Stannite


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stannite

[′sta‚nīt]
(mineralogy)
Cu2FeSnS4 A steel-gray or iron-black mineral crystallizing in the tetragonal system and occurring in granular masses; luster is metallic, hardness is 4 on Mohs scale, and specific gravity is 4.3-4.53. Also known as bell-metal ore; tin pyrites.

Stannite

 

a mineral of the sulfide class, with the chemical composition Cu2FeSnS4. Stannite contains 29.58 percent Cu, 12.99 percent Fe, 27.5 percent Sn, and 29.8 percent S, as well as admixtures of Zn, Sb, Cd, Pb, and Ag. High-temperature stannite, which occurs in pegmatites, quartz-feldspar veins, and greisens, has isometric symmetry; low-temperature stannite, a widespread mineral of cassiterite-sulfide deposits, has tetragonal symmetry and a crystal structure similar to that of chalcopyrite.

Stannite occurs as fringes around grains of cassiterite and chalcopyrite, as solid granular masses, and as faceted grains of pseu-dotetrahedral and more intricate shapes. The mineral has a steel-gray color with an olive-green tint. Its hardness on Mohs’ scale is 3–4.5, and its density is 4,300–4,500 kg/m3. Stannite is brittle and a good conductor of electricity. It is formed in hydrothermal deposits and, less frequently, in pegmatites and greisens in association with wolframite, chalcopyrite, cassiterite, sphalerite, gray copper ore, and pyrrhotite.

The largest known accumulations of stannite in the USSR are in Primor’e Krai (Dal’negorsk deposit), the Northeast (Kheta), and Central Tadzhikistan (Mushiston). Abroad, there are large deposits in Bolivia (Potosí, Atocha). In sufficient concentrations, stannite may be used as a tin ore.

A. B. PAVLOVSKII

References in periodicals archive ?
Bornite occurs as thin films on pyrite, as an alteration product of stannite (Ahlfeld and Munos Reyes, 1955).
Chalcocite has been described as an alteration product of stannite (Ahlfeld and Munos Reyes, 1955).
Covellite is seen commonly as thin films with chalcocite, both species having weathered from stannite.
The best known cylindrite specimen from Llallagua, showing cylindrite crystals on stannite, is in the Bandy Collection, Natural History Museum of Los Angeles County.
Fluorapatite crystals from the Contacto vein (on Level 250 and above Level 295) commonly are on stannite matrix and have associated jeanbandyite.
The species was identified on 36 specimens of massive stannite in the Bandy collection, most of which contain prominent crystals of colorless, blocky to tabular fluorapatite to 5 cm.
Sphalerite is common at Llallagua, in crystals to 1 cm, commonly wholly or partially replaced by younger stannite.
Stannite is much less common at Lllallagua than at Oruro, but its few surviving specimens are very probably the world's best for the species, even better than the new Chinese specimens from Yaogangxian.
Stannite at Llallagua is black to brownish steel-gray and usually massive.
Over the ensuing years, these specimens have been followed by more than 30 "best of species," including orange scheelite crystals to 20 cm, lustrous black cassiterite crystals to 15 cm, ferberite, arsenopyrite, fluorite of all colors, pyromorphite, mimetite, and rarities such as kermesite, helvite, stannite, kesterite and even common minerals such as calcite and quartz.
The sulfides and Sulfosalts are very well represented, most notably arsenopyrite, bismuthinite, bournonite, cylindrite, franckeite, pyrargyrite, pyrite, stannite, stibnite, teallite, and wurtzite Among the oxides, cassiterite and quartz are most important and siderite is the most important carbonate.