Sapphirine
Mineral (Mg,Al)8(Al,Si)6O20
About it
Blue to green grains in aluminium-rich, silica-poor metamorphic rocks, named for its sapphire-like colour; rare gem crystals from Sri Lanka and Madagascar.
- Type
- Mineral
- Group
- Silicate (inosilicate), sapphirine group
- Formula
- (Mg,Al)8(Al,Si)6O20
- Hardness (Mohs)
- 7.5
- Specific gravity
- 3.4–3.58
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Monoclinic
- Colours
- blue, green, grey, pale red, yellow
- Transparency
- transparent, translucent
- Cleavage and fracture
- poor; subconchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.