Monthly Archives June 2009

Spinel and its properties

Spinel (MgAl2O4) is a gemstone that has often been mistaken for ruby. Due to its hardness of 8 on the Mohs scale, spinel is only a shade less hard than ruby, which is 9. Its specific gravity is also similar to ruby. Many famous “rubies” in history were actually spinels. It crystallizes as octahedrons which may appear as twin crystals embedded in rock or deposited as pebbles in gravel (in Myanmar). This mineral is in fact rarer than ruby now; at one time it was plentiful in India. Now, the main deposits are concentrated in Myanmar, Tajikistan, and Sri Lanka.
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