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Note on the pleochroism of Adamite1

Published online by Cambridge University Press:  14 March 2018

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

The mineral adamite (Zns(AsO4)2.Zn(OH)2), discovered by C. Friedel in 1866 on specimens from Chafiarcillo, Chile, has since been found at only two other localities, namely Cape Garonne in France and Laurion in Greece. At the original locality it would appear to be of rare occurrence, since in the literature mention is made of only two specimens.

It was therefore of interest to find in the British Museum collection a good specimen of adamite from Chafiarcillo. This was found amongst the hornsilvers, and the associated adamite had been thought to be fluorite, which indeed, at first glance, with its violet colour and good cleavage, it closely resembles in appearance. The crystals are remarkable by reason of their very strong pleochroism, and as this feature of adamite has previously received no mention it has been thought worthy of placing on record.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 17 , Issue 79 , July 1914 , pp. 114 - 115
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1914

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Footnotes

1

Communicated by permission of the Trustees of the British Museum.

References

page 114 note 2 Since the above was written, adamite has been found also at Monte Valerio in Tuscany (P. Aloisi, 1907), the island of Thasos, Turkey (V. Rosicky, 1909), Ain-Achour in Algeria (Dusser, 1910), and Reichenbach in Baden (V. Dürrreid, 1912). Pleoehroism in the French crystals has been noted by A. Lacroix (Minéralogie de la France, 1910, vol. iv, p. 425).—L.J.S. May 1914.

page 115 note 1 Letters and indices as in Dana's 'System of Mineralogy,' 6th edit., 1892.