Pyroaurite , Pyrochroite Locality: Långban , Filipstad , Värmland , Sweden ( Locality at mindat.org ) Size: 9.6 x 7.2 x 1.8 cm. Pearlescent, tan blades of pyroaurite are richly scattered amongst black pyrochroite crystals on calcite matrix on this excellent combination specimen from the world-famous Langban deposit. Pyroaurite is a rare hydrated magnesium, iron carbonate and Langban is the Type Locality. This is a very rich example of pyroaurite in combination from the Dr. Mark Feinglos Collection, a noted rarities collector. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Pyrochroite
Pyrochroite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Mn²⁺(OH)₂.
It crystallizes in the hexagonal crystal system (space group P-3m1). It is a member of the Brucite structural group.
Key properties: Mohs hardness 2.5; specific gravity 3.25; Pearly on cleavages luster; optically uniaxial.
IMA symbol Pyc, grandfathered status — known before the IMA’s founding, named in 1864.
Found as a primary mineral in some volcanogenic massive sulfide deposits; a hydration product of manganosite, in turn metamorphosed from rhodochrosite.
It is found associated with Hausmannite, rhodochrosite, manganosite, galaxite, tephroite, alabandite, lead, barite, calcite, dolomite.
Its name comes from the Greek for fire and color, as there is a color change on ignition.