Melville, W.H.

...Contributions to the miner-Sj 

alogy of the Pacific coast... 1890,1

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DEPARTMENT OF THE INTERIOR

BULLETIN

OF THE

UNITED STATES .

*'.'" V

GEOLOGICAL SURVEY

No ,

29

CONTRIBUTIONS TO THE MINERALOjGY OF THE 

PACIFIC'COAST

WASHINGTON

aOYERNMENT PRINTING OFFICE 

ISQO

LIBRARY CATALOGUE SLIPS.

United States. Department of the interior. ( U. S. geological survey).

Department of tlie Ulterior ] : | Bulletin | of the | United 

States. I geological survey | no. 61 | [Seal of the department] | 

Washiugtou | government printing office | 1890

Second title: United States geological survey | J. W. Powell, 

director | | Contributions | to the | mineralogy of the Pacific 

coast | by | William Harlow Melville | -and | Waldemar Liudgreu | 

[Vignette] |

Washington | government printing office | 1890

8°. 40 pp. 3 pi.

Melville (William Harlow) and Lindgren (Waldemar)

United States geological survey | J. W. Powell, director | | 

Contributions | to the | mineralogy of the Pacific coast | by | William Harlow Melville | and | Waldemar Lindgren | [Vignette] |

Washington | government printing office | 1890

8°. 40 pp. 3 pi.

[UNITED STATES. Department of Ike interior. (U. S. geological survey). 

Bulletiu 61].

United States geological survey | J. W. Powell, director | | 

Contributions | to the | mineralogy of the Pacific coast | by | William Harlow Melville | and | Waldemar Lindgren | [Vignette] |

Washington | government printing office | 1890

6°. 40 pp. 3 pi.

[UNITED STATES. Department of the interior. (77. S. geological survey). 

Bulletin Cl.J

A.DVElRTISKMiEN'T.

[Bulletin No. 61.1

Tho publications of tho United States Geological Survey are issued in accordance with the statute 

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To THE DIRECTOR OK THE

UNITED STATES GEOLOGICAL SURVEY,

WASHINGTON, D. C.

WASHINGTON, D. C., June, 1890.
DEPARTMENT OF THE INTERIOR

BULLETIN

OF TIIK

UNITED STATES

GEOLOGICAL SURVEY

No. 61

WASHINGTON

NT PRINTING OFFICE 

1S90

UNITED STATES GEOLOGICAL SUEVEY

J. W. POWELL, DIRECTOR

C ONTRIBUTIONS

MINERALOGY OF THE PACIFIC COAST

BY

WILLIAM HAELOW MELVILLE

WALDEMAE LINDGEEN

WASHINGTON

aOVERNMENT PRINTINCr OFFICE 

1890

CONTENTS.

Page. 

Letter of transmittal. ................................................... 9

Cinnabar crystals from Newldria, Fresno County, California................. 11

Cinnabar crystals from Sulphur Bank, Lake Comity, California .............. 21

Cinnabar crystals from Knoxville, Napa County, California.................. 22

Cinnabar crystals from New Alinaclen, Santa Clara County, California........ 22

Metacinnabarite from Knoxville, Napa County, California ................... 22

Metacinnabarite from Cerro Gordo Mine, near Panoche, Fresno County, California......................................... ........................ 23

Sulphates from the Eedington Quicksilver Mine, Knoxville, Napa County,

California............................................................. 23

Copiapite from Redington Mine, Knoxville, California ....................... 25

Copiapite from Sulphur Bank, Lake County, California ...................... 25

Stromeyerite from Calico, San Bernardino County, California ................ 27

Chromiferous chlorite Kotschubeite ........................................ 27

Uwarowite ................................................................. 30

Scorodite................................................................... 30

Note............................ .:,....... .................................. 31

Plates...................................................................... 33

ILLUSTRATIONS.

PLATE I. Fig. 1. Cinnabar crystal, analogue pole.

2. Cinnabar crystal, antilogue pole.

3. Cinnabar crystal.

4. Cinnabar crystal, with reentrant angle.

5. Crystal with gas inclusions.

6. Cinnabar crystal. 

II. Fig. 7. Cinnabar crystal, analogue pole.

8. Cinnabar crystal with reentrant angle, antilogne polo.

9. Cinnabar crystals, with inclusion.

10. Cinnabar crystal, analogue pole.

11. Cinnabar crystal, antilogue pole. 

III. Fig. 12. Snbindividual on tectonic face.

13. Illustration of derivation of tetartohedral forms.

14. Section lines of tetartohedral forms of crystals 1 and 2 with basal 

plane.

7

LETTER OF TRANSMITTAL.

DEPARTMENT OF THE INTERIOR,

UNITED STATES GEOLOGICAL SURVEY, 

DIVISION OF THE PACIFIC,

San Francisco, February 1, 1889.

SIR: We have the honor to transmit herewith through Mr. G. F. 

Becker, geologist in charge, Division of the Pacific, a paper on mineralogical studies of certain specimens which were collected during the 

recent examination of the quicksilver deposits of California.

In this material we are able to add somewhat to the previous knowledge of the habits of cinnabar crystals, and to give measurements 

which identify those crystal forms to which are ascribed the phenomena 

of right and left rotation. Two new mineral species, into the composition of which chromium enters largely, are described and named, while 

the remaining matter is mostly confirmatory of previous observations 

to be found in the literature of mineralogy. 

Very respectfully,

W. H. MELVILLE,

Chemist. 

WALDEMAR LINDGREN,

Assistant Geologist. 

Hon. J. W. POWELL,

Director U. 8. Geological Survey.

. * 9

CONTRIBUTIONS TO THE IINEKALOGY OF THE 

PACIFIC COAST.

BY W. H. MELYILLE AND W. LINDGREN.

CINNABAR CRYSTALS FROM NEW IDRIA, CALIFORNIA.

While examining the colle'ction made by the TJ. S. Geological Survey 

at the New Idria quicksilver mines, our attention was drawn to a number of very minute cinnabar crystals having a somewhat uncommon 

habit. They were obtained from Superintendent J. W. 0. Maxwell, 

who had washed them out from a soft ore occurring in the upper workings of the mine. The ore was in all probability a soft gray arkose 

sandstone impregnated with cinnabar. Examination showed that the 

apparently simple crystals have generally a thin tabular habit and 

present the forms OE, §E, %R, combined with tetartohedral faces ot 

more or less complicated nature mostly in the zone of the terminal edge 

of f jR. The crystals are collective individuals built up of alternating 

layers of substance with opposite rotary power, dextro-gyre and levogyre, arranged with approximately parallel axes, the resulting structure being in many cases quite complex.

Long ago Des Cloizeaux1 discovered that cinnabar belonged to the 

small class of substances which exhibit circular polarization, and that 

it rotates the plane of polarization more strongly than any other known 

substance. He also found that almost all of his sections cut perpendicularly to the axis did not belong to simple crystals, but showed a 

combination of right and left turning parts analogous to the wellknown phenomena observed in quartz and its variety amethyst.2

In 1871 A. D'Achiardi 3 discovered tetartohedral faces of

but we are not aware that he determined their position. Dana4 records one scalenohedron,

1 Coinptes Rendus, vol. 44, p. 876.

2Rammelsberg, in Handbnch der krystall. Chemie, Berlin, p. 81, states erroneously 

that only left turning crystals have been noted.

