DEPARTMENT OF THE INTERIOR 

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIRECTOR

BULLETIN 490

MINERALOGICAL NOTES 

SEKIES 1

BY

WALDEMAR T. SCHALLER

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1911

CONTENTS.

Page.

Introduction............................................................. 7

Chemical composition of hulsite and paigeite...........................__ 8

Introduction.....................................................__ 8

Occurrence and association........................................_. 8

Notes on chemical examination...................__............_. 10

General statement...........................__................. 10

The gangue...................................................... 11

Methods of analyses.............................................. 13

Hulsite.............................................................. 16

Crystallography............... ... ....... ................ 16

General properties........ ................. ............... 16

Character of samples ............................................. 17

Analyses and ratios.......................__.................... 18

Discussion of formulas............................................ 20

Paigeite ................................ .......................... 21

General description .............................................. . 21

Character of samples............................................. 22

Analyses and ratios .............................................. 22

Discussion of formulas...... ................................. . 24

Chemical composition of jamesonite and warrenite .........^............._k 25

Introduction................................. ..................... 25

Formula of jamesonite................................................. 25

Composition of warrenite............................................. 27

Ludwigite from Montana................................................... 28

Occurrence and association............................................ 28

Analysis.......................................................... 28

Discussion of formula................................................. 30

Ludwigite from Hungary.............................................. 31

Summary............................................................ 32

Bismite from Nevada ..................................................... 33.

Occurrence and physical properties.................................... 33

Crystallography...................................................... 34

Chemical composition.............................................. 86

Axinite from California..... . .. .......................... 37

Localities............................................................ 37

Axinitefrom San Diego County..... .............. .. .....__ 37

Occurrence...................................... ........ 37

Crystallography............................................... 37

Chemical com position.............................................. 38

Axinite from Amador County ......................................... 42

Crystallography.................................................. 42

Chemical composition............................................. 46

3
4 . CONTENTS.

Page.

Albite from lawsonite schist, Marin County, Cal. ........ 48

Association ................. .. ........ ..... .... 48

Forms and angles..................................................... 48

Description of rarer forms............................................. 50

Combinations........................................................ 52

Habit ............................................................... 52

Notes on crystallography of phenacite ..................................... 53

Phenacite from New Hampshire..... .... ........ ...........' 53

Form system of phenacite....... . .. ..... .... 53

Notes on neptunite....................................................... 55

Neptunite from California........................ .. .......... 55

Form system of neptunite............................................. 56

Orbicular gabbro from Pala, San Diego County, Cal......................... 58

The refractive index of oil of cinnamon.......... ..... ........... 60

Introduction ............................... 4....................... 60

General description.................................. ............ 60

Measurements of refractive index...................................... 61

Summary............................................................ 64

Index of refraction of Canada balsam......... .... .............. 65

Siderite and barite from Mary land...... ...... .... ......... 66

Siderite.............................................._..._....... 66

Occurrence...................... ......... .......... 66

Chemical composition............................................. 66

Crystallography............................................. .. 67

Forms....................... ............................. 67

Etchfigures.................................................. 69

Value for c axis .............................................. 69

Barite............................................................... 70

Occurrence ...................................................... 70

Crystallography .........................."........................ 71

Notes on purpurite and heterosite ......................................... 72

Introduction........................'................................. 72

Purpurite from North Carolina........................................ 72

Occurrence.........................................._......... 72

Physical properties............................................... 73

Chemical composition ............................................ 74

Heterosite from South Dakota......................................... 77

Heterosite from Connecticut ........................................... 78

Purpurite from California............................ ............ 79

Conclusion................................................ . 79

Notes on powellite.........y............................. __......... 80

Powellite from Llano County, Tex................ ............... 80

Powellite from Nye County, Nev............................. .__. 81

Density of powellite .................................................. 82

Chemical composition of molybdic ocher........................_........ 84

Introduction ............................................ .......... 84

Physical properties................................................... 85

Optical characters ................................................ 85

Pyrognostic characters............................................ 85

Density............................................._......_. 86

Solubility in water ............................................... 86

Chemical analyses................................... ..*... .... 86

Molybdite from New Hampshire .................................. 86

Molybdite from other localities.................. ....r ............. 88
CONTENTS ILLUSTRATIONS. , 0

Page. 

Chemical composition of molybdic ocher Continued.

Artificial molybdite....................................... 91

Occurrence of natural trioxide of molybdenum ......................... 92

Analysis of tourmaline from Elba.......................................... 93

Evansite from two American localities.. .................... _. 94

Evansite from Idaho.......................................__. .. 94

Evansite from Alabama.................................. ......... 95

Literature..................................... ........ 95

Manganotantalite from Mount Apatite, Me........__.....____._.. 96

Zinnwaldite from Alaska...-...................._...... ...... ._......... 98

Some new forms of calcite crystals......................................... 99

Calcite from Andreasberg, Germany.................................... 99

Calcite from England ............................. ............ 100

Calcite from San Francisco, Cal........................................ 103

Calcite from Hillsboro, N. Mex......_..._............... ....... 104

Calcite from Lincoln, R. I................................. ........ 107

ILLUSTRATIONS.

Page.

FIGURE 1. Bismite crystal................_........'........................ 36

2. Bismite crystal................................................. 36

3. Variation in index of refraction for oil of cinnamon............... 63

- 4. Siderite from Maryland......................................... 68

5. Etch figures of siderite.......................................... 69

6. Barite from Maryland ......................_____....___ 71

7. Heterositefrom South Dakota................................... 77

8. Calcite from Germany....................................._.. 100

9. Calcite from England........................................... 102

10. Calcite from England........................................... 102

11. Calcite from California ......................................... 103

12. Calcite from New Mexico....................................... 104

13. Calcite from New Mexico....................................... 106

14. Calcite from Rhode Island...................................... 108

MINERALOGICAL NOTES-SERIES 1.

By WALDEMAK T. SCHALLER.

INTRODUCTION.

The miscellaneous papers here assembled are submitted as a report 

on the mineralogical work of research character conducted by the 

author in the chemical laboratory of the United States Geological

Survey from 1905 to 1909. A similar report on earlier work (1903- 

1905) was published as Mineralogical Notes in Bulletin 262 (1905), on 

pages 121-144. Besides these papers, a report on an investigation 

of the mercury minerals of Terlingua, Tex., made in collaboration 

with Dr. W. F. Hillebrand, has been published as Bulletin 405, and 

the study of the tourmaline field of southern California has been 

continued.

Many of the minerals described in this Bulletin were received for 

identification and study from members of the United States Geological Survey. Some specimens, however, were received from persons not directly connected with the Survey, and a few were collected 

by the author in California. Several investigations could not be 

completed, owing to loss of material by fire on December 16, 1908. 

Certain of these interrupted studies will be pursued further as opportunity affords.

Some of the papers have, in substance, if not in the exact form 

here reproduced, already appeared in scientific journals. A number 

of these papers were originally written and published in conjunction 

with some of the geologists of the Survey. Full credit has been 

given to these geologists for their contributions, some of which have 

been slightly rearranged.

A report similar in character to this one and giving the results of 

studies extending from January, 1910, to July, 1911, has been 

prepared and submitted for publication as a Bulletin entitled 

"Mineralogical notes series 2."
CHEMICAL COMPOSITION OF HULSITE AND PAIGEITE. 

INTRODUCTION.

A description of two new borates, hulsite and paigeite, was published in 1908 * by the writer in conjunction with Adolph Knopf, 

who discovered these minerals in Alaska. These borates contained 

both ferrous and ferric iron, magnesia, and a small amount of water. 

The boric acid was determined by distillation with methyl alcohol 

and subsequent weighing as lime borate, and although only a single 

determination was made for each mineral, the analyses footed up 

well and the ratios were so close to simple numbers that no doubt was 

entertained as to the correctness of the results obtained. Later, 

however, Prof. F. W. Clarke, chief chemist of the Geological Survey, 

informed the author that the determination of boric acid in minerals 

was being investigated by E. T. Wherry and W. H. Chapin, under 

tjie direction of Prof. Edgar F. Smith, of the University of Pennsylvania, and through the kindness of Prof. Smith the boric acid content 

of the new minerals was redetermined by methods devised by Wherry 

and Chapin.2 By this redetermination it was found that the amounts 

first obtained were much too high. Another examination of the 

minerals, made to explain the discrepancy, showed the presence of 

tin in appreciable quantity in both minerals. It therefore became 

necessary to revise and extend the original analyses in order to fix 

definitely the composition of the minerals.

OCCURRENCE AND ASSOCIATION.

The occurrence of these borates and their relation to the tin 

deposits of Alaska have been described by Knopf. A summary of 

his description, together with brief mention of the associated minerals, 

follows.

The Alaskan .tin deposits of known economic importance, which 

are limited to the extreme western part of the Seward Peninsula, 

about 100 miles northwest of Nome, are genetically associated with 

granitic intrusives which have invaded limestones of Paleozoic age. 

Along the margins of the granite bosses an intense pneumatolytic

1 Knopf, A., and Schaller, W. T., Two new boron minerals of contact metamorphic origin:, Am. Jour. 

Sci., 4th ser., vol. 25,1908, p. 323. 

8 Determination of boric acid in insoluble silicates: Jour. Am. Chem. Soc., vol. 30,1908, p. 1687.

8
CHEMICAL COMPOSITION OF HULSITE AND PAIGEITE.

contact metamorphism has frequently been produced and a considerable variety of minerals developed. The largest granite boss of 

the region is that of Brooks Mountain, and the most energetic contact 

action is displayed along its periphery. Tin deposits also occur in 

connection with a smaller intrusive a few miles south.

On the northeast flank of Brooks Mountain a prospect cut has been 

opened on an exposure of contact metamorphic minerals occurring in 

marmorized limestone 10 feet from the granite contact. Examination of this deposit showed hulsite, often intergrown with magnetite 

and vesuvianite, in considerable abundance. In the hand specimen 

taken from this exposure brown-green vesuvianite, magnetite, hulsite, and brown garnet occur scattered through a matrix of coarse 

white calc-spar. Occasionally some fluorite is visible. The characteristic forms of vesuvianite are a{100}, w{110},/{120}, c{001},

p(lll}, 2(331}. Less prominent forms are ft{130}, d\W}, i{H2),

&{221}. Among rare and somewhat doubtful ones are {150}, {180}, 

{1.10.0},-y{151}, and a few others. The angles measured are given 

in the table below.

Forms and angles for vesuvianite.

Letter.

a 

c

(?) 

(? 

(?)

h

f 

m

V

S 

i

I

t

Symbol.

100 

001 

1. 10. 0 

180 

150

130 

" 120 

110 

151 

113

112 

111 

221 

331

Reflection.

Fair.... 

Fair.... 

Poor.. . 

Poor... 

Poor...

Poor... 

Poor... 

Fair.... 

Poor... 

Poor...

Poor. . . 

Fair.... 

Poor... 

Poor...

Size of face.

Large. .........

Line face.... . . .

Line face.... . . .

T & T&f*

Narrow. .......

Measured.

*

o /

0 00

5 49 

7 -13 

10 47

18 26 

26 14 

45 00 

10 01 

45 00

45 00 

45. 00 

45 00 

45 00

P

o /

90 00 

0 00 

90 00 

90 00 

90 00

90 00 

90 00 

90 00 

69 47 

14 20

20 54 

37 17 

57 03 

66 42

Calculated.

$

o /

0 00

5 43 

7 08 

11 19

18 26 

26 34 

45 00 

11 18 

45 00

45 00 

45 00 

45 00 

45 00

P

0 /

90 00 

0 00 

90 00 

90 00 

90 00

90 00 

90 00 

90 00 

69 57 

14 13

20 49 

37 14 

56 40 

66 19

The forms {1.10.0}, {180}, and {150} are too doubtful to warrant 

their establishment as well defined without additional confirmation. 

On the Alaskan mineral, they form the merest striae, and the close 

agreement in angles for. {1.10.0} and {180} may be accidental. 

When the vesuvianite is treated with fluorite mixture, it gives a distinct boron flame, and as it contains 0.89 per cent B203 is regarded 

as belonging to the variety wiluite. The magnetite shows o{lll},
10 . MINEKALOGICAL NOTES SERIES 1.

m{311}, «{100}, and d{110} with om large and ad small. The angles 

are shown below.

Forms and angles for magnetite.

Symbol.

a/\m=001/\113

a/\o =001A1H 

a/\d =001A101

Measured.

. o /

25 20

54 42 

45 06

Calculated.

0 /

25 14

54 44 

45 00

The characteristic features of hulsite are its strong metallic luster' 

black color, good prismatic cleavage, and tendency toward tabular 

development. Its surface weathering is almost identical with that 

of magnetite, and it may, on casual inspection, easily be confounded 

with that mineral. The tabular individuals of hulsite vary in thickness from a fraction of a millimeter to a little more than a centimeter, 

so far as known. Under the microscope it is absolutely opaque, and 

appears dark black in reflected light.

Thin sections show that magnetite is often intimately intergrown 

with the hulsite, from which it inay be distinguished by its bright 

metallic reflection.

The other mineral, paigeite, which was found at Brooks Mountain 

in loose blocks and at Ear Mountain, 40 miles northeast, in place, is a 

lustrous, coal-black mineral of foliated appearance. A thin section 

of the matrix from Brooks Mountain shows vesuvianite, calcite, 

hedenbergite, a small amount of biotite, and arsenopyrite in sporadic 

grains. The paigeite is abundant, and occurs in many .places in 

capillary or trichite-like forms transfixing the various other associated minerals. At Ear Mountain a granite intrusion has produced

an extensive development of contact metamorphosed limestones, 

especially lime silicate hornfels, some of which is flecked with paigeite 

and chalcopyrite. Under the microscope this variety of hornfels is 

seen to consist of a confused intergrowth of calcite, zonally banded 

tourmaline, pleochroic in tones of blue and brown, vesuvianite, 

fluorite, and zoisite,, with accessory phlogopite, chalcopyrite, and 

magnetite. Paigeite fibers and matted aggregates are embedded in 

the various constituent minerals, especially in the tourmaline and 

calcite.

NOTES ON CHEMICAL EXAMINATION.

GENERAL STATEMENT.

These borates, hulsite and paigeite, which are similar in composition, contain ferrous and ferric iron, magnesia, tin, water, and boric 

acid. In solutions of samples in hydrochloric acid, silica, alumina, 

and lime, derived from the gangue, also appear.
CHEMICAL COMPOSITION OP HULSITE AND PAIGEITE. 11

The results of considerable work performed on these minerals 

herein presented are not altogether satisfactory. A complete revision 

of all the chemical data is highly desirable, but such revision, in 

order to make determinations exact, would require new material, 

in considerable quantities, free from gangue.

The present investigation was carried on under great disadvantages, for the amount of material for analysis was insufficient and 

the presence of foreign matter in very appreciable quantities could 

not be avoided. Less than a gram of hulsite free -from magnetite 

was available, and only a few grams of paigeite could be obtained 

in approximately pure condition. In consequence, solutions to 

various questions that developed after some of the analyses had been 

completed could not be worked out, owing to lack of material. 

Individual samples of the minerals, moreover, differed somewhat in 

composition, owing to the nature of the gangue and to isomorphous

replacements in the minerals themselves. All these conditions, 

which were brought out as the analyses progressed, served to render 

the results unsatisfactory.

A brief description of the gangue and a somewhat more detailed 

account of certain of the analytical methods employed will be given 

in order to present properly the evidence on which are based the 

formulas here proposed for hulsite and paigeite.

THE GANGUE.

The material here designated as gangue comprises those minerals 

vesuvianite, arsenopyrite, and several others which were associated with the borates and could not be separated from them. The 

amount of gangue present in the specimens available for analysis 

ranged from 10 to 30 per cent. Hulsite is .in nearly all specimens 

mixed with magnetite, and nonmagnetic hulsite seems to be extremely 

rare. In the preparation for the new analyses all the material 

available was broken up and the hulsite was picked out with a hand 

lens. The greater part of the hulsite that in which magnetite was 

present was then removed with a magnet, leaving less than a gram 

of nonmagnetic and magnetite-free material, which, however, contamed appreciable amounts of vesuvianite, calcite, and other gangue 

minerals. This sample is referred to later as hulsite sample No. 3.

The samples of paigeite comprised several pieces about an inch 

thick. The mineral is coal black and massive and of laminated or 

radiating fibrous structure. The gangue, with which it is intimately 

mixed, is stained brown, presumably by ferric oxide. Samples of the 

black paigeite were so. selected as to exclude all visible gangue; 

but a microscopic section of one sample showed that the paigeite 

occurs as small fibers and irregular masses as inclusions in the gangue
12 MINEKAL.OGICAL NOTES SERIES 1.

minerals and it therefore contains considerable extraneous matter 

generally about 20 per cent.

A small amount of arsenopyrite is always present, even though 

none is visible to the eye, and appears amid the main mass of whitish 

residue after the paigeite is dissolved out by hydrochloric acid. 

Microscopic examination indicates that this gangue or whitish residue 

is for the most part vesuvianite. Calcite and magnetite seem, in 

general, to be absent from the massive paigeite samples, but, in addition to the arsenopyrite, tourmaline and fluorite may be present in 

varying but small quantities. When the paigeite is dissolved out 

by hydrochloric acid, these substances remain behind and may be 

filtered off.

Certain conditions, however, indicate that the gangue as a whole 

is considerably attacked and dissolved by the acid. First, more 

than 3 per cent of silica was found in the hydrochloric acid solution 

of one sample of paigeite. Whether the silica has isomorphously 

replaced the tin in the borate or whether it comes from the gangue 

is not definitely known, but the latter supposition is by far the most 

plausible. The excessive values for gravimetric R2O3 determinations, 

which are always several per cent higher than the total amount of 

iron, are doubtless due to silica and alumina derived from the gangue. 

Confirmation of the presence of alumina in the solution, however, 

would not necessarily point to the gangue as its source, for it might 

come from the iron borate as an isomorph of Fe203 . Second, some of 

the gangue, as shown by the microscope, is stained yellow by iron 

chloride. Hydrochloric acid does not dissolve the stain, and this 

fact seems1 to show that the gangue either consists in part of, or is 

coated by, a layer of colloidal matter able to retain the iron chloride. 

Crystallized vesuvianite, which is unattacked by acid, is not able 

to retain the iron chloride stain so tenaciously. Third, when the 

gangue or insoluble residue was heated at 110° to constant weight 

it retained considerable water, which was not given off until the 

crucible was heated to a low red heat. If the gangue were unattacked, its weight dried at 110° should be but little, if any, more than 

what it weighs on being ignited. The percentages of the insoluble 

gangue of paigeite, first dried at 110° to constant weight and then 

carefully ignited, follow:

Percentage of insoluble gangue in paigeite.

Insoluble gangue dried at 110°. ........

No. 5.

20. 24

17.32

No. 6. .

20.60

17.51

No. 7.

19.29

16.99
CHEMICAL COMPOSITION OF HULSITE AND PAIGEITE. 13

The presence in tHe paigeite solution of considerable calcium, 

which was shown by qualitative tests on small pieces of the purer 

mineral to be almost absent from some samples of the borates, also 

indicates the extent to which the gangue is attacked. The silica and 

bases thus entering into solution seriously complicate the interpretation of the analyses.

When vesuvianite and arsenopyrite, the chief constituents of the 

gangue of paigeite, are ignited, they decrease somewhat in weight. 

Arsenopyrite changes in accordance with the following reaction: 

2FeAsS +100 = Fe203 + As203 + 2S02 . The weight of the ferric oxide, 

which remains after the reaction, is about half that of the arsenopyrite; therefore half the weight of the arsenopyrite is lost in ignition. Vesuvianite loses only about 2 per cent water when heated, a 

loss which, if the amount of material in the paigeite sample were 

15 per cent, would amount to 0.3 per cent. The amount of arsenopyrite in the original samples of paigeite is about 2 per cent, and 

when the gangue is ignited there is a loss of half this amount plus 

the 0.3 per cent loss of vesuvianite, making a total loss of 1.3 per cent. 

This amount must therefore be added to the final value of the ignited 

residues of paigeite, as has been done in the analyses given in this 

paper.

The amount of calcite in the gangue is generally very small and 

was not determined in these investigations. The per cent was 

largest in hulsite sample No. 3. Magnetite was removed from all 

the samples of hulsite except No. 2, a magnetite-hulsite mixture.

METHODS OF ANALYSES.

Ferrous iron is present in both borates in large amount, and was 

determined by a modification of Pratt's method, which has been 

shown by W. F. Hillebrand to give reliable values. 1 Both new 

borates here described dissolve readily in hydrofluoric acid, so that 

no difficulty was experienced in making the ferrous-iron determinations. The hulsite powder was always coarser than 100 mesh and 

the paigeite powder coarser than 60 mesh, so that very little, if any, 

oxidation of the ferrous iron resulted from the grinding. That such 

oxidation occurs and may be extensive has recently been shown by 

Mauzelius.2 Oxidation due to grinding is considerable on the FeO 

contained in these borates, for in paigeite the amount for FeO falls 

from 44 per cent in <20> 60-mesh material to 39 per cent in the 

same material finely ground. The data given below indicate the 

results of grinding paigeite and a similar borate, ludwigite, from 

Hungary.

i The analysis of silicate and carbonate rocks: Bull. U. S. Geol. Survey No. 305,1907, p. 138.

a Sveriges Geol. Unders6kning, Yearbook 1, No. 3,1907. Consult Chem. Abstract, 1907, p. 2861, for an 

abstract of this article. See also Hillebrand, W. F., The influence of fine grinding on the water and ferrousiron content of minerals and rocks: Jpur. Am. Chem. Soc., vol. 30,1908, p. 112Q,
14 MINERALOGICAL NOTES SERIES 1. 

Oxidation of ferrous iron on samples of paigeite.

FeO «40> 100 mesh):

FeO «20>.40mesh):

Pratt's method.

Per cent. 

43.87

41.38

40.23

39. 78

44.30

42.24

39.39

Cooke's method.

Per cent. 

43.91

40.88

39'. 98

39.59

A sample of ludwigite containing about 16 per cent of ferrous iron 

gave the following results on the oxidation of FeO by grinding:

Oxidation of ferrous iron on ludwigite (two determinations by Pratt's method).

FeO «20>40mesh):

1

Per cent. 

15.84

15.50

15.43

2

Per cent. 

15.88

15.53

15.34

The oxidation of ludwigite is not nearly so great as that of paigeite, 

the remarkable oxidation of which is probably largely due to the 

presence of an abundance of gangue material, such as vesuvianite 

and arsenopyrite, much harder than the borate itself.

The amount of ferrous oxide given in the analyses of hulsite and 

paigeite also includes that of the vesuvianite present, but this amount

is probably so small that it may be neglected. The vesuvianite has 

not been analyzed, but the ferrous iron in it is doubtless less than 1 

per cent. The arsenopyrite present had no effect on the determination of ferrous oxide, for the mineral particles were so large that the 

arsenopyrite remained undissolved in the hydrofluoric-acid solution.

The total iron content of the borates, and thereby the amount of 

ferric iron present in them, was determined in 'the usual manner by 

dissolving the precipitated R203 m sulphuric acid or by fusion of the 

ignited precipitate with sodium pyrosulphate and subsequent titration with potassium permanganate. By fusing the ignited precipitate the silica present could be recovered and determined.

The amount of tin was determined by precipitating it with H2S 

from the HC1 solution of the minerals and by weighing it as oxide. 

The easy solubility of both the minerals in cold dilute acid indicates 

that the tin occurs as some form of stannic acid. Qualitative tests 

showed that the tin was present in solution in the stannic condition.
CHEMICAL. COMPOSITION OF HULSITE AND PAIGEITE. 15

Boric-acid determinations were made in the original analyses by 

distilling with methyl alcohol. It is not known why high results 

were obtained, for the method is more likely to give low values. 

The method adopted for the reanalyses of the borates, that proposed 

by Wherry/ was first tested on samples of known B203 content. 

The values here given do not agree closely, because of the small 

amount of material available and the varying amount of gahgue 

present in the samples.

The percentage of water was determined by heating the mineral 

to be tested (size <20> 60 mesh) in a glass tube and weighing the 

water directly in a portion of that tube (Penfield's method).

As the determination of total water was made on coarse material 

the amount of hygroscopic water in the sample was reduced to a 

minimum. What increase in the water content is caused by grinding 

these borates is not known, but experiments with ludwigite, a mineral 

of analogous composition, show that a very considerable amount of 

water is taken up. (See p. 15.) Total water determinations for 

such minerals as these borates must, therefore, to be of value, be 

made on coarse material, such as was used in these investigations. 

It is believed that the water content given for these minerals is an 

essential part of their composition, rather than hygroscopic or accessory water, but definite proof of this hypothesis is lacking, and future 

work may show the water associated with these two minerals to be 

extraneous. Hillebrand,2 who has made a study of the effect of grinding on the ferrous-iron content of minerals, called the writer's attention to these conditions, which served to explain the varying results 

first obtained on paigeite for ferrous iron.

The same general method was followed in the analyses. The 

powdered or coarsely crushed sample was treated in a beaker with a 

small amount of HC1 and allowed to stand some hours. Platinum 

dishes should not be used, as the large amount of iron chloride and 

possibly also tin chloride readily attacks and dissolves the platinum. 

Solution of the finely crushed borate samples was usually complete 

in a few hours. Solution of the coarser samples was hastened by 

gentle warmth. The solution must not be allowed to boil, on account . 

of volatility of SnCl4 in steam. Under the conditions described the 

arsenopyrite is not attacked, though partial solution of the vesuvianite occurs. After filtration and ignition of the gangue (see p. 13), 

H2S was conducted into the diluted solution, the tin sulphide filtered 

off and determined, the solution boiled, the iron oxidized, and the 

analysis continued as usual. A determination of the alkalies was 

made in one sample, 0.54 per cent of K2O and 0.70 per cent of Na2O 

being found. As the operations were made in glass vessels and 

many reagents had been added to the solution, these values, even

i Determination of boric acid in insoluble silicates: Jour. Am. Chem. Soc., vol. 30,1908, p. 1687, 

> Jour. Am. Chem. Soc., vol. 30,1908, p. 1120.
16 MINEBALOGICAL NOTES SEEIES 1.

though small in quantity, probably do not represent alkalies originally in the mineral. Traces of manganese and titanium are 

present in the samples, but the following elements and radicals 

were never found, though several qualitative tests for them were 

made: Ba, Bi, Cd, Zn, rare earths, Cb, Ta, Li, Mo, Te, W, U, Zr, 

V, F, sulphates, phosphates, and chlorides.

HTJLSITE.

CRYSTALLOGRAPHY.

Hulsite always occurs in crystalline form, either as small crystals 

about 1 millimeter in diameter or as large tabular masses, extending 

several centimeters and, showing well developed prismatic cleavage. 

The crystals, though they may be complete, are always uneven, 

and the faces dull and rough, so that no measurements could be 

obtained from any of the natural faces. Inspection with a hand 

lens shows that these crystals are often rectangular, and as hulsite 

is provisionally considered orthorhombic these rectangular prisms 

consist of the three pinacoids. Sometimes the crystals are bounded 

by the prism faces and the basal pinacoid, though it is not always 

possible to decide whether the prisms are natural crystal faces or 

whether they are due to cleavage. Often one pair of prism faces 

becomes much larger than the other pair. The cleavage parallel 

to the prism is good, and measurements of three such cleavage 

angles gave the values:

m Am'" = 57° 44', 57° 38', 57° 33'. Average value 57° 38'. Assuming that hulsite is orthorhombic, the crystallographic elements 

become:

a : b : c=0.5501 :1 : ?

Forms : a{100}, 6{010}, c{001}, m{110}.

