlorites are 

remarkably similar to those of serpentine-group minerals. Fortunately, the chlorites associated with serpentines are easily detected by other means and they 

can be accounted for when they are present as admixtures in samples studied by DTA.

The magnesium-rich micas, phlogopite, andmagnesian 

biotite are sometimes found with serpentines. A DTA 

pattern of a mixture of phlogopite with gome serpentine, 

probably chrysotile, is shown in figure 41 as curve 

C-730. This specimen, F-68, is from the Verdolite 

quarry, Easton, Pa.

Stevensite, the magnesium end-member of the 

montmorillonite-group (Faust and Murata, 1953), is 

also an associate of the serpentine-group of minerals. 

Samples of serpentine minerals containing stevensite as 

an admixed impurity are given in figure 31 as curves 

C-94 and C-93. The rather large size of the lowtemperature endotherm and the more complicated 

character of the curve in the range of the exothermic 

peak are caused by the presence of stevensite in the 

samprles. The absence of stevensite in the DTA curve 

C-92 (fig. 31), prepared from part of the same specimen 

from which the material for curve C-94 was obtained, 

is apparent.

All the carbonates associated with serpentine produce 

large endothermic troughs, when they dissociate in

thermal-analysis studies, that make their presence 

apparent. The hydrous carbonates have even more 

complicated patterns arising from the loss of water as 

well as carbon dioxide. Calcite when present as a 

major constituent produces a considerable endothermic 

trough; it appears in the normal temperature range at 

which calcite decomposes, between 850° to about 

975°C, so that abundant calcite does not confuse the 

interpretation of the pattern. Such an admixture is 

represented by specimen F-20A, and is shown as curve 

C-817 in figure 30. Small amounts of calcite, less than 

25 percent, may complicate the DTA records as is 

shown in the curve for N-6 (Cr75, fig. 41). This 

specimen consists of a clinochrysotile (Globe-type) 

with some calcite. The calcite in this admixture has a 

temperature for the minimum of 809°C. This endothermic reaction is followed by an exothermic reaction. 

The DTA curve indicates that there is an overlapping 

of the two reactions and that these curves represent in 

part an algebraic addition of the two opposing reactions. Dolomite likewise, in large amounts, is usually 

easy to recognize and account for in the DTA curve of 

a mixture with serpentine. It does however complicate 

the DTA curve because the average temperatures of the 

minima of its two endotherms are about 790° and 

948°C for pure material. Curve C-143 (fig. 41) 

illustrates the behavior of such a mixture. This curve 

was prepared from a specimen from the Ala-Mar deposit, Nye County, Nev. In smaller amounts dolomite 

may prove troublesome. A clinochrysotile (Globetype), specimen F-41, from the Windous deposit, 

White Pine County, Nev., contains a small amount of 

dolomite (as observed under the microscope and verified by X-rays) and its DTA pattern (curve C-133, 

fig. 30) reveals a small trough at about 777°C and an 

inflection on the principal endotherm at 590°C.

DTA curves for magnesite generally show the minima 

on its endothermic trough in the temperature range of 

650° to about 700°C. This mineral may be present in 

small amounts in some chrysotile specimens. Its presence is indicated by a separate small endothermic 

trough at a lower temperature than the principal 

endotherm of the curve of the chrysotile mineral or as 

an inflection on the low temperature side of the principal endotherm of the chrysotile curve. Brucite is 

always apparent in a DTA pattern of a serpentine 

because it produces an endotherm, usually somewhere 

near 450°C, that is sharp and well separated from any 

DTA manifestations of serpentines. Likewise the 

DTA patterns of hydromagnesite and artinite occur at 

temperatures well below the principal endotherm in 

curves of the serpentine minerals. Their DTA patterns 

are noteworthy for the abundance of endothermic 

troughs.
76

C-540

STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2~H2O 

389 813

638 732

929

C-730 813

I_LJ 

Q

CD

CJ

CO 

l_Ll 

l_Ll 

CZ 

CD 

l_Ll 

Q

680

111 948

696*7^735

816

C-75 394

141

809

680

816

C-143

LU 

Q_

S

LU

106

LU

cr

LU 

Lu 

Lu

Q

774

908

INCREASING TEMPERATURE, IN DEGREES CENTIGRADE

FIGURE 41. Differential-thermal-analysis curves of serpentine-group minerals admixed with paragenetically associated minerals. C-540, hydrous talc, Atwater 

serpentine quarry of the Westfleld Marble Co., Russell, Mass., a portion of the tube sample used by Foshag; C-730, F-68, serpentinized phlogopite, Verdolite 

quarry, Easton, Northampton County, Pa.; C-75, N-6, clinochrysotile plus calcite, vein filling, Nevada magnesite deposit, Currant Creek, White Pine County 

Nev., similar to F-41; C-143, A-1008, dolomite plus clinochrysotile, Ala-Mar deposit, Currant Creek, Nye County, Nev. All curves obtained with a resistance 

of 600 ohms in the galvanometer circuit.
THE SERPENTINE-GROUP MINERALS 77

Quartz, if present in any quantity at all, is generally 

recognized by the characteristic trough it produces at 

573°C. Opal very commonly does not affect the DTA 

pattern of serpentine. However, it is always necessary 

to remember that if the opal contains cristobalite it 

may produce an effect in the temperature range of 

70° to 280°C.

The spinels magnetite and chromite, if they are 

present as an essential constituent in a sample of 

serpentine, will produce two broad exothermic peaks 

with maxima at about 350° and 850°C for magnetite 

and 450° and 900°C for chromite. The low-temperature exotherm is generally larger than that appearing 

at higher temperatures.

APPLICATION OF THE DTA STUDIES ON THE 

SERPENTINE-GROUP MINERALS TO PROBLEMS OF 

IDENTIFICATION

The DTA studies of the serpentine-group minerals 

show that it is possible to determine whether a given 

sample of serpentine consists of antigorite or the undifferentiable pair chrysotile and lizardite. This in itself 

is very valuable differentiation. A comparison of the 

curves of the chrysotiles and lizardite with those of 

antigorite shows, that the former dissociate at a much 

lower temperature than do the antigorites. The curves 

for chrysotiles and lizardite have a temperature for the 

minimum of 637° to 715°C with an average temperature 

for 32 curves of 693°C. The curves for antigorites 

have a temperature for the minimum on the endotherm 

in the range of 790° to 802 °C. In curves for mixtures 

of antigorite with other serpentine-group minerals, the 

temperature of the minimum drops to the range of 

733° to 763 °C. In addition to the considerable difference in the temperatures of the minimum of the 

principal endotherm, there is another characteristic of 

the curves for the chrysotile-lizardite pair which is 

noteworthy that is, the appearance of an exothermic 

peak at 83° to 145°C above the temperature of the 

minimum. This exothermic peak does not appear, in 

these studies, on the DTA curves of pure samples of 

antigorite. It does, however, appear on curves for 

antigorite which contain some chrysotile or lizardite. 

On such curves the separation of the minimum of the 

principal endotherm from the maximum of the exotherm 

ranges from 38° to 72°C. This value is notably lower 

than that in curves for the chrysotile-lizardite specimens. The data further indicate that a gentle or pronounced bowing in the temperature range of 200° to 

400 °C is caused by*the presence of chrysotile or lizardite 

or both in a sample.

