Solution Studies of 

Chrysotile, Lizardite 

and Antigorite

GEOLOGICAL SURVEY PROFESSIONAL PAPER 384-B
Solution Studies of 

Chrysotile, Lizardite 

and Antigorite

By GEORGE T. FAUST and BARTHOLOMEW S. NAGY

STUDIES OF THE NATURAL PHASES IN THE SYSTEM 

MgO-SiO2 -H2 O AND THE SYSTEMS CONTAINING THE 

CONGENERS OF MAGNESIUM

GEOLOGICAL SURVEY PROFESSIONAL PAPER 384-B

Revaluation of the differential 

solution method for 

serpentine-group minerals

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

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

Washington, D.C. 20402 - Price 20 cents (paper cover)
CONTENTS

Abstract- _ _ ___________________________

Introduction ____________________________

Early investigations-_________________

Recent studies.______________________

Acknowledgments__ _ _______________

Reexamination of serpentine-group minerals. 

The solution process.__________________

Page 

93 

93

93

94

94

95

99

	Page

Critical examination of the experimental procedures..--- 99

Description of the material selected for study. _____ 99

Qualitative examination.________________________ 100

Quantitative examination________________________ 100

Conclusion.____________________________---_---_---_ 101

Literature cited__________-_---__---__-----__-------- 105

ILLUSTRATIONS

FIGURE 43. Tracings of X-ray diffractometer patterns of the (002) reflections of natural and IN hydrochloric acid treated

specimens of serpentine-group minerals from Quebec, New Jersey, and Cuba _____________________________ 96

44. Photomicrographs of serpentine-group minerals similar to some of those studied in this research and illustrating

the complexity of the mixtures-__-_-_-_-_-_-_-_-___---_---_--__---_--------------------_----------- 98

45. A graphic representation of a selected portion of the X-ray powder diffraction pattern of a natural mixture of

lizardite and clinochrysotile from Snarum, Modum Canton, Parish of Buskerud, Norway ___________________ 100

46. Tracings of X-ray diffractometer patterns of the (002) reflections of natural and IN hydrochloric acid treated

specimens of serpentine-group minerals from Norway, California, Maryland, and England.________________ 102

TABLES

Page 

TABLE 1. Chemical studies of serpentine-group minerals by Clarke and Schneider (1890)____________________________ 94

2. X-ray diffraction studies of some serpentine-group minerals previously examined by Nagy and Faust (1956) _ _ _ 95

3. Effect of treatment with cold dilute hydrochloric acid for 1 hour on the appearance of selected lines in the X-ray

powder diffraction pattern of clinochrysotile__________________________________________________________ 101

4. X-ray diffraction studies of acid-treated lizardite and mixtures of chrysotile and lizardite____________________ 101

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

OF MAGNESIUM

SOLUTION STUDIES OF CHRYSOTILE, LIZARDITE, AND ANTIGORITE

By GEOBGE T. FAUST and BABTHOLOMEW S. NAGY X

ABSTRACT

A reevaluation of the differential-solution method for discriminating among chrysotile, lizardite, and antigorite was made 

in the light of the studies reported by E. J. W. Whittaker and 

Jack Zussman in 1958. The solvent used is IN hydrochloric 

acid. The stability of lizardite under the conditions of tae test 

was reaffirmed and accordingly five of the samples previously 

studied by Nagy and Faust in 1956 were reexamined for lizardite. The method was critically examined both qualitatively and 

quantitatively on four natural admixtures of clinochrysotile 

and lizardite and on the lizardite from the type locality, Kennack Cove, The Lizard, Cornwall, England. The solution test 

differentiates quantitatively between chrys>otile and the pair of 

platy phases lizardite-antigorite. The identity of the platy 

phase must 'be determined by X-ray methods. Early work on 

solution studies of serpentine-group minerals is reviewed and 

interpreted.

INTRODUCTION

EARLY INVESTIGATIONS

The use of solution and solubility studies as an aid 

in the identification of minerals has had a long and successful qualitative application in blowpipe analysis and 

chemical mineralogy. Mineral chemists of an earlier 

period also made quantitative studies of the effects of 

acids, alkalies, and salt solutions on minerals. Typical 

of such studies was the work of Clarke and Schneider 

(1890). These scientists made a particular study of the 

solution and decomposition relations of a group of magnesium silicates olivine, talc, serpentine, chlorite, vermiculite, and phlogopite. Their work on the serpentine-group minerals is of special interest to us.