Many of the crystals are twinned', one individual being turned 

about 120° to the other and the two basal pinacoids remaining in 

the same plane. They are also often grouped in parallel position, 

especially when the individual crystals are elongated parallel to a 

prism face.

GENERAL PROPERTIES.

Hulsite is black, but when free from inclosed magnetite has a 

greenish, brownish, or reddish tinge. Many of the smaller crystals 

are covered with a brownish coating, probably limonitic in character. 

The streak is black and the luster generally submetallic, though that 

of the pure mineral tends rather to vitreous, like hornblende. The 

hardness is about 3 and the density is 4.31. The cleavage is good, 

being prismatic parallel to ra{110}. Hulsite is readily soluble in 

HC1 and HF, but dissolves in other acids with some difficulty. It
CHEMICAL COMPOSITION OF HULSITE AND PAIGEITE. 17

gives off water in a closed tube, and fuses quietly before the blowpipe to a dull bla^ck slag, giving a slightly green flame. When heated 

with potassium bisulphate and fluorite, it gives a persistent green 

color to the flame.

The composition of sample No. 2 (see beyond) was found by 

calculation to be approximately as follows:

Vesuvianite................................................... 2.2

Hulsite....................................................... 80.6

Magnetite.................................................... 17.2

100.0

The density of this mixture is 4.438. If the density of vesuvianite is taken as 3.40 and that of magnetite as 5.17, the density 

of hulsite is found by calculation to be 4.31.

CHARACTER OF SAMPLES.

The sample of hulsite first submitted for chemical investigation 

was apparently homogeneous. It was, however, strongly magnetic, 

and though it was suspected that it consisted of a mixture of a nonmagnetic borate with magnetite, various tests failed to show the 

presence of the latter mineral. When powdered finely and suspended 

in water, the particles were still attracted by the magnet, and none 

of the many chemical tests attempted led to a separation of the 

magnetite from the borate.- After the analytical work on this 

sample had been finished, some specimens of hulsite collected in 

previous years were tested and found to be nonmagnetic. These 

specimens showed that the earlier ones contained admixed magnetite 

and a careful examination of all of the samples on hand showed the 

very common presence of magnetite in varying amounts included 

in the hulsite.

The few specimens that were nonmagnetic and free from magnetite seemed to weather more easily than the others, and several of 

them were, more or less altered to a limonitic substance, so that the 

amount of fresh material on hand was very small. After the presence of tin in hulsite was established, all the specimens at hand 

were again gone over for material for reexamination, but only a 

very small quantity of hulsite free from magnetite was obtainable. 

' Three samples of hulsite were obtained and .analyzed. Sample 

No. 1 consisted of about half a gram of hulsite free from magnetite, 

which was crushed into grains of <60> 100 mesh size and partially 

analyzed, only ferrous and, ferric iron, magnesia, and the insoluble 

matter being determined. The value given for the magnesia content is. doubtless high, for a little lime was probably present and, if 

so, was determined as magnesia. A part of the magnesia,, too, was

99946° Bull. 490 11 2
18 MINERALOGICAL NOTES SEBIES 1.

derived from the gangue. Sample No. 2 consisted of about a gram 

of material at first supposed to be homogeneous, but later found to 

consist of a mixture of hulsite and magnetite with a small amount of 

gangue. Tin was not determined in either sample, and the value 

for boric acid in sample No. 2 was furnished by Wherry and Chapin. 1 

Sample No. 3 was obtained by reexamining all the available material 

and picking out a small amount of nonmagnetic hulsite mixed with 

considerable gangue. The relatively large amount of gangue soluble 

in acid complicated the interpretation of the results.

ANALYSES AND RATIOS.

The analysis of the first sample yielded the following results: 

Partial analyses of hulsite, sample No. 1.

FeO... ..'.................

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

Fe203 ............. .......

Total iron as Fe203 . .......

Insoluble. ................

B203 ,Sn02 ,H20............

1

33.27

54. 40

2

10.17

54.20

10.00

Average.

33.27

10.17

17.83

10.00

The ferrous iron and magnesia are doubtless not present in any 

definite ratio, but vary reciprocally, so that hulsite may be considered as a mixture of a ferrous with a magnesian borate. In the 

above analysis the ratio of FeO : MgO is about 9:5. Ferrous iron 

and magnesia are probably isomorphous in hulsite as well as in 

paigeite, and similarly in the related borate ludwigite. An analysis

of ludwigite from Montana shows this isomorphism particularly 

well, for this mineral contains but little ferrous iron, while that 

from Hungary contains about 15 per cent. (See' p. 32.) 

The ratios in sample No. 1 are shown in the following table:

Ratios of average analysis of hulsite, sample No. 1. 

FeO.................................................... 0.462

MgO................................................... =6.63 .254

Fe203 .............................................^.... .108 =1.00

The ratio of RO : Fe203 as given by the analysis is.6.63 : 1, but 

the true value is probably better represented by the ratio 6:1, for, 

as already stated, the magnesia value is doubtless high.

The second sample, in which the hulsite was mixed with magnetite, 

gave the following results on analysis:

iLoc. oil.
CHEMICAL COMPOSITION OF HULSITE AND PAIGEITE.

' Analyses of'hulsite, sample No. 2.

19

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

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

Fe203 .......................

Total iron as Fe203 . . ........

H20....... ................

B203 ..... .......I... -- ---

Insoluble....................

Sn02 ............. '..........

1

34.48

8.60

66.24

1.63

2.25

2

34.35

8.83

67.08

 1.68

1.97

3

8.36

65. 70

2.24

4

8.12

65.42

2.48

5

65.32

10.44

Average.

34.44

8.48

27.64

1.66

10.44

2.24

The ratios obtained from the above analyses, as given, are:

Ratios of average analysis ofhulsite, sample No. 2.

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

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

Fe203 ......... .......

H20.. ................

B203 - ...............

SnO,. ...............

......................................... 0.479

......................................... .212

......................................... .173

......................................... .092

......................................... .149

Analysis of sample No. 3 shows the ratio of B203 to Fe203 to 

be 3 : 2. From this ratio the amount of magnetite present in sample No. 2 can be calculated, for the amount of ferric iron entering 

into the composition of the borate can be easily determined, and the 

remainder must therefore belong to the magnetite. When the proper 

amount of FeO required to form FeO.Fe203 is deducted from the 

ratios, they reduce to figures representing the composition of the 

magnetite-free hulsite.

Ratios showing composition of hulsite free from magnetite.

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

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

Fe203 . . ...................................... H2b.3..... ..................................

BO

Sn02 . .......................................

Ratios 

from 

analysis.

} 0. 691

.173

.092

.149

Ratios of 

magnetite.

-0. 074

- .074

Ratios of 

hulsite.

0. 617 12. 4

. 099 2. 0

. 092 1. 9

. 149 3. 0

The ratios from the above analyses give as the formula for pure 

hulsite 12.4RO. 2.0Fe203, 1.9H20. 3.0B203 +?Sn02 .

The results obtained from the analyses of sample No. 3 are given 

below. Considerable insoluble gangue was present, but magnetite 

was entirely absent. The results shown under the heading la were 

obtained from analysis of a small sample of less pure material. They
20 MINERALOGICAL NOTES SERIES 1.

are not taken into the average, and are of value chiefly because they 

confirm the figures given for tin in the other analyses. The amount 

of ammonia precipitate in la was not determined, since it was used for 

various qualitative tests, and the calcium precipitate was accidentally 

lost. The higher value for the amount of boric acid is taken in the 

average instead of the mean of the two values, for the second determination is believed to be low.

Analyses o/hulsite, sample No. 8.

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

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

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

Fea08 ............. ..................

Total iron as Fe203 . ..................

SnOa ... ..............:..............

B2O3 . ;..............................

H20,C02 ,Si02 ,AU)3 . . ...............

la

3.62

6.13

27.42

1

7.98

6.85

9.20

19.92

2

4.i3

9.82

46.30

7.15

8.27

17.52

diff.

3

27.71

4.45

9.54

45.67

7.20

18.44

Average.

27.71

4.29

9.11

15.21

7.07

9.20

18.63

8.78

100. 00

The following ratios were calculated from the figures for the average 

analysis: °

Ratios of'average analysis of'hulsite, sample No 3. 

FeO...........,...!................................. 0. 385\

MgO.....................................:............ .107/=I°- 47

FeaOg- - - --- -- -- -- - -- - -- --- -- -- - 095 = 2- 02 

Sn02 .................'................................ .047 = 1

B203 ................................................. .131 = 2. 79

Analyses of paigeite samples reported in this paper indicate the 

amount of calcium oxide derived from the gangue. Where the 

insoluble matter is approximately 15 per cent, the calcium-oxide 

content is about 4 per cent. If this ratio remains fairly constant, 

there should be in the above analysis of hulsite sample No. 3 about 

5 per cent of lime derived from the gangue, leaving approximately 

somewhat less than 4 per cent of CaO, which may belong to the 

borate mineral. If this CaO enters into the composition of the borate, the ratio of (FeO, MgO, CaO) to Fe203 would become 11.9 : 1, 

or nearly 12 : 1. The analysis of sample No. 3. shows the formula of hulsite to be either 10fR0.2Fe203 .Sn02 .3B203 + ?H2O or 

12RO.2Fe203 .Sn02 .3B203 + ?H20.

DISCUSSION OF FORMULAS.

From the results of the analyses of the three samples of hulsite, as 

given, there are derived the following partial formulas for the mineral;
CHEMICAL COMPOSITION OP HULSITE AND PAIGEITE. 

Partial formulas for hulsite.

21

Sample.

No. 1...

No. 2...

No. 3..{

RO.

13.2

12.4

10.5

12.0

Fe203 .

. 2.0

2.0 2.0'

2.0

Sn02 .

1.0

1.0

BA3.0

2.8

2.8

H20.

1.9

From this incomplete compilation the most probable formula is 

12R0.2Fe203 .lSn02 .3B203 .2H20 or (Fe,Mg) 12Fe4SnB6H403 i- Hulsite 

can hardly be considered a borate of iron (ferrous and ferric), tin 

and magnesia, for the bases are present in overwhelming amount; 

therefore the ferric iron may be considered to be present as an acid, 

playing the same rdle as the borates. On the basis of this assumption 

the formula may be written R"9 (B03) 6 .R"3 [Sn(OH)]"'H3 (Fe03 ) 4 .

The tin in hulsite occurs in a condition so easily soluble in dilute 

acid that it is probably present in some form of stannic acid. 

The possible presence of stannic acid, however, in combination with 

boric and possibly some iron acids, leads to complications which can 

not well be discussed at present.

PAIGEITE.

GENERAL DESCRIPTION.

Specimens of paigeite from Brooks Mountain are coal black and 

lustrous. The mineral has a laminated appearance. No distinct 

crystals were visible, but the entire mass has a crystalline appearance 

and in thin sections is seen to be composed of innumerable hair-like 

needles, which often form radiating groups. The hardness of paigeite 

is about 3, and the density is 4.78. Both color and streak are coal 

black. It dissolves readily in HC1 and HF, and resembles hulsite in 

its pyrognostic properties.

The density of sample No. 1 was determined as 4.544. Calculation 

shows the density of pure paigeite to be 4.78, in accordance with the 

following analysis of the sample:

Component minerals and densities of paigeite, sample No. 1.

Paigeite ........................

Densities.

3.40

6.0

4.78

Per cent of 

sample.

19

2

79

100
22 MINERALOGICAL NOTES SERIES 1.

CHARACTER OF SAMPLES.

Three different samples of paigeite were prepared and analyzed. 

The amount of gangue varied only slightly as compared with the 

large variations encountered in hulsite. The first analysis was made 

on sample No. 1; on this sample no determination of tin was made, 

and the value given for B2O3 is that determined by Wherry and 

Chapin. The other samples were prepared from specimens at hand. 

Sample No. 2 consisted of finely ground material, and consequently 

the value given for FeO may be somewhat low. The material of sample No. 3 was coarser, but otherwise very similar in character to No. 2.

ANALYSES AND RATIOS. 

The results of the analyses of sample No. 1 are shown below.

Analyses of paigeite, sample No. 1.

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

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

Fe203 - .............................

Total iron as Fe203 .................

H20........ .......................:

B203 .......... ......................

1

43.91

1.70

66.26

2.03

15.55

2

44.30

1.22

65. 95

15.76

3

45.82

1.39

66. 22

15.65

4

43.87

9.83

Average.

44.48

1 44

Ifi 79

9 03

Q K3

15.65

The amounts of Sn02 and of its soluble gangue were not determined.

Ratios from average analysis of paigeite, sample No. 1. 

.................................................. 0.618

MgO.

Fe£)3 ......... ......................................... .105 = 5

H20......... ......................................... .113 = 5.4

B2O3 - .................................................. .140 = 6. 7

From the above analysis, the incomplete formula derived for 

paigeite is' 3 1.1RO. 5.0Fe2O3 , 5.4H2O. 6.7B2O3 + ?SnO2 . 

Analyses of the second sample yielded the following results :

Analyses of paigeite, sample No. 2.

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

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

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

Fe203 . ...........................:..........

Total iron as Fe,03 ..........................

Sn02 .......................................

B203 . ........................................

SiO.,, A12O3 ,H2O (difference) ...................

1

40.82

2.02

4.28

18.19

63.54

3.15

9.10

16.18

2

2.01

4.31

19.34

64.69

3.14

15.74

3

2.10

3.81

18.48

63. 83

3.26

16.38

Average.

40.82

2.04

4.13

18.67

3.18

9.10

. 16. 10

5.96

100. 00
CHEMICAL COMPOSITION OF HULSITE AND PAIGEITE. 23

If all the lime is considered as resulting from solution of the gangue, 

the ratios deduced from the above analyses are:

Ratios of average analysis of paigeite, sample No. 2.

FeO.................................................. 0.567\_2q 4

MgO................................................... .051/~^- 4

Fe208 ................................................... .117 = 5.6

SnO,..: ............................................... .021 = 1

B.,03 -................................................. . 130 = 6.2

H20.................................................. ...... ....

These ratios give the following formula, which is incomplete in 

respect to the water content: 29.4RO. 5.6Fe2 03 . lSn02 .6.2B2 03 + ?H20.

Evidence that the gangue was considerably dissolved by HC1 led 

to direct determinations of the silica and alumina in analyses of the 

third sample, with the following results:

Analyses of paigeite, sample No. S.

FeO

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

cao......:.................................

FeA'------.----.----- - --- - ----. ........

Total iron as Fe203 ..........................

Sn02 ............. ...........................

B203 - .........-...:........................

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

AL,03 .... ...................................

H20, etc. (difference). . .......................

1

34.68

2.25,

8.97

14.69

53.22

2.77

18.62

3.28

2.51

2

34.86

1.89

8.56

14.84

53.57

2.86

6.71

18.81

2.78

2.41

3

35.52

2.22

8.84

15.18

54.62

a 2. 76

7.16

18.29

-3.25

2.09

Average.

35.02

2.12

8.79

14.90

2.80

6.94

18.57

3.10

2.34

5.42

100. 00

<» A fourth determination of SnO» gave 2.97 per cent.

In the ratios derived from the above analysis, which are given 

herewith, the CaO, Si02 , and A1203 are excluded as belonging with the 

insoluble matter of the gangue.

Ratios of average analysis of paigeite, sample No. 3.

FeO.................................................. 0.4861

MgO................................................... .056J

FeoOo.................................................. .093 = 4.9

=28.5

SnO, .019 = 1

B20.........................:........ ................ .099 = 5.2

As in one of the hulsite analyses, the amount of calcium oxide is 

considerably higher in sample No. 3 than in sample No. 2, a fact that 

seems to indicate that some of the lime belongs to the borate. Only 

1.57 per cent of CaO would be needed to raise the ratio of FeO + 

MgO + CaO to Sn02 from 28.5 : 1, as given above, to 30 : 1, and this
24 MINEBALOGICAL NOTES SERIES 1.

small amount of lime is therefore considered as belonging to the 

borate. The ratios obtained above are 28.5 or 30.0 RO. 4.9Fe2O3 . 

!SnO2 . 5.2B2 03 + ?H2 0.

DISCUSSION OF FORMULAS.

The following formulas are deduced for paigeite from the above 

three series of analyses:

Formulas for paigeite.

Sample.

No. 1...

No. 2...

No. 3..{

RO.

31.1

29.4

28.5

30.0

Fe203 .

5.0

5.6

4.9

4.9

. Sn02 .

1.0

1.0

1.0

B203 .

6.7

6.2

5.2

5.2

H20.

5.4

Averages of these figures give as the most probable formula for 

paigeite, and the one proposed for the mineral, 30Fe0.5Fe203 .lSn02 . 

6B203 .5H20.

The above formula is complex and yields a high ratio of FeO to 

SnO2 , but no other interpretation of the analyses can be made. It is 

not impossible that paigeite may be a mixture of two or more closely 

related minerals, but only the unusual composition indicates such a 

mixture. The constant small percentage of tin oxide shows the 

material to be essentially different in ratios from the corresponding 

hulsite. The occurrence of the mineral in wavy, lamellar masses or 

in fine radiating fibers, its intense shiny black color, and the marked 

tendency shown in thin sections by the individual fibers and masses 

to fray out at the ends into a bunch of very thin fibers serve to differentiate this mineral from hulsite, which never shows any indication of

fibrosity.

An alternative interpretation of the composition of paigeite is that 

it is a mixture of hulsite and a fibrous borate. Subtracting from the 

formula 6f paigeite the constituents of hulsite in the amounts necessary to include all the tin, the following results are obtained:

Paigeite.................. 30 FeO 5 Fe203 1 Sn02 6 B203 5 H20

Equivalent of hulsite... 12 FeO 2 Fe203 1 Sn02 3 B203 2 H20

Remainder............. 18 FeO 3 Fe203 ....... 3 B203 3 H20

This remainder may be written 6FeO.Fe2 03 .B203 .H2O.

Should future investigation prove this interpretation correct, the 

material now called paigeite would consist of a mixture of 1 part of 

hulsite and 3 parts of the borate 6FeO.Fe2 03 .B2 03 .H2 0, to which the 

name paigeite could then be referred. It is most reasonable, however, from the evidence at hand, to regard paigeite as homogeneous 

and as having the composition ascribed to it.
CHEMICAL COMPOSITION OF JAMESONITE AND WARRENITE.

INTRODUCTION.

Knowledge of the difficult group of sulpho-salts has, in the last few 

years, been much enriched by the labors of English mineralogists, 

particularly those of the British Museum. Spencer, whose work has 

been especially notable, in a recent paper considers warrenite, 

which was described as a new mineral by Eakins, a former member of 

the U. S. Geological" Survey laboratory, as identical with jamesonite, 

for which he proposes a new formula.1

This criticism naturally created considerable interest at the Survey 

laboratory, and at the suggestion of Prof. F. W. Clarke, the writer

undertook a reexamination of the subject. W. F. Ferrier generously 

furnished for the investigation his collection of warrenite, consisting 

of over a dozen specimens, which agreed in general character with 

those in the British Museum, as described by Spencer.2 The gangue 

of the specimens examined consists of pink rhodochrosite, in the cavities of which the felted aggregates of short and straight needles characteristic of the mineral occur.

As much of the felted material as possible was picked out. Though 

the bulk was large, the weight was inconsiderable; in fact, the quantity of material was entirely insufficient to warrant any chemical 

analysis. Press of routine work necessitated laying the problem 

aside for a time, and before more material could be separated from 

the gangue the specimens were practically ruined by fire on December 

16, 1908. The loss precluded any chemical work being done, but 

some of the results obtained by review of previous work led to conclusions which may further contribute to knowledge of these minerals.

FORMULA OF JAMESONITE.

Spencer concluded that the most probable formula for jamesonite was 7(Pb*,Fej)S.4Sb2S3 . If this be expanded, we obtain 

Pb28Fe7Sb40S95 , a formula resembling so closely the simple formula 

Pb28Fe7Sb42S98 , or Pb4FeSb6S14 , that inquiry was directed as to 

whether or not the latter might represent the composition of jamesonite. The suggestion that iron seems to be present in amount 

nearly constant (between 2 and 3 per cent) certainly seems to be 

justified by the analyses given. Spencer has selected from the literature of the subject those analyses of jamesonite made on material 

with characteristic and well defined physical properties, such as the

1 Spencer, L. J., Note on "feather ore;" identity of "domingite" (="warrenite") with jamesonite: 

Mineralog. Mag., vol. 14, 1907, p. 207; Analysis of crystallized jamesonite, idem, p. 310. 

a Idem, p. 208.

25
MlNERALOGlCAL NOTES SERIES 1.

basal cleavage. Since these are the only analyses that can be used, 

they are repeated below,1 together with the values calculated for a 

new formula proposed for jamesonite, namely 4PbS.FeS.3Sb2S3.

Analyses of jamesonite.

s.. .........

Sb... .......

Pb. ........

Fe... .......

Cu..........

Zn... .......

Bi..........

Ag.. .......

Calculated.

21.86

35.10

40.32

2.72

100. 00

1

20.52

34.53

41.18

2.76

.26

.01

99.26

2

21.37

34.70

40.08

2.79

.22

.13

99.29

3

22.15

34.40

40.75

2.30

.13

99.73

4

22.53

34.90

39.45

2.65

.19

99.72

6

[23. 01]

33.47

40.35

2.96

.21

100. 00

6

21.78

32.62

39.97

3.63

.42

1.06

99.48

7

21.52

33.03

40.13

(°)

.36

........

8

20.86

31.94

42.79

2.83

1.01

1.84

101. 27

9

21.35 V1 '1

40.47

2.68

.50

5.82

10

21.75

32.00

39.05

2.00

3.45

.62

1.34

.20

100. 41

a Not determined.

Copper and zinc in considerable quantities are present in the last 

three analyses, provided, of course, that the samples were pure, an 

assumption not necessarily true. These analytical figures are very 

close to the values calculated for the formula here proposed, and 

support that formula quite as much as the more complicated one of 

Spencer. Loczka has published an analysis 2 of "a felted aggregate 

of dark steel-gray fibers," which he refers to plumosite, and from 

which he calculated a formula identical with the one here proposed, 

namely 4PbS.FeS.3Sb2S3 . In abstracting Loczka's article Spencer 

states 3 that "the figures agree still more closely with the jamesonite 

formula, 7(Pb4Fe^)S.4Sb2S3 ," a statement hardly borne out by the 

facts. Loczka's analysis and the values calculated for Spencer's 

formula 4 7(PbtFe.)S.4Sb2S3 , and for the formula 4PbS.FeS.3Sb2S3 , 

appended for purposes of comparison, are given in the following table:

Loczka? s analysis and values calculated for the two formulas.

Loczka's analysis.

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

Sb.......... ................

Pb. .........................

Fe................ ..............

Mn. ..........................

Zn... ..........................

Cu. ..........................

Insoluble matter...... ..........

1

21.59

35.80

39.38

2.65

.12

.10

Trace.

.50

100. 14

7(Pb|Fe^) S.4Sb2S3.

21.70

34.23

41.29

2.78

100. 00

4PbS.FeS.3Sb2S3 .

21.86

35.10

40. 32 .

2 79

100. 00

i Analyses 1 and 2 (Bolivian material), are by Prior; 3, 4, and 5 by Rose (1826,1829); 6 and 7 by Schaflgotsch (1836); 8 and 9 by Rammelsberg (1849); 10 by Sievert (1873). For references see Mineralog. Mag., 

vol. 14, 1907, p. 313.

8 Loczka, Josef, Analysis of plumosite from Felsobanya: Ann. musei Nat. Hungarici, vol. 6,1908, p. 586.

8 Jour. Chem. Soc., vol. 96, 1909, p. 153.

* The figures are calculated from the 1909 table of atomic weights and differ very slightly from those given 

by Spencer.
CHEMICAL COMPOSITION OP JAMESONITE AND WARRJGNITE. . 27

Loczka's analysis agrees more closely with the simple formula, 

which is certainly the one to be preferred. It is much to be regretted 

that Loczka did not state definitely whether the fibers were flexible 

or brittle, but from the analytical figures alone his analysis must 

be referred to jamesonite and not to plumosite.

The evidence herein cited gives ample support to the formula 

first given by Loczka and reached independently by the writer. 

The chemical formula for jamesonite may then be given as 4PbS. 

FeS.3Sb2S3 (Loczka), while for plumosite the simpler composition 

2PbS.Sb2S3 (Spencer) holds, the two minerals being distinguished 

chemically by the respective presence and absence of iron.

COMPOSITION OF WABKENITE.

Spencer includes warrenite under jamesonite, and the analysis

given by Eakins agrees well both with Spencer's and with Loczka's

formulas, though the iron is nearly 1 per cent low. Spencer states* 

that "It was, however, determined that the needles (of warrenite) 

are brittle' and not flexible. * * * This latter character indicates 

that the material must be referred to jamesonite." He further 

classifies "feather-ores" as flexible and brittle, all the latter being 

referred to jamesonite and the former either to zinckenite, plumosite, boulangerite, or meneghinite. His statement that the needles 

of warrenite are.not flexible was not confirmed by an examination 

of the specimens at the writer's disposal, for many were so flexible 

that they could be bent double without breaking, and sprang back 

to their original position when released. Other needles, however, 

were decidedly brittle, and instead of bending always broke across 

the elongation. Warrenite, then, has both flexible and brittle 

needles, and Eakin's analysis shows it to consist of a mixture of jamesonite and zinckenite.

Eakin's analysis of warrenite, with ratios.

s.. ....... ...........

Sb...... ...... .......

Pb...................

Fe............. ......

Analysis.

21.19

36.34

39.33

1.77

.52

99.15

Ratios Jame" Zinck- *atlos- sonite. enite.

0. 661=0. 448+Ci. 213

. 302= . 196+ . 106

:190= .128+ .062

.032= .032+ .0

Zinckenite ratios recalculated.

4.00

2.00

1.17

The last column of ratios leads to the zinckenite formula, PbS. 

Sb2S3 . The analysis of warrenite, then, shows it to consist of a 

mixture of about 2 parts of jamesonite with 3 parts of zinckenite.

'Spencer, L. J., Note on "feather ore;" Identity of "domingite" (="warrenite") with jamesonite: 

Mineralog. Mag., vol. 14,1907, p. 207.
LUDWIGITE FROM MONTANA.

OCCURRENCE AND ASSOCIATION.

The ludwigite here described was collected at Philipsburg, Mont., 

by Donald F. MacDonald, and was sent to the chemical laboratory 

of the survey for determination by F. C. Calkins. It is said to occur 

in metamorphosed limestone in connection with large bodies of 

magnetite. Examination of a thin section showed that a member of 

the olivine group was sprinkled throughout the ludwigite, and that 

a carbonate and a secondary fibrous mineral were,also present in 

minute amounts.

The ludwigite forms small spherulites composed of radiating fibers 

of a very dark green or nearly black color, and resembles in its 

physical properties the original ludwigite from Hungary. With 

high magnification the fibers extinguish parallel and show a strong 

pleochroism, parallel to the elongation a sea green, and normal 

thereto a chestnut brown, with stronger absorption in the brown 

than in the green. The refractive index is much higher than 1.67. 

The olivine mineral has a mean refractive index of about 1.66, and 

cleavage sections parallel to 6(010) showing a and /? have refractive 

indices lying between 1.65 and 1.66. The mineral must therefore be 

very low in ferrous iron, and is referred to forsterite. As no calcium

was noted in the analysis, the carbonate is either magnesite or

siderite.

ANALYSIS.

The sample free from magnetite, but containing a small quantity 

of forsterite and minute amounts of the colorless fibrous mineral and 

the carbonate, gave on analysis the following results, the figures in 

the last column showing the values with the forsterite and carbonate 

deducted and the analysis recalculated to 100 per cent/

28
LUDWIGITE FROM MONTANA. 

Analyses of ludwigite from Montana.

