Tourmaline
Tourmaline is known as "electric stone" and possesses the unique property of having positive and negative charges at both ends of its crystal. It comes in a wide variety of hues, with specific names for each color. Because of its complex chemical composition containing various elements, it is a fascinating stone both gemologically and mineralogically.
Polychrome tourmaline rough stone
Basic Information
| Chemical Formula | XY₉B₃Si₆O₂₇ (X: Ca,Na,K,Mn / Y: Mg,Fe,Al,Cr,Mn,Ti,Li) |
|---|---|
| Crystal System | Trigonal |
| Hardness | 7–7.5 (Mohs scale) |
| Specific Gravity | 3.03–3.31 (varies by type) |
| Features | Electrical charge (pyroelectricity), complex composition, diverse colors |
Color Variations
- Verdelite (Green)
- Rubellite (Red)
- Siberite (Purplish-red)
- Indicolite (Blue)
- Schorl (Black)
- Achroite (Colorless: very rare)