Andesine with Pyrrhotite and Biotite (ex Kay Robertson Collection)

Item Description

Mineral specimens of any variety are rare from this ancient polymetamorphic iron sulphide deposit, hosted in cordierite-garnet gneiss that is disseminated by quartz veins. First documented mining took place in 1436 and continued intermittently until 1962 (MINDAT). Andesine specimens are extremely rare. This piece features sharp, blocky, lustrous black-skinned Andesine crystals associated with golden metallic Pyrrhotites and minor Biotite mica. A few of the contacted Andesines are partially translucent, and show a slightly jade-green interior. A rare old classic. and nearly IMPOSSIBLE to find on the market these days. Ex Kay Robertson Collection (#2305). Kay is a prominent California collector, who specialized in European classics (see the article in the March-April, 2007 Mineralogical Record and the 50+ page article in the German Magazine "Mineralien Welt" November-December 2017).