Garnet

Garnet are a group of silicate minerals that used since the Bronze Age as gemstones and abrasives. Garnets possess similar physical properties and crystal forms but different chemical compositions. The different species are pyrope, almandine, spessartine, grossular, uvarovite and andradite.

Garnet species found in many colors including red, orange, yellow, green, purple, brown, blue, black, pink and colorless. The rarest of these is the blue garnet, discovered in the late 1990s in Bekily, Madagascar. It changes color from blue-green in the daylight to purple in incandescent light, as a result of the relatively high amounts of vanadium.

Because the chemical composition of garnet varies, the atomic bonds in some species are stronger than in others. As a result, this mineral group shows a range of hardness on the Mohs scale of about 6.5 to 7.5. The harder species like almandine often used for abrasive purposes.