| Name: Lazurite |
Origin of name: from the Persian lazhward, meaning blue |
Chemical composition: [(Na,Ca)8(Al,Si)12O24(SO4,Sn)] |
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Lazurite is usually massive or compact in form, rather than crystalline. It forms in limestones which have been metamorphosed at high temperature.
Lazurite is the main component of the precious decorative stone, lapis lazuli, which is shown in the illustration here. In lapis, lazurite is often associated with blue sodalite, white calcite and golden streaks and specks of pyrite, Lapis lazuli has been highly-valued for over 6,000 years, for use in jewellery, carvings, mosaics and decorative inlays. In powdered form, it was used as pigment for paints, producing an intense blue colour. |
Crystal system: cubic |
| Class: Silicates |
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| Hardness: 5.0-5.5 |
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| Cleavage: imperfect |
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| Colour: deep blue |
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| Specific gravity: 2.4-2.5 |