delafossite

{{infobox mineral | name = Delafossite | image = Cuprite-Delafossite-133433.jpg | imagesize = 260px | alt = | caption = Discrete, wine-red cuprite crystals on matrix covered by brightly reflective delafossite microcrystals | category = Oxide minerals | formula = CuFeO2 | IMAsymbol = Del | molweight = | strunz = 4.AB.15 | dana = | system = Trigonal | class = Hexagonal scalenohedral (m) H-M symbol: ( 2/m) | symmetry = Rm | unit cell = a = 3.04, c = 17.12 [Å]; Z = 3 | color = Black | colour = | habit = Tabular to equant crystals; botryoidal crusts, spherulitic, powdery, massive | twinning = Contact twins on {0001} | cleavage = Imperfect on {101} | fracture = | tenacity = Brittle | mohs = 5.5 | luster = Metallic | streak = Black | diaphaneity = Opaque | gravity = 5.41 | density = | polish = | opticalprop = Uniaxial | refractive = | birefringence = | pleochroism = Distinct; O = pale golden brown; E = rose-brown | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = Weakly magnetic | prop1 = Strongly anisotropic | prop1text = | references = }}

Delafossite is a copper iron oxide mineral with formula CuFeO2 or Cu1+Fe3+O2. It is a member of the delafossite mineral group, which has the general formula ABO2, a group characterized by sheets of linearly coordinated A cations stacked between edge-shared octahedral layers (BO6). Delafossite, along with other minerals of the ABO2 group, is known for its wide range of electrical properties, its conductivity varying from insulating to metallic. Delafossite is usually a secondary mineral that crystallizes in association with oxidized copper and rarely occurs as a primary mineral.