Needle like sprays of delafossite (SEM-EDS). From: San Miguel Mine, Vall de Ribes mining district, Ribes de Freser, Girona, Catalonia, Spain. — Photo: Joan Rosell , from rosellminerals.com · CC BY 4.0
Delafossite
A copper-iron oxide whose layered ABO₂ structure stacks linear copper sheets between octahedral iron layers — namesake of the delafossite group.
Intro adapted from Wikipedia (CC BY-SA).
Delafossite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Cu¹⁺Fe³⁺O₂.
It crystallizes in the trigonal crystal system (space group R-3m).
Key properties: Mohs hardness 5.5; specific gravity 5.41; Black streak; Metallic luster; optically uniaxial.
IMA symbol Del, grandfathered status — known before the IMA’s founding, named in 1873.
Principally as a secondary mineral near the base of the oxidized zone of copper deposits; less commonly a primary mineral.
It is found associated with Cuprite, copper, tenorite, malachite, hematite, kaolinite.
The name refers to the French mineralogist and crystallographer, Gabriel Delafosse (1796–1878).