Thursday, August 28, 2014

Corundum


Corundum is a type of gem stone that can be many different colors, red, yellow, pink-orange, green or blue.

If the corundum is red, it is called a ruby. Otherwise it is called a sapphire.

Corundum is very hard and rough, is sometimes used on sandpaper or on large cutting machines.
corundum
(from: wikipedia - corundum)


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