They investigated the stability relations of the serpentine-group minerals under the following conditions: 

1. Heating the mineral in dry gaseous hydrochloric 

acid at 383°-412°C for periods ranging from 41 

to 78 hours, and at 498°-527°C for 18 hours.

1 School of Science and Engineering, University of California, San 

Diego, La Jolla, Calif.

2. Heating the mineral in aqueous hydrochloric acid, 

1.12 specific gravity (7.32^), to dryness, extracting 

with weak acid, and weighing the residue. (The 

temperature reached in the vessel over the steambath was approximately 90 °C and the evaporation probably required about 1 or 2 hours.)

3. Treating the sample as in 2 but using weak hydrochloric acid as the solvent.

The five specimens studied were:

A, Dull green serpentine (alteration product of pyroxene) from Montville, Morris County, N".J.

B, Dark-green serpentine from the well-known locality at Newburyport, Mass.

C, Silky, fibrous chrysotile from Montville, KJ.

D, Grayish-green picrolite from Buck Creek, N.C.

E, A grayish-green serpentine from Corundum Hill, 

N.C.

Our studies on similar materials from these localities

suggest the following identifications:

A, Chiefly lizardite, with some chrysotile.

C, Chiefly chrysotile, possibly with some lizardite.

D, Chiefly antigorite, with some chrysotile.

Clarke and Schneider's data and our interpretations

thereof are summarized in table 1.

Bearing in mind the experimental conditions the 

strength of the acid, the duration of the heating process, 

and the subsequent extraction of the decomposed residue by weak acid the results of these experiments do 

show a pattern of stability. The data obtained using 

very dilute hydrochloric acid indicate that specimen D, 

chiefly antigorite, is the most stable sample. The stability of sample A, lizardite, is also indicated. The results of the stability test in which the sample is heated 

in dry gaseous hydrochloric acid suggests that the fibrous structure of the chrysotile, sample C, may actually increase the resistance of the mineral to chemical

93
94 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O 

TABLE 1. Chemical studies of serpentine-group minerals by Clarke and Schneider (1890)

Mineral sample

A. Dull green serpentine, 

Montville, Morris 

County, N.J. 

B. Dark-green serpentine, 

Newburyport, Essex 

County, Mass. 

C. Silky, fibrous chrysotile 

Montville, Morris 

County, N.J.

D. Grayish-green picrolite, 

Culakenee mine, Buck 

Creek, Clay County, 

N.C. 

E. Grayish-green serpentine, 

Corundum Hill, Macon 

County, N.C.

Interpretation of Faust and Nagy

Chiefly lizardite, with 

some chrysotile.

(2)

Chiefly chrysotile, but 

some lizardite. (See 

also Nagy and Faust, 

1956, p. 828, fig. 4.) 

Chiefly antigorite, with 

some chrysotile.

Result of heating sample in dry, gaseous 

HC1 at 

383M12°C

MgO 

extracted 

(percent)

10. 14 

16.73

9.98

11.38 

15.25

Time 

(hours)

54 

68 

54

78 

41

498°-527°C

MgO 

extracted 

(percent)

10.83 

14.28

Time 

(hours)

18 

18

Result of heating sample in 7.32 7VHC1 at 

about 90°C to dryness followed by treatment 

with 

Dilute HC1 1

Completely 

decomposed.

_____do.______--

___-_do_-_-.__-_

_____do_____-__-

_____do_-___ 

Very dilute HU1 '

Partially decomposed.

Do.

Partially decomposed; 

most stable.

1 Not defined by the authors; based on the value of 7.327V given above, the dilute 

HC1 was probably 3.67V (1 :1) and the very dilute HC1 0.7N (1 :10) (W. T. Schaller, 

oral commun. 1964).

attack from vapor phase reactions by armoring it with a 

less pervious coating of silica.

Solution studies of the stability of serpentine-group 

minerals in hydrochloric acid, bromine, ammonium 

chloride solution, acetic acid, potassium hydroxide 

solution, and sodium carbonate solutions were made by 

Lindner (1893). He repeated the work of Clarke and 

Schneider (1890) in an attempt to determine the structural formulas of these minerals. Terreil (1885) noted 

that in boiling acids the compact serpentine rocks decompose slowly, the lamellar and fibrous varieties, more 

rapidly, and the finely fibrous chrysotiles from Canada 

and the Tyrol, almost immediately.

