Formula: SnO2 simple oxide, rutile group
Specific gravity: 6.98 to 7.01
Hardness: 6 to 7
Streak: Brownish white, white, greyish
Colour: Black, yellow, brown, red or white.
Solubility: Slightly soluble in hydrochloric and nitric acid; insoluble in sulphuric acid
Plutonic igneous environments
Cassiterite is widely distributed. It occurs as a primary mineral
pegmatites but it is more commonly found as an unaltered
primary mineral in
hypothermal (high temperature) hydrothermal quartz veins of tin deposits in
granitic rocks. Because of its durability it is also found frequently in
In high temperature quartz veins associated with granitic intrusions cassiterite is often associated with ferberite, molybdenite and arsenopyrite.
At Llallague, Bolivia, cassiterite in hydrothermal veins crystallises at about 300oC (Mineralogy and Petrology 111.547-568).
At Wheal Coates, St Agnes, Cornwall, Engand, UK, a cassiterite pseudomorph after a Carlsbad twin of orthoclase has been found (KL p141).
At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, cassiterite has been found as crystals to several centimetres and as masses to 60 cms. Sometimes it is found in intimate intergrowth with columbite group species. The Emmons pegmatite is an example of a highly evolved boron-lithium-cesium-tantalum enriched pegmatite (R&M 94.6.505-506).
Common impurities: Fe,Ta,Nb,Zn,W,Mn,Sc,Ge,In,Ga
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