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aid of fluxes. Carnegieite was first prepared by Thugutt^ by
fusing an artificial ' nepheline hydrate.' lie obtained a mineral
with polysynthetic twinning and high extinction angles, prob-
ably triclinic. Following the suggestion of Lemberg, this
mineral was called soda-anorthite.

In 1905, carnegieite was prepared at the Geophysical labor-
atory and the new name proposed. (Published 1910.)' But

*The index of this glass correspoDds approximately with that calculated
for it from the indices of anorthite glass and carnegieite glass in the propor-
tion 86 : 64.

t With slow cooling, the temperiitare of the preparation is for a long
period in the region slightly below the inversion point, permitting the for-
mation of the low temperature form, nephelite.

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568 N. Z. Bowen — The Binary System.

few thermal determinations were made, so that its melting
point and its relation to nephelite were not ascertained. It
was not known at that time that some soda might be volatilised
during the preparation of the compound, but a reexamination
of some of the samples then made gives evidence that there is
a slight shortage in soda demonstrated by a slight excess of
alumina. The optical properties of this material vary slightly
from those of the purer material, since prepared, the figures
for which are given here. For the same reason the density
2*513 found here is probably more accurate than that formerly
found (2-571),

Gerh. Stein,* by crystallizing " soda-nepheline" directly from
the melt, obtained a granular, strongly double-refracting mass.
It is possible that Stein obtained carnegieite, of which the
double refraction, though hardly strong, as ordinarily under-
stood, is higher than that of nephelite.

Nephelite, — The formation of soda-nephelite was first accom-
plished by Fouqa6 and L6vy in 1878 by simple fusion of its
constituents. With the addition of a flux (sodium vanadate)
Hautefeuille (1880) succeeded in making measureable hexago-
nal crystals."

In 1884 Doelter" prepared not only the simple orthosilicate,
NaAlSiO^ but mixtures with excess silica and the potash and
lime content of natural nephelite.

Many others have succeeded in making nephelite as one
constituent of a complex mixture, or by tlie action of aqueous
carbonate solutions on various compounds. This work has no
special interest from the point of view of this paper, and will
merely be referred to here.

Doelter found that Na,Al,Si,Q, (NaAlSiO,) and CaAl.Si.O,
were capable of forming mix-crystals, as did the present writer.
It appears that Doelter found a somewhat greater mnge of

Wallace,**^ by the slow cooling of a melt of composition NaAl
SiO^, obtained a completely crystalline mass with low refrac-
tive index and low birefringence which he refers to as soda-
nephelite. At the same time it should be noted that "Wallace
observed in thin section a microline-like structure and since
this is a structure charcteristic of carnegieite there can be no
doubt that some carnegieite was present.

On account of the long time necessary to obtain complete
inversion in the direction carnegieite-nephelite, it may be stated
as more than probable that much of the material prepared by
direct fusion and described as soda-nephelite in the literature
has contained some carnegieite. A rough similarity in optical

Properties is the reason for the failure to differentiate the two.
'he method of identification by immersion in refractive liquids
eliminates this possibility.

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N. Z. Bowe^i — The Binary System. 569

Wallace found that a mixture of composition NaAlSiO^ was
completely molten at 1350°. The writer finds that NaAlSiO^
does not melt till a temperature of 1526° is attained, the actual
figures obtained in two determinations beinff 1527° and 1525°,
of which the figure given is the mean (Table I). Possibly
Wallace approached the unstable equilibrium nephelite-melt
on cooling.

An indistinct heat effect was obtained by Wallace on the
cooling curve at 1260°. The writer found a small heat effect,
due to inversion, on the heating curve at 1305°. Allen found
a point at 1289°.* The diversity of results is due to the
indefinite nature of heating-curve breaks representing a slug-
gish transformation involving no great heat effect. The
determination by the method of quenching gave 1248°
(approx.) for the inversion point (Table II).

Anorthite, — Anorthite, like nephelite, was first prepared in
1878 by Fouqu6 and L6vy" by simple fusion of its oxides.
No special interest attaches to the numerous other preparations
of this mineral.

The melting point of artificial anorthite is sufficiently sharp
to be used by Day and Sosman" as a reference point (1550°)
on the temperature scale. Brun** obtained by his very different
method (calori metric) 1544°-1562°.

Mixtures. — Schleimer** has made determinations of the melt-
ing 'points' of mixtures of anorthite and nephelite using natural
mmerals. Eis mixtures are of very different composition from
those used in this investigation and the temperatures found
need have no relation to those found here.

Application to Natural Minerals.

