Auricupride

Auricupride is a natural alloy that combines copper and gold. Its chemical formula is Cu3Au. The alloy crystallizes in the cubic crystal system in the L12 structure type 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.[2]

Auricupride
Auricupride
General
CategoryNative elements
Formula
(repeating unit)		Cu3Au
Strunz classification1.AA.10a
Dana classification1.1.2.1
Crystal systemCubic
Crystal classHexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space groupPm3m
Identification
Formula mass387.60 g/mol
ColorYellow with reddish tint
FractureMalleable
Mohs scale hardness​3 1⁄2
LusterMetallic
Streakyellow
DiaphaneityOpaque
Ultraviolet fluorescenceNon-fluorescent
References[1][2][3][4]

A variant called tetra-auricupride (CuAu) exists. Silver may be present resulting in the variety argentocuproauride (Cu3(Au,Ag)).[1]

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.[2][1]

References
  1. "Auricupride: Auricupride mineral information and data". Mindat.org.
  2. http://www.handbookofmineralogy.org/pdfs/auricupride.pdf Handbook of Mineralogy
  3. Mineralienatlas
  4. Webmineral
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