What is "umangite"

n. A selenide mineral, with chemical formula Cu₃Se₂, blue to red in color.

Umangite is a copper selenide mineral, Cu Se, 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 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.