Sapphire



FormulaAl2O3
ColorMostly blue, but also anything but red
LusterVitreous
Hardness9
TransparencySemi-Transparent
StreakWhite
CleavageDoes not cleave
FractureConchoidal
LocalitySoutheast Asia and Australia

Sapphire is a variety of corundrum that can take on any color except red, which is classified as ruby. Some sapphires are even composed of various colors and are worth considerably more than the mono-color varieties. The different colors are dependent on the concentration of different impurities, such as iron and titanium. Pure sapphire is colorless and totally transparent.

The hardness of sapphires is remarkable and rivals that of diamonds. Sapphires are mostly used for jewelry and laser applications. In jewelry, it has proved useful for creating watch faces that rarely, if ever, scratch due to the harness of the crystal.

Sapphire is frequently synthesized using the Verneuil process and can be grown to sizes of several inches in diameter. Synthesized sapphire is used mostly for lasers, but it has also proved useful as a substrate for growing semiconductors for light emitting diodes.

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