3 Boll. Cora. Geol. Ital., vol.2, 1871, p. 163. The monograph of Schabus(Ber. Wien. 

Acad., vol. 6) is unfortunately not accessible to us.

* A System of Mineralogy, by J. D. Dana, fifth edition, 1884, p. 55.

6 11
12 MINERALOGY .OF THE PACIFIC COAST. [BULL. 61.

The crystals hitherto found in the California quicksilver mines have 

either a prismatic or a rhombohedral habit and present no uncommon 

forms.1 In the thin sections made by the Survey for the petrographical study of the quicksilver mines of the Pacific coast, the cinnabar 

whenever crystallized has a prismatic habit. The tabular crystals now 

under consideration are very small, almost microscopic, the diameters 

of which range from 0.05 mm to 0.6mm, and the thicknesses from 0.02mm 

to 0.2mm. The trapezohedral faces which replace the terminal edges of 

the rhombohedrons are much broken and curved in the larger crystals, 

while in the smaller they are sometimes quite well developed and so 

large as to influence the general triangular habit of the tables. The 

individuals are often grouped in more or less complex bunches and 

irregularly interpenetrate one another; two crystals may be frequently 

seen connected in such a way that one has grown either perpendicularly 

or obliquely into the basal plane of the other. There does not appear to 

be any general law governing these groupings.

On account of the tabular habit and their minute dimensions these 

crystals are admirably adapted for optical examination. They are 

translucent and deep red in color, the tint, however, being so dark that 

the phenomena can only be properly observed with low objectives. 

The apparently simple crystals present, when examined in parallel 

polarized light, considerable tectonic complications. On account of the 

feeble gyroid power of quartz this phenomenon can not be well observed 

in very thin sections of that mineral with common light. Cinnabar, 

on the other hand, rotating the plane of polarization more than quartz, 

according to Des Cloizeaux's measurements, fifteen to seventeen times 

as strongly, shows this property very well in the tabular crystals. The 

exact value of the angle is difficult to determine on account of the dark 

color in transmitted light. The crystal in Fig. 10 is drawn with the 

analyzer 26° to the right, its thickness is 0.09mm. This gives a rotation 

of 289° for lmm, or 16.8 times as large as that of quartz, which for the 

red line C is 17.2. The arrangement of the dextro-gyre and levo-gyre 

parts is evidently governed by the law of regular grouping with parallel 

positive rhombohedrons, as in quartz, although there is reason to believe 

that the law is not strictly but only approximately true. The deviations at all events are small.

Generally speaking a composite crystal is formed of six sectors of 

60° angle, whose directions of rotation are different, as illustrated in 

Figs. 7 and 8. The numbers of right or of left turning sectors are not 

constant, but may alternate regularly, or several adjacent sextants may 

be composed of the same substance. In the latter case they are usually 

separated by a narrow band of opposite rotary power and marked by 

a reentering angle between rhombohedral and trapezohedral planes 

(Figs. 4 and 7). With crossed nicols the sectors have a dark intermediate tint traversed by black radiating lines, indicating overlapping of

1 E. Bertrand, Neues Jahrbuch, 1878, p. 657. (Redington mine, oo R,$R).
PHENOMENA UNDER THE MICROSCOPE. 13

the different parts. ' These black bars move a short distance when the 

analyzer is turned. Deducted from the amplitude of the movement 

and the thickness of the crystal the dividing plane was found in some 

instances to have an inclination of 110° to 120° to the basal plane. 

Very frequently, however, the dividing surface is altogether irregular, 

and often only shadows moving indistinctly can be observed on turning 

the analyzer, as in Figs. 5 and 6. There are not uncommonly found 

alternating parallel layers within one sector, appearing with crossed 

nicols as a system of black equilateral triangles. Thin cuneiform 

pieces of different rotary directions are inserted in larger areas which 

are uniform .in rotation. When the crystals rest on the basal plane 

they remain perfectly isotrope on turning the table of the microscope. 

Exceptionally a faint change in the intensity, may be observed in isolated 

places, as in Fig. 9 at the point marked A in the dextro-gyre section. 

The cause is probably a local state of tension.

Gas and fluid inclusions have beeji recognized. The latter are small 

and have sometimes a movable bubble which does not change in volume 

on heating. The gas inclusions often take the form of negative crystals. In Fig. 8 a series of beautiful inclusions are represented. They 

surround a hexagonal figure in the interior of the crystal, the sides 

of which are parallel to the rhombohedral planes, and appear in transmitted light deep black on the red background of the crystal. A small 

red spot is to be seen in the center. This phenomenon is easily 

explained by the very high refracting power of cinnabar £=3.20, considerably higher than that of the diamond. The angle of total reflection is consequently about 20£°. In reflected light the inclusions appear 

brilliantly red on the now black background.

Crystal forms. Bhombohedrons : In order to determine the symbols 

of the crystal faces an attempt was made to measure them under the 

microscope with micrometer screw and eye-piece. It was found, however, that the error in the very small vertical measurement was so large 

as to seriously impair the results. The next resort was the determination of the rhombohedral faces and the calculation of other forms, 

as far as possible, by means of their zone relations and horizontal measurements on the stage of the microscope. The rhombohedral faces 

and basal plane, in spite of the minute size of the crystals, gave tolerably good signals in a Fuess goniometer, and in a series of the larger 

crystals the zone [OjR, jR] was closely measured, as shown in the following table:
14 MINERALOGY OF THE PACIFIC COAST.

Interfacial angles OE A w»-B-

[BULL. 61.

Crystal.

a

b

c

d

e

f

9

h

k

OAr(r= It).

O 1

127 6

127 15

127 38

OAr,,(r;/ =-§.R).

O 1

138 36

138 59

138 4

138 56

139 4

138 28

138 42

138 53

138 58

138 55

0 A » ,(» ,:= £JR).

O '

146 32

147

147*

147t

147 11

146 13

Hem arks.

Calculated angles.

Reflex TU, elongated.

Reflex r,,; elongated.

Reflex 0 duplicated.

r,i, indistinct.

± oo R observed.

r=+ R ; r,,i duplicated.

+ R observed.

* Closely. t Approximate.

Crystal/was subjected to a revolution of 360°, and measurements 

were taken, as follows:

O.BA pj

 |BA OR'

O.R'A %R

 §.RA OR

Between normals.

0 '

41 18J

138 42

41 1

138 58J

360

Interfacial.

O '

138 41$

41 18

138 59

41 1£

360

Eeflected light, but no signal, was obtained from planes £.R, oo R 

and possibly +mR in this same zone.

Crystal g contained the prism face oo R as shown by measurements 

in zone [OJR, $R]:

ORf^ *R

 Pi! A <aR

Between normals.

O '

41 7

48 57

Interfacial.

O '

138 53

89 56

On crystal h the following measurements were recorded;

 §KA §R

 iRA OR

O.RA OR'

OR'A+R

Between normal 8.

0 '

8 13

32 49

180

52 22

 piAOJi

 £BAO.R

+ JJAOJJ

+ RMR'

luterfacial.

