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Mohs scale of mineral hardness Reference Libraries

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Corundum
2005-05-26 11:05:25

Corundum is the crystalline form of aluminium oxide and one of the rock-forming minerals. Corundum is naturally clear, but can have different colors when impurities are added. Transparent specimens are used as gems, called ruby if red, while all other colors are called sapphire. The word corundum comes from the Hindi kurand. The oxygen atoms in corundum are arranged in a hexagonal...

Word of the Day
baudekin
  • A rich embroidered or brocaded silk fabric woven originally with a warp of gold thread.
'Baudekin' seems to be an alternative form of 'baldachin,' from the Italian 'Baldacco,' Baghdad, the city where the material was made.
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