RECENT STUDIES

Nagy and Bates (1952) made preliminary studies of 

the stability of chrysotile asbestos. This work was further refined and standardized by Nagy (1953). Using 

purified sample materials a chrysotile from Thetford, 

Quebec, and an antigorite from Val Antigorio, Italy 

a solution test was devised which differentiated between the two minerals on the basis of their resistance 

to acid treatment. The specimens were placed in IN 

hydrochloric acid, and the temperature was held at 

95 °C for 1 hour. Chrysotile was decomposed by 

this treatment, and antigorite was unaffected. The 

destruction of the crystal structure of chrysotile by hydrochloric acid was measured by means of the X-ray 

diffractometer using the intensity of the (002) reflection 

at 20=12.02°± (Cu/Ka=1.5418 A Ni filtered) as a 

standard.

2 Selfridge (1936) examined similar material, and his data suggests lizardite probably 

admixed with chrysotile.

The method was then applied to a suite of serpentinegroup minerals, and the results were reported by Nagy 

and Faust (1956). The results of the solution tests 

were interpreted on the basis of chrysotile and antigorite being the only phases present. Chief reliance 

was placed on the electron microscope examinations of 

the specimens studied which showed two types of material; one fibrous (tubular), the other irregular or 

flaky.

Whittaker and Zussman (1958) questioned the reliability of the interpretation that all flaky particles are 

antigorite and showed that the polymorph lizardite, 

which has a platy structure, could have been easily mistaken, in some of the samples, for antigorite. They 

further investigated the solution behavior of one of 

their specimens of lizardite under the identical conditions used by Nagy and Faust (1956) and found that 

its powder diffraction pattern is only slightly weakened. (Treatment with somewhat stronger acid destroys the lizardite structure while still not affecting 

that of antigorite.)

ACKNOWLEDGMENTS

We wish to acknowledge the help of Brian J. Skinner 

and Dora von Limbach, both of the U.S. Geological 

Survey, who prepared the diffractometer patterns for 

this study. Professors Thomas F. Bates and O. F. 

Tuttle of the Department of Mineralogy, Pennsylvania 

State University, very kindly arranged to have us supplied with fragments of the minerals from the Frederick A. Genth Collection, which are similar to those
SOLUTION STUDIES OF CHRYSOTILE, LIZARDITE, AND ANTIGORITE 95

previously studied at that institution. Dr. George 

Switzer, Curator of Mineral Sciences. U.S. National 

Museum, supplied us with a specimen of lizardite from 

the type locality at The Lizard, Cornwall, England.

REEXAMINAT1ON OF SERPENTINE-GROUP MINERALS

Recognizing the validity of the doubts expressed by 

Whittaker and Zussman (1958), we have reexamined 

some of the samples studied previously and have found 

that some of the flaky and platy phases actually are 

lizardite and not antigorite.

We have used X-ray powder diffraction methods to 

examine five of the specimens on which we previously 

reported and which we considered, on the basis of the 

studies of Whittaker and Zussman (1958), to contain 

lizardite. The data are given in table 2 and figure 43. 

The specimens studied here were taken from the same 

hand specimen as the previously studied samples, but 

they are not necessarily identical. All samples examined with the X-ray diffractometer were prepared 

as smear mounts on glass.

Photomicrographs of serpentine-group minerals 

similar to those studied previously by Nagy and Faust 

(1956) and reinvestigated in this study are shown in 

figure 44. The photomicrographs illustrate the structural complexity of the natural mixtures. Material

that exhibits a smearlike appearance and stringy 

character yields X-ray powder diffraction patterns 

having broad and diffuse bands and lines.

The original specimens used in the previous study 

by Nagy and Faust (1956) were taken from the Genth 

Collection at the College of Mineral Industries, Pennsylvania State University. Professor O. F. Tuttle of 

the Department of Mineralogy very kindly arranged to 

have these specimens resampled for us. Representative, but not necessarily identical, samples were obtained 

for four of the minerals. We were unable, however, 

to get sufficiently pure specimens of No. 14, aphrodite 

from Grenville, Canada, which contained calcite, talc, 

and probably a trace of clinochrysotile, and of No. 16, 

marmolite from Blandford, Mass., which contained 

magnesite, chlorite, and quartz.

We have added the data on the clinochrysotile from 

Thetford, Canada, to table 2 to record the absence of 

both antigorite and lizardite from this sample.

The data in table 2 show that an unequivocal determination of the polymorph which constitutes the platy 

phase in these natural admixtures is necessary for the 

interpretation of the results of the solution study. The 

differences between some of the quantitative results obtained in the two studies can be explained only by the 

demonstrated heterogeneous nature of the hand 

specimens.