29

FeO.....................:.

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

Total iron as Fe-jOj .........

Fe,08 .. .:...................

SiO....... ..................

AI n

HaO+. ....................

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

rn

BA--- /i - 

Analyses of ludwigite mixed with forsterite 

and carbonate.

1

6.12 

39.09 

36.33

8.97 

1.98 

.97 

.91 

.28 

13.48

2

5.53 

38.60 

36.01

8.74 

1.64

.95 

.43

3

5.74 

39. 42

8.85

.85

Average.

5.79 

39.04

29.73 

8.85 

1.81 

.97 

.90 

.36 

13.48

100. 93

Analysis 

of ludwigite.

7.27 

33.78

37.37

2.27 

1.24 

1.13

16.94

100. 00

The ferrous iron- was determined by a modification of Pratt's 

method,1 the material used being finely ground. Experiments conducted by Hillebrand on samples of this mineral showed that the 

oxidizing effect of grinding on the ferrous iron was slight. The first 

value for alumina, 1.98 per cent, was obtained as the difference 

between the gravimetric determination of R2O3 and the subsequent 

volumetric titration of the iron with permanganate solution. The 

iron and aluminum chloride solution was repeatedly evaporated with 

methyl alcohol to expel all the boric acid. The second value, 1.64 

per cent, was determined by precipitating the alumina by phenylhydrazine, as described by Alien.2 As the two determinations agree 

fairly well, the presence of a small amount of alumina in the sample 

seems well confirmed. The higher result of the first case is probably 

due to retention of a small amount of boric acid. Whether the 

alumina belongs to the ludwigite or to one of the accompanying 

minerals is difficult to decide, but it has here been included in the 

borate. The boric acid content has also been determined by Wherry 

and Chapin,3 who give as the average of their results 12.82 per cent 

B2O3 , a value slightly lower than the one here given.

The water content, though small, is still of sufficient importance to 

merit consideration. Although no definite conclusion has been reached!, 

it is believed that the greater part, if not all, of the water is not 

essential to the composition of the mineral. The determinations 

were made on finely ground material, which no doubt took up con1 Hillebrand, W. F., The analysis of silicate and carbonate rocks: Bull. U. S. Geol. Survey No. 305,1907, 

p. 138.

2 Jour. Am. Chem. Soc., vol. 25,1903, p. 421. See also Bull. U. S. Geol. Survey No. 305,1907, p. 95. 

* Wherry, E. T., and Chapin, W. H., Determination of boric acid in insoluble silicates: Jour. Am. 

Chem. Soc., vol. 30,1908, p. 1691.
30 MHSTEKALOGICAL NOTES SERIES 1.

siderable water. A preliminary experiment on some ludwigite from 

Hungary gave the following values for the amount of water given off 

by the mineral when heated in a toluene bath at 110° in a current 

of dry air. Duplicate determinations were made, first on coarsely 

crushed material and then on another part of the same sample finely 

ground.

(1) (2) 

Sample crushed <10> 20 mesh....... 0.09 per cent. 0.12 per cent.

Same finely ground.................... 0.50 per cent. 0.52 per cent.

As some water may also have been furnished by the fibrous material, 

it seems justifiable to conclude that a large part, if not all, of the 

water reported in the analysis is extraneous. It has been omitted 

in the consideration of the ratios deduced from the analyses.

DISCUSSION OF FORMULA.

Ratios calculated from the figures of the average analysis are as 

follows:

Ratios of average analysis of ludwigite.

M&O:..... ........................

FeO

FeA.............................

Al O

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

CO,........:......................

B203 - ............................

Ratios.

9760

804

1858

177

1475

82

1926

Forsterite 

and 

magnetite 

deducted .

8195

i.475

82

Ludwigite.

\7^2-4/3 - 57 MS°- |7532_4|0 43 Fe()

J2035=1.08.

.

1926=1.02.

Th.6 ratios agree well with the formula generally given for ludwigite, 

4RO.Fe2O3 .B2O3 . The high water content obtained by Whitfield,1 

on Hungarian material, 3.62 per cent, is substantiated neither by the 

analysis of the Montana mineral given above nor by the analysis of 

Hungarian ludwigite described in this paper, but each sample yields 

about 1 per cent of water which can not as yet be proved foreign to 

the mineral and may ultimately be shown to be one of its essential 

constituents. If the water given off above 107° (H20 + ) be considered as essential to the mineral, a formula of about the proportions, 

RO :Fe2O3 :B203 :H20 = 16:4:4:1 would result.

Although the ratios agree well with the general formula of ludwigite, the amount of ferrous iron is too small for the formula 

FeO.Fe203 .3MgO.B203 , even if all the ferrous iron in the analysis is 

referred to ludwigite and none either to forsterite or to the car1 Whitfield, J. E., Natural borates and borosilicates: Am. Jour. Sci., 3d sen, vol. 34,1887, p. 284. ' .
LTJDWIGITE FROM MONTANA. 31

bonate. These data indicate that the formula for the Montana ludwigite may be written .57MgO. .43FeO. Fe203 . 3MgO.B203 , thus 

showing an isomorphous mixture of & ferrous ferric magnesian borate 

with a magnesian'iemc magnesian borate, the latter being in excess.

Analyses by Ludwig and Sipocz and by Whitfield are confirmed by 

the analysis published in this paper in the respect that the Hungarian 

mineral approximates, closely to the definite formula FeO.Fe203 . 

3MgO.B203 . Only one analysis by Ludwig and Sipocz hows a slight 

deficiency in the ferrous iron.

The mineral from Montana, however, is very much lower in ferrous iron and correspondingly higher in magnesia, the ratios of 

B203 :Fe203 :FeO+MgO remaining constant. This condition supplies 

sufficient evidence of the existence of a magnesian ferric borate 

MgO.Fe203 .3MgO.B203 free from ferrous iron, not yet found in nature 

in the pure state, but preponderant in the Montana ludwigite, in which 

it is present in isomorphous mixture with the corresponding ferrous 

ferric magnesian borate to the extent of 57 per cent. If some of the 

ferrous iron present in the sample belongs to the forsterite or to the 

carbonate, the percentage of the magnesian borate would be still 

greater.

LUDWIGITE FROM HUNGARY.

For comparison with the Montana mineral, an analysis was made 

of a sample of ludwigite from Hungary. The results of the quantitative analysis, made on the finely radiating black mineral, is as 

follows:

Analyses of ludwigite from Hungary.

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

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

Fe203 - ..........................

H26-. ..........................

H20+. ..........................

C02 .............................

BA--------- --------------------

1

15.84

28.88

53.35

.50

.78

.90

.32

[17. 02]

2 .

15.68

28.88

52.74

KO

.86

.40

3

15.80

53.72

........

Average.

15.84

28.88'

35.67

.51

.82

.90

.36

[17. 02]

100. 00
32 MINEEALOGICAL NOTES SERIES 1.

The ratios from the average analysis give, after the C02 is deducted, 

together with sufficient MgO to form magnesite, the formula 

FeO.Fe2 03 .3MgO.B203 , as shown below.

Ratios of average analysis of ludwigite from Hungary.

FeO................ :...........'....

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

Fe208 .. ............................

Ba08 ..... ......................... 06,!. ..............................

0.220

.702

.223

.243 '

.020

0.99

3.06

1.00

1.09

SUMMARY.

The isomorphous relation of FeO and MgO in ludwigite can be well 

shown by bringing together the available analyses, which also show 

how closely the mineral from Hungary agrees with the calculated 

values for the pure ferrous-iron ferric magnesian borate. The first 

column gives the calculated values for FeO.Fe203 .3MgO.B203 , the 

second, third, fourth, and fifth the analyses of the Hungarian mineral, 

and the sixth that of ludwigite from Montana.

Analyses of ludwigite.

FeO............. MgO.: ..........

Fe203 - ..........

Al O

BA----. ........

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

H20-. ..........

H30+. ...........

SiOa .. ..........

C0a .. ...........

FeO. 

Fe203 . 

3MgO. 

B203 -

1

17.01 

28.61 

37.81

16. 57

100.00

Ludwigite from Hungary analyzed by 

Ludwig 

and 

Sipocz.

2

17.67 

26.91 

39.29

15.06 

Trace.

98.93

Schaller.

3

15.84 

28.88 

35.67

[17. 02]

.511 

.82J 

.36 

.90

100. 00

Whitfield.

4

15.78 

30.57 

37.93

12.04 

.16

 3.62J

100. 10

Ludwig 

and 

Sipocz.

5

12.46 

31.69 

39.92

16.09 

Trace.

100. 16

Ludwigite from 

Montana.

6

7.27 

33.78 

37.37 

2.27 

16.94

1.13 

1.24

100. 00

The last analysis by Ludwig and Sipocz (No. 5 above) shows a 

slight replacement of the ferrous iron by magnesia, which has been 

carried out to a much larger extent in the mineral from Montana. 

All new occurrences of ludwigite should ,be carefully examined chemically, as the possibility of the existence of the ferrous-iron-free mag-^ 

ne§jan J?orate is. strongly indicated by the above analyses,
BISMITE FROM NEVADA. 

OCCURRENCE AND PHYSICAL PROPERTIES.

According to Ransome, 1 bismite occurs in the Goldfield district of 

Nevada in the January, Combination, and Sandstorm mines, and 

probably also in other, mines, as minute, pearly scales of brilliant 

and almost metallic luster, which suggest at first glance delicate and 

untarnished crystals of native silver. This mineral, identified by 

him as bismite, is limited to the oxidized zone,-is generally accompanied by limonite, and is not uncommonly associated with rich ore. 

It occurs as single glittering scales or specks on the walls of cavities 

in spongy limonite or rusty ledge matter/ fts delicate frost-like films 

on the same materials, and as spongy aggregates with quartz. In 

the last-named form it is clearly pseudomorphous after bismuthinite, 

the material having consisted originally of a mass of bismuthinite 

prisms held together by a siliceous gangue. The prismatic structure 

of the bismuthinite is retained as hollow casts in the quartz, lined or 

partly filled with scales of bismite. The single scales are doubtless 

also derived from bismuthinite, but migration has taken place either 

during or after oxidation, and the bismite scales do not occupy the 

exact position of the parent needles of bismuthinite.

Natural crystals of bismite do not appear to have been found 

hitherto, and, inasmuch as the mineral has been assigned to the 

orthorhombic system in Dana's and Hintze's mineralogies on the 

basis of Nordenskiold's work on artificial crystals in 1860 and 1861, 

considerable interest attaches to the Goldfield occurrences on account 

of the crystallinity of the material.

When examined under the microscope in gently powdered material, 

the crystals appear as thin colorless scales, with occasionally a suggestion of hexagonal outline. On account of their tenuity, it is rare . 

that an edge view of a scale can be obtained. The larger flat-lying 

scales are dark in all positions between crossed nicols, and give a 

negative uniaxial figure with convergent light. There are no colored 

rings, and double refraction, apparently, is not great. The refractive 

index, on the other hand, is comparatively high greater than that 

of anorthite. The mineral has a perfect basal cleavage and the 

scales, when viewed without the analyzing nicol, commonly show 

delicate interference colors, due to refraction and reflection at the 

surfaces of the exceedingly thin cleavage sheets.

1 Ransome, F. L., The geology and ore deposits of Goldfleld, Nev.: Prof. Paper U. S. Geol. Survey 

No. 66,1909, p. 121. .

99946° Bull. 490 11 3 -33
34 MINEBALOGICAL NOTES SEEIES 1.

CRYSTALLO GRAPHY.

The minute, tabular crystals are too incomplete to make possible 

a determination of their geometrical form by crystallographic measurements alone. The uniaxiality and hexagonal outline of the crystals, 

the triangular markings on their bases, and the distribution of faces 

so far as known justify their provisional reference to the rhombohedral division of the hexagonal system.

The value. of the c axis, derived in a manner presently to be 

described, is 0.5775. Seven faces are recognized the base and one 

negative and five positive rhombohedra and indications of two 

more positive rhombohedra appear. A brief description of these 

forms follows.

c{0001}. Always very large, even, and highly polished. When 

triangular markings or striae are shown the faces parallel to these 

markings are taken as positive. °

o{10l6}. Occurs on two crystals as broad faces, giving, however, 

poor reflections. One face was considerably striated, giving two 

signals a degree apart.

#{1015}. Broad faces giving fairly good reflections.

it{10T4}. Narrow faces, one striated with a fair reflection, and one 

as a line face giving a very poor reflection.

fc{1013}. Usually as a line face, striated and giving a very poor 

reflection.

(?){2025}. A doubtful face, narrow, giving no distinct signal.

(?) d{W12}. Another doubtful face, narrow, and giving no distinct 

reflection.

y{2021}. Line faces, giving exceedingly faint reflections.

2J01T1}. The only negative rhombohedron observed. Very faint 

line faces, giving no reflection. Its negative position could be determined only on crystal No. 6.

The measurements of the forms are shown below.

Measurements of forms on bismite crystals. .

Symbol.

cAo=(0001) : (1016) ......................

cA?=(0001) : (1015). .....................

cAw=(0001) : (1014). I....................

cA£=(0001) : (1013)......................

cA«/=(0001) : (2051). .....................

cA2=(0001):(OlIl)......... ..............

Doubtful forms: 

cA?=(0001) : (2025)......................

cArf-(OOOl) : (1012).. ............'........

Measured.

0 f /

6 37 

7 33 

9 31 

f 12 11 

1 13 18. 

54 

35

15 

16 20

0 /

6 41 

7 36 

9 31 

12 26 

13 

54 

32}

Calculated.

0 /

6 21 

7 36 

 9 28

| 12 32

53 08 

33 42

14 56, 

18 26
BISMITE FROM NEVADA. 35

The value for the c axis was obtained from three measurements 

considered most accurate. The others gave values agreeing fairly 

well with the one adopted, as is shown in one of the following tables. 

The crystals were measured on the two-circle" goniometer and the p 

angle for these forms is the angle between that. form and the base. 

The value p0 is obtained directly from the p angles and from the 

values for p0, the c axis is readily calculated. The three best measurements are:

Three best values ofp0, bismite.

Crystal No. 1: /o{1015}=7° 33'; therefore p0 =0.6627 

Crystal No. 4: io{10l5}=7 0 36'; therefore p0= .6672 

Crystal No. 2: <o{10l4}=9° 31'; therefore p0= .6706

Average............ .............. ..=0.6668; c=0.5775

An average of the other measurements gave 'values closely agreeing.

Other values ofp0 , bismite.

Crystal No. 3: p{Wl<o} = 6° 37'; therefore p0=0. 6960

Crystal No. 6: ,o{1016}= 6° 41/; therefore p0= . 7031

Crystal No. 6: p{Wl4}.= 9° 31'; therefore p0= .6706

Crystal No. 6: />{10l3}=12° 11'; therefore p0= . 6477

Crystal No. 4: jo{10l3}=12° 26'; therefore pn= . 6614

Crystal No. 1: jo{10l3}=13° 18'; therefore p0= . 7102

Average. .......................... =0. 6815 .

The following measurements of faces giving no distinct reflections 

also showed close agreement:

Additional values of p0 , bismite.

Crystal No. 1: ^{lOlS} =12°-14° (average 13°); therefore p0 =0. 69

Crystal No. 2: ,o{2025}?=150 ; therefore p0 = .67

Crystal No. 1: /o{1012}?=16°-20° (average 18°); therefore p0 = .65

Crystal No. 5: (OJOlIl} =35°; therefore p0 . 70 '

Crystal No. 6: (OJOlIl) =32£; therefore p0 = . 64

Crystal No. 1: ^{2021} =54°; therefore p0 = . 69

Crystal No. 6: jo{202l} =54°; therefore p0 = . 69

The values for p0 given in these tables show that the interpretation 

of the forms is the correct one.

Of the six crystals (all incomplete) that were measured, only two 

require special mention. Figure 1 is an orthographic projection of 

crystal No. 1, showing the trigonal distribution of the rhombohedra, 

and the triangular markings on the base. Figure 2 shows a similar 

projection of crystal No. 6, with a negative rhombohedron.
36 MINERALOGICAL NOTES SERIES 1.

So uneven is the development of the faces of these crystals that 

no two faces of the same form are present on the upper half of a 

crystal. This feature is, however, due in part to the incompleteness 

of the crystals.

FIGURE 1. Bismite crystal No. 1, orthographic 

projection.

FIGURE 2. Bismite crystal No. 6, orthographic 

projection.

CHEMICAL COMPOSITION.

The best material obtainable consisted of the spongelike aggregates with quartz, and this, on analysis, yielded the following results:

Analyses of bismite.

Matter insoluble in HC1 (mostly quartz gangue). 

Bi203 ... ---..-.....---..----..-..-----.-.

H20 (lo 

Fe203 -

;,

1

78.95 

17.29 

3.96

.36

2

78.87 

17.00

.50

3

79.01 

16.84

.21

Average.

78.94 

17.04 

3.96 

.36

100. 30

The phosphate, chloride, carbonate, and sulphate radicles, as well 

as vanadium, arsenic, calcium, magnesium, and the alkalies were 

absent.

The analysis shows that the mineral is either bismite or a hydrous 

oxide of bismuth. If it is the latter, the mineral is a new species 

(providing, of coursej that Bi203 is the correct formula for the bismuth 

ocher found in nature and called bismite). Attempts to isolate a 

sufficient quantity of the pearly scales from the gangue for separate 

analysis were not successful. According to a recent paper l by the 

writer the mineral bismite is probably Bi(OH) 3, as it seems very 

doubtful if Bi203 exists in nature as such.

i Schaller, W. T., Bismuth ochers from San Diego County, Gal.: Jour. Am. Chem. Soc., vol. 33,1911, 

p. 162.
AXINITE FROM CALIFORNIA.

LOCALITIES.

Well-crystallized axinite has been found at two widely separated 

points in California. In 1903-4 some large brownish crystals were 

found in Moosa Canyon, near Bonsall, San Diego County, by Mr. T. 

Freeman and^forwarded by him to Dr. G. F. Kunz of New York, who 

determined them as axinite. The writer visited the locality in 1904 

and collected a suite of the specimens which form the basis of this 

description. The work of collection was greatly facilitated through 

the kindness of Mr. Freeman and of Mr. J. J. Mack, both of San

Diego County, whose assistance was of great value. A specimen of 

axinite from the Consumnes Copper Mine, Amador County, was lent 

to the writer from the collection of the University of California 

through the kindness of Prof. A. S. Eakle. The axinite, which is 

probably of contact origin, is associated with large epidote and small 

quartz crystals.

AXINITE FBOM SAN DIEGO COUNTY.

OCCURRENCE.

The axinite of San Diego County appears in detached crystals 

associated with quartz, epidote, and a little, laumontite in a much 

decomposed granite, and its true mode of occurrence is not determinable, for all the rock in the vicinity is greatly altered. The crystals 

range from minute size to a length of nearly 5 centimeters; they are 

generally flattened, rough, worn, and opaque, with small transparent 

areas scattered throughout the crystal mass. A few, which are 

highly decomposed, appear as a black mass consisting largely of 

manganese dioxide. The quartz on which the axinites are often 

grouped is found both in massive pieces and in distinct crystals. It 

is characteristically of the smoky variety, and often very closely 

resembles the axinite in color. A very few specimens consisted of 

radiated greenish epidote, surrounded by idiomorphic axinite into 

which the epidote fibers penetrate. The laumontite occurs sparingly 

as isolated white crystals situated on the other minerals.

CRYSTALLOGRAPHY.

The larger crystals of axinite are simple in their combinations 

and show the usual axinite forms, such as m, 'M, r, z, c, s, and x. 

The smaller crystals are more perfect and show a greater number of

37
38 MINERALOGICAL NOTES SERIES 1.

forms. Only a few of the crystals are at all suitable for measurement, most of them being too dull and uneven. Many, too, are considerably striated, and often a number are grouped in nearly parallel 

position.

The forms identified on these crystals are as follows, the position 

chosen being that of Miller as modified by Goldschmidt in his 

WinkeltabeUen: {010},_{110}i_{lTO]i {120}, {031}?, {Oil}, {Ol2}, 

{101}, {112}, {121}, {111}, {III}, {112}, {221}.

The following table gives the measurements of these forms as compared with the calculated values taken from Goldschmidt's WinkeltabeUen and with the letters and symbols given by Dana for the 

same forms:

Forms and angles for axinitefrom San Diego County.

Goldschmidt's 

symbols.

Letter.

c

w

u

I0

r

z

a

0

s

X

n

8

Symbol.

010

110

no

120

031

Oil

012

101

112

121

111

111

112

Dana's symbols.

Letter.

M

w

m

a

<£

r

z 

y

0

s

X

n

8

Symbol.

no

130

110

100

331

111

112

021

132

201

111

131

132

Measured.

0

o /

0 00

60 27

135 22

150 42

176 50

172 03

164 07

106 00

53 38

153 31

138 44

117 17

115 27

.P

0 /

90 00

90 00

90 00

90 00

68 11

46 22

27 36

49 00

32 00

68 29

59 44

57 43

40 28

Calculated.

*

0 /

0 00

60 16

135 24

151 23

177 20

172 02

164 24

104 04

53 49

153 49

138 48

117 16

115 08

P

0 . /

. 90 00

90 00

90 00

90 00

71 36

45 21

27 32

49 10

31 19

68 32

59 36

57 38

40 26

Of these forms {010}, {110}, {110}, {121}, and {011} are large, 

the other forms occur as small faces.

The form « {221} was noted on one crystal in a zone with the forms 

{110} large, {221} line face, {TTl} medium, and {TT2} line face.

CHEMICAL COMPOSITION.

A large sample was crushed and the clear fragments of axinite 

picked out. Treatment with heavy solution served to remove a 

little quartz similar in color and appearance which had been picked 

up with the axinite. The following is the average of several analyses. 

The water was given off above 110° and its amount was determined 

directly.
AXINITE FROM CALIFORNIA. 39

Analysis of axinite, San Diego County.

SiOa .......................................................... 42.61

A1203 ......................................................... 17.43

Fea08 ......................................................... .38

FeO......................................................... 7.53

MnO........................................................ 4.10

MgO.......................................................... .44

CaO.......................................................... 19. 74 . H20......................................................... 1.56

B203 . ......................................................... 6.04

99.83

As this analysis was made before the oxidizing effect of grinding 

was known, the true amount of ferric oxide in the mineral may be 

even less than that given. 

. The ratios calculated from the analysis are shown herewith.

'J .173=1.95

Ratios of analysis of axinite, San Diego County. 

Si02 .................................................... 0. 710=8. 00

AIA..............................................

Fea03 ..............................................

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

. MnO. ................................................. K 174=1. 96

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

CaO.................................................... .353=3. 97

H20................................................... . 087= . 98

B203 .................................................... . 086= . 97

The above figures indicate the formula for axinite to be 8Si02 . 

2Al2 03 .2(Fe,Mn,Mg)0.4Ca0.lH20.lB2 03 . If all the bivalent bases are 

grouped together, the formula reduces to 8Si02 .2Al203 .lB203 .7RO, 

the one proposed by Ford 1 for the mineral in a discussion of several 

analyses including his own, in the course of which paper he shows 

that the general formula for axinite may be written:

8Si02 . B203 . 2R3 '"03 . 7R"0

R'" = Al,Fe'"

R" = Ca,Fe",Mn,Mg,H2

Examination of the more recent trustworthy analyses of axinite 

has convinced the writer that the calcium content is constant, and 

that, as the iron and manganese vary reciprocally, there are two 

end products, one free from iron and the other free from manganese, 

and that all axinites may be considered as isomorphous mixtures of 

these two end products.

Thirteen trustworthy analyses, in nearly all of which the-water was 

determined directly, were selected, and the ratios of the various 

constituents calculated. These analyses, arranged in the order of 

increasing amounts of manganese, are given below.

1 Ford, W. J., On the chemical composition of axinite: Am. Jour. Sci., 4th ser., vol. 15,1903, p. 195.
40

 Analyses ofaxinite.

No.

1

2

3

4

5

6 

7

8

9

10

11

12

13

SiOa .

42.89

43.46

42.78

41.53

42.10

42.40 

42.40

42.55

41.96

42.85

41.80

42.47

42.77

B,08 .

6.02

5.61

6.12

4.62

4.64

4.71 

4.88

4.20

4.61

5.17

5.61

5.05

5.10

A1303

18.25

16.33

17.67

17.90

17.40

17.39 

17.26

16.37

17.69

16.96

17.15

16.85

16. 73

FejO8

0.64

2.80

.99

Q on

3.06

.59 

1.33

^ 7Q

.81

e* ftn

1.11

1.16

1.03

FeO.

7.11

6.78

6.02

4.02

5.84

4.89 

4.27

4.06

3.61

2.84

MnO.

1.06

2.62

2.99

3.79

4.63

6.16 

6.97

7.69

8.51

9 <;Q

10.71

13.14

13.69

CaO.

19.89

20.19

20.16

21.66

20.53

19.57 

19.53

19.28

19. 71-

18.49

19.51

18.35

18.25

MgO.

2.23

1.73

2.41

.74

.66

1.69 

1.30

1.02

.97

.87

.21

.26

.23

H 2O.

2.14

1.45

1.40

2.16

1.80

1.64 

1.90

a

qq\

1.93

( 75)

1.22

1.21

1.29

KsO.

0.11

.11

.25

NajO.

0.36

.24

(Cu, Zn, 

Pb)0.

(F=.22)

(F=l.ll)

.19

1.73

1.60

1. Jannasch and Locke, Zeitschr. anorg. Chemie, vol. 6,1894, p. 57.

2. Rammelsberg, Zeitschr. Deutsch. geol. Gesell., vol. 21,1869, p. 689. 

3,11. Ford, Am. Jour. Sci.. 4th ser., vol. 15,1903, p. 195. 

4, 5. Whitfleld, Am. Jour. Sci.. 3d ser.. vol. 34,1887, p. 286. 

6, 7, 9. Mauzelius, Geol. for. Forh., voi. 17,1895. p. 279. 

8. Cleve, Geol. for. Forh., vol. 17,1895 p. 279. 

10,12,13. Genth, Am. Jour. Sci., 3d ser. vol. 41,1891, p. 394.

In analyses 8 and 10 the water content was determined by ignition, 

and the ratios are for that reason omitted in the following table. 

The figures for the water content in analyses 12 and 13 are those 

obtained by Ford. 1 The percentage of fluorine (1.11) given in analysis 

9 is undoubtedly too high.

Ratios from the foregoing analyses are shown in the following table. 

The small amounts of zinc, lead, copper, soda, and potash present 

have been added to the magnesia ratio.

Ratios ofaxinite analyses.

Analysis No. 

1 

2 

3 

4 

5 

6 

7 

8

9 

10

11 

12 

13

SiOj.

7.96 

8.14 

8.02 7.82 ' 

7.92 

7.84 

7.84 

8.10

7.88 

8.10

7.84 

8.08 

8.38

Bj03 .

0.96 

.90 

.98 

.76 

.74 

.76 

.78 

.70

.74 

.84

.92 

.84 

.86

Als03 .

2.06 

2.00 

1.98 

2.28 

2.14 

1.96 

2.00 

2.12

2.02 

2.26

1.98 

1.98 

1.96

FeO.

1.10 

1.06 

.94 

.64 

.92 

.76 

.66 

.64

.56

.44 

None. 

None.

MnO.

 j.16 

.42 

.48 

.60 

.74 

.98 

1.10 

1.24

1.36 

1.54

1.72 

2.12 

2.28

CaO.

3.98 

4.04 

4.04 

4.38 

4.14 

3.92 

3.90 

3.96

4.00 

3.78

3.98 

3.76 

3.84

MgO.