O '

138 58

147 11

52 22

127 88
MELVILLE AND"] 

LINDGREN. J CRYSTAL FORMS AND THEIR SYMBOLS. 15

Also in the same zone reflected light from prism planes was observed. 

These latter planes are very narrow, occur along the lateral edges of 

the tabular cinnabar crystals, and are quite common, but in rare cases 

only can good signals on the goniometer be seen.

The rhoinbohedral face, §.R, is invariably perfect, and the basal 

plane, O.R, is usually so; but the latter is oftentimes broken, the angle 

between its parts sometimes amounting to 1°. In some crystals the 

irregularities may be seen to follow the line between dextro-gyre and 

levo-gyre substance, indicating that the positions of the different parts 

are not strictly parallel. Planes of the rhombohedrou, $.R, on the 

other hand, never give good reflections and are always striated. These 

striations are parallel to the combination edges of the rhombohedral face 

and the trapezohedral faces on either side. They are interesting and 

will be subsequently considered. Positive rhombohedral forms, +mR, 

are seldom present. In Fig. 9 one' small face of +§JK (r2) and one of -f JJB 

(r3) are noted.

In giving the negative sign to the dominant rhombohedron, we were 

led by considerations based on the nature of the trapezohedral faces, 

as well as by previous descriptions of the habit of cinnabar crystals.

The simple forms observed are tabulated thus:

Naumaiin.

OR

-3UZ

-±R

 K

+ K

+m+jfi

oojR

Brayais-Miller 

(hkli).

(0001)

K(022~3)

(c(01I2)

ic(OlIl)

(C(10I1)

K(202~3)

»c{10l2)

K(10IO)

Of these forms OR and $R are by far the most prominent.

Some typical crystals were selected, mounted in balsam and drawn 

under the cainera-lucida. Tke greatest care was taken to reproduce a 

perfect image in the drawing, and this position of the crystals seemed 

best adapted to illustrate their irregularities and the relations of the 

trapezohedral planes to the other forms. The drawings could be made 

conveniently only with strong reflected light. Whenever special measurements of angles in a horizontal section were necessary, they were 

made by cross-hair and graduated table and were not taken from the 

drawings.

Tetarto-trapezoJiedrons. Obliquely replacing the terminal edges of 

 $R and %R (Figs. 1 and 3), there appeared a series of faces often 

broken and irregular, which from their position and connection with the 

dextro-gyre and levo-gyre substance of the cinnabar could only be regarded as tetartohedral forms of a dihexagonal pyramid, The interest
16 MINERALOGY OF THE PACIFIC COAST. [BULL.OI.

arose from the fact that in many individuals these forms were more 

largely developed, than in any cinnabar crystals heretofore described. 

Trapezohedral faces lying in the terminal zone of jR have been observed 

on quartz crystals 1 and on hypoiodate of sodium3 but there seems to 

be no record of such faces in a zone of more obtuse forms.

The relation between the sectors of different rotating power and the 

trapezohedral faces must now be considered. Applying the law of 

rhombohedral hemihedrism to the dihexagonal pyramid mPn, two scalenohedrons, i7^ or i m'Rn1 , are derived, which differ in position by

A

60°. Again applying the law of trapezohedral tetartohedrism to

we obtain four enantiomorph forms, i- and 2 44

right and left trigonal trapezohedrous. Furthermore, the hexagonal 

pyramid of the second order, mP2, when subjected to trapezohedral

tetartohedrism, yields two trigonal pyramids r _. and I which

can be regarded as the limits between positive and negative trigonal 

trapezohedrons (Fig. 13).

The connection between the trapezohedral forms and the rotating 

direction in the case of quartz 3 is as well known as that dextro-gyre 

crystals are modified by planes of

and levo-gyre crystals1 by planes of

j mP2 . 7 mPn mPn ; z -T->+' >-r 

If the positive rhombohedron should be taken as negative, the first 

of the two divisions above would correspond to levo-gyre, and the second 

to dextro-gyre crystals.

In combination with a positive rhombohedron in right turning

crystals 4 (the face of +E being held in front of the observer), r ^ - 

is placed on the right terminal edge obliquely towards the observer ;

_Z lies between r aud %R, and +r-~ replaces the combination edge of +R and r

In levo-gyre crystals the planes +Z^r - and -r" 1 ~ are placed on

the other side of this terminal edge. In combination with a negative 

rhombohedron the relations are reversed, so that the dextro-gyre forms

1 Websky on quartz crystals. Neues Jahrbuch, 1871, p. 732,

2 Grotli: Physik. Krystall, 1876, p. 302.

3 Grotb: Physik. Krystall., 1876, p. 301.

*P. Groth; Monatsbericht d. Berlin Akad,, 1869,
MELVILLE AND"! 

LINUGKEN. J

MEASUREMENTS OF TRAPEZOHEDRAL PLANES. 17

here correspond in relative positions to the levo-gyre forms in the case 

of the positive rhoinbohedrou.

In order to determine the nature of these trapezohedral faces and 

the form to which they belonged, measurements in the horizontal section 

were taken of the angles which the combination edges of ( wEAOjK) 

made with those of the trapezohedral planes over the same basal plane. 

The crystal in Fig. 1 was chosen for this purpose and the angles on 

both the analogue and the antilogue poles were ascertained by means 

of cross-hair and stage of the microscope. The angles in Fig. 1 are 

designated or, /?, etc.,1 lettered in order; those in Fig. 2 are self-evident. 

In the first series of measurements low magnifying power was employed, 

and in the second, higher power for the determination of the angles 

where two trapezohedral faces formed re-entering angles. The latter 

should be accurate within one degree!

First series.

Fig. 1.

o

a = 141

ft = 100

X = 137

<J = 103

Tj=135J

0 = 104

Fig. 2.

o

Above d= 140

Above c= 99

Above6=137

Above a =104

Above/=130

Above e=104i

Second series.

Fig. 1.

o

a=138i

/3= 99

y' = 139

y2 =183

8 =100

7,' = 130

e =103J

The angles lettered y2 and if are re-entering and are formed by two 

trapezohedral planes. Those edges forming y2 make with the combination edge ( W.RA OJK) on the right angles of 139° and 142°, respectively, 

and those forming rf make in the same way angles of 130° and 135f°, 

respectively. That these trapezohedral planes belong to the same 

class of derivatives from the scalenohedron and possess the same 

general symbol, is evident from Fig. 14, in which is shown the projection of the combination edges of the negative rhombohedrou, wR, 

and of the trapezohedral planes with the basal plane. The heavy lines 

represent the positions of these edges as they appear in Fig. 1, and 

the dotted lines the corresponding, edges of Fig. 2 in their true relation to the crystal and Fig. 1. Figs. 13 and 14 show. further that the 

trapezohedral planes in relation to mR have the general symbol ,

+r - and that the angles may vary in the basal section of (1) +rm n 4 4

for az from 120° tp 150°, and for /3 from 90° to 120° j ft on left hand

(2) l for a from 150° to 180°, and for ft from 60° to 90°; ft on left

Bull, 61-

1 Compare Fig. 11.

 * /?=tke less obtuse angle.
18 MINERALOGY OF THE PACIFIC COAST. [BULL. 61. 

hand (3) + 1 mPn for a from 120° to 150° and for ft from 90° to 120°; ft on

right hand (4) r for a from 150° to 180°, and for ft from 60° to 90°;

ft on right hand. From the discussion above, the tetartohedral planes 

must belong to the form trigonal trapezohedron, and in this special

*)W rv?

case, Figs. 1 and 2, to -\-r -. Notwithstanding the large deviation

in the angular measurements of the basal section, as in «, y*t rj and in 

ft, #, 6, the trapezohedral planes, three above and three below, must 

constitute a complete form, and we are obliged to seek explanation of 

these discrepancies in the errors of measurements, in the distortions of 

the crystals, and in the fact that narrow planes, almost mere lines, 

which are present, may correspond to missing trapezohedral faces. 