The application of DTA methods in a regional 

mineralogical study of an area containing considerable 

serpentine-group minerals may reveal that it is even

possible to detect or infer the presence of mixtures of 

chrysotile and lizardite. Such a relationship would 

have to be established first by other techniques before 

it could be used.

X-RAY STUDIES

X-RAY CLASSIFICATION OF THE SERPENTINE- GROUP 

MINERALS

Selfridge (1936) examined a suite of about 100 serpentine-group minerals by the X-ray powder diffraction 

method and found that he could classify the powder 

patterns into two groups as follows :

The first, here considered to belong to the mineral serpentine 

consists of varieties whose interplanar spacing is similar to that 

of chrysotile . . . The name chrysotile, however, is reserved 

for serpentine that occurs in veins and consists of flexible 

fibers . . . The second, here considered to belong to the mineral antigorite, includes varieties structurally similar to antigorite 

from the Antigorio valley, Piedmont, Italy.

Gruner (1937) confirmed the work of Selfridge and he 

attempted to index the lines in his powder patterns. 

As a result of his study he was lead to suspect that the 

crystal structure determinations of Warren and Bragg 

were incorrect, a conclusion later shown to be true.

Whittaker and Zussman (1956) restudied the powder 

patterns of the serpentine-group minerals using the 

excellent structural studies of Whittaker (1951, 1952, 

1953, 1954, 1955a, b, c) as a basis for indexing. Their 

work constitutes a valuable contribution to the study 

of the serpentine-group minerals. They classify the 

serpentine group of minerals as follows :

Serpentine

[ Orthochry sotile 

Chrysotile- ______ ! Clinochrysotile

Lizardite [ Parachrysotile 

Antigorite

X-RAY POWDER DIFFRACTION STUDIES

X-ray powder diffraction patterns were made on our 

specimens, using rolled spindles. For a few specimens, 

coated rods were also used. The most satisfactory 

patterns were obtained with copper radiation and a 

nickel filter although for a few specimens iron radiation 

and a manganese filter were more useful.

The results of our study are given in table 23. The 

criteria used for the identification were those of Whittaker and Zussman (1956).

We have followed the classification, given above, in 

this paper. Early in our studies we recognized the 

presence of additional lines in some of our powder patterns and it was concluded that they represented 

either polymorphism in the serpentine composition or, 

for some of the lines, an orientation effect due to the 

fibrous character of the chrysotile specimens. The 

work of Whittaker and Zussman (1956) has supplied us 

with the answer.
78 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

TABLE 23. Classification of the serpentine specimens studied 

by X-ray powder diffraction methods

Specimen

F-54.

F-52. 

F-22.

F-40.

F-50. 

F-58.

F-70.

F-60. 

F-61.

F-46-

F-47. 

F-63-

F-23.

F-42- 

F-43.

Locality Remarks

A. Clinochrysotile

Synthetic mineral prepared by

Bowen and Tuttle (1949). 

Sylmar, Chester County, Pa._.. 

Turkey Mountain, near Montville, Morris County, N.J. 

Prairie Creek area of peridotite,

south-southeast of Murfreesboro, Pike County, Ark. 

Chrome mine near Moa, Oriente

Province, Cuba. 

Canyon of Clear Creek, New

Idria quadrangle, San Benito

County, Calif. 

Near Thetford, Megantic County,

Quebec, Canada, 

.do

.do.

Taken as representative pattern 

Deweylite, stevensite(?).

Deweylite.

Deweylite, stevensite(?).

Partly decomposed by treatment 

withl^VHCl.

B. Clinochrysotile (Globe-type)

F-20--- ~

F-20AF-53- - .

F-24 - 

F-45.._ 

F-26 

Ariz. 

 - do _. . 

 do 

ville, Morris County, N.J.

magnesite deposits. White Pine 

County, Nev.

County, Pa.

Contains much calrite.

Deweylite.

Deweylite. A study of three 

X-ray powder patterns shows 

Clinochrysotile plus some stevensite. A fourth pattern 

shows, in addition, dolomite.

Deweylite. Contains much stevensite.

C. Clinochrysotile plus orthochrysotile

F-56

F-64... ..

F-74- 

neur Talc Co., Balmat Corners, 

St. Lawrence County, N.Y.

ville, Morris County, N.J.

County, Calif.

D. Chrysolite pins lizardite, C>L

F-57 

F-51- .

F-73 -

F-26 - 

ville, St. Lawrence County, 

N.Y.

County, Calif.

ville, Morris County, N.J.

E. Lizardite plus Clinochrysotile, L>C

F-71 

F-75.-- 

F-76-- -

F-3_ 

of Buskerud, Norway.

of Technology, Castle Point, 

Hoboken, Hudson County, N.J. 

do ... . 

Near Forest Hill, Harford County,

Md.

Deweylite.

F. Lizardite

Near Bellows Falls, Windham

County, Vt.

Tyrol, Austria...- __ 

Staten Island, Richmond County,

N.Y. 

Dognacska, 10 km west from Reschitza, Severin Province,

Hungary.

Near Norris, Union County, Term. 

Mineral Hill, Delaware County,

Pa.

Deweylite.

TABLE 23. Classification of the serpentine specimens studied 

by X-ray powder diffraction methods Continued

Specimen

F-15-. .

F-8- 

F-13... 

F-19

Locality

G. Antigorite

Antigorio, Novara Province, 

Piedmont region, Italy.

Pa.

R.I.

Liaoning Province, Manchuria.

ster Station, Putnam County, 

N.Y.

Md.

Remarks

Williamsite.

H. Stevensite plus chrysotile S>C

F-48- Mine Creek, BakersviUe, MitcheU

County, N.C.

The Clinochrysotile patterns are divided into two 

groups: Clinochrysotile and Clinochrysotile (Globetype). These patterns differ slightly but significantly 

enough to separate them. The chief differences are as 

follows:

1. In a pattern of Clinochrysotile such as that of the 

synthetic material, F-54, there is a strong line at 

about 2.456A and a band extending from it to 

about 2.594A. The band is medium weak in 

intensity.

2. In a pattern of Clinochrysotile (Globe-type) such as 

F-20, there are two lines of medium intensity at 

about 2.456A and 2.604A. In between these lines 

there is a band of medium weak intensity.

A survey of the intensities of the 201 reflections other 

than the 201 at 2.604A and the 202 at 2.456A did not 

disclose any real differences in these patterns. A line 

in the "Globe-type" at 2.500A also appears to be absent. 

From the work of Whittaker and Zussman (1956) it 

seems that these differences might arise from the 

presence of a small amount of orthochrysotile in the 

"Globe-type" specimens.

STATUS OP DEWEYLITE

Ebenezer Emmons (1826) first described deweylite as 

follows: "Colour white, yellowish and greenish white. 

Translucent. Lustre vitreous, inclining to resinous, 

faint . . . Surface rough and sometimes drusy, exhibiting small mammillary concretions."

Thomas Nuttall (1822) had previously described the 

variety of serpentine occurring at Hoboken, N.J., which 

he called marmolite. This is a thin foliated variety and 

the folia are thin and separable. The usage was extended to specimens in which the laminae are not sepa-
THE SERPENTINE-GROUP MINERALS 79

rable. Dana (1850, p. 255) notes that this variety has 

been misnamed kerolite by some mineralogists.

These two varietal names have been used over the 

years to include many similar materials until confusion 

over what is truly deweylite has now arisen. A number 

of specimens of so-called deweylite which we have seen 

in various collections and some of which we have studied 

do not fit the description of Emmons.