0.70 

.50 

.74 

.20 

.18 

.54 

.12 .32'

.28 

.26

.06 

.32 

.30

HjO.

1.34 

.90 

.86 

1.36 

1.14 

1.16 

1.18

1.32

.76 

.78 

.84

The average of the above ratios of the 13 analyses given is 

7.99Si02 . 0.83B203 - 2.06' (Al,Fe) 203 . 2.07 (Fe,Mn,Mg)0. 3.90CaO. 

1.05H20. The boric acid ratio is a little low because of the incomplete extraction of B203 in the analyses. The average ratios, like

> Loc. cit.
PROM CALIFORNIA. 41

those of the analysis of axinite from Bonsall, San Diego County, are 

very close to the simple formula:

8Si02 .2Al203 .lB208 .2(Fe,Mn;Mg)0.4Ca0.lH20.

As can be seen by the table of analyses on page 40, the ferrous iron and 

manganese vary reciprocally, because of which fact the writer considers axinite an isomorphous mixture of the two minerals, ferroaxinite, Al2BHCa2FeSi4016 and manganoaxinite, Al2BHCa2MnSi4016 . Whitfield 1 suggested that there were two such end products, but his 

formulas differed from those given above. These two compounds may 

be readily distinguished qualitatively, where either preponderates sufficiently in a mixture, by the color of the bead of the fused mineral. 

That of ferroaxinite is black, and that of manganoaxinite is very 

light colored or gray if a slight amount of iron is present. 

One analysis, that by Baumert,2 is purposely omitted, as the high

calcium content (30.21 per cent) obtained occasions some doubt as to 

the accuracy of the analysis, especially as the sequioxides are also low. 

The .specific gravity of the mineral apparently increases with the 

amount of manganese present, as is shown in the following table, but 

it is probable that careful determinations on pure material will show 

that ferroaxinite is slightly the heavier.

Specific gravity of axinite.

Analysis 

No. 

1 

2

3

4

. 5

6

7 

8

9 

10

11 

12 

13

Per cent 

MnO.

1.06 

2.62

2.99 

3.79

4.63.

6.16 

6.97 

7.69

8.51 

9..59

10.71 

" . 13.14 

. 13.69

Specific 

gravity.

3. 268

3.287

3.28 

3.30

3.30 

3.299

03.302 

3.306 

3.358

a Given by Ford (loc. clt.) as 3.028 by mistake. Ford has Informed the writer that the value should be 

as given above.

It was proposed to investigate the various, physical constants of 

axinite in order to see if corresponding variations could be determined 

for the different ratios of FeO to MnO, but the material available was 

lost by fire before the work could be undertaken.

t Am. Jour. Scl., 3d ser., vol. 34,1887, p. 286.

8 Zeltsch. Nat. Halle, vol. 42,1889, p. 1, and Dana's System of Mineralogy, 6th ed., p. 529.
42 NOTES SEMES 1.

AXINITE FKOM AMADOR COUNTY.

CRYSTALLOGRAPHY.

The crystals of axinite from the Consumnes copper mine, Amador 

County, are very small, their dimensions rarely exceeding 2 millimeters, and are for the most part transparent and highly polished. 

They. are associated with large epidote and quartz crystals, which 

are covered with a drusy coating of small axinites. These axinites 

lie on the epidote and quartz, and also penetrate them to some 

extent, some axinite being entirely embedded in the quartz. Preliminary measurements of two crystals showed that the small crystals 

were very rich in forms, and it was intended to continue the study of 

these crystals, as well as of the mineral axinite in general, at some 

future time. Of 24 forms noted on the -crystals, 8 are apparently 

new. The list of forms follows, the symbols being given in Miller's 

orientation as modified by Goldschmidt in his Winkeltabellen. New 

forms are starred. {010}, {100}, {110}, *{210}, {120}, *{14JL.O}, 

{110}, {340}, {230}, {350},_{l30}, {970}, *{940}, *{720} L*{9.10.0}, 

*{290}, {120}, *{780},*{1.13.0}, {112}, {Oil}, {Oil}, {121}, {111}.

The average measurements of these forms as compared with the 

calculated values are shown in the table below.

1 Forms and angles, axinite. 

[Asterisks indicate new form.]

Goldschmidt.

Letter.

C - M

r

w *A

*C 

*D

*E 

S 

u

*F . *G 

a 

H 

P 

I 

h *N 

*P 

e

X

s

Symbol.

010 

. 100 

120 

110 

210

14. 1. 0 

720 

940 

970

no

9.10.0 

780 

340 

230 

350

120 

130 

290 

1. 13. 0 

Oil

111 

121

Dana.

. Letter.

M

b

w

m

a 

H 

P 

a 

h

e

X

s

Symbol.

110 

010 

120 

130 

160

1. 29. 0 

160 

270 

7. 11. 0 

110

540 

430 

210 

310 

510

100 

310 

950 

13. 15. 0 

111

111 

201

Measured.

0

0 /

0 00

102 27 

36 15 

61 58 

80 22

99 23 

113 56 

'119 45 

129 55 

135 . 24

137 ' 49 

138 22 

142 19 

144 07 

147 24

151 21 

159 18 

165 18 

174 34 

6 36

138 45 

153 00

P

0 /

90 00

90 00 

90 00 

90 00 

90 00

90 00 

90 00 

90 00 

90 00 

90 00

90 00 

90 00 

90 00 

90 00 

90 00

90 00 

90 00 

90 00 

90 00 

45 42

60 57 

69 05

Calculated.

*

0 /

0 00

102 30 

36 15 

60 16 

80 06

99 22 

114 08 

119 51 

129 58 

135 24

137 47 

138 26 

141 58 

144 40 

147 03

151 23 

158 58 

165 12 

174 26 

7 58

138 48 

153 49

P

0 /

90 00

90 00 

90 00 

90 00 

90 00

90 00 

90 00 

90 00 

90 00 

90 00'

90 00 

90 00 

90 00 

90 00 

90 00

90 00 

90 00 

90 00 

90 00 

45 16

59 36 

68 32
AX1HITE FROM CALIFORNIA. 43

Of the above forms, 7-{120} was first given by Sjogren * on axinite 

from Nordmarken. 

The measurements of the narrow face gave the following values:

Measurements- of 7- {120}.

Symbol.

010A120 

110A120 

110A120

Measured.

0 /

36 15 

24 12 

98 55

Calculated.

0 '/

36 15 

24 01 

99 09

Difference.

0 /

0 00 

0 11

0 14

The form ${970} was first noted by Franck 2 and was observed 

once as a narrow face giving a poor reflection.

Measurements of S { 970}.

Symbol.

OIOA970 

120A970

100A970

9. ffi OA970

Measured.

0 /

50 05

21 27

27 07

7 54

Calculated.

0 /

50 02 

21 25

27 28

7 49

Difference.

o /

0 03 

0 02

0 21

0 05

Franck's 

measurement.

0 /

49 44

The following eight prisms are evidently new at least they are not 

described in the literature of the subject, so far as known to the writer. 

The form .4 {210} occurs as a line face giving a poor reflection.

Measurements of A { 210}.

Symbol.

100A210 

14. 1. OA210

Measured.

0 /

22 08 

19 01

Calculated.

0 /

22 24 

19 16

Difference. .

0 /

0 16 

0 15

The prism #{14.1.0} has more of a vicinal symbol than most of 

the new prisms, but the measured and calculated angles agree so well 

that the form is considered established. It occurs as a line face giving 

a poor reflection.

1 Sjogren, Hj., Beitrage z. Mineralogie Schwedens: Bull. Geol. Inst. Upsala, vol. 1,1892, p. 1. 

* Franck, A., Bull. Acad. Belgique, vol. 25,1893, p. 17.
44 M1NEBALOG10AL NOTES SERIES 1. 

Measurements of C{14.1.0}.

Symbol.

. 1IOA-14.1.0 

. 100A14.1.0

Measured.

0 /

36 01 

3 07

Calculated.

0 /

36 02 

3 08

Difference.

0 / .

0 01 

0 01

The new form D{720} is present once as a line face giving a poor 

reflection.

Measurements of D { 720}.

Symbol.

010A720 

100A720 

940A720

Measured.

o /

66 04 

11 08 

5 49

Calculated.

0 /

65 52 

11 38 

5 43

Difference.

0 /

0 12 

0 30 

0 06

The prism £"{940} occurs with the preceding form, and, like it, is a 

line face giving a poor reflection.

Measurements of E{940}.

Symbol.

010A940 

100A940 

9. 10. OA940

Measured.

0 /

60 15 

16 57 

18 04

Calculated.

0 /

60 09 

17 21 

17 56

Difference.

0 /

0 06 

0 24 

0 08

The form F{9.10.0} approaches to a vicinal form, though the 

measured and calculated angles agree well. It is present as a narrow 

face much broader than a line face and gives a fairly good reflection. 

Apparently, it replaces the form u{TLQ}, for the two are not found 

together.

Measurements o/jP{9.10.0}.

Symbol.

OIOA9. ID. 0

. 120A9. 10. 0

100A9. 10. 0

Measured.

0 /

42 11

13 33

35 01

Calculated.

0 /

42 13

13 36

35 17

Difference. 

0 /

 0 02

0 03

0 16
AXINITE FROM CALIFORNIA. 45

The new prism 6r{780} is very close to the above, though the 

measured and calculated angles agree well. It is probably identical 

with or near to the form {15.T7.0}, described by Offret and Gonnard. 1 

It is present as a line face with -MJlIO} on the crystal from Amador 

County. The reflection was fairly good.

Measurements ofG {7§0}. x

Symbol.

OIOA780.......

110A780......

120A780......

Measured.

0 /

41 38

. 2 58

12 39

Calculated.

o /

41 34

3 02

12 57

Difference.

0 /

0 04

0 04

0 18

Measured

by Offret 

and Gonnard.

0 /

2 48

The form jV{290} occurs as a narrow face giving a fairly good 

reflection.

Measurements of N{ 250}.

Symbol.

OIOA290......

120A290......

110A290......

Measured.

0 /

14 42

13 45

29 54

Calculated.

0 /

14 48

13 49

29 48

Difference.

0 /

0 06

0 04

' 0 06

The new prism P{1.13.0} is of a vicinal character, but, like some of 

the other forms here described, the measured and calculated angles 

agree well. It is present as a narrow face next to {OTO}, and gives a 

good reflection.

Measurements o/°P{ 1.15.0}.

Symbol.

OlOAl-13-0... 

120 Al. 13.0... 

lIOAl- 13.0...

Measured.

0 /

5 26 

23 11 

39 10

Calculated.

0 /

"5 34 

23 25 

39 02

Difference.

0 /

0 08 

0 14 

0 08

1 Offret, A., and Gonnard, F., Note cristallographique sur 1'axinite de 1'Oisans: Bull. Soc. franc, min6ral.. vol. 16,1893, p. 75.
46 MINERALOGICAL NOTES SERIES 1. 

CHEMICAL COMPOSITION.

Lack of material made it impossible to obtain enough axinite for a 

more complete analysis than is here given. The sample analyzed was 

not quite pure, for small amounts of impurities were plainly visible 

before the sample was ground. It was necessary to determine the 

boric acid content by difference. The analysis and ratios follow:

Analysis and ratios of axinite from Amador County.

SiOa ... ..............................

A1203 ............ ....................

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

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

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

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

5aO.. ..............................

B203 (by difference) .................

Analysis.

42.79

16.38

4.22

8.76

0.09

19.21

1.85

.6.70

100.00

Ratios.

8.00

1.81

2.05

3.85

1.16

1.02

The ratios approximate those proposed in the first part of this 

paper, but the material was of too poor quality and of too slight 

amount to admit of accurate deductions from the analysis. It may 

be noted that in the Amador County axinite the manganese predominates over the iron, whereas in the axinite from San Diego County 

the reverse is true.

In a recent number of Tschermak's Mineralogische und Petrographische Mitteilungen Fromme * gives, in connection with a description 

of several minerals from the Radautale, an analysis of axinite. The 

formula derived from that analysis and Fromme's discussion of the 

composition of axinite require some comment. The analysis given is

as follows: '

Analysis of axinite from Radautale (by Fromme).

Si02 ......................................................... 41.73

B203 -....................................................... 6.30

A1203 ........................................................ 17.08

Fe203 ....................................................... L87

FeO.......................................................... 1.35

CaO......................................................... 18.65

MnO......................................................... 11.54

MgO......................................................... 0.34

H,0. 1.81

100. 67

1 Fromme, J., Chemisch-mineralogisclie Notizen aus dem Radautale: Min. pet. Mitt., vol. 28, 1909, 

pp. 305-323,
AXINITE FROM CALIFORNIA. 47

Fromme rightly combines the ferric iron with the alumina, and also 

places the manganese and magnesia together in deducing the formula 

from the analysis. His view that the ferrous iron and calcium replace 

each other is, however, open to serious question, for in general FeO 

and CaO do not isomorphously replace each other in silicates, as is 

shown, for example, by the behavior of these compounds in hedenbergite and ilvaite. The fact that FeO and CaO are not isomorphous 

in axinite is made clear by the table of analyses given on p. 40. 

The proportion of CaO + FeO to Si02 , for instance, is variable, and 

depends on the amount of FeO present, for both the Si02 and CaO 

are fairly constant.

Curiously enough, Fromme deduces from his analysis the formula 

of a magnesium axinite, which he regards as the primary type or 

"Grundtypus," even though his analysis shows only 0.34 per cent

MgO and. despite the fact that an analysis of axinite in which MgO

predominates has never been published. Fromme calls his axinite a 

relatively pure manganese axinite, even though in the same sentence 

he speaks of the magnesium axinite as the type.

The formula proposed by Fromme for manganese axinite, namely* 

HMnCa2BAl2Si4016 , is identical with that advanced by the writer; the 

isomorphous relation of the FeO + MnO+MgO seems, however, to have 

escaped Fromme's notice. The general formula HR/'R2 //BAl2Si4016 

was long ago proposed by Rammelsberg, though Ford grouped the 

bivalent bases together rather than consider them present in fixed 

amount. It is the writer's belief that the evidence shows that the 

CaO is beyond question definite in amount and that the H2O and the 

FeO + MnO + MgO are probably in definite proportion. Among the 

many other writers who have accepted calcium as constant is Tschermak, who, however, writes the formula for axinite HMgCa2BAl2Si4016 

with admixture of the related iron and manganese oxides. Whitfield 

proposed the isomorphous relation of the FeO and the MnO, but 

otherwise his formulas do not accord with more recent data. Therefore 

the view here proposed that axinite consists essentially of the two 

minerals, ferroaxinite (HFeCa2BAl2Si4016) and manganoaxinite 

(HMnCa2BAl2Si4010) although by no means new, puts forward clearly 

the evidence as it rests to-day. The existence of the corresponding 

magnesium axinite in a pure state is strongly indicated, but has not 

yet been demonstrated, for the ratio of MgO is, in all the analyses 

available, much less than that of FeO + MnO.
ALBITE FROM LAWSONITE SCHIST, MARIN COUNTY,

CALIFORNIA.

ASSOCIATION.

Among the minerals found in the lawsonite schist at Reed Station, 

Marin County, Cal., albite is represented in a number of specimens by 

well-developed crystals, some of which are nearly a centimeter across. 

The albite seems to be concentrated at one point where the ground 

is strewn with small cavernous specimens, consisting chiefly of glaucophane and albite. Lawsonite has not been found directly associated 

with albite, the only mineral occurring with the albite being glaucophane.

The results herewith presented were attained some eight years 

ago, but they have been withheld, a's it was planned to present a more 

complete paper on all the minerals mentioned herein. As almost all 

those collected by the writer were lost in the fire in the Survey Building, in December, 1908, the plan had to be abandoned and the data 

obtained for the albite are now presented. A brief note on lawsonite 

was published some years ago by the writer in conjunction with Dr. 

W. F. Hillebrand. 1

The other minerals found in the schist with lawsonite are, as enumerated by Ransome, 2 glaucophane, actinolite, muscovite (first 

erroneously described as margarite), epidote, garnet, rutile, titanite,

chlorite (pseudomorph after garnet), zoisite, pyrite. Besides these,

there were found albite, abundant and in good crystals, chlorite in 

large sheets (several centimeters across) of a dark-green color, limonite 

pseudomorph after pyrite, anthophyllite (?), and talc.

FORMS AND ANGLES.

A number of new forms were found on these albite crystals when 

they were measured, but the forms have all since been described by 

other writers. A very important paper on the crystallography of 

albite has recently appeared 3 to which frequent reference will be 

made.

* Schaller, W. T., and Hillebrand, W. F., Crystallographical and chemical notes on lawsonite: Am. Jour. 

Sci., 4th ser., vol. 17,1904, p. 195; and Bull. U. S. Geol. Survey No. 262,1905, p. 58.

* Bull. Dept. Geology Univ.'California, vol. 1,1896, p. 301.

s Dreyer, C., and Goldschmidt, V., Ueber Albit von Grb'nland: Meddelelser om Gr^nland, vol. 34,1907, 

separate, 60 pp., 5plates, 2 figs.

48
ALBITE FROM LAWSONITE SCHIST, MARIN COUNTY, CAL. 49

The forms determined by measurements on the albite crystals are 

as follows:

Forms on albite.

001

010

021

021

101

C {150} 

/ 130} 

Z {120} 

#{350}

.¥{110}

130

112

111 

221 

112 

o {III

X

521 

241 

131 

312 

a {100}

The measurements, on which the more common forms were identified, are given below: 1 - ' °

Forms and angles, albite.

Symbol.

c A& = 

c /\e =( 

c AC = 

c /\m= 

c /\M=

c Ay = 

x/\y =

6A/ = 

c Ap = 

c AO =

cA<5 = 

o A* = 

b/\p = 

b/\X= 

b /\u =

yA*= 

b/\f = 

b/\Z=

001) : (010) .......

001) : (021).. ........

(001): (001)........

001) :(110)........

001) :(1IO)........

001) : (201)... .....

101) : (201)... .....

010) :(130)........

001) : (111)........

001) : (111)........

001) : (112)........

Ill) : 101)... .....

(010) : 111)........

'010) :(241)........

(010) :(221)........

'131) : (241)........

(010) :(130)........

(010) :(120)........

Measured.

0 /

93 36 

43 49 

7 08 

65 12 

69 02

98 03 

29 59 

30 23 

56 10 

57 38

30 05

27 22 

60 14 

39 40 

59 42.

18 25 

30 25 

40 34

Calculated.

0 /

93 31 M). 

43 10 D). 

7 02 M). 

65 12 M). 

69 05 M).

97 52(M). 

29 57 M). 

30 24 G). 

55 53 D). 

57 41 M).

30 04(M). 

27 26(M). 

60 16(M). 

39 24(D). 

59 32(D).

18 55(D). 

30 24(G). 

41 25(G).

1 The letter following the value of the calculated angles refers to the source of the angle, as it was not 

deemed necessary to recalculate all the angles used: M=Melczer, G., Zeitschr. Kryst. Min., vol. 40, 1905, 

p. 571; D=Dana, E. S., System of mineralogy, 6th ed., 1892, p. 328; G=Dreyer, C., and Goldschmidt.V., 

loc. cit.

99946° Bull. 490 11-
50 MINERALOGICAL NOTES SERIES 1.

The crystals showing the rarer forms were remeasured on the twocircle goniometer, the most important of the values obtained being 

shown below.

. Measurement of rare forms, albite.

Letter.

n

g

X

. u 

a

Symbol.

150 

350 

021 

221 

312

241 

131 

221 

100

Measured.

 *

 o /

19 19 

46 29 

154 04 

49 13 

70 '07

146 16 

164 00 

125 32

87 26

P ''.

0 /

90 00 

90 00 

49 28 

62 20 

46 12

68 45 

59 08 

60 05 

90 00

Calculated.

. *

0 /

19 21 

46 40 

154 30 

50 29 

69 32

145 50 

163 17 

125 16 

90 28

P

0 /

90 00 

90 00 

49 21 

62 12 

46 04

69 01 

59 08 

60 51 

90 00

There was also present on crystal No. 2 a very narrow face in the 

prism zone giving a distinct but faint signal. Its position could not 

be definitely determined, but its symbol is near to {490}, though the 

measurements agree closer with the more complex {5.11.0}. The 

form must, therefore, be referred to the already large class of doubtful 

forms. The angle values are shown below.

Measurements of doubtful prism.

130 A ?------ ------

150 A ?- -----------

350 A ?- -----------

110 A ?- -----------

010 A ?------------

Measured.

0 /

8 19

19 07

8 03

21 57

38 26

Calculated 

for {5.11.0}

0 /

8 19

19 22

7 57

21 55

38 43

Calculated 

for {490}.

0 /

7 41

18 44

8 35

22 33

38 05

DESCRIPTION OF RARER FORMS.

e{021} was noticed but once as a line face, and the form is very 

rare on these'crystals, the corresponding dome rt{021} being observed 

fairly often.

£{150} was found only once as a line face, on crystal No. 2, with 

IfkmMz. The form was only recently definitely determined by 

Dreyer and Goldschmidt.
ALBITE FROM LAWSONTTE SCHIST, MAEIN COUNTY, CAL. 51

Z{120}, a rare form, but well confirmed by Dreyer and Goldschmidt, was found once as a narrow face on crystal No. 14.

^£{350}, determined as a new form when measured, was found by 

Dreyer and Goldschmidt, who report its occurrence on five crystals 

with 8 faces. By the writer it was observed on four crystals. The 

records of the measurements of the form on crystals Nos. 12 and 15 

are lost, but for Nos. 2 and 8 they are as follows:

Measurements of JST{350}, albite.

Symbol.

Crystal No. 2 

CAK=

/AK=

m/\K= 

Crystal No. £

&AK= 

/AK=( 

m/\K=

.

150) : (350 

130) : (350 

110) : (350,

010) : (350 

130) : (350 

110) : (350

).....

.....

Measured.

0 /

27 30 

16 18 

13 34

47 29 

17 04 

11 39

Calculated.

0 /

27 19 

16 16 

13 58

46 40 

16 16 

13 58

#{221} and ^{221} are rare forms, noted several times on«these 

crystals, though never were both forms seen on the same crystal.

JT{241}, also new when first observed, was described at the same 

time as new by Bowman 1 and was found once by Dreyer and Goldschmidt. The form was noticed on two crystals by the writer, in both 

cases with r?{T31}. -

^{THl}, first determined by Viola (1895) and fully confirmed by 

the measurement of 23 faces by Dreyer and Goldschmidt, was 

noticed twice by the writer each time with X{241}.

w{312}, was measured as a small face with poor development on 

crystal No. 2. The form was first found by Dreyer and Goldschmidt 

and as the measured and calculated angles found by the writer 

agree well, no hesitancy is felt in referring the face measured to this 

form.

A very narrow face gave a poor reflection whose measurement 

approximated to the value for a{100}, a determined form.

» Mineralog. Mag., vol. 13,1902, p. 115.
52 MINERALOGICAL, NOTES SERIES 1. 

COMBINATIONS.

The combinations observed on these albite crystals are given

below.

Combinations on albite crystals.

Crystal No. 

1

2

0

4

5

6

7

8

10

11

12

13

14

1 z

16

17

18

19

20

c b

ft

h

ft

ft

ft

ft

ft

ft

ft

ft

ft

ft

ft

ft

ft

ft

ft

ft

ft

ft

e n X y

y

y

y

v

y

V

y

y

y

y

y

y

y

y

y

y

y

y

y

C

c

/

t

:

t

',

z

7

K

K

K

K

W

m

m

M

M

M

M

M

M

M

M

M

W

M

MMM

M

M

M

M

M

z r P

V

P

P

P

P

P

P

P

P

P

P

P

P

P

P

9

g

g

g

9

ft

a

*

fl

ft

ft

a

0 u X

X

X

1) tii

From the table of combinations, it can readily be seen that the 

common forms are: c, &, x, y,f, m, M, z, p, o, while the less common 

forms, or those that were noted on more than two crystals and yet 

on less than half of those measured are: n, /-, g, d, K, which leaves, 

as the forms of the third or rare class: e, £, Z, u, X, TJ, cu.

HABIT.

In habit the crystals are usually short prismatic or nearly equidimensional, rarely somewhat elongated prismatic or slightly tabular, 

parallel to &{010}. Though one simple crystal (No. 1) was observed, 

all the others are twinned on the albite law. Usually there are but 

two individuals, though in a number of cases several twinning lamellae run through the center of the crystal and sometimes give bright 

lamellae, in the zone Ix, which faces were at first thought to be new 

forms, but as shown by Dreyer and Goldschmidt * for the forms {797} 

and {757} of Melczer, 2 are probably induced by twinning lamellae. 

Thus there was measured, in the zone lx, for the face Z: b AZ = 66° 10', 

67° 14'; zAZ = 26° 05', 27° 03'; pAZ = 6° 19', 7° 02'; but l/\p = 

60° 16' and pA</ = 6° 32'; therefore &Ao' = 66° 48'. Further, 

since zAo' = 27° 32' and pAo/ = 6° 32', the face Z, the measurements 

of which correspond to the angle values just given, is doubtless o in 

twin position.

1 Dreyer, C., and Goldschmidt, V., Ueber Albit von Gronland: Meddelelser om Grjtaland, vol. 34, 1907, 

separate, p. 11.

2 Zeitschr. Kryst. Min., vol. 40, 1905, p. 583,
NOTES ON CRYSTALLOGRAPHY OF PHENACITE.

PHENACITE FROM NEW HAMPSHIRE.

Some crystals of phenacite from Bald Face Mountain, Chatham, 

N. H., were received for investigation through Prof. F. W. Clarke. 

The loose crystals resemble very much those described by Farrington 1 from the same locality, but the ones at the writer's disposal were 

somewhat richer in forms, a total of 12 having been noted. Of the 

forms_given in the table below,_a {1120}, m { 1OTO}, r { 1 Oil}, d { 01 12}, 

p {1123}, s {2131}, and Sj {3T21} were observed by Farrington.

Forms and angles on phenadtefrom Chatham, N. E.

Letter.

a

m

r

d

z

u

8 .

V

X

s

Si

p

Pi

0

Symbol.

1150

1010

1011

0112

0111(?)

0221

1456

2134 '

1232 :

2131'

3151 '

1123

2113

4223

Measured.

4>

0 1

30 00

0 00

0 03

0 12

0 02

0 00

11 13

19 05

19 01

19 04

19 19

30 10

30 18

30 01

P

o /

90 00 

90 00

37 24

21 20

40 42

56 46

30 11

27 11

45 04

64 03

63 30

24 01

23 59

41 29

Calculated.

 *

0 /

30 00

0 00

0 00

0 00

0 00

0 00

10 53

19 06

19 06

19 06

19 06

30 00

30 00

30 00

P

0 /

90 00

90 00

37 21

20 53

37 21

56 46

30 14

26 47

45 17

63 39

63 39

23 47

-23 47

41 23

Size of face.

Medium.

Medium.

'Large.

Medium.

Line face.

Line face.

Minute.

Line face.

Minute.

Line face.

Line face.

Small.

Small.

Minute.

FORM SYSTEM OF PHENACITE.

The forms for phenacite are given in the orientation chosen by 

Dana in preference to that of Goldschmidt, in which the symbols 

are more complex than in the former. A review of the literature 

of phenacite since the publication of Goldschmidt's Winkeltabellen 

has shown that a number of new forms are to be added to the list 

given by him, in order to have a complete form system for the mineral. 

The following table of forms has therefore been compiled and gives

i Farrington, 0. C., Notes on various minerals in the museum collection: Field Columbian Museum 

Publications, Geol. ser., vol. 3,1908, p. 157.