TABLE 2. X-ray diffraction studies of some serpentine-group minerals previously examined by Nagy and Faust (1956)

Sample

3 _____

4__ ______

7_______.

9________

10 ____

Sample label

Porcellophite, 

Pa. State Univ. 

No. 481.36. 

Chrysotile__

Marmolite, 

Pa. State Univ. 

No. 481.63. 

Antillite, 

Pa. State Univ. 

No. 481.25. 

Antillite, 

Pa. State Univ. 

No. 481.26. 

Chrysotile

Locality

Coleraine Township, 

Megantic County, 

Quebec, Canada. 

Near Montville, 

Morris County, N.J.

Castle Point, Hoboken, Hudson 

County, N.J. 

Havana, Havana 

Province, Cuba.

-___do-----------

Near Thetford, 

Megantic County, 

Quebec, Canada.

Physical character

Fibrous (see 

Nagy and 

Faust, 1956, 

fig. 4, p. 828).

Massive (showing 

a few flakes) .

-___ _do -

White bundles of 

fibers.

X-ray determination

Mineralogy of 

untreated sample

Lizardite, chrysotile and dolomite. 

Chrysotile and 

lizardite.

Lizardite and 

Chrysotile.

_____do-------

do.1 _-_-_-_--

Clinochrysotile 

and a little 

magnetite.

Mineralogy of 

acid-treated sample

Lizardite _

___--do__-____-__

__-_do _-

_____do_---_--_--_

___--do_-___---_-_

Dehydrated silica 

gel with a few 

protected fibers 

of clinochrysotile in the 

larger bundles.2

Lizardite 

content 

(percent) 

(remainder is 

Chrysotile)

48 

50

23 

56 

46 

0

Weak lines at 2.10 A± and 1.61 A± suggest corundum. 2 Trace of clinochrysotile indicated by faint lines of the (002) and (004) reflections.
UNITS) (ARBITRARY INTENSITY 

33

- w 2 

^ <* 2 

in Q) ~' 

o5'S

UNITS) (ARBITRARY INTENSITY 

96 HHi IVHIliVN SHSVHd MI HHi 
60

Lizardite plus chrysotile (labeled antillite) 

from Havana, Havana Province, Cuba, 

West Indies. Pa. State Univ. No. 481.25; 

Nagy and Faust No. 9

50 - 40

OL

a: 5 30QL

tCO

20 -

10

60

50

40

£30 <

Lizardite plus chrysotile (labeled antillite) from'Havana, Havana Province, 

Cuba, West Indies. Pa. State Univ. No. 

481.26; Nagy and Faust No. 10

20 - 10 - 10° 12°

26

TREATED

14° 10° 12°

26

UNTREATED

14° 10° 12°

26

TREATED

14° 10° 12°

26

UNTREATED

14°

3 

S

02

OH

M

F 

H

N t>

ga

H

FIGUKE 43. Tracings of X-ray diffractometer patterns of the (002) reflections of natural and IN hydrochloric acid treated specimens of serpentine-group minerals.
98 STUDIES OF THE NATURAL PHASES IN THE SYSTEM MgO-SiO2-H2O
SOLUTION STUDIES OF CHBYSOTILE, LIZARDITE,' AND ANTIGORITE 99

THE SOLUTION PROCESS

The extent of the reaction between hydrochloric acid 

and the serpentine-group minerals depends on the following factors:

Concentration of the acid. In their studies, Clarke 

and Schneider (1890) and others noted that too strong 

a concentration may cause such rapid attack as to armor 

the undecomposed material with silica and thus effectively remove it from reaction. An acid concentration 

that is too weak, however, requires inordinate time for 

the reaction process. Nagy and Bates (1952) and Nagy 

(1953) found that IN hydrochloric acid was suitably 

concentrated.

Temperature of the reaction. Nagy and Bates (1952) 

and Nagy (1953) found that 95°±1°C was a suitable 

and convenient temperature, and that it permitted the 

reaction to proceed at a speed sufficient for a practical 

laboratory test.

Duration of the chemical process. Nagy and Bates 

(1952), Bates (1952), and Nagy ,(1953) found, by trial 

and error, that 1 hour was an optimum time limit. This 

was confirmed in the present investigation. If the 

sample, consisting only of serpentine-group minerals, is 

attacked by the acid, the color of the solution at the end 

of the run will in general be greenish yellow because of 

the entry of iron and other ions into the solution.