Specimens F-3, F-40, F-41, F-26, F-48, and F-43 

were labeled deweylite. All these except F-43 fall on 

the line connecting the calculated formulas for serpentine and stevensite (fig. 19); F-43 falls within the rectangle of the serpentines. Specimen F-45, for which 

there is no analysis, is also a mixture of serpentine and 

stevensite. The evidence obtained by the DTA, X-ray, 

and chemical studies is given in table 24.

The data contained in table 24 show clearly that 

deweylite is not a mineral species but is actually a finegrained mixture of a serpentine-group mineral, usually 

clinochrysotile, but occasionally lizardite, and the mineral* stevensite. There is no justification for keeping 

the name deweylite except as a field term. Two other 

unanalyzed samples called deweylite give DTA patterns 

which suggest that they contain stevensite; they are

F-52 (curve C-501, fig. 28) and F-50 (curve C-470, 

fig. 29).

The chemical analyses taken from the literature also 

support this conclusion. There is a very good distribution of analyses astride and close to the line connecting theoretical serpentine and theoretical stevensite 

(fig. 21). Not all the analyses falling in this area are 

necessarily mixtures with stevensite; some are mixtures 

with other minerals such as the residual cores of the 

pyroxenes diopside and enstatite, and the amphiboles 

tremolite and hornblende. Such mixtures will, however, be close to the serpentine rectangle.

It is quite easy to detect stevensite if it is present by 

the use of DTA and X-ray techniques. Mixtures of 

stevensite and clinochrysotile are completely decomposed by hydrochloric acid.

GEOCHEMICAL STUDIES

The results of the studies by Faust, Murata, and 

Fahey (1956) on the minor elements in serpentines of 

different origins have a distinct bearing on the theory 

of the origin of ultrabasic rocks. This subject is being 

briskly controverted again by those who advocate the 

genesis of ultrabasic rocks from sedimentary rocks. It

TABLE 24. Chemical, differential-thermal-analysis, and X-ray data on some minerals called deweylite

Specimen

Theoretical 

serpentine.

F-43-------.

F-3.

F-40.

F-41

F-26.

F-48-

F-45.

Stevensite (calculated as 

serpentine).

Calculated formula based on the chemical analysis

[Mg8][Si4]010 (OH) 8

[MgB ,4Fe£FeSAl.os][Si4.M]0,o(OH)7 

2 = 5.88 2 = 4.02 

oct tet

[Mg,.MFeSFe&Al. 18Ni.01 ][Si«.o«]0,o(OH) s 

2 = 5.75 2 = 4.09 

oct tet

[Mg5 .45Fe20tFe3o+9A1.03Ti.oi][Si4.i5]01o(OH) 8 

2 = 5.63 2 = 4.15 

oct tet

[Mg5 . 54Fe3otAl.o1 ][Si4. 22]01o(OH) 8

2 = 5.56 2 = 4.22 

oct tet

[Mg5 .o6Al.o2 Mn.oiNa.oi][Si4.45]O10 (OH) 8 

2 = 5.10 2 = 4.45 

oct tet

[Mg4.33Fe24tCa.02][Si4.6o]Oio(OH) 8

2 = 4.80 2=4.60 

oct tet

No analysis--_______________________

[Mg3 . 82][Si6>o9]010 (OH) 8

Phases identified by 

DTA

C-105. "Chrysotile-like" pattern..

C-135. "Chrysotile-like" and 

probably some stevensite. Note 

mo ntmorillo nit e-gro up-type 

low-temperature endotherm.

Curve C-91. Chrysotile plus a 

low-temperature endotherm at 

121 suggestive of stevensite.

Curve C-133. Chrysotile with 

probably some stevensite.

Curve (^93. 

Chrysotile.

Stevensite and

C-546. Stevensite with chrysotile.-

C-94. Stevensite and chrysotile-__

C-92. Chrysotile and small 

amount of stevensite.

X-ray

Lizardite.

Lizardite and clinochrysotile L>C.

Clinochrysotile.

Clinochrysotile (Globetype) .

Clinochrysotile (Globetype).

Stevensite and clinochrysotile.

Clinochrysotile and stevensite.

1 See also the static dehydration curve (fig. 26) for sample F-41a which was made on very similar material.
80 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

is desirable therefore to (a) review briefly some of the 

data on the geochemical distribution of the minor 

elements related to this study, (b) to present our data, 

(c) to review briefly the theories that have been proposed on the processes that generate ultrabasic rocks 

from sediments, and (d) to draw some conclusions from 

our studies.

DISTRIBUTION OF MINOR ELEMENTS IN 

MAGNESIUM-RICH MINERALS AND ROCKS AND 

IN SOME CONTRASTED ROCK TYPES

To provide background for our studies it is desirable 

to review the work of others on the distribution of 

minor elements in magnesium-rich rocks and minerals. 

This subject has attracted the attention of geochemists 

for a long time. Goldschmidt and Peters (1931), using 

spectrographic methods, noted that scandium is usually 

present in the olivines and pyroxenes of ultrabasic rocks. 

Kobinson, Edgington, and Byers (1935) studied the 

infertile soils from the serpentine barrens of the United 

States, Cuba, and Puerto Kico and found that they 

contain a comparatively high percentage of Chromium 

and nickel. The Cr2O3 content ranges from 0.03 to 

5.23 percent, and the NiO content ranges from a trace 

to 0.45 percent. Only one of the soil samples was 

tested for cobalt, which was found to be present.

Grimmet (1938-39) showed that ultrabasic rocks 

were much richer than limestones in cobalt, finding 

67 to 115 ppm cobalt in the former and 0.2 to 5.1 

ppm cobalt in the latter. Kigg (1942) obtained similar values, namely, 83 ppm cobalt in serpentine rich 

rocks and 0.2 to 12.5 ppm for limestones. Sedletskii 

and Ivanov (1941) studied the distribution of copper 

in the main soil types of Kussia and found that an 

olivine basalt having 0.0092 percent copper weathered 

to a copper-enriched product having 0.0110 percent 

copper.

Wells (1943) described the relative abundance of 

nickel in the earth's crust and stressed its relation to 

the ultrabasic rocks. Sahama (1945) determined the 

boron content of ultrabasic rocks from Finland. Pieruccini (1946a, b) measured spectrographically the 

concentration of nickel and chromium in the ophiolite 

formations of Italy. He reported for 24 serpentines 

and amphibolites that the Cr2O3 content ranged from 

0.0000 to 1.634 percent; NiO ranged from 0.00278 to 

0.403 percent; and CuO ranged from 0.000024 to 

0.00716 percent (one sample gave 0.0141 percent). 

Pieruccini concluded from his studies that the CuO 

in the ophiolite was too small to account for the copper 

deposits in the ophiolites.

