Indicolite
Variety Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
Also called Blue tourmaline and Indigolite
About it
Blue tourmaline, often very dark when viewed down the long axis of the crystal. Brazil, Namibia, and Afghanistan produce it; bright blue stones are among the costliest tourmalines.
- Type
- Variety
- Group
- Elbaite variety (tourmaline)
- Formula
- Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
- Hardness (Mohs)
- 7–7.5
- Specific gravity
- 3–3.26
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Trigonal
- Colours
- blue, greenish blue, dark blue
- Transparency
- transparent, translucent
- Cleavage and fracture
- poor; uneven to conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.