Auricupride

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 not Radioactive.

It was named for the gold and copper in the composition, which in Latin are aurum and cuprum, respectively. It is a rare mineral that can be found in localities in Russia, the island of Cyprus, Switzerland, Chile, and additional localities in Argentina, South Africa, Australia, the Czech Republic, and Greece.

General Information

  • Category: Native elements
  • Formula: Cu3Au
  • Crystal system: Cubic
  • Crystal class: Hexoctahedral (m3m)
  • Transparency: Opaque
  • Color: Pink.

Properties

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)).

  • Formula mass: 387.60 g/mol
  • Color: Yellow with reddish tint
  • Fracture: Malleable
  • Mohs scale hardness: 3.5
  • Luster: Metallic
  • Streak: yellow
  • Diaphaneity: Opaque
  • Ultraviolet fluorescence: Non-fluorescent.

Occurrence

It was first described in 1950 for an occurrence in the Ural Mountains Russia. It occurs as a 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.

In serpentinites as the product of low-temperature ordering and unmixing of Au–Cu solid solution alloys (Karabash deposit, Russia); in reduction halos in Permian red beds (near Zurich, Switzerland).

 

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