"Lepidomelane" (iron-bearing Mica) (ex Kay Robertson Collection)

Item Description

"Lepidomelane" is a term used for dark iron-bearing Mica species, which can include Annite, Tetra-ferri-annite, Siderophyllite, and perhaps other species too. This particular piece was labeled as "Ferrian Biotite", but since Biotite is no longer a species, it is "used as a generic field term for any incompletely analyzed dark mica" according to mindat.org. With that said, it's an attractive and very well-formed, thick crystal group of semi-metallic black Mica crystals free of matrix. Classic material and very hard to find on the market. Ex Kay Robertson Collection (#4296). 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).