Grain size. The differential solution rate of the serpentine-group minerals is strictly valid only if the 

specific areas of the samples are similar. Nagy and 

Bates (1952) measured the surface area of the chrysotile from Thetford, Quebec, and the antigorite from 

Val Antigorio, Italy, using the Brunauer-EmmettTeller gas adsorption method and found the values to 

be 7.24 m2 per g and 11.40 m2 per g, respectively. These 

were the standard samples used in their original work. 

In the present study most of the samples were ground 

to pass 65-mesh bolting cloth. We tested, for several 

samples, the nature of the residue left after the acid 

treatment to see if texture or intimacy of association 

in the natural admixtures perceptibly slowed down the 

decomposition of the chrysotile. We did not find any 

significant evidence of such behavior. Microscopic, 

X-ray powder diffraction, or differential thermal analysis methods can be used to confirm such a relationship 

if there is any suspicion that textural control fortuitously protects the chrysotile from attack. Differential 

thermal analysis and X-ray studies by Nagy (1953) 

have also shown the efficacy of the acid attack. That 

very small amounts of chrysotile may be protected from 

reaction is always a possibility, and when realized it 

means that the solution value for chrysotile is minimal.

The solution method is independent of the common 

impurities in serpentines because it is specifically adjusted to bring about the destruction of the clinochrysotile structure. Thus brucite, stevensite, the carbonates, 

and talc do not interfere because there is no coincidence 

with the (002) spacing of chrysotile at 7.36 A. If a 

member of the 14 A chlorite group is present as an 

impurity, a correction may have to be made to the area 

at the base of the (002) peak on the high-angle side. 

The pyrogenic minerals olivine, enstatite, and magnetite also do not interfere with X-ray measurements. 

Some of these impurities, if present with either the 

chrysotile-lizardite assemblage or the chrysotile-antigorite assemblage, may, however, because of their 

solubility, help to color the acid solution so that even 

if the attack on the antigorite or lizardite is slight, the 

color of the solution may be misleading.

The solution process is differential, and therefore it 

is necessary to recognize the fact that lizardite and 

antigorite are also slightly attacked by the acid solution, 

particularly in the exceedingly fine grain sizes, whereas 

the crystal structure of the chrysotile is completely 

destroyed. It is this disparity in stability that makes 

the method practical.

CRITICAL EXAMINATION OF THE EXPERIMENTAL 

PROCEDURES

DESCRIPTION OF THE MATERIAL SELECTED 

FOR STUDY

To check on the stability of lizardite we used a specimen from the type locality, Kennack Cove, Cornwall, 

England (U.S. Natl. Mus. No. 114569). This sample 

contains about 5-10 percent talc. To prepare the lizardite for study it was gently crushed, inspected under 

the binocular microscope so that obvious grains of impurities could be removed, and then sieved through 65- 

mesh bolting cloth. Most of the sample consists of 

pseudohexagonal plates. A diffractometer trace of 

this sample shows a peak for talc at 9.3 A.

Four mixtures of the polymorphs lizardite and clinochrysotile were examined qualitatively, quantitatively,

FIGURE 44. Photomicrographs of serpentine-group minerals similar to some of those studied in this research and illustrating the complexity 

of the mixtures. A, Lizardite plus chrysotile (porcellophite), from Middletown, Delaware County, Pa., U.S. National Museum No. R4645. 

Fabriclike aspect interrupted) by areas of discontinuity. Crossed polars. Material is similar to Nagy and Faust (1&56I) No. 3. B, Chrysotile plus lizardite C>L. From underground workings, New Almaden mine, Sainta Clara County, Calif. Crossed polars. Material is 

similar to that reported in table 3. G, Chrysotile plus lizardite (antillite), from Havana, Havana Province, Cuba, West Indies. U.'S. 

National Museum No. 46265. Shows distorted character of poorly crystallized and stringy serpentine group minerals. Crossed polars. 

Material is similar to Nagy and Faust (W5&) No. 10. D, Chrysotile plus lizardite (antillite). Same thin section shown in G, but shows 

a slightly different orientation of the fibers and plates. Material gives very poor X-ray powder diffraction patterns. Crossed polars.
100 STUDIES OF THE NATURAL PHASES IN THE SYSTEM

or by a combination of the two methods. These samples 

are described as follows:

1. Lizardite plus clinochrysotile, from Snarum, Modum 

Canton, Parish of Buskerud, Norway.

2. Clinochrysotile plus lizardite, from the New Almaden mine, Santa Clara County, Calif.

3. Lizardite plus clinochrysotile, from near Forest Hill, 

Harford County, Md.

