Whewellite is a rare calcium oxalate mineral known from low temperature primary hydrothermal carbonate-sulphide veins, coal measures deposits and some uranium deposits. This staggeringly large and immaculately formed monoclinic Whewellite crystal comes from a discovery in 1983, at Feldstrecke 1300, 435 Meter Level (Sohle), Upper Floor, Level 3, Shaft 396 at Paitzdorf mine near Ronneburg in Thuringia, Germany. Not only is this an exceptional crystal for this rare calcium oxalate species, but it is on matrix too - a small plate coated with finely crystallized Calcite and Pyrite. Allied to its superb crystallographic shape, the Whewellite is colour-zoned from light to dark grey and brown, caused by inclusions of metallic Smythite, an iron nickel sulphide. Fine Whewellite crystals are extremely rare and this is an exceptional example, reaching 3.1 cm in length. There are a few 'nibbles' along the two edges of the termination, but Whewellite is a soft mineral and for perfection in crystal form for the species this is a remarkable specimen.
