Topaz from Topaz Mountain, Utah
Topaz crystals from Mexico
Crude "lumps" of Topaz from Brazil.
CHEMISTRY - Al2SiO4(F,OH)2
CRYSTALLOGRAPHY - Orthorhombic
CRYSTAL GROWTH AND HABITS - Single well formed crystals are common, usually with complex face development. Normally topaz crystals are prismatic with striations parallel to the "C" axis. It can also be columnar and massive.
COLOR AND OPTICAL PROPERTIES - Topaz has a large range of colors - clear, brown, pink, blue, reddish, green or violet. It is transparent to translucent.
HARDNESS - 8
SPECIFIC GRAVITY - 3.49 - 3.57
LUSTER - Vitreous
STREAK - White
BREAKABILITY - Excellent basal {001} cleavage with an uneven to subconchoidal fracture.
OCCURRENCE - Topaz is found in granite, rhyolite, granitic pegmatite and high temperature, gas rich hydrothermal deposits. It can also be formed through high grade metamorphism of aluminum rich fluorine containing sediments.
ASSOCIATED MINERALS - Quartz, Tourmaline, Beryl, Microcline, Albite, Fluorite, Garnet, Cassiterite, Hematite, Bixbyite.
MINERAL NAME - From the Greek "topazion" meaning to seek in reference to the Island of Zabirget in the Red Sea. This island was known for its olivine gemstones (peridot and chrysolite) which were referred to as "Topaz".