Anorthite (From Volcano, in 1870!)
Thumbnail, 1.6 x 1.2 x 1.0 cm
Miyake Island (Miyake-jima), Izu Archipelago, Tokyo Prefecture, Japan
These are euhedral crystals of one of the rarest members of the plagioclase feldspar family, typoical but rare for the locality on the market these days - I have only seen a few in overa decade since seeing the first one. These crystals are opaque white and reach 1 cm across. From mindat: This locality is a small island with active volcano. Augite-olivine basalt. Famous as the classic locality for anorthite crystals, thousands of which were thrown out loose by the 1870 eruption and distributed in collections around the world; usually coated with a film of reddish or blackish glassy lava.