Lundegardh (1945a, b, 1949) studied the occurrence 

of chromium, cobalt, nickel, and zinc in 253 samples 

of Swedish minerals, rocks, and soils and noted that

in the early differentiates produced by fractional crystallization of a basic magma the sequence is Cr>Ni 

>Co, and that in the late differentiates the order is 

Co>Ni>Cr. In the Swedish argillaceous sediments 

and their metamorphosed phases the order is Zn>Ni 

>Co>Cr. Fenoglio (1948, 1949-50, 1950, 1952) in 

a series of papers described his trace-element studies 

on the peridotites and serpentines of the Alps of Piedmont, Italy, which occur in Mesozoic calcareous 

schists, and the ophiolites of the region of Monte 

Kosa-Monte Viso. The peridotites contain from 0.04 

to 0.22 percent NiO. The serpentines of San Vittore 

(Balangero) contain 0.24 percent NiO; the Bee Barmasse (Champorocher) serpentines contain 0.19 percent NiO. Fenoglio notes an enrichment of nickel 

in the hydrous magnesium silicates. Sundius (1949) 

likewise noted an enrichment of nickel in the hydrous 

magnesium silicates and found that a sample consisting 

chiefly of serpentine contained 0.23 percent NiO and 

0.26 percent Cr2O3 . Minguzzi (1953) studied the inorganic composition of plants grown on the ophiolites 

of Impruneta, Italy, and concluded that the infertility 

of the serpentine soil is due to the presence of nickel, 

chromium, and cobalt. Young, Benfield, and Strachan 

(1954) found that 10 samples of kimberlites from the 

Premier diamond mine, Transvaal, contained 0.003 to 

0.008 percent cobalt and 0.09 to 0.15 percent nickel.

Du Kietz (1956) studied the occurrence of nickel 

in Swedish ultrabasic rocks, both in fresh and serpentinized rocks. He found that the weathering of 

these rocks had been so slight that no secondary 

enrichment of the nickel was observed at or near the 

surface. Earley (1958) noted an increase in the chlorine content of serpentinized dunite over that of dunite 

in the Precambrian dunites from Ontario, Canada, 

"the amount ranging from a few thousandths of a 

percent to several tenths of a percent." HahnWeinheimer (1959) studied the abundance of the 

minor elements in the lens-shaped masses of serpentine 

and eclogite within the Munchberger Gneismasse and 

in the border zone of this mass. For the elements 

chromium, nickel, cobalt, manganese, scandium, vanadium, titanium, barium, strontium, and zirconium, 

she noted that the variation is greater within the 

serpentinites of the border zone than for the centrally 

located serpentinites.

All these scientists agree that the rocks of the ultrabasic suite and their hydrothermally altered forms 

rich in serpentine contain an unusually high concentration of nickel, chromium, cobalt, and scandium. 

Moreover, some of them have observed that the carbonate-rich rocks, in contrast, contain very small to 

practically negligible concentrations of these elements.
THE SERPENTINE-GROUP MINERALS 81

Goldschmidt's (1954) statement on this problem is 

particularly cogent.

In calcareous marine sediments the amounts of nickel and cobalt 

are always exceedingly small, a few parts per million or less, and 

the same is true for dolomite rocks. Special attention has been 

paid by the author and his colleagues to the problem of whether 

nickel is associated with magnesium not only in magmatic rocks, 

but also in the processes leading to the formation of dolomite. 

The question can in general be answered in the negative. In 

nearly all dolomites the amount of nickel is of the order of a very 

few ppm that is, distinctly less than 0.01 percent of the magnesium. This is also true for nickel in hydrothermal dolomites, 

and ankerites and siderites from hydrothermal veins. In such 

veins nickel usually concentrates in the sulphides and arsenides.

MINOR ELEMENTS PRESENT IN THE SERPENTINE 

MINERALS STUDIED

Faust, Murata, and Fahey (1956) showed the relation of the minor-element content of serpentine minerals to their geological origin. The data for these and 

additional samples and a graphical plot of the data for 

eight of the elements are presented here as table 25 and 

figure 42, respectively. The data on these samples are 

given in table 26. Fuller details on the description, 

mineralogic composition and geologic occurrence are to 

be found in the section on "Description of the minerals" 

and elsewhere in the text.

Data are given for 20 elements for many of the 

samples. Consideration of the ionic radii suggests 

that of these elements the following enter octahedral 

sites in the serpentine structure: Nickel, chromium, 

cobalt, scandium, copper, manganese, titanium, zirconium, aluminum (in part), zinc, gallium, and vanadium. Some of the aluminum, the boron, germanium, 

arsenic, and beryllium may be located in the tetrahedrally co-ordinated sites. The enigmas, the alkali 

sodium and the alkaline earths calcium and barium, 

are probably entrapped or absorbed.

A study of the data on the minor elements shows that 

the serpentine minerals derived from ultrabasic rocks 

through deuteric or subsequent hydrothermal replacement (class A) are notably richer in minor elements 

than those derived from various types of metamorphic 

limestones and dolomites, from contact metamorphic 

deposits, and from hydrothermal replacements and 

hydrothermal veins contained in the aforementioned 

types (class B), and that the serpentines of class A are 

characterized by a distinctive suite of minor elements 

(namely, nickel, chromium, cobalt, and scandium) 

present almost always in geochemically significant 

amounts.

Ni

Cr

Co

Cu

Sc

B

Ti

Mn

o !

<

A

o Q0

J

'-1

o

> o <

 °d

L

 '

I

<

1

r:

»

;

A

o

> 0

1

.

A

1 1

o o(

0 <

> 

I

0

S°

:

A

O <

i

1 1 \A

\ '

' °.s

i 0 00

oo 

( 

 1

o

0 

> o 000

o 

 c

k. 1

1 1

0 

. 

o

1 

1 

1

> o 

1 I

1 1 1

I

v

(

 o 

) 

1 1 1

1

>° * 0° 

0 0 

0 '.'

°o c'

(

1

1 1

. 

oo

0 0

(

 «0

1

1 1

1 1 1 

<

o

o

1 1 1

1

 <

o

) O

1

1 1

1

1 1

1 1 1

1 1 1

0.0001 0.0003 0.001 0.003 0.01 0.03 0.1 0.3 0.6 1.0

WEIGHT PERCENT

FIGTJBE 42. Graphical representation of the concentration of some minor elements in the serpentine-group minerals. Triangular index represents sensitivity limit for the 

element. Points to the left of the index are samples in which the element was not detected. Dots represent serpentines associated with ultrabasic rocks. Circles 

represent serpentines from other rock associations.
82 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

TABLE 25. Minor elements in serpentines

[Most of these spectrographic analyses were made by K. J. Murata, and a graph of his data is given in Faust, Murata, and Fahey (1956). Harry Bastron and Harry J. 

Rose supplied additional spectrographic data. Data are given in weight percent for the elements. 0 = looked for but not found; -- = not looked for. Also looked for 

but not found: Ag, Cu, Cd, In, Tl, Sn, Pb, Bi, Te, Pt, Mo, W, Nb, Y, Sb, La, Li, and P]

Ni Cr Co Sc Cu B Mn Ti Zr Al Ca Ba Zn Oe Ga As V Na Be Hg

Class A

[Geological occurrence: formed in ultrabasic rocks]

F-40-- ... 

F-74 ....

F-51 -

F-72_ .... ..

F-73 ....

F-3.. .- 

F-42. -- 

F-43 ....

F-46 . ...

F-l..- ....

