Whewellite, provenance inconnue. Musée d'histoire naturelle de Lille. — Photo: Vassil · CC0
Whewellite
Calcium oxalate monohydrate — an organic-origin mineral found in coal seams and kidney stones alike.
Intro adapted from Wikipedia (CC BY-SA).
Whewellite is an IMA-recognized mineral species in the organic mineral class, with the chemical formula Ca(C₂O₄)·H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Oxalate structural group.
Key properties: Mohs hardness 2.5–3; specific gravity 2.21–2.23; Vitreous, pearly on {010} and some cleavages luster; optically biaxial.
IMA symbol Whe, IMA status: approved, named in 1852.
Of uncommon occurrence as a low-temperature primary hydrothermal mineral in carbonate-sulfide veins, geodes, or septarian nodules.
It is found associated with Calcite, barite, sphalerite, pyrite, weddellite, waxy hydrocarbons.
The mineral was named to honor William H. Whewell (1794-1866), English naturalist and philosopher.