Umangite

 Umangite is a copper selenide mineral, Cu₃Se₂, discovered in 1891. It occurs only in small grains or fine granular aggregates with other copper minerals of the sulfide group. It has a hardness of 3. It is blue-black to red-violet in color with a black streak. It has a metallic luster.

Umangite
Umangite (purple) on clausthalite. Other copper selenides (green secondaries) and likely chalcomenite (non-metallic blue)
General
Category	Selenide mineral
Formula (repeating unit)	Cu3Se2
Strunz classification	2.BA.15c
Crystal system	Tetragonal
Crystal class	Scalenohedral (42m) H-M symbol: (4 2m)
Space group	P421m
Identification
Formula mass	348.56 g/mol
Color	Red, bluish red-black
Crystal habit	Massive granular
Cleavage	Distinct on [010] and [001]
Fracture	Uneven
Mohs scale hardness	3
Luster	Metallic
Streak	Black
Diaphaneity	Opaque
Specific gravity	5.62 - 6.78
References

Umangite is named after the locality of Sierra de Umango, La Rioja province in Argentina. It also occurs at other localities including the Harz Mountains in Germany, and at Skrickerum, Sweden.

This article uses material from the Wikipedia article  Metasyntactic variable, which is released under the  Creative Commons Attribution-ShareAlike 3.0 Unported License.