Cassiterite

cassiterite

[kə′sid·ə‚rīt]

(mineralogy)

SnO₂ A yellow, black, or brown mineral that crystallizes in the tetragonal system in prisms terminated by dipyramids; the most important ore of tin. Also known as tin stone.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Cassiterite

 

(or tinstone), a mineral with the chemical composition Sno₂. Theoretically it contains 78.62 percent Sn but usually includes impurities of Nb, Ta, Zr, Sc, W, and Fe; thus, the Sn content varies within 68–78 percent.

Cassiterite crystallizes in the tetragonal system, forming prismatic or dipyrimidal crystals. Geniculated twins are characteristic. The crystalline structure is analogous to that of rutile. Cassiterite is usually encountered in the form of small and large crystals, drusoid aggregates, or compact granular masses as well as in the form of cryptocrystalline, colloform segregations, concretions, and sinter formations. The color is dark brown, almost black, yellow with a reddish brown cast; nearly colorless varieties are also known. Cassiterite has an adamantine luster, a hardness of 6–7 on the mineralogical scale, and a density of 6, 040–7, 120 kg/m³ (lowest in light-colored cassiterite).

The deposits are usually genetically linked with granitic rocks. The most interesting commercial accumulations of the mineral are characteristic for hydrothermal quartz-cassiterite and sulfide-cassiterite veins. Cassiterite is stable in zones of oxidation and surface weathering; with the destruction of primary deposits, it accumulates in placers. In the USSR, cassiterite deposits are found in the northeast in Primor’e, in Middle Asia, and in the Kazakh SSR. Abroad, it is found in Malaysia, Thailand, Indonesia, the People’s Republic of China, Bolivia, Nigeria, and elsewhere. Cassiterite is the chief ore for obtaining tin.

A. B. PAVLOVSKII

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.