Anorthite. — Several natural anorthites approximate closely
to the theoretical composition. The melting points of some
of these have been determined. Brnn,** working with Soger
cones, and Douglas,'* the latest worker with the meldometer,
have obtained figures that differ comparatively little from the
figure given by Day and Sosman for pure anorthite.

Anorthite from Idsn, 'Japan, 1490-1520°— Brun.
Anorthite " Mte. Somma, 1505°— Douglas.

Nephelite. — In a recent paper" the writer has shown that
experimental results are in accord with Schaller's statement
that natural nephelites may be regarded as solid solutions of
the three molecules NaAlSiO,, KAlSiO, and NaAlSi.O,.

Natural nephelites, then, differ considerably in composition
from the compound NaAlSiO^ used in this work and the
* Geophysical Laboratory, trnpnblished notes.

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670 N. Z. Boweii — The Binary System.

difference in thermal properties is correspondingly great. Thus
it was found by the writer that nephelite from Magnet Cove
quenched from 1370° gave only a clear glass and therefore
melts at some temperature below 1370°. Moreover, Wright*
has found that molten ' nephelite ' (Magnet Cove) crystallizes
directly as nephelite without first showing the carnegieite
form. In this respect nephelite from Magnet Cove behaves
like the artificial nephelites with 28'5-35 per cent CaAl,Si,0,
in solid solution.

Nephelite Mix- Crystals. — The extreme nephelite mix-
crystals with 35 per cent CaAl,Si,Og contain approximately 7
per cent CaO. The lime content of natural nephelites never
approaches such an aniount. In nature, however, nephelite
never occurs in intimate association with pure anorthite,
altliougli very often it does occur with a plagioclase. A plag-
ioclase is a solution of anorthite in albite just as the mix-
crystals above referred to consist of a solution of anorthite in
nephelite. When all three substances are present there is,
theoretically, a definite distribution ratio of anorthite between
albite and nephelite, this ratio being equal to the ratio of
solubilities. Albite dissolves anorthite to an unlimited extent.
Nephelite dissolves 35 per cent. We have

c;= =K=a6/ioo='*'<*PP~^-^

where C,= concentration of anorthite in the plagioclase.
C,= concentration of anorthite in the nephelite.

Obviously only when C,=l (i. e. pure anorthite) will
C,=35/]00. For every other plagioclase there corresponds a
definite composition of nephelite in equilibrium with it and
the concentration of anorthite in plagioclase is three times that
in the nephelite. The natural minerals always contain import-
ant quantities of other molecules which introduce variations,
and viscosity may be such as to inhibit equilibrium, but the
distribution should probably be of the order indicated. The
analysis of a nephelite from Vesuvius shows the higiiest lime
percentage (2*20 per cent) (11 per cent CaAl^SijO,) of all
analyses of that mineral that have been made with sufficient
care to warrant tiieir consideration." This nephelite should
be in equilibrium with a plagioclase of approximate composi-
tion Ab,An,.

OtJier Solid Solutions. — The zeolite, thomsonite, consists of
CaAl^SijO^ with Na,Al,SiaOg up to 50 per cent, and corre-
sponds in composition with some of the writer's mixtures with
the addition of water. If, as Zambonini'* concludes from the
result of experiments, thomsonite is not a definite hydrate, the

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N, L. Bowen — The Binary System. 671

existence of anhydrous orthorhomic crystals of like composition
is to be expected. The orthorhorabic mineral barsowite may
represent one of these anhydrous thomsonites. The best
analyses of that mineral give it a composition close to that of
anorthite, with some soda and small quantities of other oxides.

No orthorhombic mix-crystals were encountered in the
present work, but it is quite possible that such a series may
be capable of existence at low temperatures where changes are
so slow as to be obtainable only with the efficient fluxes of

That uephelite will hold 35 per cent anorthite in solid solu-
tion, whereas camegieite, which, like anorthite, is triclinic, will
hold at most 5 per cent, comes rather as a surprise. That
miscibility in tne solid state does not always follow from
crystallographic similarity is, however, well exemplified in a
number of cases.

