Greisen

Greisen is a quartz- and mica-rich metasomatic rock formed when hydrothermal fluids alter granite. It commonly hosts tin, tungsten, and other metal deposits.

Metasomatism: Chemical alteration of rock by fluids that add or remove elements. Greisen forms as fluids chemically replace minerals in granite.
Tin ore: Rock or mineral material mined for tin, commonly extracted from cassiterite. Greisen deposits are an important source of tin-bearing ore.
Granite-related mineralization: Ore formation associated with the emplacement and evolution of granitic magmas. Greisen deposits are one expression of mineralization around evolved granites.
Cornwall tin mining: A historic mining industry in southwest England centered on tin and other metals. Cornwall's granite-hosted lodes include greisen alteration linked to tin mineralization.
Hydrothermal alteration: Chemical and mineralogical change in rocks caused by heated aqueous fluids. The fluid-driven alteration process creates greisen's distinctive mineral assemblage.
Cassiterite: A tin oxide mineral and the principal ore of tin. Cassiterite is the main tin mineral found in many greisen deposits.
Pegmatite: An exceptionally coarse-grained igneous rock, commonly formed from volatile-rich residual magma. Greisen and pegmatite can form in related late stages of granite evolution.
Erzgebirge: A mountain region on the Germany–Czechia border with a long history of mining. The Erzgebirge contains granite-related tin and tungsten deposits associated with greisen.
Granite: A coarse-grained intrusive igneous rock composed mainly of quartz and feldspar. Granite is the usual precursor rock that greisen-forming fluids alter.
Wolframite: A family of iron-manganese tungstate minerals and a major source of tungsten. Wolframite can concentrate in greisen-associated tungsten ores.

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