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Superhard materials 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
ultimo
  • In the month which preceded the present; in the last month, as distinguished from the current or present month and all others.
  • In the month which preceded the present; in the last month, as distinguished from the current or present month and all others.
The word 'ultimo' comes from the Latin phrase 'ultimo mense', 'in the last month'.
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