Whewellite

Whewellite is an unusual mineral due to its organic content and is a hydrated calcium oxalate.  This lovely specimen is composed of solid Whewellite forming nested, bright glassy blades, each of pale lemon-cream to light grey and all with plumose, feather-like growth structures on the crystal surfaces.  It is a great example from the mining town of Oberschlema in Erzgebirge, Saxony, Germany.  The specimen has a low density and two faces are smooth and curved, properties which contribute to the specimen almost feeling like a sliver of bone when handled (bone from a nice roast dinner I hasten to add!).  Whewellite is a mineral thought to have organic-related origins, although this remains under investigation.