F-15 - 

F-19 - 

0.043

.1

.2

.2

.2

.046

.10

.059

.16

.17

.28

.13

.12

.2

.05

.2

.3

.0052

.0062

.0007

.0003

.041

.22

.092

0

.005

.008

.005

.006

.0018

.0037

.0016

.0067

.0070

.0013

.0051

.0068

0

.0001

.0003

.0014

.0017

0

.0002

.0001

.0009

.0009

.0002

.0010

.0002

0. 0024

.001

.002

.002

.0003

.0038

.0004

.0025

.0013

fifiKO

.0047

0 003

.009

.01

.02

.004

.002

.005

flfl^

.003

0

.004

0 049

03

.08

.008

.033

.030

nqo

.081

0"il

0 049

.006

.03

.02

flQO

.0019

.0011

.0037

noq

.0061

0

0

0

0

0

0

0

0

0.40

.76

.65

.29

.17

59

1 9

.58

0.03

.02

08

.03

.01

.01

.01

.07

0.007

^ nnno

<.0009

^ anno

0

001

0

.007

001

.001

0

0

0

0

0

0

0

0

0

-.02

0

0

0

0

0

0

0

0

0

0

0

001

0

0

0

0

0

0

0

0

0

0

0

0

0

0

004

0

0

0

0

0

.006

0

0

0

0

.05

.06

0

.05

0

0

0

.0002

0

0

0

0

0.00005

.00005

.0001

.0001

Class B

[Geological occurrence: formed in various types of metamorphic rocks and in hydrothermal veins]

F-22 - ...

F-20 ....

F-24-. 

F-41. ... ...

F-53

F-66 .... 

F-25 -

F-57. ...

F-23 ....

F-8. - 

F-13 .

F-14.. ........

0

0

0

.0009

.0012

.0008

0

.0007

0

.0010

.0010

0

0.0001

0

0

0

ftftfl9

.0037

.0001

0

0

.0006

0

.0001

0

nni q

0

0

0009

0

0

0001

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0. 0004

0004

0007

.0013

.0005

.0003

.0014

0007

.0012

0008

.0024

0.042

.051

.012

.039

.045

022

.08

.028

.011

.010

.004

.10

noK

i q

.017

1.0

.017

.002

H7q

.004

.0020

.0011

0007

0031

.020

.08

.013

0

nnoq

.0027

0

0

0

.006

0

0

0

003

0

0

0

qi

.12

H4.q

.13

.21

.33

.06

VI

.35

0.05

.01

.01

1.6

.03

.33

.02

.09

.11

.35

.01

0

0

0

.002

0

0

0

0

0

0

0

0

.02

0

0

0

0

0

.02

.03

0

0

0

0

0

0

0

0

0

0

.004

0

0

0

0

0

0

0

0

0

.001

0

0

0

0

0

0

0

0

0

.04

0

0

0

0

003

0

.003

0

0

0

0

0

0

0

0

0

.05

0

.10

0

0

.01

0

0

0

0

0.0002

.0001

0

0

0

0

0

0

0

.0001

0

0.0001

.0001

0

.00009

The characteristic suite nickel, chromium, cobalt, and 

scandium are just those elements which Goldschmidt 

(1954) and Goldschmidt and Peters (1931) have shown 

to be overwhelmingly concentrated in the early crystal 

fractions, rich in magnesium, which accumulate during 

the differentiation of the magma and which under 

suitable chemical and geological conditions may give 

rise to ultrabasic rocks. The minor elements of the 

serpentines of class A thus inherit their distinctive suite 

of elements from their parent ultrabasic rocks.

Goldschmidt (1954) and his colleagues have shown 

that the parent rocks of the class B serpentines, the 

magnesian limestones and dolomite, are unusually low 

in nickel and cobalt. Scandium is likewise generally 

present in negligible amounts in carbonate sediments 

(Rankama and Sahama, 1950) and the same is true for 

chromium.

The concordance between the content of the minor 

elements nickel, cobalt, chromium, and scandium of 

the parent rocks of class A and class B, as determined 

by other scientists and of the values obtained in this 

study from serpentines derived from similar rocks, is 

clear.

A comparison of the average data for the nickel 

content in ultrabasic rocks as determined by other 

scientists and such data as are available for the parent 

rocks of some of the serpentines studied here with the 

data presented in this study for serpentines derived 

from ultrabasic rocks (class A) strongly indicates that

there is no loss of nickel during serpentinization. The 

process of serpentinization is defined here as the formation of serpentine group minerals from preexisting 

magnesian or ferromagnesian minerals by hydrothermal 

solutions. The hydrous magnesium silicates stevensite, 

talc, saponite, and chlorite are commonly part of the 

same paragenetic sequence and they too may contain 

notable quantities of nickel, becoming in some environments nickeloan stevensite, genthite, and pimelite, but 

the total amount of these minerals is generally small 

compared to that of the serpentine-group minerals.

The geochemistry of boron in these serpentine minerals is more complex than that of the other elements. 

Sahama (1945) investigated the boron content of 

dunites and of their serpentinized equivalents and concluded that boron was introduced during serpentinization. The boron content of the serpentine minerals 

reported here ranges from 0.0002 to 0.05 percent and 

there seems to be a tendency for the serpentine minerals of class B to be richer in this element. It is a 

well-known geologic observation that pegmatites of a 

later age than the serpentinized ultrabasic rocks are 

commonly present in close proximity to them, or they 

may actually intrude them. The late-stage hydrothermal solutions associated with these pegmatites, if 

they serpentinize the ultrabasic rocks could easily 

introduce boron into the serpentine thus formed. This 

field relationship between ultrabasic rocks and associated pegmatites places the interpretation of the boron
THE SERPENTINE-GROUP MINERALS 

TABLE 26. Basic data on the serpentine group minerals studied geochemically

83

Sample Locality Mineralogy Geological occurrence

Class A

[Geological origin: formed in ultrabasic rocks]

F-40.

F-74. 

F-51. 

F-72.

F-73. 

F-3_.

F-42. 

F-43.

F-46. 

F-47.

F-15.

9

F-19.

Prairie Creek area of peridotite in T. 8 S., R.

25 W., 2% miles south-southeast of Murfreesboro, Pike County, Ark. 

New Almaden Mine, Santa Clara County,

Calif. 

Nicaro, Orieiite Province, Cuba.____________

Near Almaden Mine, Santa Clara County, 

Calif.

New Forest Hill, Harford County, Md. 

Near Norris, Tenn____________________

Crump's Quarry, Mineral Hill, one-fourth mile

north of state road, about one mile west of

Media, Delaware County, Pa. 

Near Bellows Falls, Windham County, Vt___. 

Tyrol, Austria.___________________________

State Line Pits, Low's Mine, approximately

1.2 miles west-northw.est of Rock Springs,

Cecil County, Md. 

North of Domodossola in Val Antigorio,

Novara Province, Piedmont region, Italy. 

Bare Hills, Baltimore County, Md___________

Clinochrysotile.

Clinochrysotile plus

orthochrysotile. 

.....do.-.-..--.--.

Chrysotile plus lizardite, C > L.

Lizardite plus Clinochrysotile, L > C. 

Lizardite _____________

.do.

Antigorite.

.do.

Antigorite plus chrysotile.

Hydrothermal veins formed through the 

alteration of ultrabasic rocks. Alnoitekimberlite-mica peridotite suite.

Highly sheared serpentine derived from 

Iherzolite. Ultramafic suite.

Hydrothermal alteration of ultrabasic 

rocks. Ultramafic suite.

Completely serpentinized Iherzolite. Ultramafic suite. 

Do.

Hydrothermal alteration of ultrabasic 

rocks. Ultramafic suite.

Hydrothermal alteration of a micaperidotite.

Hydrothermal alteration of ultrabasic 

rocks. Ultramafic suite.

Do. 

Do. 

Do.

Hydrothermal alteration of ultrabasic rock 

(augite-olivine rock), Ultramafic suite.