Unfortunately, these narrow planes scarcely admit of a representation 

on the scale of the drawings, and much less of even an approximate 

measurement.

On studying the relations of the angles a and ft to the other parts in 

many crystals, it was discovered that in the dextro-gyre sectors the 

angle ft is always on the left side when the trapezohedral face is held 

towards the observer, and in levo-gyre sectors 011 the right. This, considered in connection with what has been said before concerning the 

positions of trapezohedral faces, can only be true if we consider the 

dominant rhombohedron negative, always of course under the supposition that the relation between differently rotating substance and the 

trapezohedrons (see p. 16) is the same as in quartz. If we reverse this, 

the rhombohedron must be considered positive. The most common

face is that of +i in the left turning sectors and of

in the right turning; negative trapezohedrons, where the angle /?<90° 

are quite rare; twice ft was measured to 90°, corresponding to a section 

line of a trigonal pyramid.

The larger and more regular planes replacing the terminal edges of 

the rhombohedrons appear to be exactly iu the zone of [ § R, + ^JK], 

since under the microscope the combination edges of the trapezohedral 

face with the adjoining rhombohedral faces $R are parallel and make 

with the combination edge ( §22 A OR) on the right and left respectively 

equal angles of 150° in the horizontal projection. On the goniometer a 

faint, elongated flash of light, scarcely to be called a signal, was reflected 

fromjeach of these planes in the zone [ |E, §E]. Calculated from 

the observed values of ft and the zone equation complex symbols of the 

trapezohedral forms are obtained. It was found by comparison of the 

different values that the position of the planes oscillates about the

2. ps. _ _ simpler forms +r5±-l and+J^p, nn" [2.4.6.15] corresponding to a

value of yS=100° 53'+, but only once actually measured. The following
HBLVinLK ANO 

UNUGUEN. . AXIAL KATIO OF TRAPEZOHEDRONS. 19

table shows the angles /?, measured on several crystals, and the more 

obtuse angles a corresponding to these. The third column contains 

the measured angles a, and the fourth the symbols calculated from the 

angle ft.

jS measured.

0 /

When/3= 93

95

99

100

100 53

101

102

103

104

105

107

a = 2tO° /3.

0 /

a = 147

145

141

140

139 7

139

138

137

136

135

133

a. measured.

o

139

(*)

139J

137

136

134$

, , inPn Symbols, +r g 

V« : «' -Vtt" : $c

-'/-a : a' Ha" : T"sc

V» : a' -V a" : 41"

c -%"ffl : tt' ^?<*" i t"

< 2.889a : a' 1.532a" : 0.407c

f 3a : a' ^a" : «c

i 2.999a : a' 1.5a" : 0.4c

^ 3a : a' %a" : gc

? 3.015a : a' 1.496a": 0.3996c

r -^a : a' !<!«" : gc

< 3.165a : a' 1.462a" : 0.396c

-^a : a1 tya" : J5 c

$a . a' la," : &c

tya : &' }s~a" ' T"TIC

Y« : «' i^a" : Jc

* Not measured.

The frequent occurrence of trapezohedrons on quartz with complex 

symbols has often been commented on. Websky1 has attempted to 

explain these by the theory of the induced faces, supposing the crystal 

to be built up of alternating layers of substance turned 180° around 

the vertical axis so that in thi£ twin position +-55 of one individual 

covers R of another. The trapezohedral forms in the upper layer 

are consequently influenced by those belonging to a different series in 

the lower layer, and, not being able to develop in their proper places, 

they take positions intermediate between these and those of the inducing face. This view seems not improbable in the present case under 

discussion.

Even in the more regular crystals, Figs. 1, 3, 7, the trapezohedral 

faces are seldom perfectly smooth, but generally slightly broken and 

curved. Figs. 7 and 10 show this tendency increased (t and d!', Fig. 6; 

w', w, a?, Fig. 10). Finally, in Figs. 5, 6, and 9 the faces are exceedingly 

rough, and broken into a number of irregular planes. Such phenomena 

have also been observed on the tetajtohedral faces of quartz crystals.2 

Partially, at least, these irregularities may be explained by the hypoparallel position of the differently rotating parts composing the whole 

crystal.3

The fact that the basal plane is frequently broken, confirms- the explanation just given. It appears peculiar, however, that the rhombol StGG paper regarding Quartz Crystals from Strigau in Neues Jahrbuch, 1871, pp. 

132, 785.

2 Websky. Uber Doforinitiiteo. an Quarz-krystallen. Neues Jahrbuch, 1870, p. 353. 

"Sadebeck. Krystallotektouik, p. 184.
20 MINERALOGY OP THE PACIFIC COAST. [BULL. 61.

hedral faces, §jR, do not show more markedly the effects of this hypoparallelism if it is really the cause of all the disturbances. On the 

goniometer the reflected signals from %R are frequently duplicated, 

but striations are wanting.

The tectonic face of JBhas been alluded to. This face presents 

irregularities which under strong objectives appear as distinct figures 

formed by trapezohedrons and rhombohedrons, Fig. 12. Sometimes 

the whole face is covered by these protruding " subindividuals," bordered by vicinal planes,1 causing either a rough (Drusigkeit) or a striated appearance, Fig. 12 a, &, Fig. 5. The tendency of £JR to form vicinal faces is well shown in Fig. 8, and is illustrated by the irregularly running edge ( §RA £J2). When re-entering angles are formed, which 

is very often the case, then the edge ( %R/\QB,) becomes broken and 

irregular, thus accounting in great measure for the large variation of 

ft in the table on page 19. In Fig. 4 at the point marked st'" there is 

a coarse striation, which under strong objectives can be seen to be due 

to the combination of $R with a trapezohedron, the same which lies 

in zone [ §.R, f R].

Description of crystals. Crystal 1, Figs. 1 and 2. Bather uniformly built and principally of dextro-gyre substance. Angle /?d measured 99°, angle /3b 103£°. Both trapezohedral planes have the general symbol + r i- and lie on either side of -f rr~ 2 . The symbols 

corresponding to the measured angles are, as shown on page 19,

1.5 PI 1 . i-pj_ -fr37 7 and -f r^- ^- respectively. There are other triangular trapezohedral planes, m, w, p, q, which belong to a more acute form than 

those determined. The symbols of these could not be ascertained either 

by measurement or by zone relations.

