Tourmaline
October's Birthstone

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CHEMISTRY Elbaite, Na(Li,Al)₃Al₆B₃Si₆O₂₇(OH)₃(OH,F)
CRYSTALLOGRAPHY Hexagonal
REFRACTIVE INDEX 1.603 - 1.655
HARDNESS 7 - 7.5
SPECIFIC GRAVITY 2.84 - 3.10
CLEAVAGE No
HEAT SENSITIVE Some

WEARABILITY* Very Good
SPECIAL CARE INSTRUCTIONS Multicolored gems are often weak where the colors meet

ENHANCEMENTS Heat treatment, common on dark gems, otherwise occasional. Irridation, occasional.

*Wearability is graded as Excellent, Very Good, Good, Poor, and Forget It!
For more details see the article on "Hardness and Wearability."

... See natural Tourmaline gemstones of all varieties including Paraiba tourmaline.

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