Hydrothermal alteration of ultrabasic 

rocks. Ultramafic suite.

Class B

[Geological origin: formed in various types of metamorphic rocks and in hydrothermal veins]

F-22_ 

F-20. 

F-24_ 

F-41.

F-53. 

F-56_

F-25. 

F-57. 

F-23.

F-8__ 

F-13. 

F-14.

Turkey Mountain, near Montville, Morris

County, N.J 

Asbestos deposits, Gila County, Ariz_-______.

Montville, Morris County, N.J.

Windous deposit, Currant creek magnesite 

deposits, White Pine County, Nev.

Asbestos deposits, Grand Canyon, Ariz____.

Fifth level, at the shaft, Gouverneur Talc Co., 

Balmat, N.Y.

Montville, Morris County, N.J__________-.

Talcville, St. Lawrence County, N.Y.

Dognacska, 10 kilometers west from Reschitza, Hungary.

Smithfield, Providence County, R.I__________

Tilly Foster iron mine, near Brewster station, 

Putnam County, N.Y.

Pei-wa-kou (and Lao-yeh-ling), Hsiu-yen 

Hsien, Liaoning Province, Manchuria.

Clinochrysotile.

Clinochrysotile (Globetype). 

. do 

.do.

. do 

Clinochrysotile plus

orthochrysotile 

Chrysotile plus lizardite, C > L. 

.....do-----.-------.

Lizardite.

Antigorite _______

Chiefly antigorite. 

. do 

Hydrothermal alteration of diopside in

metamorphosed limestones. 

Hydrothermal vein deposits in limestone.

Hydrothermal vein deposit in metamorphosed limestone.

Hydrothermal replacement of calcareous 

tuffs by magnesium-rich solutions.

Hydrothermal vein deposits in limestone.

Replacement of diopside in a diopsidic, 

calcitic marble.

Hydrothermal alteration of diopside in 

metamorphosed limestone.

Replacement of diopside in a diopsidic 

calcitic marble.

Hydrothermal alteration of ferromagnesian minerals in a contact-metamorphosed limestone.

Hydrothermal alteration of ferromagnesian minerals in metamorphosed limestone beds.

Hydrothermal alteration of ferromagnesian minerals in a contact-metamorphic deposit.

Hydrothermal replacement of ferromagnesian minerals in metamorphosed dolomite of Precambrian age.

content of these serpentine minerals in doubt. In 

order to answer this problem at a given locality, further 

study will be necessary on specimens of known spatial 

relationship with respect to the ultrabasic rocks, the 

pegmatites, and the hydrothermal rocks, which entered 

into this geologic environment.

SOME THEORIES ON THE ORIGIN OF SERPENTINE 

AND SERPENTINE-RICH ROCKS

The field observation that ultrabasic rocks, especially 

the ultramafic suite, alter into serpentine has been 

known for a long time. In those occurrences where the 

olivine could not be easily recognized, the origin of the
84 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO~SiO2-H2O

mineral serpentine and of serpentine-bearing rocks was 

a subject of considerable debate, sometimes quite 

heated. The pseudomorphism of serpentine after olivine, and the chemistry of the process involved, at the 

famous locality in the "Waldes des Hofes Uhlen" in 

Snarum, Modum Canton, Parish of Buskerud, Norway, 

was the subject of vigorous disputation. Here the 

ultrabasic rocks are enclosed as elliptically shaped 

masses in an area of gneisses, granites, mica schists, and 

hornblende schists. Quenstedt (1835, 1836), Bobert 

(1838), Haidinger (1850), Scheerer (1846), and Gustav 

Rose (1851) all participated in the controversy. The 

observations of Quenstedt (1835) and Gustav Rose 

(1851) on the morphology of the serpentine pseudomorphs and Rose's interpretation of Scheerer's chemical 

analysis of this material as a mixture of serpentine and 

olivine dispelled all doubt regarding the preexistence of 

olivine and the derivation of serpentine from ultrabasic 

rocks. Helland (1873) further strengthened the proof. 

A summary of many observations on the origin and 

paragenesis of serpentine is given as chapter 40 in the 

classic reference work on chemical geology by Gustav 

Bischof (1855). Bischof's comment on one statement 

is particularly pertinent to this discussion (p. 422-423) :

V. Buch states that in the dolomite, which occurs as a bed in 

crystalline schistose rocks, near Rothzechau, in Silesia, there are 

veins of serpentine, at the utmost, an inch and a half thick. G. 

Rose is of opinion that in this later instance, the serpentine is a 

product of the alteration of dolomite. Assuming that the dolomite 

contained the silicates of which the serpentine consists, no objection 

can be offered to this veiw. [Italics by authors.]

Bischof's remark shows clearly that he recognized the 

importance of the presence of ferromagnesian silicates 

in the dolomite rock for the formation of serpentine by 

hydro thermal solutions.

T. Sterry Hunt (1859) proposed a new theory of 

origin of serpentine-rich rocks as follows:

In like manner the interstratified serpentines of these regions are 

undoubtedly indigenous rocks resulting from the alteration of 

silico-magnesian sediments, although the attitude of the serpentine in many countries has caused them to be ranked with granites 

and traps, as intrusive rocks.

In his book Hunt (1875, p. 317) states his theory more 

fully, and for the large deposits of serpentine commonly 

associated with hornblende, talc, and chlorite he writes 

that they were formed from: "... the molecular rearrangement of diagenesis of aqueous magnesian sediments, and not from the chemical alteration or eqigenesis 

of erupted plutonic masses." Delesse (1861), apparently unaware of the paper by Hunt, likewise advanced 

the theory that the magnesian rocks were formed by 

the recrystallization of sepiolites or "magnesian clays" 

in the sedimentary rocks into serpentine, talc, and 

chlorite. If the magnesian clay is rich in silica, talc 

will form; if it is poor in silica, serpentine will form, and

if alumina and iron oxides are sufficiently abundant in 

the magnesian clay, chlorite will form. Some of Hunt's 

views were sharply contested by James D. Dana (1872). 

For nearly a hundred years, these theories of T. 

Sterry Hunt, Delesse, and others have lain essentially 

dormant. The occurrence of serpentine in ultrabasic 

rocks and as replacement or vein deposits in carbonate 

rocks has been well established by both field and laboratory studies. Save for the paper on the serpentines 

of the Pyrenees by Michel Longchambon (1912), who 

proposed that "basic" and ultrabasic rocks in the 

Pyrenees were formed according to the following 

equation by the process of assimilation,

granitic magma + dolomite * CO2 + basic magnesium 

silicates + pegmatites ("fumeroles"),

almost all have agreed to a magmatic origin for ultrabasic rocks. With the development of another school 

of thought in petrology based on the principal that solid 

diffusion is probably a dominant mechanism in petrology, the old theories of T. Sterry Hunt and Delesse have 

been rejuvenated with an injection of a "dry elixir." A 

recent summary of the work of those scientists maintaining these views is given by Henri and Genevi&ve Termier 

(1956) in their book "L'e" volution de la lithosph&re, v. 1, 

Petroge"nese," p. 398:

The formation by metasomatism of basic and ultrabasic rocks 

starting with dolomitic limestones, as one can infer from the preceding considerations seems proved in several ways Kabylie de 

Collo (Roubault), Sud de 1'Espagne (Van Bemmelen), Pyrenees 

(Longchambon), ,Groenland (S0rensen), monzonites (Ogilvie 

Gordon).

