Millerite (redirected from Nickel sulfide)

millerite [′mil·ə‚rīt]

(mineralogy)

NiS A brass to bronze-yellow mineral that crystallizes in the hexagonal system and usually contains trace amounts of cobalt, copper, and iron; hardness is 3-3.5 on Mohs scale, and specific gravity is 5.5; it generally occurs in fine crystals, chiefly as nodules in clay ironstone. Also known as capillary pyrites; hair pyrites; nickel pyrites.

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Millerite 

(named after the British crystallographer W. Miller [1801–80]), a mineral of the sulfide class; nickel sulfide, NiS, containing 64.7 percent Ni and 35.3 percent S. Millerite crystallizes in the trigonal system, forming characteristic slender brass-yellow hairlike crystals. It also forms fibrous, radiating, and other kinds of aggregates. Millerite has a hardness of 3–4 on Mohs’ scale and a density of 5,200–5,600 kg/m³. It occurs rarely in nature, usually in hydrothermal ore veins in association with other Ni and Co sulfides and arsenides, which are contained in copper-nickel ores (in Noril’sk and Monchegorsk in the USSR). Millerite is also formed during the sur-face weathering of nickel-bearing ultrabasic rocks by acidic surface waters saturated with H₂S.

REFERENCE

Mineraly: Spravochnik, vol. 1. Moscow, 1960.