Crystal 2, Fig. 3, has two well- developed trapezohedral planes, and 

angle fiu measured 103°, and fi0 103°. Corresponding to this angle

2. PlO. 9.-P10. c=-f r2a 7 and M=+r23 7 

4 4

The upper edges show some irregular trapezohedral faces.

Crystal 3, Fig. 4. A re-entering angle is formed by r,, and a broken 

trapezohedral face fc. A narrow plane lying in the zone [r,,, r,,] belongs 

probably to the trapezohedron of which & forms a part. There are 

present one right-handed and one left-handed trapezohedron,

&= + r and t= + 1 , where /?b and /?t=105°. 4 4

Crystals 4 and 5, Figs. 5, 6. These crystals show how the irregularities of the trapezohedral faces increase as the complexity of the arrangement of dextro-gyre and levo-gyre parts increases. It does not seem 

improbable that most of the deviations from the correct positions of the

1 Websky. Zeitach. Deutsch. geol. Gesell., vol. 15, p. 677, Berlin. §adebeck, 

Krystallotektojxik, p. 195,
ANin 

.N. J DESCRIPTION OF CRYSTALS. 21

faces are caused by a conflict between series of forms of different rotating power belonging to cinnabar. rtll( £JB), as well as r,,( |JB) becomes very prominent and is characterized by striations and grooves. 

Crystal 6, Fig. 7 and Fig. 8 opposite poles. Built of alternating sectors with smooth trapezohedral faces.

Anglo 

measured.

ft.

ft 

ft,

ft/,

ft,/,

Fig. 6a.

0

105

Fig.G&.

o

104

IftO

97

Symbol.

+rfsPU

^ 4

-H?W

4

7 P7 _J.j.TH-M?

4

+lfP13

+ 4

3 Ps j_rir ' a

+ 4

In Fig. 7, at the lower right-hand of the drawing a re-entering 

angle appears, causing a thin wedge of dextro-gyre substance to occur 

in a levo-gyre sector. At this part of the crystal there are three planes, 

<2, <3, f, the special symbols of which could not be determined. The

plane t* belongs td the form + 1 mPn. and t3 to The triangular

planes o, o', p are probably more acute trigonal trapezohedrons. The 

re-entering angle at d was so irregular and the combination edges with 

OJK so broken that no reliable information could be obtained concerning 

the planes. The opposite pole, Fig. 8, does not present such complex 

combinations of forms.

Crystal 7, Fig. 10, is very similar to crystal 7, but almost wholly levogyre. Measured, /?w=103°, /?#=95°. Therefore

u=-J[-l 2-, and #=-{-£!£ L1 

4 4

The remaining planes were not determinate. Fig. 11 represents the 

antilogue pole. /?, /?', ft" measured 106°, 107°, 103°, respectively.

Crystal 8, Fig. 9, is levo-gyre for the most part, and exhibits beautiful 

gas inclusions. The usual trapezohedrous are here present with combination edges very much broken. Plane g is probably a trigonal pyramid, 

for angle /?=90°, while the measured angle a==15Q° (g : rnl on the right).

The form is then r - '^ r2=-f %R, and r3=+&R. 4

CINNABAR CRYSTALS FROM SULPHUR BANK, LAKE COUNTY, CAL.

In the collection of the Survey appears a coating of cinnabar crystals 

upon an argillaceous rock, which has resulted from the decomposed and 

disintegrated basalt abounding in the quicksilver workings at Sulphur 

Bank. Throughout this rock run seams of persulphide of iron, probably marcasite, and patches of this mineral form the lining of cavities
22 - MINERALOGY OF THE PACIFIC COAST.

upon which have grown calcite crystals. Cinnabar is also very abundant 

in the mass of the rock, and in many places has crystallized contemporaneously with the calcite. The crystals in the coating are brick-red, 

possessing a rather metallic luster, by no means so highly adamantine 

as the tabular crystals from New Idria, while the powder yields a brilliant vermillion. The crystals, varying in diameter from 0.5 to 0.75ram, 

were found to be simple rhoinbohedrons with no other hexagonal modification. The rhombohedral faces are curved much as they often are in 

mineral dolomite, and, owing to this fact, as well as to the dull luster, 

great difficulty was experienced in obtaining close measurements. The 

most reliable angular measurements were those taken over the terminal 

edge of the rhombohedron. This angle is 74° 40' between normals, 

the mean of over a dozen determinations, from which is deduced the 

symbol if JR. The calculated angle for ±fJK is 75° 8£' between normals, 

or 104° 51£' interfacial.

CINNABAR CRYSTALS FROM KNOXVILLE, NAPA COUNTY, CAL.

Large masses of marcasite, which is often vesicular and carries fragments of quartz and opal, occur in the quicksilver deposits at Knoxville. The marcasite is frequently crystallized in the cavities. Metacinnabarite forms the greatest part of the sulphide of mercury which 

these specimens contain, while upon its surface brilliant needles of cinnabar have crystallized sometimes in tufts and again in irregular network. The needles vary in length from 0.5 to 2mm and their diameter 

is rarely greater than O.lmm. Excellent measurements were obtained 

which resulted in the identification of the crystal forms f R (or -ff .R) 

and the hexagonal prism oo P (or dboo R). The angle between normals 

 fRA co B=43°26', interfacial 136°34'. The calculated angle for 

(-fR AOjK)=46°34' between normals, 133°26' interfacial (133°24' Dana) 

This habit of cinnabar has been observed also by E. Bertrand. (See 

note p. 12.)

CINNABAR CRYSTALS FROM NEW ALMADEN, CAL.

Many crystals were examined which were found on specimens from 

New Almaden mines. These stout and brilliant crystals usually exhibited the forms O.R, %R, §E, 2JB, ± oo R ; one had the form +mR. An 

angular measurement was obtained, mR/\QR=7b° T (normals), which 

corresponds to the form ^B. This form has not been given by Dana, 

and by us was observed only once.

METACINNABARITE FROM KNOXVILLE, CAL.

The metacinnabarite associated with the needles of cinnabar previously described occurs in seams from 2 to 4mm wide, is easily detached 

and but slightly contaminated with quartz and possibly marcasite. 

Occasionally small nodules of metacinnabarite are seen on the specimens and appear to be formed of crystals which present dull and curved
MELVILLE ANDT 

LLNDOKEN. J METACINNABARITE AND SULPHATES. 23

faces baffling all attempts at recognition and identification. In the following analysis the mercury, iron, and silica were determined, and the 

amount of sulphur was calculated for the metals, analysis (I) on the 

assumption that iron is combined as FeS 5 (II), that FeS2 is the combination :

HgS...... ........

JFeS..... ..........

Si02 ..............

I.

Per cent. 

98.48

0.691

0.707

99. 878

HgS....... .......

FeSj. .............

SK^. .............

II.

Per cent. 

98.48

0.942

0.707

100. 129

In order to ascertain if possible in which state of combination the 

iron existed in the sample, two experiments were made. Crystals of 

marcasite were taken from the same specimen which furnished the 

sample for analysis, and the fine powder was boiled with dilute hydrochloric acid (1HC1: lOAq). Appropriate tests gave barely a trace of 

sulphureted hydrogen, ^n the other hand a portion of the sample employed for analysis yielded an abundance of this gas when slightly 

heated with the dilute acid. In the absence of other sulphides the 

conclusion must follow that the iron exists wholly or in. part in the 

form of protosulphide.