Ramberg (1952) attempts to explain the occurrence of 

dunitic (or ultrabasic) masses in gneisses by the process 

of "basification"; he writes 

Within the zones of metamorphism where quartzo-feldspathization takes place, basification appears to be a rather local and 

small-scale phenomenon, in agreement with the reasonable conclusion that calco-ferromagnesian elements are less mobile in 

ordinary rocks than are granitic elements. Along growing pegmatites, calco-ferromagnesian minerals may concentrate (fig. 

120), and inclusions or remnants in metasomatic granites may be 

basified. The Mg-Al metasomatism creating cordierite-anthophyllite rocks may also represent a facies of basification (Bugge, 

1943). Several authors have reported field observations indicating that dunitic bodies have grown by Mg metasomatism of 

dolomites or limestones. Relationships between small dunitic 

bodies and amphibolites in gneisses from West Greenland are 

interpreted as if the ultrabasites formed by extraction of Ca, Al, 

Na, and Si from common amphibolites (unpublished observations 

by the writer). The latter are but small-scale processes.

That olivines do form in small clots in metamorphosed 

dolomites and impure marbles is, of course, a matter of 

petrologic observation, but the extension of this theory 

to explain a body of olivine the size of a dunitic mass is 

a totally unjustified extrapolation. Moreover, the
THE SERPENTINE-GEOTJP MINERALS 85

geologic setting is not that characteristic of the alpine 

type. Hess (1955, p. 401-402) has emphasized the observation that

The serpentines are most abundant along the margins of the 

alpine systems where the deformation has not been intense. 

They form extensive concordant sills in low-dipping sedimentary 

rock-shales, graywackes, sandstones and phyllites.

As observed today, these are the ultrabasic masses, 

sometimes completely altered to serpentine, as at 

Snarum, Norway, occurring within granitic gneisses and 

schists. The serpentines of such rocks are characterized by the suite of minor elements, nickel, cobalt, 

chromium, and scandium, whereas the serpentines derived from the forsterites of metamorphosed dolomites, 

will be totally lacking in these elements, or contain some 

of them in negligible amounts.

MINOR ELEMENTS IN SERPENTINE MINERALS AS 

PETROLOGICAL INDICATORS

Our studies of the minor elements in the serpentine 

minerals differentiate between serpentine derived from 

the alteration of ultrabasic rocks and serpentine formed 

in the metamorphosed dolomites and limestones. The 

ability to do this may be of much help in unraveling the 

history of rocks which have passed through one or more 

facies change or have been altered by hydrothermal 

solutions.

Ultrabasic rocks are very commonly the source rocks 

of serpentines and their serpentinization commonly takes 

place in more than one stage. The sequence of serpentinization given by Du Rietz (1935) for the Caledonian 

ultrabasic rocks of Sweden is typical of many other areas 

in the world. In Sweden the ultrabasic rocks occur as 

lens-shaped bodies, a little less than a kilometer in 

length, enclosed conformably within folded sedimentary 

rocks. The simplest sequence of serpentinization is 

(1) during intrusion, (2) during folding, and (3) during 

regional metamorphism when the ultrabasic rocks are 

invaded by granites and pegmatites. Stage (1) may 

range from a very minor effect to a major process. 

Host (1949) describes the serpentine-gabbro occurrence 

of Wurlitz, Germany. On the basis of petrographic 

and chemical studies, he concludes that the original 

rocks were an ultramafic suite consisting of peridotite, 

wehrlite, gabbro, and plagioclasite. Metamorphism 

took place in several stages. The olivine was serpentinized; the plagioclase saussuritized. Subsequently 

tremolite and chlorite were formed. The last stage is 

represented by the action of granite intrusions which 

caused the formation.of garnet and idocrase. Host 

gives spectrographic data on nickel, cobalt, manganese, 

chromium, scandium, vanadium, and titanium. It will 

be observed that his minor-element data are in accord 

with our observations that such serpentines as were

formed have been derived from ultrabasic rocks. The 

studies by Hahn-Weinheimer (1959, 1961) on the serpentines of the Mtinchberger gneismasse likewise support the conclusions that their minor-element content 

indicates their derivation from ultrabasic rocks. Lundegardh (1949) concluded from spectrographic studies 

that the trace elements nickel, cobalt, chromium, and 

zinc are immobile during palingenesis.

Serpentines formed in metamorphosed limestones and 

dolomites and contact-metamorphic deposits and as 

hydrothermal veins may also have been formed in more 

than one stage. Where replacement of ferromagnesian 

minerals has taken place, it is not uncommon to find 

in addition to the pseudomorphs lenses, pods, and 

small veins of serpentine, which have derived their constituents from the preexisting minerals and which probably formed as a result of the increase in bulk volume 

during serpentinization. Merrill (1888) has described 

such a replacement of diopside in massive dolomite at 

Turkey Mountain, Montville, N.J., with the formation 

of nodules of serpentine and, to a lesser extent, of small 

seams and veins of serpentine. Our minor-element 

studies of this serpentine show either absence of or a 

very low concentration of nickel, cobalt, chromium, 

and scandium.

Solutions rich in magnesium may be derived by the 

dedolomitization of dolomites, brucite marbles, predazzite and pencatite (Faust, 1949). Serpentine deposited 

from such solutions will contain a suite of minor elements that is typical of serpentine of class B. Faust 

and Callaghan (1948) described serpentine occurring 

with magnesite in deposits which were formed in the 

replacement of calcareous tuffs by hydrothermal solutions rich in magnesium and carbon dioxide. The suite 

of minor elements in a sample of the serpentine mineral, 

F-41, shows that it is not related to the serpentine from 

ultrabasic rocks but belongs to our class B serpentine. 

Our studies on the minor elements in class B serpentine 

lend no support to the views of T. Sterry Hunt and 

Delesse of the early school, or to those of Roubault and 

others of the later school, that ultrabasic rocks are produced by metamorphism from magnesian limestones, 

dolomites, or other magnesian sedimentary rocks.

Since the publication of the paper by Faust, Murata, 

and Fahey (1956) a study of the serpentine derived from 

the peridotite of di Germagnano in the Val di Lanzo, 

Italy, by Rigault (1958) has been made. Nickel and 

chromium were determined to be present by quantitative chemical analysis. Spectrographic examination 

revealed the presence of scandium and cobalt. Hill 

(1958) used the minor-element data for the nickel, 

chromium, and cobalt content of the schistose serpentinite at Minas Carlota, Cuba, in judging its igneous 

origin. He concluded on the basis of the various data
86 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O

that the schistose serpentine was derived from gabbro 

and microgabbro.

The chemical analyses of the serpentine minerals of 

class A (table 2) and class B (table 3) show a greater 

concentration of FeO, Fe2O3, and A12O3 in those of class 

A. The values are as follows: Class A, average of 11 

selected analyses, FeO = 1.40 percent, Fe2O3 = 2.56 

percent, A12O3 = 1.18 percent; class B, average of 10 

selected analyses, FeO = 0.34 percent, Fe2O3 = 0.49 

percent, and A12O3 = 0.44 percent. As a result of the 

greater concentration of the iron oxides (and alumina) 

in class A serpentine minerals, their color is generally 

darker than those of class B. Low-iron serpentine minerals are likely to be found among those of class B which 

are derived from the alteration of low-iron olivines and 

pyroxenes. Class B serpentine forming in hydro thermal deposits with sulfides would likely be low-iron 

serpentine because the distribution coefficient of iron 

between silicates and sulfides would appear to favor the 

sulfides over the silicates. The color of most of the 

analyzed specimens is given in the section on the 

"Description of the minerals." The few exceptions to 

the generalization on color in class A are minerals 

labelled deweylite, and they probably represent later 

generation of serpentine-group minerals than the darker 

colored varieties.

