Lazurite
Mineral (Na,Ca)8Al6Si6O24(SO4,S,Cl)2
Also called Lazuli
About it
The intense blue mineral that colours lapis lazuli; rare as dodecahedral crystals in marble at Sar-e-Sang, Afghanistan. Its blue streak sets it apart from sodalite.
- Type
- Mineral
- Group
- Silicate (tectosilicate), sodalite group
- Formula
- (Na,Ca)8Al6Si6O24(SO4,S,Cl)2
- Hardness (Mohs)
- 5–5.5
- Specific gravity
- 2.38–2.45
- Streak
- bright blue
- Lustre
- vitreous (glassy), dull
- Crystal system
- Isometric (cubic)
- Colours
- deep blue, violet-blue, greenish blue
- Transparency
- transparent, translucent, opaque
- Cleavage and fracture
- imperfect dodecahedral; uneven fracture
Typical values: real specimens vary. For more, see mindat.org.