METACINNABARITE FROM OERRO GORDO MINE, CAL.

At the Oerro Gordo Mine, 11 miles west of Panoche, Fresno 

County, was found a specimen of metacinnabarite associated with chalcedony and crystallized quartz. The quantity collected for analysis 

amounted only to 0.0159 grains, and this sample contained a small 

percentage of cinnabar. 95.62 per cent. HgS was obtained on analysis, 

the residue, 4.38 per cent., consisted of quartz and a little iron which was 

undetermined.

SULPHATES FROM THE REDINGTON QUICKSILVER MINE, KNOXVILLE,

CAL.

The mass of the rock specimen is a black opal which is much fractured. The seams contaiiuthree distinct salts.

(1) Small black crystals belonging to the isometric system and presenting the forms 0 and oo 0: The substance is a double sulphate of 

iron and potassium, an alum in which both the ferrous and the ferric 

states of iron occur.

(2) The mass is fibrous, often so fine that the fibers can hardly be 

distinguished under the microscope; seldom are seen massive portions 

with crystalline structure. The color is pale purple. The parallelfibrous aggregates are sometimes white with silky luster and only 

purple on the surface perpendicular to the fibers. Under the micro-
24 MINERALOGY OF THE PACIFIC COAST. [IUJI.L.GI

scope they are colorless with no visible crystalline form. The system 

of crystallization is probably tricliuic, as extinctions parallel to the 

fibers are never obtained. Extinction 13° to 38°. Double refraction 

feeble. Specific gravity=1.761. Soluble in water.

Analysis.

H80 at 100° C-...........-..-....'.......................... 27.093

H20 above 100° C......._............................... 14.340

S03 -..-........................................ 35.352

A1203 -.......................................... 5.136

Cr2O3 .......................................... 7.512

Fe2 O3 .......................................... 0.186

FeO........................................... 4.579

NiO.......... ................................. 1.001

MnO........................................... trace.

MgO....................................... .... 1.850

Residue......................................... 3.457

100.506

The atomic ratio is therefore R": Rvi : Svi : H2 =£: % : 2f: 4f, and 

the simplest symbol 9RO. 8R2O3 . 33SO3 . 171H2O. A portion of this 

large amount of water can be accounted for in the moisture of the sample. There seems to be a possibility of an isoinorphous mixture of different sulphates in this substance, but a mechanical separation of the 

massive from the fibrous portions was quite out of question. We propose for this mineral the name Redingtonite.

(3) This sulphate coats the purple salt in small quantities. Under 

the microscope it is found to consist of rhombic tables with angles of 

78° and 102°. The system is rhombic. The cleavage is excellent, parallel to OP. and good parallel to ooP and oP ob. The color is greenish 

yellow ; the mineral is somewhat dichroic; the color being most intense 

when the short diagonal of the tables is parallel to the principal section 

of the nicols. It is doubly refracting. The tables are too small to show 

the emergence of the optic axis. Tests with mica plates show, however, that of the two axes of elasticity lying in the basal plane the one 

parallel to the brachydiagonal is the larger. This also agrees with copiapite, which is negative.

The following analysis was made with 0.1482 grams material which 

was separated from associated substances as well as possible. The water above 100° 0. was determined by difference.

H8OatlOO° C.........................-.....---.----- 9.296

H3 0 above 100° C..................................... 17.596

S03 - .................-.. .. -.- 35.905

CftO,....-.........................-... - 7.409

AUOs- .... - 4- 835

Fe.03.-.......................- .. --- W.360

FeO......................--..-.------ - 3.813

MO..................-.-..-. ........... 0.835

MgO........ -. ..................... 3.216

Residue..... ..-.-...----.---..-.- --- - - 1.735

100.00
MELVILLE AND-] 

LINDGREN. J

The atomic ratio is B": Evi : S vi : H^-^-: -J: V : & From its optical 

and some of its chemical characters there are evidences of its isomorphism with copiapite from Knoxville, a mineral hereafter described, 

and a comparison of the atomic ratio with that obtained by analysis of 

the latter mineral shows rather close analogy. This sulphate is more 

basic than that, and its composition indicates a derivation from other 

sources than persulphide of iron. We propose for this mineral the 

name Knoxvillite.

COPIAPITE FROM REDINGTON MINE, KNOXYILLE. i '

The specimen! of copiapite consists of a soft mass composed of 

microscopic scales and crystalline particles, the color of which is 

sulphur-yellow. The optical properties of the mineral species have 

been described by E. Bertrand 1 and this specimen confirms his description in all important points.

The mineral is rhombic, and the microscopic fragments are mainly 

cleavage pieces from 0.04 to 0.2mm in diameter. The cleavage is perfect 

parallel to OP, and fairly good parallel to <& P. The angles of the prism 

are 78° and 102°. The plane of the optic axes is co P&. The second 

median line is perpendicular to OP. The double refraction is negative. 

The pleochroism is quite distinct, especially on OP; a slightly greenishyellow, \) nearly colorless, c yellowish.

Analysis.

H20 .................................................... 30.43

SO3 .................................................... 39.97

Fe2O3 .................................................. 26.54

FeO ................................................... 0.46

MnO................................................... 0.21

MgO................................................... 3.06

100.67

Atomic ratio Eu : Evl : Svi : H2=l: 6 :18 : 20, corresponding to the 

formula

KG. 2E2O3 . 6SO3 . 20H2O.

COPIAPITE FROM SULPHUR BANK, LAKE COUNTY, CALIFORNIA.

In the surface mines of the quicksilver deposits at Sulphur Bank 

bright red cinnabar is associated with the products of the decomposition of marcasite. Among these are ferrous sulphate, a white silky 

sulphate of iron and alumina, and a yellow ferric sulphate. The latter 

salt was studied in order to ascertain how closely it approached the

1 Groth's Zeitschr. fur Krystall. u. Min., vol. vi, 1882, p. 296.
26 MINEKALOGY OF THE PACIFIC COAST. [BULL.61.

copiapite from Knoxville in its characters. Under the microscope it 

entirely resembled this mineral, and the description above given for 

copiapite answers for this ferric sulphate. The following analysis was 

made, in which the water above 100° 0. was determined by difference:

H2O ................................................... 29.575

SO3 .................................................... 38.820

A12O3 ...I-............................................. 0.371

Fe203 --................................................ 26.792

FeO ................................................... 3.277

MnO................................................... trace.

CaO................................................... 0.255

MgO................................................... 0.156

Residue................................................ 0.754

100.000

The atomic ratio is Eji : Evi : S : H2=l: 10 : 30 : 33£, corresponding 

to the formula f EO. 5E2O3 . 15SO 3 : 50H2O.

