cassiterite

Cassiterite is a mineral and the most important tin ore. It is tin oxide (SnO2) and serves as the primary source of crude tin. It forms in hydrothermal veins and greisen bodies associated with granitic rocks, and also occurs in alluvial placer deposits where it is concentrated by weathering and transport.

In terms of physical properties, cassiterite has a tetragonal crystal system and commonly forms prismatic crystals with a square cross-section. It ranges in color from pale brown to black, has a white to pale streak, and a resinous to adamantine luster. Its hardness on the Mohs scale is about 6 to 7, and its specific gravity is typically 6.8 to 7.1. Cleavage is imperfect or absent, and the mineral can be transparent to opaque.

Geology and distribution: cassiterite is found worldwide, with major producers in China, Indonesia, Peru, Bolivia, Russia, and the Democratic Republic of the Congo. Historically important deposits have occurred in Malaysia, Thailand, and other tin-producing regions. It is commonly associated with quartz, muscovite, and other tin-bearing minerals in hydrothermal veins, greisen after granitic intrusion, and in alluvial placers.

Mining and processing: cassiterite ore is usually mined by open-pit methods in primary deposits or extracted from alluvial concentrates in placer deposits. Because of its high density, gravity separation methods (such as jigs and spirals) are effective for concentration. The concentrated ore is then smelted and refined to produce metallic tin, often with fluxes to remove oxides and impurities.

Economic significance: as the principal tin ore, cassiterite has long been vital for tin production, which is essential for solder, tinplate, and various electronics applications.