:Locality: Ojuela Mine, Mapimi, Durango, Mexico Size: 4 × 3.5 × 3 cm Description: In this specimen we can observe a matrix formed by goethite and calcite crystals that are partially covered by kobyashevite, a very rare copper hidroxyl sulphate, with a blue-green color. It is accompanied by small needles of gypsum. In the matrix we can observe some yellowish beudantite crystal aggregates. This specimen has been analyzed. New 2017 find in mina Ojuela. Collected: 2017 — Photo: Joan Rosell , from rosellminerals.com · CC BY-SA 4.0
Kobyashevite
Kobyashevite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Cu₅(SO₄)₂(OH)₆·4H₂O.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 2.5; specific gravity 3.16; Bluish green streak; Vitreous luster; optically biaxial.
IMA symbol Kby, IMA status: approved, named in 2011.
Found as a secondary mineral in pyrite-chalcopyrite veins cutting fenites in an alkaline igneous complex.
It is found associated with Calcite, quartz.
The mineral was named to honor Russian mineralogist Yuriy Stepanovich Kobyashev (1935-2009), a specialist on the mineralogy of the Urals.