Locality: Clara Mine, Rankach valley, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany Field of view: 2.12 mm Copyright © Gerhard Niceus

Chemical Formula: CuFeO2
Locality: Calumet and Arizona mine, Bisbee, Cochise Co., Arizona, USA.
Name Origin: Named for Gabrial Delafosse (1796-1878), French mineralogist and crystallographer.

Delafossite is a copper iron oxide mineral with formula CuFeO2 or Cu1+Fe3+O2. It is member of the delafossite mineral group with a general formula ABO2, a group characterized by a sheet of linearly coordinated A cations stacked between edge-shared octahedral layers (BO6).

Delafossite along with other minerals of the ABO2 group has been recognized for its electrical properties from insulation to metallic conduction. Delafossite is usually a secondary mineral that crystallizes near oxidized copper and is rarely a primary mineral.

Geologic occurrence

In 1873, delafossite was discovered by Charles Friedel in a region of Ekaterinbug, Siberia. Since its discovery it has been identified as a fairly common mineral found in such places as the copper mines of in Bisbee, Arizona. Delafossite is usually a secondary mineral often found in oxidized areas of copper deposits although it can be a primary mineral as well. Delafossite can be found as massive, relatively distinct crystals on hematite. Delafossite has since been found in mines around the world from Germany to Chile.

Physical Properties of Delafossite

Cleavage: {1010} Indistinct
Color: Black.
Density: 5.41
Diaphaneity: Opaque
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Hardness: 5.5 – Knife Blade
Luminescence: Non-fluorescent.
Luster: Metallic
Magnetism: Magnetic after heating
Streak: black

Photo :

This sample of delafossite is displayed in the Smithsonian Museum of Natural History. This sample is about 10×10 cm overall. It is from Calumet and Arizona Mine, Cochise County, Arizona.
Delafossite, Cuprite Locality: Le Moulinal Mine, Saint-Jean-de-Jeannes, Paulinet, Alban, Tarn, Midi-Pyrénées, France Dimensions: 41 mm x 35 mm x 31 mm Field of View: 9 mm Copyright © Pascale & Daniel Journet
Delafossite, Copper Locality: Clara Mine, Rankach valley, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany FOV: 3 mm. Copyright © Stephan Wolfsried