Cupalite
| Cupalite | |
|---|---|
| General | |
| Category | Native element class, alloy |
|
Formula (repeating unit) |
(Cu,Zn,Fe)Al |
| Strunz classification | 1.AA.20 |
| Crystal system |
Orthorhombic Unknown space group |
| Identification | |
| Color | Steel-gray yellow |
| Mohs scale hardness | 4-4.5 |
| Luster | Metallic |
| Specific gravity | 5.12 g/cm3 |
| Other characteristics | non-magnetic, non-radioactive |
| References | |
Cupalite is a rare mineral which is mostly composed of copper and aluminium, but might contain up to several percent of zinc or iron; its chemical structure is therefore described by an approximate formula (Cu,Zn)Al or (Cu,Fe)Al. It was discovered in 1985 in placers derived from serpentine, in association with another rare mineral khatyrkite (CuAl2). Both minerals are thus far restricted to the area of Listvenitovyi Stream, in the Khatyrka ultramafic (silicon-poor) zone of the Koryak–Kamchatka fold area, Koryak Mountains, Beringovsky District, Chukotka Autonomous Okrug, Far Eastern Federal District, Russia. The mineral name derives from cuprum (Latin for copper) and aluminium. Its holotype (defining sample) is preserved in the Mining Museum in Saint Petersburg, and parts of it can be found in other museums, such as Museo di Storia Naturale di Firenze.
Cupalite forms dendritic, rounded or irregular grains, typically below 0.1 millimeter in size, which are intergrown with khatyrkite. They have an orthorhombic crystal structure with a yet uncertain space group and the lattice constants a = 0.695(1) nm, b = 0.416(1) nm, c = 1.004(1) nm, and 10 formula units per unit cell. Their Mohs hardness is between 4 and 4.5 and Vickers hardness is in the range 272–318 kg/mm2 for a 20–50 gram load.
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