Tourmaline
is the most colorful of all gemstones. It occurs in all colors, but pink, red, green, blue and multicolored are its most well-known gem colors. Scientifically, tourmaline is not a single mineral, but a group of minerals related in their physical and chemical properties. The mineral Elbaite is the member of the Tourmaline group that is responsible for almost all the gem varieties. Three other members of the group - Schorl, Dravite and Liddicoatite, are seldom used as gemstones.
| Chemical Formula | Tourmaline is a series of several different minerals with unique chemical formulas. See The chemical formula of Tourmaline for details. |
| Color | White, Colorless, Blue, Red, Green, Yellow, Orange, Brown, Pink, Purple, Gray, Black, Multicolored |
| Hardness | 7Â -Â 7.5 |
| Crystal System | Hexagonal |
| Refractive Index | 1.616Â -Â 1.650 |
| SG | 2.9Â -Â 3.3 |
| Transparency | Transparent to opaque |
| Double Refraction | .018 |
| Luster | Vitreous |
| Cleavage | 3,2 |
| Mineral Class | Tourmaline |
is the most colorful of all gemstones. It occurs in all colors, but pink, red, green, blue and multicolored are its most well-known gem colors. Scientifically, tourmaline is not a single mineral, but a group of minerals related in their physical and chemical properties. The mineral Elbaite is the member of the Tourmaline group that is responsible for almost all the gem varieties. Three other members of the group - Schorl, Dravite and Liddicoatite, are seldom used as gemstones.
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