DELAFOSSITE

    Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal system : Trigonal
    Chemistry : CuFeO2
    Rarity : Rare

Delafossite is a rare oxide of copper and iron. It is essentially a secondary mineral from the oxidation zone of copper deposits which is associated with other secondary copper or iron minerals (cuprite, hematite, tenorite, malachite, etc...). It was named in honor of the French mineralogist and crystallographer Gabriel Delafosse. Delafossite forms small tabular to equant crystals (up to 8 mm), botryoidal crusts, spherolites or powdery masses, black in color.

Main photo : Delafossite from Gosenbach, Siegen, Germany © Matthias Reinhardt

Delafossite from Clara Mine, Germany © Michael Förch
Delafossite from Clara Mine, Germany © Gerhard Niceus
Delafossite from Duadello Mine, Fraine, Lombardy, Italy © Enrico Bonacina
Delafossite from Moulinal, Tarn, France © Elise Chaigneau and Eric Penet

Delafossite in the World

Very aesthetic specimens come from Bisbee (Arizona), but beautiful samples are also known at Tsumeb (Namibia), Akjoujt (Mauritania), in Germany, notably in the polymetallic veins of the Black Forest (Clara Mine) and in the Urals ( Russia).

Dawsonite in France

In France, delafossite is reported at Salsigne and the Tistoulet mine (Aude), at Kaymar (Aveyron), at Montroc and at Moulinal (Tarn), at Oms and Fontcouverte (Pyrénées-Orientales) and at Cabrière (Hérault).

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 5.5
Density : 5.41
Fracture : Undetermined
Streak : Black

TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None

Solubility : Sulfuric acid and hydrochloric acid


Magnetism : Paramagnetic
Radioactivity : None

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