The very limited solubility of Na,Al,Si,0, in anorthite has
some importance in the light of the Linosa feldspar of abnor-
mal composition recently described by Wasnington and
Wright.* These writers came to the decision that the com-
position of the feldspar might be written Ab,An,oCgi. The
writer has found that solid solution of Ne in anorthite extends
only up to 2 per cent, while, if the explanation of the Linosa
feldspar oflEered by Washington and Wright is correct, solid
solution of Ne in the plagioclase Ab^An,^ extends to 5*5 per

Camegieite. — The mineral camegieite has never been
definitely identified in nature. Most natural nephelites prob-
ably crystallized as such, for, if formed by inversion from car-
negieite, the crystals would be unlikely to show continuous

In order that camegieite might occur in a rock it is necessary
that its crystallization should have taken place at a temperature
above that at which the crystal form would change to that of
nephelite, otherwise nephelite would occur. The inversion
temperature 1248° applies only to the pure compound
NaAlSiO^. The presence of other substances aflEects tnis in-
version point only when those substances can be taken into
solid solution by the nephelite or camegieite. In this work
the effect of anorthite has been determined, and is such that
crystallization would have to occur at a temperature still
higher than 1248° in order that camegieite might form, the
maximum raising being about 100°.

The effect of the other substances which nephelite is capable
of holding in solid solution is, however, still unknown, but the
evidence is that the aggregate effect is not sufficient to carry
the inversion point below the temperature at which the crystal-

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572 N. L. Bowen — The Binary System.

lization of nephelite from most rock magmas would begin,
otherwise carnegieite would be common.

From certain magmas very rich in 'nephelite,' the crystal-
lization of carnegieite miofht be expected, but even this state-
ment needs qualification, for, as we have seen, some nephelite,
viz. that from Magnet Cove, may crystallize from its own melt
directly as nephelite.

E. Esch" describes an abnormal nephelite from the nephe-
linite of Etinde volcano in German KLaraerun. This mineral
shows inclined extinction and a complicated twinning and is
biaxial. In these properties it agrees better with carnegieite
than with nephelite. On the other hand, the crystal outhne is
like that of nephelite and the determined mean index, 1'5376,
very close to that of nephelite, but such an index is not im-
possible in carnegieite with certain compounds in solid solu-
tion. The mineral may possibly be carnegieite, but no definite
decision can be arrived at until the possibilities of solid solution
in carnegieite have been further investigated. This single in-
stance appears to be the only one in which a mineral whose
properties suggest carnegieite has been described.


In the fact of its non-appearance in nature, carnegieite is like
a great many other allotropic forms of minerals that have been
made in the laboratory. These modifications are, in nearly all
cases, the high temperature forms and their absence constitutes
one of the proofs of the prevailingly low temperatures of
natural magmas during crystallization.

It is evident from the discussion in the preceding paragraph
that care must be exercised in putting to use the inversion
of nephelite on the geologic thermometer scale."

Minerals of simple, definite composition, SiO„ CaSiO,, and
others have definite inversion points and the limits of stability
of each form give definite points on the scale. On the other
hand, a mineral of variable composition has a temperature of
inversion which varies conjointly. With known composition,
however, it will be possible, when sufficient experimental data
has accumulated, to set equally definite limits to its stability as
is exemplified in the present case of nephelite with variable
content of lime.

There is reason to believe, as has been pointed out, that
natural nephelites first crystallized as such.

In the event of the discovery of carnegieite in a rock its
crystallization above 1200°* could probably be asserted with
but little fear of error.

* It ifi necessary to leave some margin for a possible lowering due to solid

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N. Z. Bowen—The Binary System, 673

. General,

It is encouraging to note the occurrence within the mineral
kingdom of one of Roozeboom's theoretically possible types
involving both solid solution and enantrotropism. Some little
hope of the eventual discovery of general laws, applicable even
to the complex mixtures known as magmas, is aroused. The
accumulation of precise quantitative data is the means to this

In conclusion the writer desires to thank E. S. Shepherd and
F. E. Wright of the Geophysical Laboratory for much help
and advice throughout the course of the experimental work.

Geophysical Laboratory, Washington, D. C.
Massachusetts Institute of Technology,
Boston, Mass.


