Home > Mexico II Type Locales – December 22 > MS1705 Cumengeite epitaxy on Boleite

Cumengeite epitaxy on Boleite


Cumengite is a lead silver copper chloride hydroxide hydrate. Mallard (1893) named the species after Edouard Cumenge (1828-1902), a French mining engineer, who collected the first specimens and brought them to the attention of French mineralogists. More than a century later, Cruciani et al. (2005) refined the crystal structure of cumengeite and found a previously unrecognized content of molecular water, setting its currently accepted chemical formula. Following the original description of boleite in 1891, mineralogists debated the identities of boleite and its similarly appearing associates pseudoboleite and cumengeite. Friedel (1906) made thin sections of the complex intergrowths, showing optically that they consisted of different sections, and that pseudoboleite and cumengeite form epitaxially on cubic boleite. How many fine cumengeite "stars: fell to Friedel's blade?

This is an unevenly developed cumengeite epitaxy on boleite, with two principal points on opposite ends, and smaller points making a girdle around the piece. Some psuedoboleite is present between the smaller cumengeite points and the central boleite cube. All three type locality species for Boleo are present in this one crystal group!

Price: $425

Item code: MS1705

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