Lawsonite
Mineral CaAl2Si2O7(OH)2·H2O
About it
Colourless to blue-grey tablets in blueschist, a sign of high pressure at low temperature; named for geologist Andrew Lawson, from Tiburon, California.
- Type
- Mineral
- Group
- Silicate (sorosilicate), lawsonite group
- Formula
- CaAl2Si2O7(OH)2·H2O
- Hardness (Mohs)
- 6–7.5
- Specific gravity
- 3.05–3.12
- Streak
- white
- Lustre
- vitreous (glassy), greasy
- Crystal system
- Orthorhombic
- Colours
- colourless, white, pale blue, grey-blue
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect in two directions
Typical values: real specimens vary. For more, see mindat.org.