1. W. P. White, this Journal, xxviii, 458, 1909.

2. Shepherd & Rankin, ibid., xxviii, 293, 1909.

8. Ostwald»s Lehrbuch der Chemie, vol. 2, pt. 2, 88-68.

4. Die SUikatschmelzlSsnngen, ii, p. 128.

5. Barker, Science Progress, No. 6, Oct., 1907.

6. Wright, F. E., this Jonmal, xxvi, 349, 1908.

7. Neues Jahrb. B. B., ix, 561, 1894.

8. This Journal, xxix, 52.

9. Zs. anorgan. Chemie, Iv, 160, 1907.

10. Ibid., Ixiii. 1-48, 1909.

11. Synth^e des mineraux et des roches, p. 156.

12. Zs. Kryst., ix, 321, 1884.

18. Arch. sci. phys. et nat. (4), xiii, 352, 1902.

14. This Journal, xxxi, 841.

15. Arch. sci. phys. et nat. (4), xviii, 587, 1904.

16. Q. J. G. S., 1907,p. 145.

17. Neues Jahrb., i, 20, p. 158, 1884.

18. Neues Jahrb., ii, p. 1, 1908.

19. Sitz. d. k. Akad. Wien, cxvii, 581, 1908.

20. Morozewicz, Bull. Acad. Sci. Cracovie, p. 958, 1907.

21. Mem. Roy. Accad. Lincei, xiv, 140, 1905.

22. Sitzb. Berl. Akad., xviii. 400. 1901.

28. See Wright and Larsen, this Journal, xxvii, 421, 1909.
24. Bowen, N. L., ibid., xxxiii, 49, 1912.

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574 E. T. Wherry — New Occurrence of Camotite,

Abt. XLVII. — A New Occurrence of Camotite;* by
Edgar T. Whebby.


The more or less definite bright yellow uranium-vanadium
mineral known as camotite has been heretofore observed at a
number of points in western Colorado and eastern Utah5f and
as an alteration product of "davidite," a rare-earth-bearing
rutile, at " Kadium Hill," South Australia.^ The purpose of
the present paper is to call attention to its occurrence near
Mauch ChunK, Carbon County, Pennsylvania.

In Genth's Mineralogy of Pennsylvaniag autunite was
stated to "have lately been found in a conglomerate from
the neighborhood of Mauch Chunk," the exact locality being,
however, unknown. Specimens labeled similarly are included
in several of the old collections of Pennsylvania minerals, but
a study of these and of a considerable quantity of material col-
lected at what is probably the original locality, the eastern
end of Mt. Pisgah, immediately north of the town of Mauch
Chunk, has shown that the mineral in question is really to
be classed as camotite.

Although the locality was re-discovered, by accident, by
the writer in 1908, and the nature of the mineral proved by
qualitative tests, detailed study was deferred in the hope o"f
obtaining more satisfactory material when opportunity should
present itself for thorough examination of the deposit. " As this
hope has not been realized, in spite of exhaustive search, it
was decided to proceed with analysis of the specimens on hand,
and to publish an account of the occurrence.

General Description,

The mineral presents the form of an amorphous to minutely
crystalline bright yellow coating or impregnation in a conglom-
erate, often penetrating cracks in the quartz pebbles. Micro-
scopic examination sliows it to be quite impure, containing
much limonite and clayey matter, and even the most crystalline-
looking specimens show only an occasional translucent rectan-
gular flake, with straight extinction, suggesting the tetragonal
or orthorhombic system.

* Presented at the Baltimore meeting of the A. A. A. S., 1908 ; abstract
in Science, vol. xxix, p. 751, 1909.

fHillebrand and Ransome, BuU. U. S. Geol. Survey, No. 282, pp. 9-81,
1905 ; Fleck and Haldane, Kept. State Bur. Mines, Colorado, 1905-06, pp.
47-115, 1907; Gale, Bull. U. S. Geol. Survey, No. 815, pp. 110-117, 1907;
BuU. No. 340, pp. 256-262, 1908.

X Crook and Blake, Mineralogical Magazine, vol. zv, pp. 271-284, 1910.

§ Report B. 2nd Penna. Geol. Survey, p. 144, 1874.

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E. T. WJier7*y — New Occurrence of Carnotite. 576

Chemical Composition.

Material for aDalysis was obtained by scraping off the
coating from a specimen of rather friable conglomerate, and
contained accordmgly considerable amounts of quartz, as well
as some limonite and kaolin. As the yellow substance proved
to be entirely soluble in dilute nitric acid, while the greater
part of these impurities are insoluble, this seemed adequate for
the purpose in hand. Uranium and vanadium were determined
by the method of Campbell and Griffin,* which was first tested
on known solutions of the metals and found to give very
accurate results. Iron and calcium were obtained in the usual
ways, water by loss on ignition, and potassium, by difference.
Barium, lead, and phosphoric acid could not be detected with
certainty; the strong radio-activity of the mineral indicates
the presence of radium, although its amount is of course too
small to be estimated, while lack of material also prevented
establishment of the presence of helium.

