Benitoite
Mineral BaTiSi3O9
About it
Sapphire-blue triangular crystals with black neptunite on white natrolite, found in gem quality only at the Dallas Gem mine, San Benito County; California's state gem.
- Type
- Mineral
- Group
- Silicate (cyclosilicate), benitoite group
- Formula
- BaTiSi3O9
- Hardness (Mohs)
- 6–6.5
- Specific gravity
- 3.6–3.68
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Hexagonal
- Colours
- blue, colourless, white, pink
- Transparency
- transparent, translucent
- Cleavage and fracture
- poor; conchoidal fracture
- Under UV light
- bright blue under shortwave UV
Typical values: real specimens vary. For more, see mindat.org.