Smaltite

smaltite (smôl`tīt), opaque tin-white to steel-gray mineral of the pyrite group, a compound of cobalt and arsenic. It occurs in massive form, occasionally in crystals (cubes) of the isometric system. It is an important ore of cobalt and is found in Saxony, Norway, Sweden, and Ontario.

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smaltite [′smȯl‚tīt]

(mineralogy)

(Co,Ni)As_3-xA metallic-gray isometric mineral composed of nickel cobalt arsenide.

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Smaltite 

(also smaltine), a zonal mineral variety of the skut-terudite group of the arsenide class. The chemical composition of smaltite is (Co, Ni, Fe)As_3±x, where x is about 0.1. The Co and Ni substitute for one another without restriction; the Fe content does not exceed 40 atomic percent of the sum of the cations. Isomorphic zonal mixtures in which Co predominates are classified as smaltite, as distinct from mixtures in which nickel predominates, which are called chloanthite.

Smaltite crystallizes in the isometric system, forming cubic or octahedral crystals. It is usually found in the form of solid granular masses. Collomorphic phenocrysts are also common. Smaltite has a tin-white or steel-gray color and a metallic luster. The hardness of individual zones is 5.5–6 on Mohs’ scale; the density is 6,400–6,800 kg/m³.

Smaltite forms during medium-temperature hydrothermal processes in association with other arsenides of cobalt, nickel, and iron and sometimes with uranium, silver, and bismuth minerals. It oxidizes readily at the earth’s surface, becoming coated with crimson to pink erythrite. It is one of the most common minerals in ores of hydrothermal cobalt deposits. Smaltite is a valuable raw material of cobalt; sometimes, silver, bismuth, uranium, and gold are obtained from the same ores.

REFERENCES

Krutov, G. A. Mestorozhdeniia kobal’ta. Moscow, 1959.
Godovikov, A. A. Mineralogiia. Moscow, 1975.