Pyrostilpnite Locality: St Andreasberg, St Andreasberg District, Harz Mts, Lower Saxony , Germany ( Locality at mindat.org ) Picture width 2.5 mm. Collection and photograph Christian Rewitzer — Photo: Christian Rewitzer · CC BY-SA 3.0
Pyrostilpnite
Pyrostilpnite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Ag₃SbS₃.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Xanthoconite structural group.
Key properties: Mohs hardness 2; specific gravity 5.94; Yellow-orange streak; Adamantine luster; optically biaxial.
IMA symbol Psti, grandfathered status — known before the IMA’s founding, named in 1868.
Found in low-temperature hydrothermal veins as a late-stage mineral.
It is found associated with Pyrargyrite, stephanite, acanthite, silver, miargyrite, xanthoconite, andorite, fizelyite.
Its name comes from the Greek for fire and shining, in allusion to its color and luster.