Sapphires Hardest Mineral After Diamonds
|Countries where sapphires have been discovered. Sapphire country list is in alphabetical order.|
|Brazil||Kenya||Pakistan||– North Carolina|
|Burundi||Madagascar||Sierra Leone||– Montana|
|Cambodia||Malawi (PKA Nyasaland)||Sri Lanka (PKA Ceylon)||Vietnam|
|China||Myanmar (PKA Burma)||Tanzania|
THE MINERAL CORUNDUM
Corundum is best known for its gem varieties, Ruby and Sapphire. Ruby and Sapphire are scientifically the same mineral but just different colors. Ruby is the red variety, and Sapphire is the variety that encompasses all other colors, although the most popular and valued color of Sapphire is blue. Sapphire is also only used to describe the gem variety, otherwise it is simply called Corundum.
Corundum is a very hard, tough, and stable mineral. For all practical purposes, it is the hardest mineral after Diamond, making it the second hardest mineral. It is also unaffected by acids and most environments. Translucent brown Corundum and Emery are the most common forms of Corundum. These are fairly common forms, and due to their great hardness and prevalence are the most favorable abrasives. The industrial term “emery” describing Corundum abrasives is derived from the variety Emery which is mined specifically for its use as an abrasive. Erosion may cause Emery to crumble and form sand, which may be called “black sands”.
Corundum is easily synthesized, and many Corundum abrasives are synthetic. Synthetic gems are also easily created by adding traces of certain color producing elements to the Corundum solution, and letting the solution solidify into a boule, or synthetic, unprocessed “mineral” with a particular shape. This process is called the Verneuil process.
Natural Ruby and Sapphire gemstones may have their color artificially enhanced or deepened through heat treatment when used as gems. Some dark blue stones from certain localities may also be made a bright blue desirable color.