Walpurgite , Uranospinite Locality: Walpurgis Flacher vein, Weißer Hirsch Mine (Shaft 3), Neustädtel, Schneeberg District, Erzgebirge , Saxony , Germany ( Locality at mindat.org ) Size: 1 x 1 cm. This specimen contains crystals of bright yellow walpurgite showing sharp crystal form (distinguishing them from a later find of richer coverage, but smaller XL size), mixed with bright green plates of uranospinite. Zeunerite is also in association as is some minor torbernite. Ex. Clarence Bement, George Fiss, and Harvard Museum Collections. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Uranospinite
Uranospinite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Ca(UO₂)₂(AsO₄)₂·10H₂O.
Key properties: Mohs hardness 2–3; specific gravity 3.45; Waxy, pearly on {001} luster; optically uniaxial.
IMA symbol Usp, grandfathered status — known before the IMA’s founding, named in 1873.
Found as a secondary mineral in the oxide zone of U-As-bearing hydrothermal mineral deposits.
It is found associated with Metazeunerite, metauranocircite, uranophane, trögerite, walpurgite, uranosphaerite, asselbornite (Weisser Hirsch mine, Germany); schoepite, paraschoepite.
A prefix for its uranium content and from the Greek for siskin, in allusion to its typical color.