Tourmaline
Tourmalines have a variety of exciting colours with one of the widest colour ranges of any gem. Comes in many colours, including the remarkable intense violet-to-blue gems particular to Paraíba, Brazil, and similar blues from Africa. Favourite of mineral collectors.
Birthstones & Anniversaries
Tourmaline is a birthstone for October, along with opal. Tourmaline is also the gem of the eighth anniversary.
Facts
Mineral: Tourmaline
Chemistry:
Elbaite Na(Li1.5,Al1.5)Al6Si6O18(BO3)3(OH)4
Dravite NaMg3Al6Si6O18(BO3)3(OH)4
Liddicoatite Ca(Li2Al)Al6Si6O18(BO3)3(OH)3F
Chromedravite NaMg3Cr6Si6O18(BO3)3(OH)4
Colour: All colours
Refractive index: 1.624 to 1.644
Birefringence: 0.018 to 0.040
Specific gravity: 3.06 (+0.20, -0.06)
Mohs Hardness: 7 to 7.5
