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CORUNDUM

Overview:The name Corundum was derived either from the Sanskrit word "kurivinda" or from the Indian name for corundum "kauruntaka". 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.These stones have a six-ray star visible from almost any angle. Very fine needles of rutile within the corundum cause this star.Corundum gemstones are the second hardest of the most precious of gemstones.Corundum comes in many colors, and any color other than red is referred to as 'sapphire'

Usage:Due to corundum's hardness, it is commonly used in as an abrasive in machining, from huge machines to sandpaper. Corundum that has been synthetically manufactured from bauxite is most

often used for this purpose. It is also said to help release negative emotions in constructive ways while giving give inner peace.

Physical Properties:

Corundum

Corundum  Birthstone

Color
Brown to grey, less often red, blue, white, yellow.
Hardness
9
Specific Gravity
3.95 - 4.1
refractive index 
1.76 - 1.78

Sign of Corundum: Sagittarius

Legend:

Large specimens of Corundum crystals are rare,

although the 563-carat Star of India can be seen in the A

merican Museum of Natural History. There is the milky

corundum, a white opaque form of corundum also called

geuda, which for many years was regarded as useless

and discarded, often ending up lining fish tanks.

Occurrence:

Sri Lanka, Thailand, America, Cambodia, Burma,

Australia, India, and Tanzania have Corundum.