4. Lizardite plus clinochrysotile, from the campus of 

the Stevens Institute of Technology, Castle Point, 

Hoboken, Hudson County, N. J.

QUALITATIVE EXAMINATION

In the course of mineralogical and petrological 

studies of suites of specimens it is often desirable and 

sometimes necessary to treat the samples with a 1:1 hydrochloric acid solution (6.L/V) at room temperature 

 to eliminate iron oxide coatings, large amounts of carbonates, and other acid-soluble minerals to effect a 

concentration of certain other minerals. If serpentinegroup minerals are present in such assemblages it is

necessary to get some idea of the damage done to them 

by the acid treatment.

Three samples of the lizardite-clinochrysotile mixtures were treated with 1:1 hydrochloric acid at room 

temperature for periods of time generally ranging from 

15 minutes to 1 hour. Results for samples treated for 

1 hour are shown in table 3 and figure 45. The X-ray 

powder pattern shows that clinochrysotile is significantly destroyed and may be completely removed by the 

ordinary treatment for the purification and concentration of mineral grain fractions. Therefore, when effecting separations by acid treatment, the presence of 

serpentine-group polymorphs should be checked to assess the probable damage.

QUANTITATIVE EXAMINATION

Whittaker and Zussman (1958) found that the platy 

polymorph lizardite was stable in the solution technique 

used by Nagy and Faust (1956) and reported as follows : "We have treated green massive serpentine (which 

had been identified as lizardite by X-ray diffraction)

(hkl Clinochrysotile, in part) 

hkl Lizardite

hkl Clinochrysotile

Band (201,202)

hkl Lizardite

Z B

hkl Lizardite

A Natural sample

B Sample treated with cold dilute 6N HCI 

(1:1) at20°C for 1 hour

X-ray powder diffraction patterns made with 

Cu filtered by Ni, X=1.5418A, camera 

diameter = 114.59mm Straumanis technique

FIGURE 45. A graphic representation of a selected portion of the X-ray powder diffraction pattern of a natural mixture of lizardite and

clinochrysotile from Snarum, Modum Canton, Parish of Buskerud, Norway.
SOLUTION STUDIES OF CHRYSOTILE, LIZARDITE, AND ANTIGORITE 101

TABLE 3. Effect of treatment with cold (20° C) dilute hydrochloric acid (1:1) for 1 hour on the appearance of selected lines in the X-ray

powder diffraction pattern of clinochrysotile

Untreated clinochrysotile data( of 

Whittaker and Zussman, 1958)

hkl

130______

202, 006_. 

204______

206______

00.10... __

dobs

2.66

2.456 

2.096 

1.748

1.465

I

Medium 

weak. 

Strong. _

Medium _ _ 

-__do._.___.

Weak_.____

Acid treated

Lizardite plus clinochrysotile from 

Snarum, Norway

[Band almost completely 

| removed.

Band greatly reduced in intensity, almost removed.

Campus of Stevens Inst. of Technology, 

Hoboken, N.J.

Band present but weak _

VPT*V wpfllr

Chrysotile plus lizardite from New 

Almaden mine, Santa Clara County, 

Calif.

Band present but faint.

Faint suggestion of line. 

Do.

Do.

with one normal HC1 at 95 °C for one hour as prescribed by Nagy and Faust, and have found that its 

powder diffraction pattern is only slightly weakened. 

(Treatment with somewhat stronger acids destroys the 

lizardite structure while still not affecting that of 

antigorite)."

We have further investigated this stability using 

lizardite from the type locality at The Lizard, Cornwall, 

England, described by Midgley (1951) and natural admixtures of lizardite and clinochrysotile from Snarum, 

Parish of Buskerud, Norway, from New Almaden mine, 

Santa Clara County, Calif., and from Forest Hills, 

Hartford County, Md. The results are shown in table 

4 and figure 46. Our studies confirm the work of 

Whittaker and Zussman (1958) on the stability of the 

polymorph lizardite under the conditions of the differential solution test.

With this knowledge we can see that the stability of 

lizardite is also suggested by Nagy and Faust's graph

TABLE 4. X-ray diffraction studies of acid-treated lizardite and 

mixtures of chrysotile and lizardite

Name

Lizardite plus clinochrysotile, L>C.

Chrysotile plus 

lizardite, OL.

Clinochrysotile plus 

lizardite. 

Lizardite and talc. . . .

