Auricupride

Auricupride
240px Auricupride
General
Category	Native elements
Formula (repeating unit)	Cu3Au
Strunz classification	01.AA.10a
Dana classification	1.1.2.1
Identification
Formula mass	387.60 gm
Color	Yellow with reddish tint
Crystal system	Orthorhombic
Fracture	Malleable
Mohs scale hardness	3½
Luster	Metallic
Streak	yellow
Diaphaneity	Opaque
Ultraviolet fluorescence	Non-fluorescent

Auricupride is a natural alloy that combines copper and gold. Its chemical formula is Cu₃Au. The alloy crystallizes in the Cubic crystal system and occurs as malleable grains or platey masses. It is an opaque yellow with a reddish tint. It has a hardness of 3.5 and a specific gravity of 11.5.

A variant called tetra-auricupride (CuAu) exists. Silver may be present resulting in the variety argentocuproauride (Cu₃(Au,Ag)).

It was first described in 1950 for an occurrence in the Ural Mountains Russia. It occurs as low temperature unmixing product in serpentinites and as reduction "halos" in redbed deposits. It is most often found in Chile, Argentina, Tasmania, Russia, Cyprus, Switzerland and South Africa.

External links

• National Pollutant Inventory - Copper and compounds fact sheet