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The Crystallography of Plagionite: New Crystal Forms on Stephanite, Enargite and Anglesite

Published online by Cambridge University Press:  14 March 2018

L. J. Spencer*
Affiliation:
Mineral Department of the British Museum

Extract

On the British Museum specimens of plagionite from Wolfsberg, in the Harz, all the well-established crystal forms previously recorded have been detected.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1897

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References

page 192 note 1 The letters are those used by Miller (Min. 1852, p. 196) and by Goldschmidt (Index der KrystaUformen, II. p. 479): the parametral plane is that of Goldschmidt, this being the direction of cleavage, and also givin 8 rather simpler indices; other authors have taken e to be {111}.

page 192 note 2 Neues Jahrb. Min. H. 112, 1883; cf. Goldsohmidt, loc cit. p. 480.

page 192 note 3 Sandberger, ( Ber. Akad. München , XXIV. 241, 1894 Google Scholar), mentions for crystals from Goldkronach, Bavaria, the form ∞P∞; this is, however, probaby a misprint for ∞P∞, which is a very common form on plagionite; or, again, d might easily be mistaken for (010) on mere inspection of the crystals.

page 194 note 1 Loc. cit.

page 194 note 2 These angles, ac=72°28½', am=47°44', and cn=41°18', give the parameters a: b: c= 1.1538: 1: 0.8508.

page 194 note 3 Neues Jahrb. Min. II. 94, 1883. Compare Ber. Akad. München, XXIV. 241, 1894, where different symbols for the faces are given.

page 195 note 1 Comptes Rendus, LXXXIII. 747, 1876.

page 195 note 2 The abstract of Pisani's paper in the Neues Jahrb. Min. 300, 1877, mentions needle.shaped crystals, and it is probably hence that the mistake arose. Koort (Beitr. z. Kenntn. des Antimonglanzes, Inaug.-Diss., Berlin (Freiberg i. B.), 1884, p. 10), mentions acicular and capillary stibnite from this locality.

page 195 note 3 Ber. Akad. Wien, XV. 236, 1855: figs. 5 and 6, plate I.

page 195 note 4 The figure of a plagionite crystal given in Dana's Mineralogy, editions 2 to 5, more or less illustrates this case.

page 195 note 5 Zeits. für Kryst. XXVII. 50, 1896, footnote 2.

page 196 note 1 Zeits. für Kryst. XVIII. 68, 1891.

page 196 note 2 The letters for the forms are those used by Dana (Systent of Mineralogy, 6th Ed.); and the above angles are calculated from the parameters he gives.

page 196 note 3 cf. Min. Mag. XL 69, 1895.