Metastibnite Locality: San José Mine, Oruro City, Cercado Province , Oruro Department , Bolivia ( Locality at mindat.org ) Size: 2.3 x 2.0 x 1.0 cm. Metastibnite is a relatively rare antimony sulfide and is dimorphous with Stibnite. These wonderful, unique and interesting Metastibnite specimens from Bolivia were collected in the Fall of 2003. Before this discovery, Metastibnite was only known as amorphous reddish "smears" on matrix. These new specimens redefined the species for quality and size but the fact that these are crystallized specimens makes them truly desirable for collectors. This features fantastic, lustrous, bright silver color, botryoidal crystal aggregates on cuboctahedral Pyrite matrix. The "spheres" on this specimen are very good for quality and crystal size. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Metastibnite
Metastibnite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Sb₂S₃.
It crystallizes in the amorphous crystal system. It is a member of the Stibnite structural group.
Key properties: Mohs hardness 2–3; Red streak; Submetallic. Anisotropism: Moderate in air. R: n.d luster.
IMA symbol Msbn, grandfathered status — known before the IMA’s founding, named in 1888.
Appears to be of primary hydrothermal origin around fumarolic centers (The Geysers, California; Steamboat Springs, Nevada, USA); and the result of oxidation of stibnite (Copiapó, Chile).
It is found associated with Cinnabar (The Geysers, California, USA); stibnite (Copiapó, Chile; Rujevac deposit, Serbia).
Its name comes from the Greek for with, plus stibnite, in allusion to its composition.