ABOUT TOURMALINE

ABOUT TOURMALINE

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Tourmaline’s colors have many different causes. It’s generally agreed that traces of iron, and possibly titanium, induce green and blue colors. Manganese produces reds and pinks, and possibly yellows. Some pink and yellow tourmalines might owe their hues to color centers caused by radiation, which can be natural or laboratory-induced.

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BIRTHSTONES & ANNIVERSARIES

Tourmaline is a birthstone for October, along with opal. Tourmaline is also the gem of the eighth anniversary.

1554

Francisco Spinoza’s expedition discovers “Brazilian emerald”: the first recorded green tourmaline crystal.

PYROELECTRIC

Tourmaline becomes electrically charged when heated. Also when squeezed: it’s piezoelectric too.

PARAIBA

Brazilian source famous for vivid blue to green tourmalines colored by copper.

FACTS

• MINERAL: Tourmaline
• CHEMISTRY: 
• Elbaite Na(Li_1.5,Al_1.5)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
• COLOR: All colors
• 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