Cassiterite
Image: Alchemist-hp (talk) (www.pse-mendelejew.de) (GFDL 1.2)
Mineral NameCassiterite
Chemical FormulaSnO2
Mohs Hardness6.5
Crystal Systemtetragonal
Lusteradamantine
Streak Colorwhite to brownish-white
Cleavagedistinct on {100} and {110}
Fractureuneven to subconchoidal
Specific Gravity7
Colorsblack, brown, reddish-brown
Transparencyopaque
Type LocalitySoutheast slope Xuebaoding, Pingwu country, province Sichuan in China
Mineral GroupOxides
Usestin ore, collector specimens
Associated Mineralsquartz, tourmaline, topaz, fluorite, wolframite
Rarityuncommon
Description
Two dark, bipyramidal cassiterite crystals, each with an edge length of approximately 30mm, displaying a sub-metallic to adamantine luster and some surface striations.
Geological Context
Cassiterite typically forms in high-temperature hydrothermal veins, pegmatites, and greisens associated with granitic intrusions. It is also found in placer deposits due to its high specific gravity and resistance to weathering.