53
54 MINERALOGICAL NOTES SERIES 1.

all the forms found in the literature for phenacite (doubtful and 

vicinal forms not included), and is perhaps the most practicable table 

for the identification of forms when the mineral is measured by 

the two-circle method. If no reference for a form is given in the 

last column of the table, it signifies that the form has been recognized 

by at least three independent observers and therefore is well substantiated. Otherwise references to the source of the description of 

the form are given.

Forms and angles for phenacite.

No.

1

2

3

4 

5

6 .

7

8

9 

10

11

12 

13 

14

15

16 

17 

18

19

20

21o 

22

23

24 

25

Letter.

m

a

k

d, 

d

r

z

S , t 

A

eV 

X

8

b

*>

(i)

f

e

Vi 

P/n

Oio %

Goldschmidt.

ooO

oo

4oo

+ 40 -40

+ 10

-01

-02

 & § -H

+1 4

- 13

+4i -41

+ 21

+n-4f 

- ll

+ 32

+H- 

?*t

+ t - i

Symbol.

Miller.

211

]OI

312

411 

110

100

221

111

431 

321

301

212 

310 

212

201

411 

11. 5. 3 312"

305

621

423 

210

201

311 

311

Bravais.

1010

1120

4130

1012 

0112

lOll

0111

0221

1456 

1344

3142

1341 

2134 

1232

2131

3254 

2354 

2352

3251

4377

15S5 

Il23r

2I13Z

2243r 

4223Z

0

0 ' /

0 00

30 00.

10 53

0 00 

0 00

0 00

0 00

0 00

10 53 

13 54

13 54

13 64 

19 06 

19 06

19 06

23 25 

23 25 

23 25

23 25

25 17

8 57 

30 00

30 00

30 00 

30 00

P

0 /

90 00

90 00

90 00

20 53 

20 53

37 21

37 21

56 46

30 14 

34 32

54 00

70 02 

26 47 

45 17

63 39

39 45, 

39 45 

58 59

73 16

33 33

40 22

23 47

23 47

41 23 

41 23

ences.

8

4,9 

4

1,5 

2,3

7 

7

7 

6

8

a The form y { 1565} should follow No. 8.

1. Beyrich, Pogg. Ann., vol. 34, 1835, p. 519; vol. 41, 1837, p. 323 (Goldschmidt, 

Index der Krystallformen der Mineralien, vol. 2, 1890, p. 464).

2. Rose, Pogg. Ann., vol. 69,1846, p. 145 (Hintze, Handbuch, vol. 2, p. 41).

3. Seligmann, Neues Jahrb. Min., Geol. u. Pal., vol. 1,1880, p. 129.

4. Descloizeau, Bull. Soc. franc, mineral., vol. 9, 1886, p. 171.

5. Lacroix, Mine"ralogie de la France, vol. 1, 1893-1895, p. 205.

6. Spencer, Mineralog. Mag., vol. 14, 1906, p. 178.

7. Zimanyi, Ann. Musei Hungarici, vol. 7, pt. 1,1909, p. 347.

8. Slavik, Bull, intern. Acad. Boheme, 1909, vol. 14, p. 1.

9. The present paper.
NOTES ON NEPTUNITE.

NEPTUNITE FROM CALIFORNIA.

A large suite of specimens of benitoite and neptunite were collected 

by Dr. Ralph Arnold * and turned over to the writer for investigation. 

As Dr. Louderback was then intending to publish a full description of these minerals, the investigation was postponed. A single 

crystal was measured and a partial analysis was made in order to 

classify the so-called carlosite. 2 Since then the crystallography,3 the 

chemical composition,4 and the occurrence 5 of the mineral have 

been described.

The single crystal measured is prismatic and of the habit described 

by_Ford. _The forms present are c{001}, a{100}, mfllO}, s{lll},. 

o{Tll}, i{U2}, g{2ll}, p{3ll}, and *ft{887}. The measurements 

of these forms gave the following values:

Forms and angles for neptunite.

Letter.

c 

a 

m 

s

0

i 

9 

P

Symbol.

001 

100 

110 

111 

111

112 

211 

511

Measured.

<£

0 /

90 06 

90 00 

40 21 

55 07 

14 26

18 52 

48 11 

62 52

P

0 /

25 23 

90 00 

90 00 

54 16 

40 08

22 56 

51 00 

60 12

Calculated.

0

0 /

90 00 

90 00 

40 07 

55 10 

13 57

19 05 

47 29. 

62 39

P

0 ' /

25 38 

90 00 

90 00 

54 43 

39 45

23 08 

50 05 

60 22

1 Arnold, R., Notes on the occurrence of the recently described gem mineral benitoite: Science, vol. 27, 

1908, p. 312.

' Louderback, G. D., and Blasdale, W. C., Benitoite, a new California gem mineral: Bull. Dept. Geology. 

Univ. California, vol. 5,1907, p. 149.

»Ford, W. E., Neptunite crystals from San Benito County, Cal.: Am. Jour. Sci., 4th sen, vol. 27, 1909, 

p. 235.

* Bradley, W. M., On the analysis of the mineral neptunite from San Benito County, Cal.: Am. Jour. 

Sci., 4th ser., vol. 28,1909, p. 15.

6 Louderback, G. D., and Blasdale, W. C., Benitoite, its paragenesis and mode of occurrence: Bull ' 

Dept. Geology Univ. California, vol. 5,1909, p. 331.

55
56 MINERALOGICAL NOTES SERIES 1.

In addition to these forms, a large face near to s {111} is present 

on one side of the crystal. Its measurement corresponds to the symbol */&{887}, and as the form occurs as a large plane face, it is considered as well established. The face (887) is much larger than 

(111) and a little smaller than (111) and is one of the largest faces 

on the crystal. The corresponding face (887) is not present. The 

measurements are as follows:

Measurements of new form h {887}.

Measured. Calculated.

^=53° 41' 0=53° 43'

p=57° 31' (0=57° 20'

A very narrow face vicinal to (TT2) was also observed. The form 

g {211}, described as new by Ford, is present on this crystal as two 

large dull uneven faces. The form is probably characteristic of this 

locality, as it was seen on a number of other crystals.

FORM SYSTEM OF NEPTUNITE.

As the number of forms for.neptunite has considerably increased 

since the original description of the mineral in 1893, a compilation of 

all the described forms with the coordinate angles thereto is given 

below. As in a similar table appearing in this paper a reference to 

the description on which the form is based is given, unless the form 

has been three times independently described. The values <£ and 

p for the forms not given in Goldschmidt's Winkeltabellen have, 

except for ft{887}, been taken from the table furnished by Hlawatsch. 1

1 Hlawatsch, C., Bemerkunge'n zum Aragonit von Rohitsch, Natrolith und Neptunit von San Benito: 

Min. pet. Mitt., vol. 28,1909, p. 293.
NOTES ON NEPTUNITE. 57

Forms and angles ofneptunite.

Monoclinic, a=1.3164; c=0.8076; /3"=64°22'.

No.

1 

2 

3 

4 

5

6 

7 

8 

9 

10

11 

12 

13 

14 

15

16 

17 

18 

19

Letter.

b

m 

a

0

i 

r

g

V

h 

s

r 

P 

u

X

q 

f

c 

e 

d

Symbol.

Miller.

010 

110 

100 

111 

112

221 

211 

221 

887 

111

522 

' 311 

512 

311 

712

101 

001 

201 

301

Goldschmidt.

Oo=

oo 

ooO 

_]_

~'z i

_2 

-21

+2

+* +1-

-P 

-31 -H

+31 -H

-10 

0 

-20 

-30

*

0 /

0 00 

40 07 

90 00 

13 57 

19 05

22 12 

47 29 

48 44 

53 43 

55 10

56 31 

62 39 

71 42 

72 14 

78 04

90 00 

90 00 

90 00 

90 00

P

0 /

90 00 

90 00 

90 00 

39 45 

23 08

60 11 

50 05 

67 47 

57 20 

54 43

55 40 

60 22 

52 08 

69 18 

' 62 47

11 20 

25 38 

41 22 

57 21

References.

2,4

1,2 

5

 3

2 

2

2

1,2

1. Flink, G., Beschreibung eines neuen Mineralfundes aus Gronland: Zeitschr. 

Kryst. Min., vol. 23, 1894, p. 346.

2. Flink, G., Boggild, 0. B., and Winter, C., Untersuchungen uber Mineralien von 

Julianehaab: Meddelelser om Gronland, vol. 24, 1899.

3. Hlawatsch, C., Bemerkung zum Aragonit von Rohitsch, Natrolith und Neptunit von San Benito: Min. pet. Mitt., vol. 28, 1909, p. 293.

4. Louderback, G. D., and Blasdale, W. C., Benitoite, its paragenesis and mode of 

occurrence: Bull. Dept. Geology Univ. California, vol. 5, 1909, p. 331.

5. The present paper.
ORBICULAR GABBRO FROM PALA, SAN DIEGO COUNTY,

CALIFORNIA.

A large number, a hundred or more, of what seemed concretions, 

were found lying loose on the summit of Hiriart Hill, near Pala, San 

Diego County, Cal. The writer's attention was called to them by 

Mr. F. M. Sickler, of Pala, who found them while exploring the hill 

for spodumene (kunzite). Many of them are broken, and an examination of one of them showed the apparent concretions to be the 

orbicules of an orbicular phase of the hornblende gabbro which forms 

this bill. This orbicular phase has weathered away, leaving behind 

nothing but these hard balls. Careful search .of the rock revealed 

two or three poorly developed orbicules in the gabbro, but the main 

mass of 'the original orbicular rock has entirely' disappeared. These 

orbicules have an average diameter of 2 to 2 £ inches and vary somewhat in shape, rarely being regularly elliptical, but usually being of a 

distorted spherical shape.

The center is occupied by coarse-grained feldspar and some ferromagnesian minerals, which are surrounded by radiating prisms that 

can not be determined by the eye alone. The radiating mass is 

black in spots and the orbicule always shows a brownish border a 

millimeter or two wide, which is merely a zone of weathering. The 

entire orbicule is somewhat altered, brownish stains being common 

throughout. The orbicules have no concentric structure except the 

outer zone of weathering.

Microscopically, the minerals present are seen to be olivine, hypersthene, hornblende, feldspar, and iron oxides, such as magnetite and 

limonite. The olivine occurs in irregular masses nearly always surrounded by green hornblende. It is full of cracks, and near the edge 

of the orbicule it is much altered to iron oxide. It is colorless, nonpleochroic, with a very high relief and birefringence. The hypersthene is strongly pleochroic (from pink to colorless to pale green) 

and shows a high relief with low birefringence. It is in places surrounded by green hornblende. The hornblende oc,curs as a border 

around the olivine and hypersthene and also as small shreds of 

original mineral. It is generally green but becomes slightly brownish 

in places. It is commonly altered to chlorite. The feldspar is 

labradorite with symmetrical extinctions of about 37°.

The radiated structure is caused by the formation of long narrow 

masses of olivine, hypersthene, and hornblende, the olivine being the

58 .
ORBICULAR GABBRO PROM PALA, SAN DIEGO COUNTY, CAL. 59

most abundant. They are irregular in their shape and show no 

definite boundaries. They are in general continuous for some little 

distance, but many are formed of pieces lying in a straight line 

but not connected. The green envelope or rim of hornblende commonly surrounds the olivine, and a number of specimens were noticed 

where a border of pink hypersthene separated the hornblende from 

the olivine. Where there is also a fringe of deep green chlorite surrounding the hornblende the combination makes a very pretty section. 

In some specimens it seems that the hypersthene alters directly to 

chlorite. The orbicules are not so perfectly developed as those 

described by Lawson l from Dehesa, San Diego County. The 'concentric structure there found is entirely lacking in the Pala rock, 

while the radiated structure is but poorly developed. One of the 

most interesting things about the Pala orbicular rock is its peculiar 

mode of occurrence, the orbicules lying loose in the soil instead of 

being embedded in the solid rock as at Dehesa.

1 Lawson, A. C., The orbicular gabbro at Dehesa, San Diego County, Cal.: Bull. Dept. Geology Univ. 

California, vol. 3, No. 17,1904, pp. 383-386.
THE REFRACTIVE INDEX OF OIL OF CINNAMON.

INTRODUCTION.

The use of organic liquids of known refractive index (ri) for determining the index of refraction of a mineral has reached a very extensive 

application in late years. Numerous papers have appeared recently, 

several by F. E. Wright, which have set forth the different 

methods of using the liquids. One of the commonest liquids is oil 

of cinnamon, which is easily obtainable, has a rather high index 

(1.6), and mixes easily with oil of cloves (n = l.53) and oil of cedar 

(n = 1.51) to form a series which covers especially the row of plagioclase feldspars, a group of minerals very important in petrography.

Having prepared a large number of these solutions for geologists 

of the survey, the writer observed that the cinnamon oil varied in 

refractive index even while the measurement was in progress. If 

this variation was at all large it would preclude the use of the oil, 

and a detailed examination was therefore undertaken to determine 

the variation and to decide whether or not the oil was suitable 

for a standard measure. It was intended to subject to such an 

examination all the liquids commonly thus used, but lack of time 

has necessitated the postponement of the investigation. As soon as 

opportunity is presented, however, the study will be completed in 

order to furnish the information necessary for the use of the several 

liquids. This paper on the oil of cinnamon serves, therefore, as an 

introduction to the subject and shows the necessity for a complete 

knowledge of fundamental data.

GENERAL DESCRIPTION.

Cinnamon oil is obtained from the inner bark of a tree (dnnamomum zeylanicum, belonging to the natural order Laurinese) 

indigenous to Ceylon, but now also grown in Brazil, the West Indies, 

Egypt, Java, and on the Malabar Coast; Ceylon, however, produces 

by far the best quality. Cassia cinnamon.and saigon cinnamon are 

obtained from different species of Cinnamomum, and the oils derived 

therefrom differ chemically from the true Ceylon oil of cinnamon. 

The cinnamon bark contains a volatile oil (oleum cinnamoni), tannin, 

sugar, and mannite. By distillation from one-half to 1 per cent of 

oil of cinnamon is obtained. The color of the fresh oil is yellow, but 

it deepens by exposure to air, becoming browner.

The oil consists chiefly of cinnamic aldehyde, C6H5 .CH.CH.CHO, 

with smaller quantities of cinnamic acid, C6H5 .CH.CH.CO2H. Thorpe l

i Thorpe, T. E., Dictionary of applied chemistry, vol. 3,1893, p. 12. 

60
REFRACTIVE INDEX OF OIL OF CINNAMON. 61

mentions, in addition, the presence of a small quantity of a Isevogyrate hydrocarbon. Cinnamic aldehyde 1 melts at 7.5° C., and is 

'decomposed by boiling at atmospheric pressure. Its density is about 

1.05, and refractive index about 1.61. By oxidation on exposure to 

air it forms cinnamic acid, which sometimes crystallizes. from oil of 

cinnamon. Cinnamic acid forms colorless monoclinic prisms, which 

melt at 133° and boil at about 300° with or without decomposition 

according to the physical conditions. It is easily decomposed into 

styrene, C6H5 .CH.CH2 , and carbon dioxide, C02 . Oxidizing agents 

convert the acid first into benzoic aldehyde and then into benzoic 

acid.

The above description of oil of cinnamon and its chief constituent, 

cinnamic aldehyde, which readily oxidizes to cinnamic acid, clearly 

shows how unstable a liquid it is, and therefore how unsuitable for 

any purpose requiring a medium of constant physical properties.

MEASUREMENTS OF REFRACTIVE INDEX.

The first series of measurements were made to determine the variation of the refractive index according to the temperature. For this 

purpose the small bottle with a thermometer stopper combined with 

the Abbe-Zeiss refractometer was employed. This was cooled in 

ice to about 0° and then placed on the glass hemisphere of the refractometer and the readings taken when the thermometer showed the 

desired temperature. By the use of the micrometer tangent wheel, 

which gives readings to 6 seconds, the measurements could easily 

and quickly be made. The oil of cinnamon showed practically no 

dispersion, and the values given for sodium light represent closely the 

index for daylight. No difference in the value of the index could be 

detected by using red lithium or green thallium light. The values of 

the index of refraction (n) for yellow sodium light, as measured, are 

shown below for the different temperatures.

Values of index of refraction of oil of cinnamon for different temperatures.

Temperature.

e'

7

8

8*

9

10

11

12

n.

I. 5996

1. 5995

1. 5991

1. 5989

1. 5989

1. 5983

1. 5979

1. 5976

Temperature.

13

14

15

16

17

18

19

20

n.

1. 5978

1. 5973

1. 5970

1. 5966

1. 5958

1. 5956

1. 5949

1. 5946

Temperature.

21

22

23

24

25

26

27

,

n.

1. 5942

1. 5938

1. 5936

1. 5929

1. 5926

1. 5921

1. 5917

I Beilstein, F., Handljuch d. organischen Chemie, vol. 3,1897, p.
62 MINEBALOGICALr NOTES SEKIES 1.

These values are plotted and the resulting straight line shown in 

figure 3. From the readings, with a temperature variation of 21°^ 

the refractive index varies from 1.5996 at 6° to 1.5917 at 27°. Therefore there is a decrease in the index of 0.00037 for every rise of 1°. 

From the plotted line (fig. 3) the refractive index at 0° is found to be 

1.6022, and at 30° it is 1.5907, a change of 0.0115 for 30° change in 

temperature. From these values it is found that a change of temperature of 1° causes the solution to vary 0.00038 in the index. This 

change is reciprocal that is, as the temperature increases the index 

.of refraction decreases. The amount may be given as 0.0004 for a 

change of I 0.1

The variation in temperature at different seasons is therefore sufficient to cause an appreciable change in the index of refraction of the 

oil of cinnamon. Even during the day the variation in temperature 

is enough to markedly change the value. The following table gives 

the values for n at three different temperatures, which are often 

reached indoors at Washington during the year:

Variation of index of refraction of oil of cinnamon.

Temperature, 

Fahrenheit.

o -

100 

70 

50

Temperature, 

centigrade.

o

38 

21 

10

n (Oil of 

cinnamon).

1. 5877 

1. 5942 

1. 5983

Another cause of variation, and one that is much more detrimental to the use of oil of cinnamon as a liquid of known refractive index, 

is its variability on exposure to air. This is owing to the oxidation of 

the cinnamic aldehyde to cinnamic acid. That this change is very 

rapid and also important is shown by the following table, which 

represents three sets of experiments. A drop of the oil was placed 

on the glass hemisphere of the refractometer and exposed to the 

air, readings being taken at definite time intervals. An exposure of 

only half a minute is sufficient for the index to increase 0.001 in 

value.

1 The variation for nitrobenzpl is likewise 0.0004 for 1° change in temperature. Zeitschr. Kryst. Min., 

vol. 44, 1908, p. 620.
REFRACTIVE INDEX OF OIL OF CINNAMON. 

Change of refractive index of oil of cinnamon due to oxidation.

63

Time of exposure.

1 minute .................

2 minutes. ................

3 minutes ................

Gain in refractive index.

1

0.0012 

18 

27 

32 

35 

38

2

0..0015 

24 

27 

30

3

0. 0009 

15 

24 

29 

32 

36

Therefore in 5 minutes the solution increases nearly 0.004 in value. 

One set of observations (the third), showing the change in index on

 130 

120

no

100

90

1380

*60

UJ

5 

P50

1.5900

s?

^

1.5920 1.5940 1.5960 1.5980 . 1.6000 

INDEX OF REFRACTION

1.6020 1.6040

FIGURE 3. Variation in index of refraction for oil of cinnamon.

exposure to air, is given below, and the other values are combined in 

the curve shown in figure 3.
64 MINEEALOGICAL, NOTES SERIES 1. 

Values of refractive index of oil of cinnamon on exposure.

Time of exposure in 

minutes.

0

4

1

2

3

4

5

6

7

8

9

Refractive 

index.

1. 5936

45

51

60

65

68

72

 77

81

84

87

Time of exposure in 

minutes.

10

11

12

15

19

25

30

 35

50

60

75

Refractive 

index.

1. 5993

1. 6000

00

. 05

14

14

18

21

25

27

33

As may be seen by reference to the curve of figure 3, the change 

in refractive index is very rapid for the first 10 minutes; then it gradually decreases in rapidity but still slowly gains even after an hour's 

exposure. The most rapid change occurs in the first 5 minutes, 

when a gain of nearly 0.004 takes place. After 10 minutes the total 

change is 0.006, after 20 minutes 0.008, and after an hour's exposure 

0.009. The change then progresses slowly, and probably increases 

till the maximum is reached, which is probably about 1.615, though 

the writer does not know if this value has been determined. This 

would be a solution of cinnamon aldehyde saturated with cinnamic 

acid, and Wright and Larsen 1 give 1.615 for the refractive index of 

cinnamon aldehyde.

SUMMARY.

The results here given show that oil of cinnamon undergoes a 

marked change of refractive index on exposure to air. During 5 

minutes, a time which may well be consumed in manipulation, the 

refractive index of the oil increases by 0.004. The variation of 

the index for a change in temperature of 1° is about 0.0004, the variation being reciprocal. The solution should therefore be standardized for a certain temperature and correction made for any variation 

therefrom. However, the variability due to oxidation is much 

greater, rendering oil of cinnamon unsuitable for any accurate 

work. The only known way to obviate this effect is to have the oil 

form a saturated solution of cinnamic acid in the cinnamic aldehyde, 

and a long exposure to air is necessary to obtain this. The best 

procedure where accuracy is essential is to avoid the use of oil of 

cinnamon altogether.

i Wright, F. E., and Lateen, E. S., Optical study (on diopside, etc.): Am. Jour. Sci., 4th $er., vol. 27, 

J909, p. 35,
INDEX OF REFRACTION OF CANADA BALSAM.

The refractive index of Canada balsam, as it occurs in the thin 

sections made for the United States Geological Survey, was determined on the request of Mr. F. C. Calkins, who had found 1 that 

the index, or n, was not absolutely constant, but varied between two 

extremes. By the examination of 300 slides he found n to reach 

and even slightly exceed a> of quartz (1.544), though n was found 

greater than 1.544 only in the proportion of one slide in a hundred. 

The excess was very small and the balsam was decidedly yellow. 

The lowest value found by him was about 1.535±.002.

The value of n for sodium light was. determined with an AbbeZeiss refractometer by total reflection on three sets of slides, these 

being (1) not cooked as much as usual, (2) cooked ordinarily, and (3) 

overcooked. The differences found between (1) and (2) are very 

slight and, in fact, the individual values show almost as much variation as that between the groups. The values obtained for n are:

Values of refractive index for Canada balsam.

I

1.539

1.538

1.539

2

, 1.536

1.538

1.539

3

1.543

1.540

1.540

1.542

1.541

The average values are for (1), 1.5387; for (2), 1.5377; for (3), 1.5412, 

or, as the'average of all, 1.5395, which is almost identical with the 

value (1.5393) given by Becker 2 in 1898. A determination of n in a 

slide six years old gave the value 1.5390. These values show that, in 

general, n lies very close to 1.539 and that this value may well be used 

in a study of a thin section, though the actual possible variation was 

found by Mr. Calkins to be from 1.535 to 1.545, the extreme values, 

however, being but seldom reached. The uncooked liquid balsam 

has a refractive index of 1.524, which, after cooking, rises to 1.54. 

The older the slide the higher becomes the index of the balsam, and 

after some time, especially if the slide is exposed to the air, the 

index rises toward the highest value, or 1.545.

i Science, vol. 30, p. 973, Dec. 31,1909. 

99946° Bull. 490 11 5

a Am. Jour. Sci., 4th ser., vol. 5,1898, p. 349.

65
SIDERITE AND BARITE FROM MARYLAND.

SIDEBITE. 

OCCTJRBENCE.

A number of specimens of small splendent crystals of siderite were 

obtained through the courtesy of the Foote Mineral Co. of Philadelphia, the locality being given as "within 2 miles of Frostburg, Md." 

The crystals are very small and are deposited in great numbers on a 

massive gray siderite rock. A very striking feature of the siderite 

crystals is their splendent play of colors. Though brown in color, 

they are very iridescent, the light reflected from their surface being 

of all colors. Associated with the siderite crystals and intermingled 

with them are numerous small barite crystals.

The matrix is a compact impure iron carbonate, having a specific 

gravity of 3.7, in which'are embedded occasional masses of white, 

opaque barite, showing good cleavage. In the rock are numerous 

cavities lined with siderite and barite crystals derived from the 

massive rock, the specimens forming geodes.

The crystals of siderite vary from exceedingly minute ones up to 

those of a millimeter in length and breadth. Most of them are 

attached to the matrix by one end, though many irregularly scattered through the mass are attached at both ends. The entire layer 

of crystals is about a millimeter in thickness.

CHEMICAL COMPOSITION.

A number of the crystals were broken from the matrix. From 

these some were very carefully selected and were freed from a 

small amount of barite by the electromagnet. About one-tenth 

of a gram of pure crystals was finally obtained, each crystal having 

been picked out and found to be free from any foreign matter. It 

was noted that the crystals did not possess a uniform color, some 

of them being a much lighter brown than others. It was at first 

thought that the lighter colored ones contained calcium or magnesium, but such was found not to be the case. The difference between the shades of color is probably due to the varying amount of 

ferric iron in the crystals. 1 The selected crystals were dissolved in

1 Siderite should be white if chemically pure. The brown color so often observed may be due to a very 

slight oxidation of the ferrous iron to the ferric condition, which ferric compound then remains in the ferrous 

carbonate in a state of solid solution.

66
SIDERITE AND .BARITE FROM MARYLAND. 67

hydrochloric acid and the iron precipitated with ammonia and 

weighed. Tests made for manganese, calcium, and magnesium 

proved their absence. The weighed iron oxide was fused with sodium 

bisulphate, reduced and titrated with potassium permanganate, 

giving practically the same figure: There was found 62.21 per cent 

FeO (calculated 62.07 per cent FeO). ,The crystals are therefore 

pure iron carbonate and well suited for obtaining crystallographic 

constants for siderite.

CRYSTALLOGRAPHY.

FORMS.

The siderite crystals have a rather unusual habit for that mineral, 

the dominant form being the scalenohedron i;{2131}, the common 

form for calcite. A number of other forms are present, and a very 

marked feature of tliese crystals is that there are concave rounded 

hollows in approximately the places where the a face should come. 

The crystals are highly polished and seemingly should give perfect 

reflections, but on examining them on the two-circle goniometer it 

was found that the faces were not as perfect as was at first thought, 

chiefly because some of the large scalenohedral faces appear broken 

, and the parts slightly displaced, yielding more than one signal several 

minutes apart. The crystals were mounted in polar position on the 

two-circle goniometer, and so adjusted that on turning the vertical 

circle (the horizontal one being clamped) the reflections from the 

several faces of each form fall, respectively, in a vertical line coinciding with the vertical cross hair. After the crystal was adjusted 

as perfectly as possible, the reading on the horizontal circle was 

taken for each face, the signal being brought to the exact center of 

the field in each case. The forms present are: r{10Tl}, Z{7075}, 

£{5052},/{0221}, ^{2131}, </{3251}.

The form Z{7075} occurs but once as a small face below {lOTl} but 

larger than that face. The reflection was fair.

Measured and calculated angles of the form I {7075} on siderite.

*

0 /

0 14

0 00

P

0 /

52 49

53 07

« From element derived by writer.

The form £{5052} occurs as a minute line face, somewhat rounded 

and truncating the edge of the scalenohedron i>{2131}. The measurements showed that the p angle was about 68°, though no accurate 

measurement could be obtained (calculated p 67° 12'). The unit
68 MINEBALOGICAL NOTES SERIES 1.

rhombohedron r occurs on nearly all of the crystals as small faces 

truncating the apex of the crystals. The new scalenohedron y {3251} 

occurs on all the crystals and is a characteristic form for this locality. 

Though it varies in size, becoming relatively wide and short or narrow 

and long, its general size is shown in figure 4.