Locality

Snarum, Modum 

Canton, Parish of 

Buskerud, 

Norway. 

New Almaden 

mine, Santa Clara 

County, Calif. 

Forest Hills, Hartford County, Md. 

Kennack Cove, The 

Lizard. Cornwall, 

England.

Physical character

Massive, yellow. ....

Massive, flesh 

colored. 

Aggregates of small 

white crystals of 

lizardite with a 

small amount of 

talc.

Lizardite 

content (in 

percent) as 

determined by 

the X-ray 

method 

(remainder is 

chrysotile)

72

26

10 

100

(1956, fig. 6, p. 835) showing the relationship of the 

intensity of the (001) [now the (002)] reflection to the

antigorite content, if the abscissa is corrected to read 

"percent antigorite or lizardite."

The electron micrograph of chrysotile No. 4 (Nagy 

and Faust, 1956, fig. 4) from the Montville area, Morris 

County, N.J., shows it to be a mixture of clinochrysotile 

fibers and plates. The results of the present study show 

that it is actually a mixture of clinochrysotile and 

lizardite. The same admixture was found in a sample 

studied by Faust and Fahey (1962, p. 10). The solution test shows it to be a mixture of 50 percent clinochrysotile and 50 percent lizardite. A differential 

thermal analysis record of this acid-treated mixture 

shows that the residue exhibits the high-temperature 

endothermic trough of the undecomposed lizardite 

(Nagy, 1953, fig. 3).

Euotsala, Pfluger, and Dow (1964) have successfully 

used the differential solution technique in a study of 

iron-rich serpentine and chamosite from Ely, Minn. 

They used the method to determine the amounts of 

antigorite and clinochrysotile in mixtures.

CONCLUSION

We have investigated the stability of lizardite samples 

using the solution test of Nagy (1953). Our results 

confirm the observations of Whittaker and Zussman 

(1958) that lizardite is stable under the conditions of 

the test. A reexamination of five of the specimens reported by Nagy and Faust (1956) as mixtures of 

chrysotile and antigorite in the light of the studies of 

Whittaker and Zussman has confirmed their opinion 

that some of the flaky or platy phases are actually 

lizardite and not antigorite. In the paper by Nagy and 

Faust (1956), table 5 (p. 834, 835) should be corrected 

for the specimens reported here. In figure 6 (p. 835), 

the abscissa should read u% antigorite or lizardite"; and 

figure 4 (p. 828) should read "a natural mixture of 

chrysotile fibers and lizardite flakes."

The importance of the acid strength (IN hydrochloric acid), the time of the reaction (1 hour), and 

the temperature of the reaction (95°C), stressed by
UNITS) (ARBITRARY INTENSITY 

N 3 o 

2> 2- 

So. 5 

;* O >< 

A Q. 

it

"> O 

* "2, 

if 3 sin a> 

I*

,ao IYHHIVN sasvnd NI 
The patterns for A, B, and C were obtained under the 

following conditions

Cu filtered by Ni

KVP = 35

Receiving slit = l°

Multiplier^!

Scanning speed = 1/z° per min

Chart scale = 1° per inch

X =1.5418 A

MA = 20

Scale factor 2

Time constant=4 sec

80

70

60

50

QQ 40

cc

30

20

10

C Clinochrysotile plus lizardite from Forest 

Hills, Harford County, Md.

11° 12°

26

TREATED

13° 10° 11° 12°

20

UNTREA

FIGURE 46. Tracings of X-ray diflfractometer patterns of the (002) reflections of natural and IN hydrochloric acid treated specimens of ser

D on next page.
Lizardite plus talc, Kennack Cove, The 

Lizard, Cornwall, England

This pattern was obtained under the 

following conditions

Cu filtered by Ni

KVP=40

Receiving slit = l°

Multiplier=0.8

Scanning speed l/2° per min

Chart scale=l° per inch

X =1.5418 A

MA = 20

Scale factor= 16

Time constant=4 sec

FIGURE 46. Tracings of X-ray diffractometer patterns of the (002) reflections of natural and 1# hydrochloric acid treated specimens of serpent
SOLUTION STUDIES OF CHBYSOTILE, LIZARDPTE, AND ANTIGORITE 105

Nagy and Bates (1952) and reiterated by Whittaker 

and Zussman (1958), has been reaffirmed here.

The common use of dilute hydrochloric acid for the 

removal of carbonates or iron oxides from mineral separates may destroy most or all of the clinochrysotile. 

