Outstanding grass green crystals of obradovicite from the type locality in Chile (Chuquicamata Mine, Chuquicamata, Calama, El Loa Province, Antofagasta Region, Chile). Ex Vandenbroucke Museum collection specimen, from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Obradovicite-KCu
Obradovicite-KCu is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula [K₂(H₂O)₁₇Cu(H₂O)₆][Mo₈As₂Fe³⁺₃O₃₄(OH)₃].
It crystallizes in the orthorhombic crystal system (space group Pcnm). It is a member of the Betpakdalite structural group.
Key properties: Mohs hardness 2.5; specific gravity 3.55; Pale pea-green streak; Vitreous to subadamantine luster; optically biaxial.
IMA symbol Obr-KCu, IMA status: approved, named in 1978.
A rare secondary mineral found in the oxidized zone of a Cu-Mo porphyry deposit.
It is found associated with Obradovicite-NaCu, jarosite, wulfenite, quartz.
The mineral was named to honor Martin T. Obradovic, who provided the studied material. Two suffixes correspond to the dominant cations in the two different types of non-framework cation sites.