Dravite

Dravite is a very dark colored (usually brown) form of tourmaline, which is rich in magnesium. It is possible to lighten the color by heat treatment. Dravite shows strong dichroism, and should therefore be cut with the table facet parallel to the length of the crystal. It should be done in order to show a lighter and more attractive color.

The name ‘dravite’ is derived from the district of Drave, in Austria.

Occurrence

Dravite can occur as single crystals, or as parallel or radiating groups. Brown tourmaline and yellow tourmaline occur together in the gem gravels of Sri Lanka. It is also found in the USA, Canada, Mexico, Brazil, and Australia.

Dravite Properties

• Specific Gravity: 3.06
• Refractive Index: 1.61-1.63
• Birefringence (DR): 0.018
• Luster: Vitreous
• Crystal Structure: Trigonal
• Composition: Complex borosilicate
• Hardness: 7½

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Birthstone

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