The zone vyy^v is in some specimens somewhat striated between 

y and i/VI and by using the dot signal it was seen that there was a 

maximum of brightness in the position required for the faces 

{7.6.T3.1} and {1120}. It could not be shown, however, that these 

faces were actually present. The form/{0221} occurs as broad dull 

faces giving no reflection and only an almost 

imperceptible haze of light. Measurements of 

the/) angle gave values from 59° to 62° (calculated 62° 17').

The concave hollows give an indefinite blaze 

of light in the zone of the negative rhombohedrons, about 80° from the base, so that they 

do not reach down to the prism zone. A study 

of these hollows on the goniometer, the dot 

signal being used, showed that they consisted 

of vertical striations approximating in the center to the form {0661} and at the extreme edge 

to {1120} with many forms in between these. 

Figure 4 is an attempt to illustrate the actual 

appearance of these crystals showing particularly the concave hollows. The indentations 

in the orthographic projection are somewhat 

exaggerated. With the exception of these and 

the broad, dull faces, the crystals are highly

polished and do not show any etching. It 

seems more plausible to regard these hollows 

as the result of an incomplete or skeletal 

growth rather than to consider them as the 

result of etching. They are in a way analogous to the hopper-shaped crystals of sodium 

chloride in which the two planes (001) and 

(100) (in one zone) alternate and the resultant hollow has in cross 

sections a V shape. In the siderites, however, instead of an alternation of the two planes {0661} and {1120}, there is a gradation from 

the prism to the rhombohedron, and the result is a rounded hollow 

instead of a sharply angular one.

FIGURE 4. Siderite from 

Maryland.
8IDBBITK AND BAEITE FROM MARYLAND. 69 

ETCH FIGURES.

A cleavage piece of siderite was left standing in very dilute hydrochloric acid for several days and then examined under the microscope, 

when well-defined etch figures could be 

observed. As shown in figure 5, these 

are triangular in shape and possess a 

plane of symmetry parallel with the 

shorter diagonal of the cleavage rhomb 

of siderite. They resemble in symmetry the figures shown in Miers's Mineralogy FlGURE '-Etchagures of siderite. 

(p. 112) for calcite and not those given for dolomite. The symmetry 

of siderite is the same as that of calcite and not that of dolomite a 

conclusion sustained by the forms of the crystals.

VALUE FOE C AXIS.

Although siderite is a common mineral, good crystals are rare and 

the literature is very poor in accurate crystallographical data. The 

only value given for the axial ratio, which is adopted in all books, 

is one obtained in 1812 by Wollaston. His statement in regard to 

siderite is as follows: l

I have examined various specimens of this substance, some pure white, others 

brown, some transparent, others opaque. That which gives the most distinct image 

by reflection is of a brownish hue, with the semitransparency of horn. It was obtained from a tin mine, called Maudlin mine, near Lostwithiel, in Cornwall. By 

repeated measurements of small fragments of this specimen the angle appears to be 

so nearly 107° that I can not form any judgment whether in perfect crystals it will 

prove to be greater or less than that angle.,

In this instance the carbonate of iron is nearly pure, and so perfectly free from 

carbonate of lime * * *.

The measurements of the faces giving good reflections were used 

for calculating a value for the c axis. The angles for the same form 

varied somewhat on different crystals, though the values obtained 

from the measurements of different, forms agree very well with each 

other. From the average reading the following values were calculated :

Calculation of c axis of siderite.

10 measurements of r (lOll)...................... c =0. 82352

27 measurements of v (2131)...................... c = . 82463

16 measurements of y (3251)...................... c = . 82311

Average.................................. c = . 8240

An attempt was made to measure the cleavage angle directly, but 

it was found that the resultant cleavage faces were never perfectly 

plane, with the result that each face gave several signals.

i Phil. Trans., 1812, p. 159.
O MINERALOGICAL NOTES SEEIES 1

After this value for c was obtained and found to be different from 

the commonly accepted value, 10 more crystals were measured, and 

after the greatest care in so adjusting each crystal that the reflections 

from the scalenohedral faces of v fell as nearly as possible in a straight 

line each reflection was carefully measured. In the case of more 

than one signal the extremes were measured and the average taken. 

The average value for the p angle for each crystal (six faces) is:

Measurements of p for v {2131}, siderite.

68 14

68 26

68 18

68 15

68 16

68 21

68 27

68 20

68 19

68 29

Average 68? 20$'; c=.8243.

The values for the two extremes, 68° 14' and 68° 29', are: c = .8197 

and c = .8302.

Taking the average of the value found from r, v, y, namely, .8240, and 

that found from the 10 crystals, namely, .8243, we get as a value for the 

c axis for siderite of known purity c = .8241. Whether or not this 

value is more accurate than, the one commonly accepted is difficult 

to decide. Palache 1 has measured some crystals which gave values 

agreeing with the commonly accepted value of the c axis, so that the 

question as to the true value of the fundamental crystallographic 

constant of siderite is one which still remains to be determined by

more measurements.

BARITE.

OCCURRENCE.

The barite occurs in three different forms on the specimens seen 

by the writer. The first is the white massive form, which is often 

embedded in the matrix. - It is generally opaque and shows a good 

cleavage. The second form occurs as an opaque white efflorescence, 

which is composed of an aggregate of minute crystals. The third, 

form is present in transparent colorless crystals, some of which 

reach a length of several millimeters, though most of them are rather 

smaller* The largest ones seen were about a centimeter long and 

a millimeter or two thick. On some specimens these transparent 

crystals are attached by one end to the massive barite and form a 

fringe, as it were, around it, the crystals standing normal. This 

occurrence is very suggestive of a secondary formation of the crystals that they are derived from the massive barite in the matrix. 

The large clear crystals are probably a more perfect development 

than the white efflorescence and both are doubtless derived from 

the massive barite. In the massive barite there are no siderite 

crystals, though small fragments of the matrix are included therein;

1 Palache, C.. Mineralogical notes: Am. Jour. Sci., 4th ser., vol. 24,1907, p. 254.
SIDERITE AND BAEITE FROM MARYLAND. 71

and in the efflorescence crystals of siderite are commonly inclosed, 

and the clear large barite crystals are intermingled with those of 

siderite.

CRYSTALLOGRAPHY.

The crystals of barite are of especial interest, as they are of an 

uncommon habit prismatic, elongated parallel to the vertical 

axis. Such crystals have been noticed before, but they are Aot the 

common form for barite.

The faces of the crystals are highly polished and gave excellent 

signals. The prism zone is striated on some specimens, especially 

on the macropinacoid, though for the most part the zone is not 

striated and each face is distinct and plane. The forms present are 

as follows:

Forms of barite.

C

6

o

X

E

001}

010

100]

130

370

n{120

NJ230]

9(320} 

1(210} 

Oil 

102 

104 

115}

114

113

112

223}

111

551}

122}

The prism 5(370} occurs twice on two crystals as small faces, 

giving a fair reflection. The 0 angles measured are as follows: 28° 09', 

27° 52', 27° 45', 27° *!' (calculated, 27° 45'). The 

form was first noted by Diising 1 and classed as doubtful by Dana; it is not included in Goldschmidt's Winkeltabellen.

The pyramid Y{551} measured do): 84° 55', 84° 

58', 84° 08', 84° 45' (calculated do) 84° 45'). It is 

present as very narrow and small faces.

The general ideal view of these crystals is shown in 

figure 6. Some of the crystals are flat, parallel to the 

macropinacoid, but most of them are of equal diameter horizontally. Some of them, too, have one side 

of the terminated end much larger than the other 

side, but in general the crystals are fairly symmetrical.

On account of the excellence of the signals an axial 

ratio was calculated from the measurements. A value 

for a was obtained from the prism faces, and using 

this value the value for c was obtained from the 

pyramids and domes (the crystals being measured on the two-circle 

goniometer). From 44 values for a and 70 values for c, the values 

a = .8146, c = 1.3126 are obtained, and these are^very close to the 

accepted values.

"^// \ \

a 

m

m

 ir

 n

"'IGUEE 6. 

from Mary

\

r> b

Barite 

and.

i Zeitschr. Kryst. Min., vol. 14,1888. p. 481.
NOTES ON PURPURITE AND HETEROSITE 

INTRODUCTION.

The mineral purpurite, a hydrous manganic ferric phosphate, 

(Mn,Fe) 2O3 .P2O5 .H20, was first found in North Carolina by L. C. 

Graton and a description of it was published * in 1905. On account 

of its rich purple or dark-reddish color it was named purpurite, from 

the Latin purpura, purple or dark red. Since the original discovery 

the same mineral has been found at several other localities.

Lacroix, to whom some of the original purpurite from North Carolina was sent, has stated 2 that purpurite is identical with heterosite. 

In view of this the writer proposes to restrict the name heterosite to 

the ferric phosphate and the name purpurite to the manganic phosphate. Heterosite predominates (76 per cent) in the material from 

South Dakota, but purpurite predominates (65 per cent) in that from 

North Carolina.

PURPURITE FROM NORTH CAROLINA.

OCCURRENCE.

Graton gives the following description of -the occurrence and 

physical properties of the mineral:

The mineral purpurite is found in small irregular masses in the tinbearing pegmatite dikes and in the near-by schist at the Faires mine 

at Kings Mountain, Gaston County, N. C. It generally occurs in 

narrow lenses or veinlets, and appears to have been deposited from 

solution in cavities. Occasionally, however, it is found in the midst 

of the pegmatite as if it were an original mineral.

Among the primary minerals of the tin-bearing pegmatites are 

cassiterite, tourmaline, apatite, spodumene, lepidolite, and a yellowishbrown, lithia-bearing phosphate, which is doubtless lithiophilite. The 

last two minerals have been found only in small quantities. Partially 

decomposed specimens of this pegmatite frequently show much manganese dioxide as thin mammillary coatings on the other minerals. 

Ilmenite is often included in crystals of cassiterite. It is evident, 

therefore, that the elements manganese and iron (as monoxides), 

lithium, and phosphorus (as phosphate) were primary components of 

the pegmatite magma.

1 Graton, L. C., and Schaller, W. T., Purpurite, a new mineral: Am. Jour. Sci., 4th ser., vol. 20, 1905, 

pp. 146-151.

2 Lacroix, A., Mingralogie de la France, vol. 4,1910, p. 469.

72
NOTES OF PURPURITE AND HETEBOSITE. 78

The mineral presumed to be lithiophilite is always surrounded by a 

coating of black, secondary material. In one case, a narrow zone of 

purpurite was found between the lithiophilite and the black mineral. 

It is believed that this single occurrence furnishes the explanation of 

the origin of purpurite. A lithia-manganous-ferrous phosphate, probably lithiophilite, was attacked by oxidizing solutions. The lithia 

 was almost wholly carried away, and of the remaining elements the 

iron and manganese were oxidized to the state of sesquioxides and 

were recrystallized with the phosphoric acid and water to form purpurite. The trace of lithium which this mineral contains is a remnant 

of that from the lithiophilite. In some cases the recrystallization took 

place without transportation of the materials, forming pseudomorphous replacements, but in general the materials were carried in solution 

to cavities and there deposited.

PHYSICAL PROPERTIES.

Purpurite is orthorhonibic, but no specimens from North Carolina 

have been found which show crystal outline. A cleavage which is 

probably pinacoidal is rather well developed, but many of the 

cleavage surfaces are curved as if the orientation of adjoining grains 

Vere not exactly the same. A second cleavage, presumably at right 

angles, is considerably less distinct. The mineral has an uneven 

fracture and is rather brittle. It is scratched without difficulty by 

the knife, but on the other hand just scratches fluorite; hence it has , 

a hardness of 4-4.5. In color the mineral is a rich deep red or reddish 

purple, sometimes with a slight bronzy iridescence, and not uncommonly darker on the cleavage planes. The powder and the streak 

have a decided purple or deep rose color. The mineral has a peculiar 

satiny luster or sheen more noticeable on fracture surfaces than on 

cleavage planes.

Although very thin pieces of purpurite are transparent, the ordinary 

thin section allows but little light to pass through. The colors in 

transmitted light are very beautiful, the mineral being strongly 

pleochroic. Parallel to the cleavage the color is deep scarlet inchning 

to rose red, but across the cleavage the absorption is greater and the 

color becomes a beautiful purple. This absorption, it will be noticed, 

is similar to that of tourmaline and a few other minerals, in which the 

greatest absorption is at right angles to the direction of cleavage or 

elongation. Extinction is generally parallel; an inclination up to 3° 

or 4°, which has been observed in a few instances, is probably due to 

the orientation of the sections examined. It may be, however, that 

the mineral is monoclinic with a very small extinction angle. Transparent sections were not of sufficient size to give an interference 

figure. No sections showed the intersecting cleavages, and in all the
74 MINERALOGICAL NOTES SERIES 1.

sections examined the traces of the cleavages are parallel to the direction of greater elasticity of the section; so if the mineral is biaxial, 

the intersection of the cleavages is parallel to a. This is also the 

direction of least absorption. The refractive index is somewhat 

greater than that of Canada balsam, and probably lies between 1.60 

and 1.65. The difference of the indices or the double refraction is 

high, and although it could not be measured at all accurately is probably not much below .060. One effect of this high double refraction 

on the ver}~ thin sections examined is that under crossed nicols the 

mineral appears to transmit as much and as brilliant light as without 

polarization. The red interference colors are very striking.

All specimens of the purple mineral are covered or surrounded by a 

greater or less thickness of a black or brownish-black material of 

pitchy luster and uneven or subconchoidal fracture. This material, 1 

which is soluble in hydrochloric acid, contains iron, manganese, phosphoric acid, and water. Under a lens the black material can be seen 

to encroach upon the purpurite, eating in along the cleavage planes 

and gradually replacing the purple mineral. Under the microscope it 

appears to be a definite mineral, having an imperfect cleavage, and a 

brownish-yellow color in transmitted light. Extinction is nearly or 

quite parallel to the cleavage, and the trace of the cleavage is the 

direction of least refractive index of the sections examined. Pleochroism is distinct, and, as in purpurite, absorption is greatest across 

the cleavage. The index of refraction is greater than that of Canada 

balsam, and the double refraction is probably rather high.

CHEMICAL COMPOSITION.

About a gram of pure material was separated, which was divided 

into several portions, Using about one-fifth of a gram for each determination. The most interesting part of the analysis was to determine 

the state of oxidation of the manganese.

When the mineral is treated with hydrochloric acid, chlorine is 

readily given off. The manga'nese present therefore can not be in 

the manganous state, and the absence of ferrous iron and the presence 

of ferric iron suggested that the manganese was present as a manganic salt. Such was found to be the case.

A fifth of a gram was dissolved in sulphuric acid with a known 

amount of ferrous ammonium sulphate. All precautions were 

observed to exclude air, the entire operation being conducted in an 

atmosphere of carbon dioxide. The water used had been boiled and 

cooled out of contact with air. Just before the iron sulphate was 

introduced into the flask containing the mineral an equal quantity 

was removed from the stock solution and titrated with permanganate.

i Probably the pseudoheterosite of Lacroix, op. cit., p. 469.
NOTES ON PUEPUBITE AND HETEROSITE. 75

Thus the amount of ferrous iron introduced into the flask with the 

mineral was known. After the mineral had been decomposed by the 

sulphuric acid, the flask was cooled and the solution titrated, the 

amount of iron sulphate oxidized by the liberation of oxygen from the 

mineral being determined in this way. From these data the amount 

of Mn203 was calculated and found to be 30.47 per cent.

A second sample was decomposed by hydrochloric acid and the 

chlorine evolved passed into a solution of potassium iodide. The 

liberated iodine was then titrated with sodium thiosulphate, the latter 

being standardized with pure copper. Calculating from the results 

obtained, the amount of Mn203 was found to be 27.93 per cent. 

Though these results vary somewhat, yet, considering the small 

amount of material used (one-fifth of a gram) and the many operations 

necessary, the agreement is as close as could be expected. The 

average of the two results is 29.20 per cent.

A direct determination of the total manganese, weighed as anhydrous sulphate, gave as the amount of Mn203 in the mineral 29.35 

per cent, which agrees almost exactly with the average of the two 

indirect determinations.

The remaining constituents were determined as follows: A portion 

of the mineral was dissolved in hydrochloric acid and a known weight 

of iron added (as ferric chloride). A basic acetate separation was 

then made and the solution boiled for 15 minutes, which, according to 

Bunsen, will precipitate all the phosphoric acid with the iron and will 

not precipitate any manganese. The precipitate was dissolved in 

hydrochloric acid, and reprecipitated by ammonia, after the addition 

of some ammonium chloride. The two filtrates were united, manganese precipitated by hydrogen sulphide, and finally weighed as 

anhydrous manganese sulphate. Calcium was then thrown out, dissolved, and reprecipitated, and magnesia found to be absent. The 

iron-phosphate precipitate was dissolved in hydrocholoric acid and 

divided into two portions. In one portion the iron and phosphoric 

acid were precipitated by ammonia and weighed. This was then 

fused up with sodium bisulphate and tested for manganese with silver 

nitrate and ammonium persulphate. None was present. In the 

second portion the iron was reduced by hydrogen sulphide and titrated 

with permanganate. Phosphoric acid was determined in the usual 

way and a second value obtained by the difference between the iron 

and the iron plus phosphoric acid. The alkalies were determined by 

the Lawrence Smith method. The final solution of chlorides gave a 

strong spectroscopic test for lithium. The water below 105° was 

determined directly, using a toluene bath. The total water was determined directly by heating in a glass tube, according to Penfield. The 

water is all given off at a low temperature, that at 105° being given
MINEftALOGICAL NOTES SERIES 1.

off very readily and at one time. Further heating at 105° failed to 

remove any more. The values obtained are as follows:

Analysis and ratios ofpurpurite.

Fe203 - ---------------------

Mn20o. ...................... p,da ......... .......... .... tf,o............ ............

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

Na,0........................

Li20.......................

Insol........................

1

15.89

29.35

47.64

5.26

1.48

.84

Trace.

.52

2

30.47

46.96

3

27.93

Average.

15.89

29.25

47.30

5.26

1.48

 .84

Trace.

.52

100. 54

Ratios.

1. 03\2 qfi 1. 93/2- 96

3.47

3.04

971

. 14J 4i

The amount of water given off at 105° is 3.31 per cent. As all of 

the water is so readily given off, it is most probably present as water 

of crystallization.

As the calcium and soda require some phosphoric acid, the ratio of 

R'"2O3 : P2O5 : H2O is approximately 3 : 3 : 3. Combining the ratio 

of the calcium and sodium with that of the iron and manganese and 

reducing these to their hydrogen equivalent, the ratio becomes:

or

2[H2 . 97P. 03 0,.04].92H20.

The formula for the mineral then becomes R/"2O3 .P2O5 + H20, or 

R'"2P208 + H20.

The exact state of combination of the calcium and sodium is 

unknown. They most probably represent some slight impurity. If 

the manganic and ferric oxides are isomorphous in the sense that 

manganous and ferrous oxides are, the ratio of Mn2O3 to Fe2O3 being 

nearly 2 : 1 is of no significance and the formula should be written 

(Mn'" 7 T?e'") 203 .'P205 .Tl2O, the mineral purpurite being near the 

manganic end of an isomorphous series having as its two end members:

Fe203 .P205 .H20

Mn203 .PA.H20.

There are only a few hydrous phosphates of the normal division in 

which the base is trivalent, such as scorodite and strengite. All of 

these, however, contain more water than the mineral here described.

Though no manganic phosphates were noted in the literature, there 

are a number of arsenates mentioned as containing Mn2O3 , with none 

of which, however, can purpurite be classed. Synadelphite, flinkite,
NOTES ON PURPURITE AND HETEROSITE. 77

arseniopleite, and perhaps hematolite, contain Mn203 with A1203 or 

Fe203) while in durangite and arseniosiderite, Mn203 is reported in 

small amounts.

The mineral fuses easily and readily gives off water in a closed 

tube, becoming yellowish brown. It is readily soluble to a clear 

solution in hydrochloric acid, and in nitric acid a black oxide of 

manganese is separated.

HETEROSITE FROM SOUTH DAKOTA.

Some specimens of ore found near Hill City, S. Dak., were seen to 

contain a considerable amount of heterosite,1 and through the courtesy 

of Mr. J. N. Smith, who sent in the first specimens, a larger quantity 

of material was obtained. Almost all the fresh cleavage surfaces of 

the black iron manganese phosphate, which 

chiefly forms the ore, are covered with a film 

of heterosite. The black phosphate when broken transverse to the cleavage shows but little 

heterosite, which seems to be formed from the 

black mineral.

The properties of the mineral as seen under 

the microscope agree with those determined 

for purpurite from North Carolina. One small 

piece showing crystal outline was noticed and 

is shown in the accompanying sketch (fig. .?) 

The extinction is parallel and the pleochroism 

is as follows: Parallel to the cleavage lines 

(vertical direction), rose red; normal to the 

cleavage lines, blue purple. The absorption parallel to the cleavage 

lines (rose red) is less than that at right angles to this direction. 

On account of the frequent occurrence of small platy masses showing cleavage lines, the mineral has probably two cleavages at right 

angles to each other, one more perfect than the other. It is probably 

the imperfect one which is normal to the figure and whose traces 

show in the vertical lines.

A determination of the density was made, the value previously 

found from the small specimen of North Carolina material being 

unsatisfactory. The material was broken into small pieces and the 

fragments of heterosite picked out. The final sample was not pure, 

as a small amount of the black substance could not be separated. 

The density determination was made by weighing the mineral in 

water in a small test tube suspended from the balance arm. The 

result obtained is 3.40.2

FIGUKE 7. Heterosite from 

South Dakota.

1 First described as purpurite. Am. Jour. Scl., 4th ser., vol. 24, 1907, p. 152.

2 Laoroix, A., Min6ralogie de la France, vol. 4,1910, p. 469, gives 3.27-3.52 for heterosite.
78 MINEKALOGICAL NOTES SERIES 1.

The sample was air-dried for several weeks and then analyzed, 

with the results given below:

Analysis and ratios ofheterositefrom South Dakota.

p^o,. ........................

Fe203 - -----------------------

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

H20..........................

MgO,NaoO,Li,0. .............

Analysis.

43.45

38.36

12.08

.1.37

4.82

.19

Trace

100. 27

Ratios.

.306 =1

.240)

.076[ = 1.06 .oosj

.268 = .88

The ratios agree fairly closely with those found in the original purpurite, giving as the formula of the mineral (Fe,Mn) 2O3 ,P2O5 .H20. 

The iron greatly predominates over the manganese in the South 

Dakota mineral, which is therefore called heterosite.

HETEROSITE FROM CONNECTICUT.

A small specimen from the well-known mineral locality of Branchville, Conn., was kindly furnished the writer by* the late Prof. Penfield. This specimen is coated with a purple mineral whose optical 

properties as seen under the microscope agree well with those of 

purpurite.

Only a very small amount of fairly pure material (0.0197 gram) 

could be obtained for analysis. A direct determination of the water 

was made, but the phosphoric acid had to be determined by difference.

The results obtained are as follows:

Analysis and ratios ofheterositefrom Connecticut.

Fe203 - ------------- ----------

Mn203 .. .....................

P O

H20..........................

Analysis.

27

23

[44]

6

100

Ratios.

"171 i5r32

31

33

The ratios are nearly 1 : 1 : 1, giving the same formula as before, 

namely, (Fe,Mn) 2O3 .P2O5 .H2O.
NOTES ON PUKPURITE AND HETEROSITE. 79

PURPURITE FROM CALIFORNIA.

Purpurite or heterosite has been noticed on some specimens from 

San Diego County, Gal. These had been collected by the writer, and 

through the courtesy of Mr. F. M. Sickler, of Pala, several more specimens from this locality have been obtained. They are from one of 

the lithium-bearing pegmatite dikes on Hiriart Hill, Pala, San Diego 

County. The mineral occurs with lithiophilite, and possesses the 

same purple color as the North Carolina specimens. Under the 

microscope the appearance and properties of the mineral from the 

two localities are identical. There is, however, not enough of the 

California material for chemical examination.

CONCLUSION.

Considering now the three analyses from North Carolina, South 

Dakota, and Connecticut, it is seen that the iron and manganese 

vary reciprocally, so that the occurrences represent isomorphous 

mixtures of Fe2O3 .P2O5 .H2O and Mn203 .P205 .H2O.

In the North Carolina mineral the manganese predominates and 

we have purpurite; in that from South Dakota the iron predominates and we have heterosite; and in the Connecticut mineral the 

iron and manganese are present in nearly equal amounts. These 

relations can also be shown by the following table:

Percentage composition of mixtures of purpurite and heterosite.

Locality.

Approximate content.

Fe203 .P205 .H20

(Heterosite).

Per cent. 

35 

53 

76

MnA.PA-HzO 

(Purpurite).

Per cent. 

65 

47 

24

In the original paper describing purpurite the suggestion was made 

that the pure end members be called ferripurpurite and manganipurpurite. Since then the essential identity of the minerals with 

the French heterosite has been advocated by Lacroix, so that the 

names ferripurpurite and manganipurpurite should be replaced by 

the older names heterosite and purpurite, respectively. More accurately the North Carolina material should be called iron (or ferric) 

purpurite and that from South Dakota and from France manganese 

(or manganic) heterosite.
NOTES ON POWELLITE. 

POWELLITE FROM LLANO COUNTY, TEXAS.

Specimens of the powellite from Baririger Hill, Tex., described in 

tliis paper were received through the kindness of Mr. Wm. E. Hidden 

and represent a small lot that was found in January, 1907. According to Mr. Hidden, who generously placed the material at the writer's 

disposal, the specimens are similar to those found by him in 1889 and 

referred to .molybdite.1 The reinvestigation of this mineral was 

undertaken because it had been suggested that it was probably a 

natural occurrence of the trioxide of molybdenum, the writer having 

shown in a previous paper 2 that molybdite was a hydrous ferric 

molybdate. (See also pp. 84-92.) Analysis showed, however, that 

this mineral from Baringer Hill is a calcium moiybdate and is referable to powellite.

As received by the writer, the mineral is in loose pieces, some over 

a centimeter wide, associated with, coating, and in many specimens 

entirely replacing molybdenite. In fact, the powellite forms a 

pseudomorph after the sulphide of molybdenum, the foliated structure of the latter being frequently retained. The dirty white to 

gray mineral, some of which is stained brown by iron oxide, breaks up 

into small glistening scales which, when rubbed between the fingers, 

crumble to a pearly powder that adheres to the skin and resembles in 

appearance some varieties of fine-grained talc. Under the microscope the mineral shows double refraction, but no crystal outline. 

The individual crystal units are very minute, the specimens being 

aggregates of very fine scales.

A density determination was made on about 0.8 gram of the powdered sample. The pycnometer method was used and the determination was carried out with care at a temperature of 25°. The 

value obtained for the sample is 4.153, which, when corrected for 

impurities as described below, gives 4.23. Hidden 1 found the value 

4.004, which would indicate that his sample contained more impurities than the writer's.

Analysis of this mineral gave the following results, the mineral 

dissolving readily in HC1. Qualitative tests failed to show the presence of any tungstic oxide. The mineral is difficultly fusible and gives 

at the most only a trace of water in the closed tube.

i Am. Jour. Sci., 3d ser., vol. 38,1889, p. 485. 2 Am. Jour. Sci., 4th ser., vol. 23,1907, p. 297. 

80
NOTES ON POWELLITE. 81

Analysis of powellite from Texas.

CaO........................................................ 27.46

Mo03 ........................................................ 67.90

Loss on ignition .............................................. 2.33

MoS2 ......................................................... 1. 50

Si02 ........................................................ .88

100.07

The ratio of CaO to Mo03 is 1:0.96, giving the formula CaMoO4 .

