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Tourmaline

Members of the tourmaline family of minerals have the same basic crystal structure, but occur in many different colours. Rubellite (from the Latin for red) is the name given to the pink or red variety, with ruby-red stones the most highly prized. Rubellite crystals are striated, with a triangular cross-section and a rounded outline. They may also occur with a fibrous habit, and show a cat’s-eye when cut en cabochon.

Occurrence

Russian pink and red tourmaline occurs in weathered granites. Other sites include Madagascar, the USA, Burma, Brazil, and East Africa.

Remark

The specific gravity of tourmaline varies with colour; dark red has a higher SG than pink.

Crystal structure	Trigonal
Composition	Complex borosilicate
Hardness	7.5
SG	3.06
Rl	1.62-1.64
DR	0.018
Lustre	Vitreous