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Chemical Composition: SiO2
Group: Silica
System: Hexagonal
Family: Oxide
Hardness: 7
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- A type of Quartz
- Well formed crystals, sometimes enormous, weighing up
to 130 kg (289 lb)
- Hexagonal and prismatic crystals, terminated by two
rhombohedra resembling hexagonal dipyramids
- Colourless when pure (rock crystal)
- Impurities produce a whole range of colours
- One of the commonest minerals of the earth's crust
(12% by volume)
- This type of quartz turns white when heated to 300
degrees c, then yellow at 500 degrees c
- Found in: Brazil, Canada, Czech Republic, Slovakia,
Sri Lanka, Uruguay, former USSR, Zambia
- Specific gravity: 2.65
- Very common
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