Melonite: Properties and Occurrences

Melonite is a nickel telluride mineral. It is a telluride of nickel; it is a metallic mineral. A nickel telluride which occurs in reddish-white granular forms with metallic luster: found in California and also in Colorado. Its chemical formula is NiTe2. It is opaque and white to reddish-white in color, oxidizing in the air to a brown tarnish.

It was first described from the Melones and Stanislaus mine in Calaveras County, California in 1866, by Frederick Augustus Genth.

General Information

  • Category: Sulfide minerals
  • Formula: (repeating unit) NiTe2
  • Crystal system: Trigonal
  • Crystal class: Hexagonal scalenohedral (3m)
  • Color: White, reddish-white.

Properties

It has a specific gravity of 7.72 and a hardness of 1–1.5 (very soft). It an opaque reddish-white mineral that crystallizes in the trigonal system and occurs as hexagonal scales.

  • Formula mass: 313.89 g/mol
  • Crystal habit: Crystalline, foliated, granular
  • Cleavage: {0001} Perfect
  • Fracture: Brittle
  • Mohs scale hardness: 1–1.5
  • Luster: Metallic
  • Streak: Dark gray
  • Diaphaneity: Opaque
  • Specific gravity: 7.72
  • Density: 7.3
  • Ultraviolet fluorescence: None

Occurrence: Melonite occurs as trigonal crystals, which cleave in a (0001) direction. With other tellurium minerals in the late stages of hydrothermal veins formed at medium to low temperatures. Also in high-temperature Ni–Cu–PGE magmatic sulfide deposits. Melonite is usually found associated with other tellurides in quartz veins. Famous deposits are the Californian quartz veins, Cripple Creek Colorado, and Kalgoorlie Western Australia.

Association: Altaite, petzite, hessite, calaverite, coloradoite, krennerite, tellurobismuthite, montbrayite, gold, pyrite, chalcopyrite, pentlandite, pyrrhotite.

 

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