GARNET

Chemical Composition: X 3 Y 2 (SiO 4 ) 3
Refractive Index: 1.70 – 1.89
Specific Gravity: 3.3 – 4.2
Crystal System: Cubic
Moh's Hardness: 6 ½ - 7 ½

Garnets are an isomorphous stone split between two groups and have the same general chemical formula. In series one, Y is always aluminium (Al), where X can be magnesium (Mg), iron (Fe), or manganese (Mn). In series two, X is always calcium (Ca), where Y can be chromium (Cr), aluminium (Al) or iron (Fe). Almandine type garnets colour ranges from brownish red to purple red and a pale to deep mauve. Common localities include Brazil, India, Madagascar, Sri Lanka.

Pyrope type garnets colour ranges from red to purplish red. Minor amounts of chromium and or iron make this range red. Common localities include South Africa, Sri Lanka, Russia and USA.

Tsavorite garnets colour ranges from a bright yellowish green to the bluish

green. Common localities include Tanzania, Zambia, Madagascar.

Rhodolite garnets colour are a light purple red