The X-ray powder diffraction patterns of acid-treated 

specimens show a weakening in the intensity of the 

lines arising from the presence of clinochrysotile. This 

particular X-ray technique is very sensitive to intensity 

changes of the X-ray diffraction lines even though they 

are broad and diffuse.

The differential solution method was used to test the 

stability of lizardite from the type locality, The Lizard, 

Cornwall, England, and in three natural admixtures 

with clinochrysotile. Its relative stability under the 

conditions of the test was confirmed. The samples

studied in this research included specimens whose structures were flaky, fibrous, and lamellar; crystalline 

aggregates; and-massive material. For each type the 

stability of the lizardite in the admixture was observed.

An examination of the data of the previous solution 

studies on serpentine-group minerals by Clarke and 

Schneider (1890) and Terreil (1885) also shows the 

same pattern of stability of lizardite and antigorite and 

the instability of chrysotile. The parallel stability relations of iron-rich serpentine-group minerals studied by 

Euotsala, Pfluger, and Dow (1964) is noted.

In Professional Paper 384-A, "The serpentine-group 

minerals," by G. T. Faust and J. J. Fahey (1962 and 

1964 editions), the following corrections should be 

made:

Page 2, column 2, line 35 from

top. 

Page 39, figure 19

Page 40, column 2

Page 43, figure 21 

Page 46, figure 23

Page 58, figure 30 

Page 88, insert after Delesse the 

following reference.

In the formula [Mg5 .oNio.5Fe2+o.5]S4Oio(OH)8 the S4 should read Si4 .

In the tetrahedral scale, the spacing between 4.80 and 5.00 is incorrect.

When corrected the points F-26 and F-48 will lie closer to the line. 

The formula for 95 per cent serpentine and 5 per cent FeaOs should be

[Mg5 .77Pe>+.M][Si,.86]Ow (OH)8 .

Serpentine of Strunz in the lower right hand corner should be deleted. 

In the graph for the Val Antigorio serpentine, the octahedral scale should

run from 6.00 to 5.80 instead of 6.40 to 6.20. 

C-187 should be C-817. 

Dienemann, Wilhelm and Burre, Otto, 1929, Die Nutzbaren Gesteine

Deutschlands: Stuttgart, Verlag von Enke, Band 2, xvi+485.

LITERATURE CITED

Clarke, Frank W., and Schneider, Edward A., 1890, Experiments 

upon the constitution of the natural silicates: Am. Jour. 

Sci., 3d, ser. v. 40, p. 303-312, 405-415 and 452-457.

Faust, George T., and Fahey, Joseph J., 1962, The serpentinegroup minerals: U.S. Geol. Survey Prof. Paper 384-A, p. 

1-92.

Lindner, Adolf, 1893, Experimentelle Priifung der von Clarke und 

Schneider fur den serpentin aufgestellten Constitutionsformel: Inaug. diss. Breslau p. 1-36; abs. in Zeitschr. Kristallographie, v. 25, p. 589-592 [1896].

Midgley, Henry G., 1951, A serpentine mineral from Kennack 

Cove, Lizard, Cornwall: Mineralog. Mag., v. 29, p. 526-530.

Nagy, Bartholomew S., 1953, The textural pattern of the serpentines : Econ. Geology, v. 48, p. 591-597.

Nagy, Bartholomew S., and Bates, Thomas F., 1952, Stability of 

chrysotile asbestos: Am. Mineralogist, v. 37, p. 1055-1058.

Nagy, Bartholomew S., and Faust, George T., 1956, Serpentines: 

Natural mixtures of chrysotile and antigorite: Am. Mineralogist, v. 41, p. 817-838.

Ruotsala, Albert P., Pfluger, Clarence E., and Dow, Garnett M., 

1964, Iron-rich serpentine and chamosite from Ely, Minnesota : Am. Mineralogist, v. 49, p. 993-1001.

Selfridge, George C., Jr., 1936, An X-ray and optical investigation of the serpentine minerals: Am. Mineralogist, v. 21, 

p. 463-503.

Terreil, Auguste, 1885, Analyse d'une chrysotile (serpentine 

fibreuse ayant 1'aspect de 1'asbeste) ; silice fibreuse resultant de 1'action des acides sur les serpentines: Acad. sci. 

(Paris) Comptes rendus, v. 100, p. 251-253.

Whittaker, Eric J. W., and Zussman, Jack, 1958, Characterization of serpentine minerals: Am. Mineralogist, v. 43, p. 

917-920.

U.S. GOVERNMENT PRINTING OFFICE: 1966 O 229-895