Garnet

Garnet forms a group of complex silicate minerals, all of which crystalline in the cubic system. Their hardness varies from 6.5.to 7.5 and their specific gravity ranges from 3.15 to 4.3. They occur in a variety of colors and produce a white streak. Garnets commonly occur in igneous and metamorphic rocks. The transparent, garnets are used as gem stones, they are used as an abrasive when they are non-transparent.