Since all these sulphates, with the exception of redingtonite, were yet 

damp when taken for analysis, the moisture which was thus mechanically occluded by the salts can not be considered in the discussion of 

their formulae. The atomic ratios calculated for the anhydrous salts on 

the basis of 100 per cent, are tabulated as follows:

Purple sulphate, Redingtonite, anhydrous... R" : Evi : Svi = 0.44 : 0.98 : 4.77 

Green sulphate, Knoxvillite, anhydrous..... R» : Rvi : Svi = 0. 40 : 1.61 : 3. 77

Copiapite, anhydrous..........:............ R": Rvi : Svi = 0.24: 1.42:4.27

Yellow salt, Sulphur Bank, anhydrous...... R« : RVI : Svi = 0.16 : 1.47 : 4.18

Atomic ratio......

Purple sulphate.

2 : 4 : 19 

CKO.-tfkOs. 19S03

Green sulphate.

12 : 36 : 90 

6KO . 6KA . 15S03

Copiapite.

6 : 36 : 102 

SKO.eRjOs.lTSOs

Yellow sulphate.

6 : 54 : 150 

3EO . 9E2Og . 25S03

It is evident that the yellow ferric sulphate is identical with the 

copiapite from Knoxville, because the ratio of the atomicities of the 

total base to SO3 is practically the same; i. e., in copiapite, 21 : 17; in 

the yellow salt, 20 : 16£. The purple salt scarcely belongs to this 

scheme, because it proves to be a neutral sulphate according to its 

properties as well as by the atomic ratio first given in the description 

of the mineral species. Its rather compact state does not admit of the 

occlusion of much moisture. The other sulphates are loose in texture, 

and a fair comparison of their composition can be attained only through 

the above scheme. These sulphates are then basic sulphates, and in the 

anhydrous state are closely represented by the formulae in the above 

table.
SILVER ORES AT CALICO. 27

STEOMEYERITE FROM CALICO, SAN BERNARDINO COUNTY, CALIFORNIA.

On the lower levels of the Silver King Mine in Calico, a sulphide of 

copper and silver was found, which by the following analysis proved to 

be stromeyerite:

Ag .......... 53. 964 which requires 8. 018 S as Ag2S

Cu .......... 28. 575 which requires 7. 223 S as Cu^S

Fe.......... 0.264 

S............ 15.512 15. 241 theoretical S.

Residue ..... 1.552

99.867

Theory requires for Ag2S . Cu2S... Ag = 53.084

Cu= 31.148 

S = 15.768

100.000

The residue was mostly barite with a very little quartz. Comparison 

with the analyses of this mineral species which Dana 1 has tabulated, 

shows that the specimen under examination differs greatly, in composition, from those from Arizona, while it more nearly approaches specimens from localities in Siberia and Silesia. The analyses of stromeyerite from Arizona show a variation in silver from 7.42 to 14.05 per cent; 

in copper from 72.73 to 64.02 per cent.

The specific gravity of our specimen, 6.28, was found to be the same 

as that given by Dana for the mineral species. The mineral is darksteel gray on fresh fracture, but tarnishes somewhat on exposure. It 

is associated, with barite, malachite, and contains widely separated and 

minute areas of a brown oxide of manganese.2 Other minerals fouud 

in the same mining region are as follows:

Cerargyrite (horn-silver) as brown coatings; embolite (chloro-bromide 

of silver) greenish-yellow coatings, and crystalline aggregates, combinations of 0, oo 0 co, and oo 0; chalcopyrite; chrysocolla, usually microscopic; malachite; cerussite; pyrolusite; barite, massive and tabular 

crystals; calcite.

CHROMIFEROUS CHLORITE KOTSCHUBEITE.3

The great serpentine belt crossing the North Fork of the American 

Eiver above Dutch Flat contains several deposits of chromite, some of 

which are worked on a small scale. While examining the ore from one 

of these occurrences Green Valley, in the canon of the American Kiver, 

below Towle's on the Central Pacific Eailroad coatings of a micaceous

1 A System of Mineralogy, by J. D. Dana, ed. of 1883, p. 54.

8 W. Lindgren: Trans. Am. Jnst. Min. Engineers, Feb., 1887.

3 This article and those following have already appeared in print, having been 

published in the Proceedings of the California Academy of Sciences, Dec. 20, 1887, 

under the title, "Contributions to the Mineralogy of the Pacific Coast," by Waldemar Lindgren, U. S. Geol. Survey.
28 MINERALOGY OF THE PACIFIC COAST, [BULL. 61.

mineral of a beautiful peach-blossom color, together with smaller pieces 

of the same mineral, were found in the massive state. The substance 

proved to be a chlorite, and is most closely allied to that variety of 

clinochlore to which Kokscharow 1 gave the name kotschubeite. With a 

magnifying glass the micaceous coatings are seen to be composed of 

thin hexagonal tables from 0.2mm diameter down to the smallest dimensions, often roughly arranged in rosette form and in smaller fibrous 

masses, the latter being mixed with minute grains of uwarowite and 

chromite. The crystals cleave perfectly parallel to the hexagonal section, and appear to consist of a basal plane and rhombohedrons, one of 

which presents small striated faces. No accurate measurements could 

be obtained by means of the goniometer, or the micrometer and micrometer screw.

Under the microscope the tables, when resting on their bases, are pale 

purple and transparent, and between crossed nicols the crystals prove 

to be double-refracting and biaxial. The tables, apparently strictly 

hexagonal, are twinned mouocliuic crystals, the most regular forms 

being usually divided into six sectors with a common apex in the center 

and with their axes of elasticity in different position. The colors of 

interference are low on the base, not exceeding the grays of the first 

order; those of the fibrous aggregates are more vivid, more so in fact 

than is usual with the chlorites.

In convergent light the plane of the optic axes is found in each 

sector to be parallel to its base; angle of the optic axes quite large, 

probably about 30°. Double refraction positive. The character of the 

dispersion can not be well observed on account of the small size of the 

crystals.

The acute bisectrix stands nearly normal to the base OP, and the 

extinction of the fibers is consequently quite small. Pleochroism 

distinct: a and b purplish, c (vibrating perpendicularly to OP) yellowish 

red.

Streak of the mineral, white; luster of cleavage face, somewhat pearly. 

H=2. O (massive variety)=2.69.

Before the blow-pipe the mineral becomes greenish white, and is 

fusible on the edges with great difficulty. With fluxes strong chromium 

reactions.

In the following analysis the sample was quite free from associated 

chromite and uwarowite. In order to facilitate comparison two analyses 

follow, one from Dana's Mineralogy, an analysis of kiimmererite; the 

other an analysis of kotschubeite by von Leuchtenberg.

'Bull. Acad., St. Petersburg, 1861, p. 369.
MEI-VILLI5 AN1TJ 

UNUGUKN. J COMPARISONS OF CHLORITES. 29

Loss at 105° C. 

Loss above 105° 0.

Si02

CrjOa

A1203 

Fe203

IToO

NiO

CaO

MgO

0. 305 > 

12.678 } 13- 043

31. 740

11. 392

6.741

1.231

0.487

0.183

35. 178

99. 995

Kiitnmererito, 

Texas, Pa.

13.20

31.31

2.98

12. 84

2. 46

0.45

0.82

35.02

99.08

Kotscliubeito, 

Ural.

12.03

32.07

4.09

13.18 

2.22

.....