TABLE 27. Geographic finding list for description of specimens

used in this study

Locality Specimen 

Austria:

Tyrol. ________________________________________ F-47

Canada:

Quebec Province: Thetford________ F-60, F-61, F-70

Cuba:

Oriente Province:

Moa_.______________________________________ F-50

Nicaro ________________________________________ F-51

Dutch New Guinea:

Hollandia: Cyclops Mountains.__________________ F-66

Hungary: Dognacska, now Dognecea, Rumania________- F-23

Italy:

Novara Province: Val Antigorio. ___-__.___F-15, F-67 

Manchuria__ _ ______________________________________ F-14

Norway: Snarum___________________________________ F-71

United States: 

Arizona:

Coconino County: Grand Canyon____________ F-53

Gila County__.__________________F-20, F-20A

Arkansas:

Pike County: Murfreesboro._________________ F-40

California:

San Benito County: Canyon of Clear Creek___ F-58 

Santa Clara County: New Almaden mine _ F-72, F-73,

F-74 

Maryland:

Baltimore County: Bare Hills.________________ F-19

Harford County: Forest Hill___-___________ F-3

Nevada:

White Pine County: Currant Creek.___________ F-41

TABLE 27. Geographic finding list for description of specimens

used in this study Continued

Locality Specimen 

United States Continued 

New Jersey :

Hudson County: Hoboken_. _______ _____F-75, F-76

Morris County: Montville___ F-22, F-24, F-25, F-64 

New Mexico :

Organ Mountains ___________________________ F-65

New York:

Putnam County : Brewster Station. _ __________ F-13

Richmond County: Staten Island- ____________ F-63

St. Lawrence County:

Balmat-_-_-_-__.__-_- ----------------- F-56

Talcville____ ___________________________ F-57

North Carolina :

Jackson County: Webster ___ _______________ F-69

Mitchell County: Bakersville_________________ F-48

Pennsylvania:

Chester County: Sylmar ___ ________________ F-52

Delaware County : Mineral Hill _ ____________ F-43

Lancaster County:

Low's mine __ ________._-___--__--_____ F-l

Texas. -_-__________-_-----------_----- F-26

Wood's chrome mine______ _ _____F-45, F-49

Northampton County: Easton. ______________ F-68

Rhode Island:

Providence County: Smithfield. ______________ F-8

Tennessee:

Union County: Norris____ ____.-___-_-_-_-_-_ F-42

Vermont :

Windham County: Bellows Falls _ ___________ F-46

TABLE 28. Geographic finding list for chemical analyses taken

from the literature Analysis

Locality No. 

Afghanistan. __ _ ____________________________________ 150

Australia. _________________________________________ 54

Austria:

Tyrol. -_-_-------.--___-__-_-------_---------_- 11

Other. _____ _ __-_______--_________--__ _ _ _ 44

Canada:

British Columbia. ______________________________ 80

Quebec. _ 42, 53, 87, 97, 101, 192, 200, 202, 203, 206, 212, 

217, 222, 225, 228 

Thetford -_______-___-- 89, 94, 115, 134, 196, 229

--_-------------__---------- --------------- 126

Cuba-. ._.----_-___.---_--__------_----_--_------- 214

Cyprus. __________---_-_-_____-_-_---------__-----_ 76

Czechoslovakia. ________________ __ 40, 83, 124, 131, 154, 185

Finland _------_-----_------___--_----- 100, 113, 128, 226

France_---___-----_-----_---------_---_---- 6, 17, 148, 204

Germany:

Hesse-Nassau. -----___-_ _ .__.____.__-__ 138, 172, 182

Saxony. _______________-._______-_.--_---______ 187

Waldheim__. -..____._____--.__--__-------- 2, 13

Other--__-_-_-_-________--_____---_- 197, 255, 256, 257

Great Britain:

Lizard __--____-___._---____-_----- 32, 60, 77, 82, 146

Shetland Island _________________ ___. 33, 72, 112

Italy:

Tyrol-------_------_-_-__-------------------- 10, 137

Val Antigorio. -_.__. __________________ 15,20,25,30,78

Val d'Aosta--------.____--_-_--_-_-_------ 43, 190, 191

Villa Rosa---_-----___--_-_-----_-------------- 29

Other. _---_-----_-_______---_-__-----_-- 205,244,245
THE SERPENTINE-GROUP MINERALS 87

TABLE 28. Geographic finding list for chemical analyses taken 

from the literature Continued

Locality No. 

Kashmir__ _-_-_-----_____---_-___________________ 218

Madagascar_____-----_-_--___________________ 5, 149, 178

New Caledonia_______-_-----_________________ 165, 171, 176

New Zealand____________________________________ 49, 163

Norway: Snarum____________ 47, 62, 90, 114, 116, 221, 227, 243

U.S.S.R.:

Caucasus._____________________________________ 3, 175

Urals___--_-------_-___________________________ 79

Uzbek_______________________________________ 238,239

Silesia__ _____________________________________ 1,61,71, 152

Southern Rhodesia_._.______ 14, 28, 35, 37, 67, 84, 111, 129, 210

Sweden__---__--_-----_-----.____________ 127, 136, 162, 237

Switzerland....._____________ 12, 50, 63, 96, 132, 133, 199, 207

Union of South Africa:

TransvaaL__.____ 16, 18, 19, 21, 45, 66, 75, 86, 121, 164, 180

United States: 

Arizona:

Gila County----_-_--_________,___________ 250, 251

Globe_-_______._____________ 246, 247, 248, 249

California:

New Idria.________________________________ 41

Sulphur Bank..--____-___.._.___.____._____ 38, 92

Connecticut..._ _---__--__-_________-___________ 161

Maryland:

Bare Hills...___-_-_.-._____--______..____ 31, 159

Massachusetts___________________________ 98, 139, 259

Montana ______________________________________ 145

New Jersey:

Franklin______._,_.________ 147, 215, 240, 241, 242

Hoboken. _______________________________ 125,220

Montville.__-.___-_ 27, 48, 52, 64, 68, 70, 194, 258, 260 

New York:

Aboutville--__-----.____.__________________ 88, 91

Brewster Station______________ 39, 73, 81, 93, 102, 213

Orange County_-_____________________--_- 235,236

Port Henry-----_-_-_____________--__-____- 36

North Carolina...._-_---_______._____________ 130, 261

Pennsylvania:

Berks County________________ 170, 181, 193, 198, 219

Chester County.. _____________ 95, 110, 157, 177, 179

Delaware County_.-._______ 65, 69, 140, 151, 155, 166

Lancaster County:

Low's mine______.____________.__ 158, 183, 201

Texas---------____________ 34,85, 156, 173, 174

Wood's chrome mine___-________-_--___- 153

Lebanon County: Corn wall. _________________ 135

Montgomery County________________________ 186

Northampton County:

Easton.______ 4, 26, 46, 99, 122, 123, 160, 195, 216

Rhode Island___________________________ 208, 209, 211

Venezuela_______________________________________ 51, 120

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