What is probably a similar occurrence of powellite has recently 

been described 1 as possibly a natural occurrence of Mo03 , the mineral 

differing in its physical properties from the hydrous ferric molybdate. 

The mineral forms a white or grayish alteration product of molybdenite which it sometimes covers and after which it is pseudomorphous, preserving the form of the molybdenite. The luster is pearly 

and the mineral is semitranslucent, difficultly fusible to a gray scoria, 

soluble in nitric acid, and does not contain any iron or water. The 

material was too scanty for analysis.

POWELLITE FROM NYE COUNTY, NEVADA.

The powellite from Nevada was received through Mr. F. L. Hess, of 

the United States Geological Survey, who states that the specimens 

were sent him by Mr. F. 0. Byor. of Columbia, Nev. The locality 

is given as 2 miles south of Oak Springs, Nye County, Nev.

The powellite occurs in a vein about 1£ centimeters wide in a soft 

earthy mass, which seems to be an altered rock. In this rock are 

occasionally found irregular masses of powellite, some of which are 

several centimeters across. The mineral is dull in appearance, gray 

in color, and occurs in platy masses often bent and twisted in different 

directions.

Gray to white masses of scheelite are embedded in this vein of powellite and also occur as small masses and veins in the altered rock 

matrix. These masses of scheelite show good cleavage surfaces with 

highly vitreous to adamantine luster, many having also a decided 

greasy appearance. The association of scheelite with powellite side 

by side was thought to be most unusual, but other specimens showed 

that the powellite, like the Texas mineral, was secondary, being 

formed in place from molybdenite; it is in fact a pseudomorph after 

the sulphide of molybdenum. Some other specimens showed the 

various stages of alteration very well, the amount of unaltered 

molybdenite varying from a considerable quantity to almost none at 

all. The association of molybdenite with scheelite is well known 

and when the molybdenite alters to powellite, the association of

1 Oagarine, G., Molybdite from the Ilmen Mountains: Bull. Acad. Imp. Sci. St. P6tersbourj,', Oth ser., 

1907, pp. 287-288.

99946° Bull. 490 11 6"
82 MINEEALOGICAL NOTES SERIES 1.

powellite with scheelite necessarily follows. The agencies effecting 

the change from molybdenum sulphide to calcium molybdate are 

apparently without effect on the scheelite. This pseudomorphous 

character of the powellite accounts for its occurrence in platy masses, 

the structure of the original molybdenite being retained. On some 

of the specimens, notably those on which there is still a considerable 

amount of molybdenite remaining, the powellite has a reddish color 

due to iron stain.

The dull gray powellite can easily be separated by hand picking 

from the shining greasy scheelite and a sample so selected was used 

for analysis. A thin section showed, under the microscope, some 

quartz, hematite, and limonite as impurity.

The density of the mineral was determined by weighing a test tube 

containing about 6 grams of the mineral in water. The value obtained 

is 4.026, which, when corrected for impurities as described below, 

becomes 4.24.

The analysis yielded the following figures, the small amount of 

tungstic oxide present being probably due to admixed scheelite:

Analysis of powellite from Nevada.

CaO........................................................ 26.44

Mo03 ........................................................ 62.43

.Fe203 ....................................................... 1.17

Loss on ignition.............................................. 2. 69

Si02 ........................................................ 6. 80

W03 ......................................................... Trace.

99.53

The material insoluble in HC1 was tested with HF and found to be 

almost entirely silica. The ratio CaO to Mo03 is 1: 0.92, giving the 

formula CaMo04.

DENSITY OF POWELLITE.

The sample of powellite from Texas gave the value 4.153 as its 

density. This figure is corrected, on the basis of the following composition of the sample, to 4.23.

Mineral composition of sample of powellite from Texas.

Silica (density, 2.65)......................................... 0.88

Water (density, 1)........................................... 2.33

Molybdenite (density, 4.7)..................................... 1.50

Powellite.................................................... 95.29

100.00

The presence of the water as such is of course an assumption, and 

the final value, 4.23, is necessarily uncertain, depending on the 

assumptions made.
NOTES ON POWELLITE. 83

The powellite from Nevada gave 4.026 as its density, and from the 

analysis the composition of the sample was found to be as follows:

Mineral composition of sample of powellite from Texas.

Silica (density, 2. 65)........................................ 6. 80

Water(density, 1)............................................ 2.69

Iron oxide (density, 3)..................... A ................. 1.17

Powellite.................................................... 89.34

1 100.00

Allowing for the impurities, the value is raised to 4.24, which, like 

the preceding case, is dependent on certain assumptions.

As powellite and scheelite are doubtless isomorphous, we may be 

justified in assuming that they have nearly the same molecular volume. Considering the molecular volumes as identical, and taking the 

gravity of scheelite as 6.14, the density of powellite then becomes

4.267, as calculated by Melville. 1

As all previous analyses of powellite showed the presence of tungstic 

acid, the densities given are all too high for the pure calcium rnolybdate. The two values obtained by the writer, though uncertain (as 

they are based on some assumptions made in applying the corrections), 

agree so well not alone with each other, but also with the calculated 

value, that the average of the three values (4.24, 4.23, 4.27), namely, 

4.25, may be taken as being very close to the true density of the pure 

calcium rnolybdate, CaMo04 . %

i Am. Jour. Sci., 3d ser., vol. 41,1891, p. 138.
CHEMICAL COMPOSITION OF MOLYBDIC OCHER. 

INTRODUCTION.

All the textbooks on mineralogy give the composition of natural 

molybdic ocher as agreeing with that of the artificial product, molybdenum trioxide, MoO3J which may be obtained by oxidizing the natural sulphide, molybdenite. As far as known but one analysis was 

ever made of the natural ocher, and though that suggested the desirability of further examination such has never been made. This is 

doubtless due to the fact that whereas the yellow molybdic ocher is 

very widespread in its occurrence, it seldom occurs in sufficient quantity and of such purity as to warrant any chemical investigation. 

The writer was fortunate enough to receive a sample of supposed 

autunite from the Foote Mineral Co., of Philadelphia, which on investigation was found to be molybdic ocher. As the mineral occurs in 

a pure state, some qualitative tests were made, and it was found that 

beside the molybdenum considerable ferric iron and water were present. The material was then examined under the microscope and 

found to be pure and especially free from limonite. Some artificial 

crystals of Mo03 were prepared, and on comparing the two substances 

under the microscope such differences were found in their properties 

as to suggest that the mineral examined was not molybdite, but a 

new species a hydrated ferric molybdate. The investigation thus 

opened was extended, and through the generosity of several people it 

has been possible to make analyses of natural molybdic ocher from

five localities and to show that the natural ocher is not Mo03 , but 

Fe2O3 -3MoO3 .7£H2O.

Hintze's summary of the literature on molybdite is so complete that 

only such points as bear directly on the question at hand will be mentioned here. Owen 1 described a deep yellow iron molybdate from 

Nevada City, Cal., and W. J. Taylor 2 described a similar mineral 

from Heard County, Ga., but neither article contained quantitative 

data of any value. Owen found 35 per cent of Fe2O3 , but Genth 3 in 

a later publication made a determination on the same mineral and 

obtained 24.3 per cent Fe203 . He says: "That which could be 

scratched off the quartz was not quite pure and contained a trace of 

limonite * * *. The sample examined gave 24.3 per cent of sesquioxide of iron, some of which was certainly mechanically mixed

i Proc. Acad. Nat. Sci. Philadelphia, vol. 6,1852, p. 108. 

- Am. Jour. Sci., 2d ser., vol. 19,1855, p. 429. 

3 Idem, vol. 28,1859, p. 248.

84
CHEMICAL COMPOSITION OF MOLYBDIC OCHER. 85

with it." Yet it would necessitate a mixture of nearly one-third 

limonite to give 24.3 per cent Fe203 , while according to Genth the 

sample only "contained a trace of limonite." The analytical result 

was correct, but the interpretation wrong. The sample doubtless 

contained a trace of limonite, as the 24.3 per cent is slightly higher 

than the figure required for the formula Fe2 03 .3Mo03 .7£H20, which 

gives 22 per cent Fe203 .

PHYSICAL PROPERTIES.

OPTICAL CHARACTERS.

The mineral has a fibrous structure and also forms radiating groups. 

Its color is yellow and many specimens have a silky luster. All of 

the fibers examined give parallel extinction. The double refraction 

is strong and the direction of elongation is always an axis of minimum 

elasticity. The color of the mineral in transmitted light is pale yellow. The pleochroism is strong but is masked by the very strong 

absorption. Normal to the elongation of the fibers the transmitted 

light is pale yellow; parallel .to the elongation the color is a much 

stronger yellow. The absorption parallel to the elongation is so strong 

that thick fibers frequently appear almost black and opaque. This 

marked absorption is a very characteristic property of this mineral 

and can be used as a criterion for its determination. These same 

properties are mentioned by Lacroix 1 for molybdite from Corsica.

Crystals of Mo03 , prepared by roasting molybdenite in an open 

crucible, show very decided differences in their physical properties 

from those of the natural mineral. They are not fibrous, but platy 

and are colorless, nonpleochroic, and show no difference in absorption 

in different directions.

PYROGNOSTIC CHARACTERS.

On heating the mineral in a closed tube abundant water is easily 

given off and the mineral assumes a dark-olive color; on further heating it again becomes lighter in color. On heating the mineral in a 

crucible the color changes are very marked. At first the yellow 

mineral darkens and becomes a dark gray, appearing almost black 

and with slight olive tint, then it becomes a light yellow again, and 

on further heating changes to a deep-orange color. If the mineral 

now be allowed to cool the orange changes to yellow and back to 

orange again on reheating. If the dark-colored material be allowed 

to cool, it retains its dark-gray color and on reheating passes through 

yellow to the orange. On heating for some time at a higher temperature, the mineral, on cooling, becomes a permanent bright green. By

i Lacroix, A., MinSralogie de la France, vol. 3, p. 8.
86 MINERALOGICAL NOTES SERIES 1.

further heating all of the molybdenum is volatilized and the darkred ferric oxide remains. The mineral is readily soluble in hydrochloric acid, and is decomposed by ammonia, taking on a brown 

color (probably due to the separating ferric hydroxide). After a 

while, all the molybdenum of the mineral goes into solution, leaving 

the insoluble ferric hydroxide.

DENSITY.

The density of the powdered sample (No. 4, from Hortense, Colo.) 

was determined with a pycnometer, using 3 grams of material. The 

value obtained is 3.026. This is corrected on the basis of the following composition:

Mineral composition of sample of molybdite.

Molybdenite (density 4.7).................................... 5. 50

Silica (density 2.65)........................................ 16. 51

Molybdite (density 2.99)..................................... 77. 99

100.00

The corrected value becomes 2.99 in which, however, no allowance 

is made for the extraneous moisture.

SOLUBILITY IN WATER.

An experiment was made to determine approximately the. solubility of molybdite in water. About 3 grams of the mineral were 

stirred in a beaker for a day with 760 cubic centimeters distilled 

water at room temperature (about 25°), and then filtered repeatedly. 

The final filtrate showed a very faint cloudiness. It was evaporated 

down in platinum, the residue dissolved in HC1 and the iron precipitated as hydroxide with ammonia and weighed. The 760 cubic 

centimeters of water contained 0.0051 grams of Fe2O3 . On the 

assumption that this all came from the mineral, it is calculated that 

the solubility of molybdite in water is approximately 1 to 33,000 so 

that the mineral is rather insoluble.

CHEMICAL ANALYSES. 

MOLYBDITE FROM NEW HAMPSHIRE.

The purest sample examined came from Westmoreland, N. H. ; 

and was very kindly furnished from the Brush collection of Yale 

University by Prof. Wm.' E. Ford. Nearly a gram of material was 

obtained and this was divided into portions of a quarter gram weight. 

Microscopically the specimen looked more earthy and not so finely 

crystallized as those obtained from other localities, but under the 

microscope it showed its characteristic optical properties, and was 

seen to be homogeneous, free from limonite, and to contain a
CHEMICAL COMPOSITION OF MOLYBDIC OCHER. 87

small quantity of molybdenite scales. The first figure given for the 

water content, 16.98 per cent, was obtained by weighing the water 

direct, using the method of glass tubes as advocated by Penfield. The 

other two figures represent the loss up to 200°, at which temperature 

all the water of the mineral is given off. The residue was dissolved 

in HC1, and after filtering off the insoluble matter the iron was precipitated by ammonia, filtered off, dissolved in HC1, and reprecipitated and weighed, while hydrogen sulphide was passed into the combined ammoniacal filtrates until the characteristic red color was 

produced. The solution was then acidified with H2S04 and after 

heating on the steam bath to allow the molybdenum sulphide to 

settle was filtered through a Gooch crucible. The sulphide was then 

dried, changed into the trioxide at a low heat, and weighed to constant weight. The filtrate from the molybdenum sulphide was made 

alkaline with ammonia, and hydrogen sulphide was again passed 

into the solution, which was then reacidified with H2S04 and a small 

amount of molybdenum which had escaped precipitation in the first 

case was recovered. The filtrate on testing showed no more molybdenum, neither was any residue found on evaporating it to dryness. 

Tests showed the absence of calcium and magnesium. The weighed 

iron oxide was fused with sodium bisulphate, and determined volumetrically with a result that agreed with the gravimetric determination. The results obtained are as follows:

Analysis of molybdite from New Hampshire.

HO

Fe2203 . .....................

1

16.98

21. 08

57.02

4.66

2

17.95

21.07

57.49

3

17.93

58.55

Average.

17.62

21.08

57.69

4.66

101. 05

Ratios.

7 43=71

1.00=1

3. 04-3

The average analysis with the insoluble matter deducted and 

reduced to 100 per cent, is compared below with the figures calculated for Fe2O3 .3Mo03 .7iH20.

Comparison of analysis with calculated valves.

K,0. ...........................................

Fe203 - .........................................

Mo03 . ..........................................

Analysis.

18.28

21.87

59.85

100. 00

Calculated.

18.57

22.01

59.42

100. 00
88 MISTERALOGICAL NOTES SEEIES 1.

This formula has been verified by the analysis of molybdite from 

Arizona by Guild. 1 Two analyses made by him are quoted below.

Analyses of molybdite from Arizona (by Guild).

Insoluble residue ...............................

Water. .........................................

Ferric oxide, Fe,03 . ... ^. ......... .J.. ..........

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

1

4.86

16.83

20.88

57.38

99.95

2

2.66

16.61

21.18

59.79

100. 24

The average of these analyses with the insoluble residue deducted 

and recalculated gave the following values. The ratios lead to the 

-formula Fe203 .3Mo03 .7H2O, which is half a molecule lower in water 

than the formula obtained by the writer.

Recalculated analysis of molybdite from Arizona.

H20...... ......................................

¥e,03 ..... .....................................

Mo03 ............ ...............................

Analysis.

17. 355

21. 835

60. 805

Ratios.

7.06

1.00

3.09

Partial water determinations were made on two samples of molybdite from New Hampshire, as follows, the amount of water being 

represented by the loss in weight, the crucible being heated at the temperature given till 6 hours additional heating produced no difference in 

weight.

Partial water determination.

Per cent.

Total loss up to 110°.......................................... 14. 04

Total loss up to 125°.......................................... 15. 50

Total loss up to 185°.......................................... 17. 64

Total loss up to 200°.......................................... 17. 93

MOLYBDITE FROM OTHER LOCALITIES.

The quantity of material from other localities 2 was so small that 

exact values can not be expected, but the analyses all show a general 

agreement with the calculated values. The samples analyzed are 

as follows:

1 Guild, F. N., The composition of molybdite from Arizona: Am. Jour. Scl., 4th ser., vol. 23, 1907, 

p. 455.

s The characteristic optical properties of the ferric molybdite were also determined on specimens from 

Stanhope, N. J.; Gold Creek, Deer Lodge County, Mont.; Aldfleld Township, Pontiac County, Quebec.
CHEMICAL COMPOSITION OF MOLYBDIC OCHEK. 89

No. 1 is from Telluride, Colo., and is from the sample furnished by 

the Foote Mineral Co., Philadelphia.

No. 2 was very kindly furnished by Prof. A. J.-Moses, of Columbia 

University, who states that the sample is probably from California, 

though the locality is not certainly known. Two samples were sent; 

one yellow, which was seen to be pure, and one brown, which was 

seen under the microscope to consist of a mixture of the pure yellow 

mineral and limonite. The appe'arance of this sample at once suggested that it was similar to one analyzed by Owen, which gave 35 

per cent Fe203 . It also showed the ease with which a mechanical 

mixture of molybdite and limonite could be detected under the 

microscope. The opaque brown limonite was scattered through 

some of the yellow molybdite and caused it to appear almost opaque, 

besides which there were numerous patches of earthy limonite. This 

sample was not analyzed.

No. 3 is from Renfrew, Ontario, and was very kindly furnished by 

Prof. C. Palache, of Harvard University. Most 'of the material is 

massive and appears earthy, though under the microscope it is 

seen to consist of minute fibrous crystals. The material did not 

look promising, -but analysis showed values agreeing well with the 

others. Owing to an accident only the iron and molybdenum could 

be determined. These values are not given. On one of the specimens sent by Prof. Palache there was a small amount of the finely 

crystallized fibrous material which seemed to be very pure. This 

was scraped off and analyzed, and though only about 50 milligrams 

were available the results given under No. 3 were obtained.

No. 4 is from Hortense, Colo., and was received through the kindness of Mr. F. L. Hess. The yellow mineral occurs in lumps, several 

of which are over 2 centimeters in diameter. With the molybdite 

are associated molybdenite, quartz, and mica. The sample looks 

earthy, but under the microscope it is seen to be well crystallized and. 

shows the characteristic optical properties of molybdite as described 

earlier in this paper. A sample was selected as pure as could be 

obtained, but it was found on analysis to contain a large amount of 

insoluble matter. The powdered specimen caked together in the 

sample tube and probably contained some extraneous water. The 

analysis also showed too high a water content for molybdite.
90 MINERALOGICAL NOTES SERIES 1.

The methods of analysis were the same as those employed with 

the New Hampshire material. By heating in a closed tube to obtain 

the water, some of the molybdenite which was mixed with the mineral 

doubtless was oxidized to the oxide, thus increasing the amount of 

molybdenum present. The results obtained are:

Analyses ofmolybdite.

H20.... ......................

Fe203 --------------------------

Mo03 .. .......................

No. 1, 

Telluride, 

Colo.

15.8

19.0

59.3

[5.9]

100.0

No. 2, 

California.

15.4

15.8

47.7

24.0

102.9

No. 3, 

Renfrew, 

Ontario.

15.5

17.3

55.7

9.4

97.9

No. 4, 

Hortense, 

Colo.

15.87

15.95

46. 77

22.01

100. 60

By deducting the insoluble matter and calculating the analyses to 

100 per cent we obtain:

Analyses of molybdite with insoluble matter deducted and percentages recalculated.

H20....... ..........

Fe203 - ..............

Mo03 ................

1

16.8

20.2

63.0

100.0

2

19.5

20.0

60.5

100.0

3

17.3

19.6

62.9

100.0

4

20.19

20.30

59.42

100.00 .

Calculated.

18.57

22.01

59.42

100. 00

The ratios of the above analyses are as follows:

Ratios of analyses of molybdite.

No. 1...................................

No. 2...................................

No. 3...................................

No. 4..... ..............................

Fe203 .

1.0

1.0

1.0

1.0

H20.

7.3

8.6

7.8

8.8

Mo03 .

3.4

3.3

3.5

3.3

The analyses agree sufficiently well to show that the mineral is 

uniform in composition and the analyses of the material from New 

Hampshire serve to establish its formula.

The insoluble residue in No. 4, consisting of 5.5 per cent MoS2 

and 16.5 per cent Si02 , was roasted in an open crucible to change the 

MoS2 into Mo03 and then weighed. The oxide of molybdenum was 

then dissolved by HCI, leaving the silica, which was tested with HF
CHEMICAL COMPOSITION OF MOLYBDIC OCHEK. 91

for its purity. The determination of water was made in two ways 

by loss in weight and by direct weighing. It was found that the 

water given off at 110° by heating the mineral in a glass tube in a 

toluene bath while a current of dry air was passed over the mineral 

and collecting and weighing the water (A, below) was considerably 

greater than the amount given off at 110° by heating the mineral in a 

crucible in a toluene bath, determining the water by the loss in 

weight (B, below). The results are shown below:

Water content of motybdite.

Amount given off at 110° ...........

Amount given off at 200° ...........

A

13.77

2.23

16.00

B

11. 39

4.34

15.73

In considering the mode of formation of the hydrous ferric molybdate (molybdite) it may be well to call attention to the fact that the 

interaction of molybdic acid, H2Mo04 .H20, on limonite may be 

written so as to yield a product with a formula that is identical with 

the new formula and which balances the equation:

2Fe203 .3H20 + 6(H2Mo04 .H20) = 2(Fe203 .3Mo03 .7£H20;. 

ARTIFICIAL MOLYBDITE.

Chemical dictionaries mention but two hydrous ferric molybdates, 

neither of which is crystalline, and which approximate in formula to 

Fe203 .4Mo03 .7H2O and Fe203 .5Mo03 .16H2O. On adding a solution 

of ammonium molybdate to an excess of a solution of a ferric salt no 

precipitate is formed, but on reversing the process and adding the 

ferric salt to the ammonium molybdate a voluminous yellow precipitate appears. A precipitate thus prepared was air-dried for about a 

week and analyzed with the following results:

Analysis and ratios of artificial ferric molybdate.

Fe203 ................................

Mo03 ........ .......................

H20 (by difference) .................

Analysis.

15.9

61.6

22.5

100.0

Ratios.

1.0

4.3

12.5

These results are between those of the two salts above quoted. It 

was found, however, that a large amount of free molybdic acid contaminated the material, and the impossibility of air-drying the non-
92 MINERALOGICAL NOTES- SERIES 1.

crystalline mass sufficiently accounts for the high water content. It 

is therefore believed that neither of the two salts above mentioned 

and described in chemical dictionaries has any existence, but that 

they are mixtures of a salt of the formula Fe203 .3Mo03 + 7iH2O with 

molybdic acid and water.

A preliminary experiment of heating precipitated ferric hydroxide 

and molybdic acid in the correct molecular proportions with an excess 

of water in a glass bomb failed to give any result. After heating to 

about 150° for several hours there was no indication of any reaction, 

and on higher heating the bomb exploded.

An attempt was next made to crystallize the yellow amorphous 

precipitate. The precipitate was heated with water in a glass bomb 

up to 180° to 200° for several days, and when examined was found to 

consist of a mass of fine yellow crystals and a greenish, amorphous 

mass. On shaking up the tube the green part settled very quickly 

and the minute yellow crystals settled so slowly that a nearly perfect 

separation of the two products could be made. The yellow crystalline part was examined under the microscope and found to consist of 

three products, all crystallized. The most abundant salt occurs in 

minute, pale-yellow tablets of quadratic outline. Some of them 

which seem to be isotropic have an octagonal shape suggesting combinations of the cube and octahedron. They were too small to test 

for interference figures. The second most abundant salt occurs in paleyellow, fibrous prisms and also in radiated, fan-shaped masses which 

show the characteristic absorption of the natural mineral and are 

probably identical with it. The third salt also occurs in prisms, 

which, however, are not fibrous, do not show any absorption, and 

seem to be colorless. They may be- molybdic acid, but the first two 

salts are probably hydrated ferric molybdates.

OCCURRENCE OF NATURAL TRIOXIDE OF MOLYBDENUM.

The existence of the trioxide of molybdenum (Mo03 ) as a natural 

mineral has not been demonstrated,1 and what is commonly believed 

to be MoO3 is shown to be a hydrated ferric molybdate, Fe203 . 

3Mo03 .7£H2O. This composition for molybdite has been verified in 

the analysis by .Guild. The occurrence in Texas of what has been 

supposed to be Mo03 , and which has been so described, has been 

shown to be powellite, and the Russian specimen supposed to be 

Mo03 is also doubtless powellite. Until it is shown conclusively 

that an oxide of molybdenum does exist in nature, the name molybdite 

must be retained for the hydrated ferric molybdate.

1 Lacroix found the molybdite from Corsica to contain iron and water. Min6ralogie de la France, vol. 4, 

p. 296, 1910.
ANALYSIS OF TOURMALINE FROM ELBA.

While the writer was analyzing a number of tourmalines from San 

Diego County, Cal., Prof. Clarke suggested that it would be advisable 

to analyze the pale-pink variety of tourmaline from the Island of Elba. 

Rammelberg's analysis of tourmaline from this locality indicated that 

this tourmaline was probably near in composition. to one of the 

end products of the isomorphous mixtures which form the mineral 

tourmaline. A number of these crystals were purchased from the 

Foote Mineral Co., who wrote in regard to them: "All of these were 

secured in exchange from the late Prof. Bombicci, who collected them 

in Elba many years ago." The crystals were picked over and crushed 

to small fragments, after which each piece was examined under a 

hand lens and only the transparent pure material was selected. 

These were then washed with cold dilute HF to remove any albite, 

mica, etc., that might be adhering to the tourmaline. The sample 

finally powdered and analyzed was pure. The density of the mineral 

(determined by Thoulet solution) is 3.04-3.05, as the mineral sank at 

3.043 and floated at 3.050. The analysis is as follows:

Analysis and ratios of tourmaline from Elba.

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

B203 ...... ..................

A1208 . .......................

TiO

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

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

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

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

Li20. ---------------- -------- Hao.............. :.........

F....... ....................

MgO, K20......... ..........

-0-F-...................

Analysis.

37.89 

10.28 

43.85 

.04 

.11 

.11 

.07 

2.43 

1.66 

3.47 

.10 

None.

100. 01 

.04

99.97

Ratios.

0.632 

.147 

2. 5801 

.002 

.003 

.003 

.003 

.079 

.111 

.386 

.005

= 4.00 

= 0.93

.=20. 08 a

a These ratios give the hydrogen atoms equivalent to the metals.

The ratios agree very well with those proposed by Penfield, namely, 

4:1: 20. A discussion of the results will be given in a later paper on 

the California tourmalines, as at present it is only desired to place the 

above analysis on record. The state of oxidation of the titanium, iron,

and manganese are given arbitrarily.

93
EVANSITE FROM TWO AMERICAN LOCALITIES. 

EVANSITE FROM IDAHO.

Some specimens of evansite, reported as being found in the immediate vicinity of Goldburg, Idaho, were received through the courtesy 

of Mr. C. R. Potts, of that place. The massive amorphous mineral 

occurs in seams and is very brittle with a conchoidal fracture. Its 

hardness is about 3, and its color is generally brown, though it varies 

considerably. Some specimens are yellow, or white, or dark red. 

The brown specimens very much resemble common brown opal.

An analysis of the brown material gave the following results:

Analysis and loss of water of evansite from Idaho.

Analysis.

H20...... ........

P O

Fe208 ..............

Ala03 . .............

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

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

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

36.96

19.14

5.49

34.48

4.32

 Trace.

None.

100. 39

Loss of Avater

At 107°............

175°............

255°............

290°............

20.00

7.36

3.13

.94

3.90

1.61

36.94

A determination (by means of Thoulet solution) of the relation of 

the density to the amount of iron present gave the following values:

Relation of density to iron content.

Color of mineral.

Yellow......................................

Fe203 .

Per cent. 

6.60

5.49

2.15

Average 

density.

2.00

1.98

1.94

Limits.

1 QQO-9 01 fi

1. 972-1. 990

1. 927-1. 947

By plotting these values it is found that the density of the mineral 

free from iron should be between 1.88 and 1.91, though this value 

does not necessarily represent that of pure evansite, as the material 

on which these determinations were made contains appreciable calcium. Forbes * gives the following determinations of the density:

1 See literature at end of paper for reference.

94
EVANSITE FROM TWO AMERICAN LOCALITIES. 95

Densities of evansite. 