35.65

100. 44

The two forms of chlorite, penninite and clinochlore (ripidolite),have, 

according to Kainnielsberg, substantially the same composition, and 

differ only in their crystallization, penninite being hexagonal, and 

clinochlore, monoclinic. Both have varieties rich in chromium, that 

corresponding to penninite being kammererite from the Urals and the 

well-known locality, Texas, Pa. It has been proved to be uniaxial by 

Des Cloizeaux l and J. P. Cooke.2 Various authors have also designated 

it as rhodophyllite, chromchlorite, rhodochrom. The chroiniferous 

variety of clinochlore, kotschubeite, from the Urals, has been described 

by Nicholas vou Leuchtenberg,3 but has not been noticed from, any other 

locality, and its occurrence in California is therefore not without interest.

Von Leuchtenberg arrives at the conclusion that kotschubeite is a 

variety of clinochlore, but differs from it in the inclination of the acute 

bisectrix to the normal of the base; while this value amounts to 12° to 

16° in clinochlore, it has been measured to 1° to 2° in kotschubeite. The 

same writer's description applies equally to the California specimen as 

to the optical characters, but the crystal form differs. The mineral 

from the Ural had the form of hexagonal pyramids, and was apparently 

composed of simple crystals, while that here described occurs in thin 

tables composed of three individuals, and twinned according to the 

well known law of cliuochlore, so as to appear as hexagonal crystals. 

In the position of the optical axis the crystals most resemble those of 

clinochlore from Texas, Pa., described by Cooke.

A further and notable difference from Kokscharow's kotschubeite, 

and, indeed, from any known chrouiiferous chlorite, is in the very high 

percentage of Cr2O3 ; v. Leuchtenberg found 4.09 per cent, while the 

highest amount of Cr2O3 in kiimmererite is 5.50 per cent. The analysis 

of the California mineral shows more than twice that amount, viz: 

11.392 per cent Cr2O3 , replacing A12O3 , but in other respects it agrees 

well with those of kiimmererite and kotschubeite above.

1 Miiieralogie, vol. 1.

2 Am. Jour. Sci., 2<1 (series, vol. 44, p. 201.

3 Pull, Acacl. Imp. Sci., St. Petersburg, vol. 13, 1869, p. 34,
30 MINERALOGY OF THE PACIFIC COAST. [BULL. 61.

In the collection of the California State Mineralogical Museum there 

is one specimen of chromite from a locality near Jackson, Amador 

County, covered with a thin coat of massive, peach blossom colored 

chlorite. Whether it is kainmererite or kotschubeite is difficult to 

decide.

UWAROWITE.

Together with the kotschubeite, mixed with it as small grains or 

lining small fissures in chromite as almost microscopic crystals with 

brilliant faces, there occurs a deep emerald-green garnet. Under the 

microscope the crystals prove to be almost perfect dodecahedrons; 

with fluxes, strong chromium reaction. H. above 6. Eefraction very 

strong. Between crossed nicols some grains are isotropic, but the 

largest number are faintly double-refracting, some of these showing an 

approximate division into sectors. Garnets, as well known, often present abnormal phenomena of double refraction, and, according to Eosenbusch,1 uwarowite always shows these optical anomalies. Uwarowite 

is known to occur on chromite from Kew Idria, California.

A green chromium mineral, also on chromite, from the vicinity of 

Livermore, California, proved to be uwarowite in microcrystalline form, 

and not trautwinite as supposed.

Trautwinite2 is associated with chromite from Monterey County. In 

chemical composition it approaches uwarowite, but differs, according to 

Goldsmith, in crystal form, since it is hexagonal; it is, moreover, very 

soft, while uwarowite has a hardness approaching 7.

SCORODITE.

At Steamboat Springs, Nevada, metalliferous veins occur with arsenopyrite among other minerals in the metamorphic series. In cavities 

and cracks of this mineral coatings of a leek-green scorodite are found, 

which under the microscope often show perfect crystals with the usual 

combination of pyramid and pinacoids {111}, {010}, {100}. Eefraction 

and double refraction very strong. This mineral has recently been 

found by A. H. Chester at the Hornsilver Mine, Utah,3 and as deposit 

from arsenical thermal waters in the Yellowstone Park by Mr. A. Hague,4 

of the U. S. Geological Survey.

1 Microskopische Physiographic cler Miueralien, 2d ed., 1885, p. 269. 

2 E. Goldsmith: Proc. Acad. Sci., Phila., 1873, pp. 9, 348, 365. 

3 Am. Jour. Sci., vol. 33, 1887, p. 290. 

'Ibid., vol. 34, 1887, p. 171.
NOTE.

Since the foregoing was written, cinnabar crystals from the Avala 

Mountains, Servia, have been described by A. Schrnidt, in Foldtani 

Kozlouy, XYII, 551-555,1887, and in Zeitschr. f. Kryst. Bd. xm, 433-449, 

1888, and an extract from the paper appeared in Neues Jahrb. f. Mineralogie, Bd. 1, 45,1889. This admirable treatise contains an exhaustive 

description of complex crystals, upon which trapezohedral planes were 

observed, much like those on the crystals from New Idria. The Servian, 

material was much more perfect, with larger individual forms than ours, 

thus admitting of angular measurements which we found impossible to 

make. The dominant forms, viz, the basal plane and rhombohedrous, 

are the same from the two localities, while among the trapezohedrons

£. P-LJ, only one which we observed, +rii±-JL, approximates one of Schmidt's,

_i_PJi

+y|3 -. As a rule we found far more complex forms, and, as the table

on page 19 indicates, a slight deviation of angle makes considerable difference in the symbol. The reentering angles and tectonic faces apparently suggested many more trapezohedron planes than are recorded, 

but with objectives of very high power these planes were proved to be 

parallel to others whose symbols were established. In all about twelve 

different trapezohedrons were fully identified. In general, then, the 

habits of the cinnabar crystals from New Idria and Servia should be 

considered identical.

31

PLATES.

Bull. 61 3

PLATE I.

35
PLATE I.

FIG. 1. Cinnabar crystal, analogue pole.

2. Cinnabar crystal, antilogue pole.

3. Cinnabar crystal.

4. Cinnabar crystal with reentrant angle.

5. Crystal with gas inclusions.

6. Cinnabar crystal.

36
i). S. GEOLOGICAL SURVEY CULLETIN NO. 61 PL. I
PLATE II.
PLATE II.

FIG. 7. Cinnabar crystal, analogue pole.

8. Cinnabar crystal with reentrant augle, antilogue pole.

9. Cinnabar crystals, with inclusion.

10. Cinnabar crystal, analogue pole.

11. Cinnabar crystal, antilogue pole.

38
U. S. GEOLOGICAL SURVEY BULLETIN NO. 61 PL. II
PLATE III.
PLATE III.

FIG. 12. Subindividnal on tectonic face.

13. Illustration of derivation of tetartohedral forms.

14. Section lines of tetartohedral forms of crystals 1 and 2, Plato I, with basal 

plane.

40
U. S. GEOLOGICAL SURVEY BULLETIN NO. 61 PL. Ill

a

EDGE oR.-S

SUB-INDIVIDUALS ON 

TECTONIC FACE (-&/>}.

13