The analytical results are given in the first column of the
accompanying table, and the figures obtained by deducting the
insoluble matter, iron oxide and water, and recalculating the
remainder to 100 per cent, in the second. The iron is certainly
present as limonite, and while a part of the water may belong
to the carnotite, the amount in this form is indeterminate, so
it is best disregarded in calculating the formula. The results
are given in the first decimal place only because of the unsatis-
factory character of the sample. Most of this work was carried
out, under the direction of the writer, by Mr. J. S. Long of
Lehigh University, to whom much credit is due for skilful
handling of the problems presented.



and Ratios,









1 00









•050 \ *-"


K,0(diflf.) ...

. . -






- -



100-0 100-0

Without attempting to place undue confidence in these
results, it cannot be denied that they show a tendency to
approach a definite ratio, (Ca,K,)0.2U0,.V,0„ or (Ca,K,)
* Jour. Ind. Eng. Cbem., vol. i, pp. 661-665, 1909.

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576 E, T, Wherry — New Occurrence of Camotite.

(UO,\(VOJ„ which is identical with that indicated by the
previous work on carnotite.* Hillebrandf has shown, to be
sure, that different samples of the mineral from Colorado vary
rather widely in composition, yet throughout his and the other
published analyses the ratio 1:2:1 for the three oxides is
continually indicated. This is shown by the following table,
in which the analyses have been recalculated to 100 per cent
after deducting, as probably foreign to the mineral, the iron
and phosphoric acid and also the water, whose amount is so
variable tnat its role is uncertain.

Analysts of Camotite (Recalculated),

1 3 8 4 5 6

V,0, 21-16 21-28 22-03 22-72 21-60 21-89

UO 67-41 66-86 65-^4 64-72 6470 65-48

R^'O 4-59 4-12 4-73 686

R'0 11-43 11-87 7-94 8-44 907 6*77











Calcnlated 1:2:1


















- - - -










100-00 10000 100-0 100-0 100-00 100-00

1, 2f Colorado: Friedel and Camenge, Bull. Soc. Franc. Min., vol. zxii,
p. 26, 1899 and elsewhere ; considerable R'O probably present bat overlooked
and weighed with the R'aO (Hillebrand).

3-8. Colorado : Hillebrand, BnU. U. S. Geol. Survey, No. 262, p. 25, 1905.

9, South Australia : Crook and Blake, Min. Mag., vol. xv, p. 271, 1910.

10, Pennsylvania. The results of the present study.
Calculated, a, for R* = Ca ; b, for R' = K.

The cause of the variations in these analyses is not altogether
clear ; but, after all, they are perhaps no greater than is to be
expected in view of the non-homogenous character of the sam-

fles examined, and the difficulties of the analytical procedure,
n any case the evident similarity of the material from the
three widely separated localities justifies no other conclusion
than that we are dealing with a definite mineral species, of the
formula (Ca,K,) (UO,),(VO,),.

This formula at once suggests relationship with the uranite

or autunite group, the members of which contain, however,

from 8 to 10 molecules of water of crystallization. The

amount of water found in the various samples of carnotite

*Cf. Crook and Blake, loc. cit. fLoc. cit.

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E, T. Wherry — New Occurrence of Camotite. 677

varies from none in the Australian to perhaps 6 molecules
in the Pennsylvania mineral, but then it must be remembered
that most of this material is amorphous, leaving the question
open as to its possible water content when well crystallized.
The mineral may therefore be provisionally admitted to that
group, which, named according to Washington's suggestion*
(with one modification, the retaining of -ite as a termination,
which, in the writer's opinion, may be desirable, to avoid con-
fusion with chemical terms), becomes :

Uranite Group,

R"(UOJ,(R^OJ,.8lI,0 ; chiefly orthorhombic.

Autunite Ca (U0J,(P0J,.8H,0. Calcium phosphuranite

Uranospinite . Ca (UOJ,(A80J^.8H,0. " arsonuranite

Torbernite . . . Cu (UOJ,(POJj.8H,0. Copper phosphuranite

Zeunerite Cu (UO,),(A80J,.8H,0. " arsenuranite

Uranocircite . - Ba (U0,),(P0J,.8H,0. Barium phosphuranite

Carnotite (Ca,KJ (U0J,(V0J,.XH,0. Calcium-potassium


Geological Relations,

Mt. Pisgah, the ridge extending westward from the Lehigh
River just north of the town of Mauch Chunk, represents a
synclinal mass of the Pottsville formation, the great series of
interbedded sandstones, and conglomerates regarded as the
lowest member of the Pennsylvanian, overlying the Mauch
Chunk red shale, the top of the Mississipian.f The contact
between these formations, as exposed in the cuts of the high-
way and electric railroad across the eastern end of the ridge, is

Online LibraryJohn Elihu HallThe American journal of science → online text (page 57 of 61)