Colorless, translucent.......;................................... 1.822

Colorless..................................................... 1.872

Faint yellow.................................................. 2. 099

Semiopaque................................................... 1. 965

The average of these densities is 1.939, though possibly the lowest 

figure more nearly represents the density of the pure mineral. Smith 

gives the value 1.842 as the density of colorless to milky white, translucent material.1 Kovar gives for white 1.874 (0.87 per cent Fe203 ), 

and for yellow 1.937 (1.92 per cent Fe203 ). These values give an 

average for all the determinations of 1.93, and an average of the 

lowest values, representing possibly the purer mineral, gives 1.86.

A determination by F. E. Wright of the index of refraction of 

the colorless evansite from Idaho gave 1.485, the index for the colored 

varieties not varying more than 0.01 from this value.

EVANSITE FROM ALABAMA.

The second sample was received ^through Prof. Clarke from Mr. 

Charles Catlett, and the locality is given as "fronrthe coal seam just 

west of Columbiana, Ala." It is associated with coal, shows a lightyellow color with a resinous luster, and is transparent in small pieces. 

It is very brittle. An approximate analysis serves to identify the 

mineral, the phosphoric acid being determined by difference.

Analysis of evansite from Alabama.

A1203 ...................................................... 38. 33

CaO....................................................... 1.03

MgO....................................................... .75

Loss on ignition............................................. 38.19

P205 (by difference)........................................ 21. 70

100.00 

LITERATURE.

1864. Forbes, D., Phil. Mag., vol. 28, p. 341.'

1883. Woodward, A-. S., Min. Mag., vol. 5, p. 333.

1893. Smith, H. G., Proc. Roy. Soc. N. S. W., vol. 27, p. 382.

1896. Kovaf, Fr., Abh. Bohm. Akad., vol. 15, p. 1.

1896. Petterd,2 W. F., Cat. Min. Tasmania.

1902. Petterd, 2 W. F., Papers and Proc. Roy. Soc. Tasmania, pp. 18-33.

1902. Kretschner, 2 F., Jahrb. K.-k. geol. Reichsanstalt.

1903. Vernadsky, W., and Popoff, S., Centralbl. Min. Geol., u. Pal. p. 331.

1 Wrongly given as 1.939 in Dana's App. II, p. 25.

2 These references only mention the occurrence of evansite.
MANGANOTANTALITE FROM MOUNT APATITE, MAINE.

The crystals here described were received from Prof. Palache, 

who suggested that they were manganotantalite. They are associated 

with the minerals characteristic of these lithium-bearing pegmatites, as albite, lepidolite, etc. Most of the crystals are small, several millimeters in length, and are tabular to the a face (Dana's 

orientation). The specific gravity was determined as 7.14, showing that in these crystals the tantalic acid largely predominates 

over the columbic acid. A partial analysis showed further that iron 

was almost entirely absent, so that the crystals may well be termed 

manganotantalite. The analysis gave the following results:

Analysis of manganotantalite from Mount Apatite, Maine.

Ta2 CbAJ"""""""""""""""""""""""" ^4 "" 85. 35 

FeO.................................. -...-...-.---- ........ .16

MnO (by difference) ........................................ 14. 49

100. 00

The forms present are: &{010}, a{100}, c{001}, m{110}, 

?{320}, 0{530}, d{730}, fc{103}, u{133}, ^{163}. The angles 

measured are shown below. Most of the faces were dull and gave

poor reflections.

Forms and angles for manganotantalite.

Symbol.

b/\m =(

bAg = 

b/\z =(

bAd =( 

cAk =(

b/\n =( nf\n'"= 

n/\nf = 

b/\u = u/\u'"=

uf\uf =

010) : (110)..................

010) : (130)..................

010) : (530). ..................

010) : (730)..................

001) :(103)..................

010) : (163) ..................

163) : (163) ..................

163) : (163)..................

010) : 133). .................

133) :(133). .................

133).: (133).......... ........

Measured.

0 /

50 28 

21 27 

63 10 

/ 70 15 

\ 70 06 

19 38

« 30 

«118 

o22 

50 45 

81 15

30 04

Calculated.

o /

50 22 

21 55 

63 34

| 70 27 

19 42

30 50 

118 20 

19 54 

50 03 

79 54

29 57

96

Approximate.
MANGANOTANTALITE FROM MOUNT APATITE, MAINE.

Measurements for the prism j {320} are as follows:

Measurements of j {320}.

97

Crystal 

No. 

1.......

2.......

2.......

3.......

4.......

Size of face.

Broad. .........

Broad ..........

Broad ..........

Reflection.

PPf.J

Symbol.

110A320

010A320

320A320

010A320

010A320

Measured.

0 /

9 39

61 21

57 12 '

61 12

61 13

Calculated.

0 /

10 44

61 06

57 48 ,

61 06

61 06 "

The faces of (133), (100) are large, those of (163), (103), (110), 

(320) are small, and most of the others are very narrow faces.

99946° Bull. 490-11 7
ZINNWALDITE FROM ALASKA.

The occurrence of zinnwaldite with cassiterite and topaz in the 

York region, Alaska, has already been mentioned l and the results 

of a quantitative analysis of this mica are here presented. The 

axial angle, 2E, for sodium light, was measured 49° 29'. The sample 

analyzed was probably fairly pure.

Analysis of zinnwaldite from Alaska.

SiO 2-...- ...................

A1203 -. ......................

Fe-A- ------ .................

FpO

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

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

Na20... .....................

K20..........................

Li20. ........................

H20.... ......................

P. ..........................

-0-2F......................

Analysis.

46.80

24.50

.50

6.35

1.38

94

1.73

9.20

3.73

.88

8.63

103. 94 

3.63

100. 31

Ratios.

. 775 775

240 1 243

.003 / ^

.088 1

\019 I 111

.004 J

flQQ ~>

.098 / i6L

. 124 124

. 098 \ ,,2

. 454 / 552

In the ratios, the soda and potash are taken together and the 

small amount of water present is considered as hydroxyl and added

to the fluorine ratio. The empirical formula gives:

Dl775Al486.b eillK262Ll248 I1 552^2369

The total oxygen is very slightly greater than three times the 

silica, the ratio O: Si being 3.06 :1. The mineral is therefore considered as a metasilicate and the formula may be written

or

(Si03 ) 775 (AlF2 ) 276K262Li248Fe111 (A10) 44Al166 

(Si03) 12 (AlF2 ) /4. 27K/4. 08Li^3. 84Fe//1 . 72 (A10) /.68Al///2 .57

i Bull. U. S. Geol. Survey No. 262,1905, p. 129.

V
SOME NEW FORMS OF CALCITE CRYSTALS.

CALCITE FROM ANDBEASBERG, GERMANY.

Several specimens of calcite labelled "Andreasberg, Harz Mountains," were purchased from a local mineral dealer. One specimen 

shows large tabular crystals with only the base c{0001} and prism 

m{10TO}. Other specimens consist of groupings of tabular crystals 

which are somewhat unusual in their combinations. These tabular 

calcites are arranged in superimposed parallel or nearly parallel 

groupings forming vertical columns several centimeters long, the 

individual crystals being up to 13 millimeters wide and 5 millimeters 

high. The dominant forms on these crystals are the base c{0001} 

and prism m{1010}, but characteristically all of them also show the 

new prism f{7.6.T3.0} as narrow rounded faces. Very narrow faces 

of s{ 0551} and minute faces of v{2131} are present in numerous specimens. Some of these crystals, which seem to be single, show an 

easy parting parallel to the base and may be built up of many thinner 

tabular crystals in parallel position. Associated with these calcites 

are numerous fcurlings of harmotome.

Measurements of the 0 angle for s{0551} varied from 78° 38' to 

78° 47'; calculated, 78° 32'.

The dihexagonal prism faces are bright, but rounded, so that no 

accurate measurements could be made. They gave, however, a 

bright signal in the mass of reflections caused by the rounded surfaces and the measurements given below were of this bright signal. 

The faces were seen to be in the prism zone mm' and therefore could 

not be scalenohedrons with complex indices.

Measurements 0/^(7.6.13.0}.

Do....................

Do....................

Do....................

Average ..............

4>

o

27

27

27

27

27

27

/

34

20

3?,

37

31

27

This prism face is present on all of the crystals, but on few of them 

is suitable for measurement. The results given were all obtained
100 MINEEALOGICAL NOTES SEBIES 1.

FIGXTRE 8. Calcite from 

Germany.

from one crystal. It seems strange that this form has not been 

described before at least the writer could find no mention of it in 

the literature as the specimens are supposed to have come from a 

locality well known for its calcites.

It hardly seems correct to regard these prism faces as corrosion 

_____ forms or other secondary formation. Though 

the base and prism faces on these calcites 

are dull they do not show any definite signs 

of etching and though the new prism faces

^ . 3. are rounded they are considered as belong^ 

ing to a well-established form for calcite. 

As stated, the form occurs on all of the 

crystals and all 12 of the faces are present 

on each crystal. These crystals are shown in figure 8.

CALCITE FROM ENGLAND.

The crystals here described are from a group containing individual 

crystals the largest of which measures 4 by 2 centimeters. The exact 

locality is not known. The crystals have a trigonal habit due to the 

predominance of a steep negative rhombohedron. The forms present onjthese crystals are: r{10Tl}, .¥{4041}, i?{5051}, F{6061}, 

o{11.0.IT.2}, e_{01l2}, /{0221}, d{0881}, _<7{0.13.13.1}, n{4153}, 

#{7295^ w{3145}, <y{2131}, r(5382}, ^{3251}, and a new form 

p{4.20.24.7}. The following table gives the average of the measured 

angles comp.ared with the calculated values:

Forms and angles of calcite from England.

Letter.

M

*l

0

&V

e

f.

a.

C

n

G

w

V

r

y

V

Symbol.

4041

5051

11. 0. 11. 2

6061

0112

0221

0881

0. 13. 13. 1

4153

7295

3145

2131

5382

3251

4. 20. 24. 7

Number 

measured.

3

2

1

2

2

5

4

1

1

3

2

2

8

2

13

Measured.

<£

0 /

0 02

0 02

0 12

0 02

0 00

0 00

0 00

0 12

10 55

12 22

14 25

19 07

21 43

23 21

8 56

. P

0 /

75 48

78. 11

79 35

80 11

26 15

63 07

83 01

85 30

56 22

58 22

35 05

69 10

74 28

77 02

72 09

Calculated.

<£

0 /

0 00

0 00

0 00

0 00

0 00

0 00

0 00

0 00

10 54

12 13

13 54

19 07

21 47

23 25

8 57

P

o /

75 47

78 32

79 33

80 24

26 15

63 07 '

82 46

85 32

56 26

58 14

35 25

69 02

73 51

76 54

72 20
SOME NEW FOEMS OF CALCITE CBYSTALS.

The indices of the form above referred to as p {4.20.24.7} could 

not be definitely determined. Many faces of this form are present on 

these crystals; in fact the form is characteristic for this group, as it 

is present on all the crystals. But it is always rounded and uneven, 

and will give when mounted on the goniometer either a group of 

reflections or else two or three distinct signals. The various measurements for this form are as follows':

Measurements o/p {4.20.24.7}.

Crystal 

No.

1 

1

1

1

2 

2 

2

2

2

3 

3

3 

3

Size of 

face.

Minute... 

Small. ..

...do.....

...do.....

Minute... 

Small. . . 

...do.....

...do.....

Minute...

Small. . . 

...do.....

Minute... 

Small. . .

Number of 

signals.

2 

3

3

3

1 

3

3

2

2 

2

1 

1

Reflection.

1 p-

 I

PI

PPPPPp,-

1 f- P- 1 I

I*

* 

' 

P- 

( PPp. . P-

^

0 /

8 17 

8 20 

8 23 

8 20 

8 23 

8 48 

8 26

9 01 

8 23 

8 46

9 06 

8 54 

9 13 

8 52 

8 15 

9 56

10 19 

9 24

10 17 

9 16 

8 37 

8 44 

9 23 

9 07 

8 34

9 15

8 48

P

0 /

72 08 

71 36 

71 40 

72 08 

71 15 

71 59 

71 31

72 19 

71 40 

71 05

72 19 

72 15 

72 17 

71 58 

71 30 

72 20

73 23 

72 04

73 43 

72 41 

71 48 

71 56 

72 38 

72 38 

71 58

72 36 

72 51

Signal.

Distinct.

Very faint. 

Distinct. 

Very faint. 

Do. 

Distinct. 

Very faint.

Do. 

Distinct. 

Do.

Do. 

Very faint. 

Distinct. 

Very faint. 

Do.

Very faint. 

Do.

Do. 

Distinct. 

Very distinct. 

Distinct. 

Do: 

Do. 

Do.

One distinct. 

Distinct.

Cal-

-8° 45',

Average of measurements of 13 faces: <j> = 8° 56', p = 72° 09'. 

culated, 0 = 8° 57', ^ = 72° 20'.

An average of the values with "signal distinct" is 

p = 72° 11', or nearly the same.

Although these measurements are near to the angular values of 

the simple form {1562}, which are <j> = 8° 57', ^ = 70° 00', the p angle 

is sufficiently different to preclude their reference to this form. If 

we take the average measured value, $ = 8° 56', p = 72° 09', we find
102 MINEBALOGICAL NOTES SERIES 1.

that the ratio Ji : k = 1 : 5 (<£ calculated = 8° 570, and the ratio 

i : 1 = 3.392, which gives as the indices 1.5.6.J or 4.20.24.7, which 

are not especially complex and the calculated angles for which are 

0 = 8° 57', p = 72° 20', agreeing fairly well with the average of the 

measurements given above. The above detailed description is given 

in order to call attention to these trigonal calcites in the hope that 

some one may find a similar group having this new form which will 

admit of an accurate measurement whereby the symbol of the form 

may be definitely determined.

A single minute face of C"{0.13.13.1} was noted and this was poorly 

developed, giving a poor reflection. Sansoni 1 gives this form as new 

and it is also described by Hofer 2 as new, being determined by zonal 

relations, but it is considered as doubtful by Goldschmidt, 3 he suggesting that the correct symbol may be {0.14.T4.1}, though Sansoni's 

measurements, like the writer's above, agree well for {0.13.T3.1}. 

Figure 9 shows one of the smaller crystals of this group with the 

important forms developed at one corner. As shown in this figure, 

the combinations vary at similar crystallographical places, being

FMUKE 9. Calclte from England. FIGURE 10. Calcite from England.

much simpler at some corners than at others. Though all the intersection lines are here drawn straight, many of them are considerably 

curved on the crystals, especially on the larger ones, which moreover 

show a much simpler combination than the smaller ones. Figure 10 

shows the appearance of the larger crystals.

i Zeitschr. Kryst. Min., vol. 10,1885, p. 564.

a Min. pet. Mitt., vol. 12,1891, p. 487 (Ref. Zeitschr. Kryst., vol. 24, p. 431).

8 Index der Krystallformen der Mineralien, vol. 1,1886, p. 388.
SOME NEW FORMS OF CALCITE CRYSTALS. 103

J

CALCITE FROM SAN FRANCISCO, CAL.

The crystals here described were collected by the writer some years 

ago. They occurred in cavities in what seems to be an altered 

rock near Fort Point, San Francisco. They 

were found in the same locality which has 

furnished pectolite and datolite 1 as well as 

apophyllite and gyrolite,2 though the crystals 

here described were not found directly associated with any mineral other than quartz. 

The crystals are of the common scalenohedral (v] habit of calcite with e and r as 

termination, and often reach a size of several 

centimeters. They differ somewhat from the 

ordinary calcite crystals in that the form 

f {5382} is almost always present as a very 

narrow face below v and minute faces of 

^{4.16.20.3} are also almost always present. 

One single crystal, colorless and transparent 

and about 4 millimeters in- diameter, showed 

some differences from the other crystals and 

was therefore measured. The essential difference was that the e faces were replaced by 

two faces of ?/:{2358}, the e faces being 

entirely absent. In addition a new form in 

the zone re was noted. The forms present 

on this crystal are: r{10Tl}, <y{2131}, 

7"{5382}, 7/:{2358}, JV{4.16.20.3}, and the new FIGUBE n.-caidte from callform fc{1.6.7.13}. The average measured forniaangles are compared with the calculated ones in the following table:

Forms and angles of calcite from San Francisco, Cal.

Letter.

V

r

yN

b

Symbol.

2131

5382

2358

4.16.20.3

1.6.7.13

Number 

measured.

t

2

2

6

4

3

Measured.

4>

0 /

19 04

21 42

23 22

10 55

7 31

P

0 t

69 04

74 13

28 19

80 32

26 27

Calculated.

*

o /

19 07

21 47

23 25

10 54

7 35

P

0 /

69 02

73 51

28 15

80 35

26 27

Only three faces of the new form are present. They are all narrow 

and bright, but striated like almost all the faces in this zone. This

i Bull. Dept. Geol., Univ. Cal., 2, No. 10,1901. 

* Bull. U. S. Geol. Survey No. 262,1905, p. 124.
MINERALOGICAL NOTES SERIES 1.

striation caused the reflections, particularly the first one, to broaden 

out so that accurate measurement was not possible. The three 

measurements are:

Angle values for k{ 1.6.7.13}.

Calculated .........................

 Measured:

. > m. ........................ ...

(9\

>q\

0

0 /

7 35

7 57

7 04

7 01

P

0 /

26 27

26 34

26 24

26 24

The form is considered to be well established. It is shown in figure 

11, which illustrates the ideal combination found on the crystal 

measured.

CALCITE FROM HILLSBORO, N. MEX.

These crystals were received from Mr. C. H. Gordon, the locality 

being. Macey's mine, 2| miles east of Hillsboro, N. Mex. They are 

loose crystals, a centimeter thick and somewhat longer, and are associated with large endlichite crystals. Many of the calcite crystals 

have partially adhering white or pink gangue. 

Almost all the crystals, generally doubly terminated, show only the prism m{10TO} and the 

negative rhombohedron e{OlT2}. The e faces 

are striated parallel to their intersection with r, 

and the prism faces are covered with triangular 

markings or etch figures. These triangular 

markings always point toward the e face, the 

base of the triangle being nearest the r face.

Two crystals showed considerable differences 

from the others and were therefore measured, 

the results being given below. Crystal No. 1 is 

prismatic, 12 millimeters long and 4 millimeters 

FIGURE 12. Calcite from thick, colorless, and transparent. It is shown

New Mexico. .« ..^i-i ,ji .1 . m figure 12, which represents the crystal as it 

actually is, except that the narrow scalenohedra in the zone r e 

are not shown. The forms present on this crystal are: raflOTO}, 

a{1120},r{10Tl}, J/{4041}, ^{28.0.28.1}, e{0ll2}, w{3145}, £{5279}, 

£{2134}, <y{2131}, and the new form 1(3.10.13.3}.
SOME NEW FORMS OF CALCITE CRYSTALS. 

Forms and angles of caldte from New Mexico.

105

Letter.

r

M

01

e

w .

G

t

V

I

Symbol.

1011

4041

28. 0. 28. 1

0112

3145

5279

2134

2131

3. 10. 13. 3

Number 

measured.

3

3

3

1

1

2

1

4

2

Measured.

*

0 /

0 01

0 01

0 01

0 05

14 08

15 56

19 55

19 06

12 56

P

0 f

44 36

75 44

87 48

26 16

35 20

34 27

32 57

69 07

75 33

Calculated.

*

0 /

0 00

0 00

0 00

0 00

13 54

16 06

19 07

19 07

12 44

P

0 /

44 36

75 47

87 55

26 15

35 25

34 23

33 07

69 02

75 31

For the new form 1(3.10.13.3} only two faces are present, both of 

which gave poor reflections, one much poorer than the other. The 

one giving a poor but distinct signal, measured 0 = 12° 54' (calculated, 

12° 44'); |0 = 75° 36' (calculated, 75° 31')-

The limits of repeated measurements of these two faces gave:

Angle values for 1 {3.10.13.3}.

Calculated .........

Measured:

m.. ...........

?2^

Average ......

0

o / o /

12 44

12 42 to 13 03

12 24 to 13 17

12° 56'

P

O / 0 /

75 31

75 30 to 75 36

75 29 to 75 36

75° 33'

The form was seen to lie in the zone r m, and measurement of the 

angle (lOTl) : (13.10.3.3) gave 50° 35' (calculated, 50° 16'). The 

form, considered as well established, is shown in figure 12.

Crystal No. 2 is incomplete and as now formed nearly equidimensional, measuring a centimeter in diameter. It is colorless and 

though in part transparent is cloudy and translucent in other places. 

The forms present on this crystal are: m{10TO}, r{10ll}, e{OlT2}, 

/{0221jL and the three new forms o{0.14.TI.17}, 0{8.2.T0.3}, 

q{2.16.18.1} of which the latter is doubtful. The angular values 

are given in the table following.
106 MINEEALOGICAL NOTES SERIES 1. 

Forms and angles of calcitefrom New Mexico.

Letter.

r

e

f

o .

0

1

Symbol.

1011

0112

0221

0. 14. 14.17

8. 2. 10. 3

2. 16. 18. 1

Number 

measured.

1

3

2

3

2

4

Measured.

#

0 /

0 29

0 00

0 00

0 00

10 29

5 43

P

0 f

44 56

26 15

63 33

39 02

70 58

86 33

Calculated.

*

o /

0 00

0 00

0 00

0 00

10 54

5 49

P

0 /

44 36

26 15

63 07

39 05

71 38

86 36

The large faces of 0(8.2.10.3} are dull and give no distinct signal, 

only a blaze of light. Two faces were measured with the following 

result:

Angle values for 0(8.2.10.3}.

Calculated .........................

Measured: g). ............................

'*

o /

10 54

10 21

10 36

P

0 /

71 38

71 07

70 48

Although the faces are dull and give no distinct reflections the

measurements serve to fix the indices, 

and as the form occurs in large plane 

faces it is considered as well established. 

The corresponding negative scalenohedron 5(2.8.10.3} has been noted a 

number of times.

Measurements for the form 

o{0.14.11.17} are as follows, the faces 

being bright and giving fairly good reflections :

The angles between the three faces of this form and e were measured.

{0.14.14.17} : {0112}=12° 52' to 12° 53'; therefore ^=39° 07' to 39° 08'. 

{0.14.14.17} : {0112} =12° 44' to 12° 45'; therefore <o=38° 59' to 39° 0(K. 

{0.14.13.17} : {0112}=12° 43' to 12° 44'; therefore ^=38° 58' to 38° 59/.

Average GO)=39° 02'. 

Limits, 38° 58' to 39° 08'.

FIGURE 13. Calcite from New Mexico.
SOME NEW FORMS OF CALCITE CRYSTALS. 107

The only form for which the angle agrees is the complex one 

{0.14.TI.17}. Two simple forms which approximate to {0.14.11.17} 

are given in the table below, but, as can be seen, neither is sufficiently close to the measured values.

Calculated for {0556}, (0=39° 25'. 

Calculated for {0.9.911}, ^=38° 54'.

Four faces of the form q {2.16.T8.1} are present, the remainder of 

the crystal having cleaved off. Though all the faces are bright, they 

are very rounded, and in some cases form with ra {lOTO} a rounded 

surface. They gave, however, a bright signal in the midst of the 

mass of signals caused by the rounded surfaces, and it is these single 

bright signals that were measured.

Angle values for q{2.16.18.1}.

Calculated .........................

Do............................

Do............................

Do............................

*

o /

5 49

5 48

5 31

5 54

5 37

5 43

P

0 /

86 36

86 39

86 27

86 33

86 33

86 33

Measurements of the prism face (in zone cem) gave ^ = 89° 58' 

instead of 90° 00'. While the above measurements agree very well 

with the calculated angles, the form can not be considered as determined, for it is too rounded. It must be classed as a doubtful form. 

The forms are shown hi figure 13, an attempt to show the crystal 

.as it actually is.

CALCITE FROM LINCOLN, R. I.

The crystals here described were received from Mr. A. L. Stevens, 

of Providence, R. L, and the locality is given as Dexter lime quarry, 

Lincoln, R. I. For the kindness of Mr. Stevens in sending the 

specimens the writer's thanks are due. The crystals are on limestone and are associated with a pearly mineral forming almost colorless spherulites which have become brown on the surface. Other 

specimens show "nacrite" a talcose or micaceous mineral, quartz 

in flattened crystals, and curved rhombohedra of dolomite.

The calcite is found in three types of crystals: (1) Simple rhombohedra r{10Tl}, abundant; (2) crystals apparently prismatic, and 

more fully described below; (3) scalenohedral crystals showing large
108 MINEEALOGICAL NOTES SERIES 1.

faces of v{2131}, but the crystals were so rounded that no measurements were made of them. Those of the second type are found on 

the rhombohedra of the first type and are not over several millimeters 

long, and the simple rhombohedra are seldom over a millimeter thick. 

Though the rhombohedral crystals are generally smooth and bright, 

those of the second type are very much etched and rounded, making

it difficult to obtain satisfactory readings. 

The crystals have a prismatic appearance due to the presence of the negative 

rhombohedron ^{0.17.17.1}, and a form 

vicinal to a{1120}, and having the approximate symbol t{ 17.16.33.1}. No 

prism faces were noted on the single 

crystal measured. The forms present 

are: e{01l2}, e{0l!l}, r{0.17.17.1}, 

£:{11.8.I9.3}(?) t{17.16.33.1}(?). The 

faces of most of these forms were so 

poor that the correct symbols could not 

be definitely determined. Figure 14 

shows the general appearance of the 

crystal except that while the intersection 

of two faces is here shown as a straight 

line on the crystal they are frequently 

curved and rounded. The crystal was set in polar position by means 

of the e faces, and the other forms gave the following measurements: 

£ {OlTl}: p calculated = 44° 36'; p measured = 47° 53', 45° 45', 

42° to 45°. All faces gave a mass of signals.

r{0.17.T7.1}: p calculated^ 86° 35'; p measured^ 87° 07', 86° 12', 

86° 45', 86° 16', 86° 30', 86° approximately. All faces gave merely 

a mass of brightness, and the angles measured represent the center of 

this mass.

Measurements of S : {11.8.19.3}.

FIGURE 14. Calcite from 

Rhode Island.

Calculated .........................

Measured ...........................

Do. ...........................

tf

0 /

24 48

25 15

25 35

P

0 /

79 34'

78 42

78 05

The agreement is only approximate, but the faces were so poor 

that only two out of the six could be even approximately measured.
SOME NEW FORMS OF CALCITE CRYSTALS. 

Angle values for t {17.16.33.1}.

109

Measured ...........................

Do............................

Do............................

Do............................

<£

o /

28 59

29 27

28 41

29 21

28 26

P

0 /

87 58

88 08

87 51

87 21

87 28

Here again the symbol is only approximate. If we change the 

orientation of the crystal to that given by Goldschmidt in his 

Winkeltabellen the indices of this last form become {49.1.50.1}, and 

it is not possible to say they should not be, for instance, {50.1.5L1}, 

etc. Even, in the orientation here taken, the average of the four 

measured angles agrees well for a number of forms.

Measured and calculated angles oft.

Calculated for 17.16.33.1. ...........

Calculated for 16.15.31.1. .......:...

Calculated for 15.14.29.1. ...........

<£

0 /

28 59

28 59

28 56

28 52

P

0 /

87 42

87 58

87 50

87 41

However, though the correct indices could not be determined, we 

have here a form with indices near one of those given above and still 

too far removed from the prism a {1120} to be referred to that form. 

The writer could find no form for calcite approximating that just 

given, and the form would seem to be new, though it can not be 

definitely determined.

O