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Stanniferous Argyrodite from Bolivia: The Identity of the So-Called “Crystallised Brongniardite” with Argyrodite-Canfieldite

Published online by Cambridge University Press:  14 March 2018

G. T. Prior  and
L. J. Spencer
G. T. Prior
Affiliation:
Mineral Department of the British Museum
L. J. Spencer
Affiliation:
Mineral Department of the British Museum
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Extract

The occurrence in Bolivia of minerals containing the rare element germanium has been recently noted by Prof. S. L. Penfield. One of these minerals from Potosi, described bv him in 1893, has the chemical composition of the Freiberg argyrodite (the original source of germanium), but was determined to be cubic, and not monosymmetrie, the system to which argyrodite was originally referred. To the supposed new mineral the name eanfieldite was given, but when Weisbach's reexamination showed that the Freiberg argyrodite was possibly ctlbie, the name was transferred by Penfield to another mineral containing germanium, which he described in 1894.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 12 , Issue 54 , June 1898 , pp. 5 - 14
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1898

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References

1 "Canfieldite, a new Germanium mineral, and on the Chemical Composition of Argyrodite. Amer. Journ. Sci., 1893, XLVI, 107-113; Abstract, Min. Mag. X, 336.

2 " On Argyrodite and a new Sulphotannate of Silver from Bolivia." Amer. Journ. Sci. 1894, XLu 451-4; Abstract, Min. Mag. XI, 40. Under this title Penfield's two papers are united in Zeits. Kryst. Min. 1894, XXIII, 240-8.

1 Aullagas is close to the town of Colquechue, and lies cast of the great lake Aullagas (or Poopó) and north of the town of Po'osi. The mines here are nottd for their very rich ore, consisting mainly of red silver and native silver. They have been described by H. Reck, Pelermann's. qeograph. Mirth. 1867, 247; R. Peele, Jnnr. " The Silver Mines of Colquechaca, Bolivia," Engineering and Mining Journal, New York, 1894, IHII, 78, 100 (abstract, Zeits. prakt. Ged. 1894, 215); A. W. Sielzner, Zeits. deutsch, geol. Ges. 1897, XLIX, 89.

2 On the crystals of stophanite the following forms were observed (the letters and indices are as given by Dana, System of Mineralogy, 6th edition, 1892):--

(i.) c{001}, b{010}, m{110}, p{130}, q{114}, M{113}, P{'11}.

(ii.) c, b, t{023}, k{011}, d{021}, q, M, h{112}, P.

(iii.) c, b, m, t, k, M, P. All these crystals are twinned on m(110). Partial raeasnrements of minute crystals implanted on an octahedron of the stanniferous argyrodite gave-

(iv.) c, b, s{012}, t d, etc.

(v.) c, b, t, d, d{071}, etc.

1 Zeits. deutsch, geol. Ges. 1869, XXI, pp. 654, 636; figs. 10, 11, Plate XVII.

2 This figure is reproduced in Dana's System. of Mineralogy, 6th edition, 1892, p. 150, fig. 2.

3 C. F. Nanmann, Lehrb. d. Kryst. 1830, II, p. 232, fig. 621. This figure is given in Dana's System, p. 429.

4 loc. cit. p. 634, fig. 19.

1 A. Weisbaeh, Neues Jahrb. für Min. 1894, I, 98.

2 The shining streak is obtained when a fragment of the mineral is crushed with a knife point on biscuit porcelain or on hard smooth paper; when the mineral is crushed on soft paper of loose texture, the streak is dull black, with a sooty appearance.

1 "Notice sur la Brongniardite, nouvelle espèce minérale." Annales des Mines, 1849, [iv], XVI, 227-231; and F. de Castelnau, Expédition clans les parties centrales de l' Amérique du Sud, 1851, vol V, p. 440.

2 Not Mexico, as at first stated, and as quoted in the text-books.

3 "Note sur la cristallisation de la brongniardite, espèce minérale." Annales des Mines, 1854, [V], VI 146-7.

1 He noted, however, that the yellow sublimate on charcoal obtained from the crystals was less marked than that furnished by the massive mineral.

1 The precipitate was only a slight one, indicating that the mineral was in composition nearer to argyrodite than to canfieldite.

2 Anales Soc. Espanola Hist. Nat. 1895, XXIV, Actas, p. 94.

3 See Abstract, this vol. p. 46.

4 A. W. Stelzner, Neues Jahrb. Min. 1893 II, p. 114; Zelts. deutsch, geol. Ges. 1897, XLIX, p. 141.

5 A. Frenzel, Neues Jahrb. Min. 1893, II, p. 125.

6 Also mentioned from Trinacria, near Poopó (Zeits. dentsch, geol. Ges. 1897, XI, IX p. 693); and from Arangaro ia Chili (Bull. Soc. Fran. Min, 1895, XVIII, p. 340).

1 Zeils. deutsch, geol. Ges. 1892, XLIV, p. 531; 1897, XLIX, pp. 51-142; Abstr. Min. Mag. X, 261.

2 A case of the Occurrenec together of cassiterite and andorite is noted by us in the last munber of this Magazine (Vol. XI, p 299).