Gonnardite
Mineral Na2CaAl4Si6O20·7H2O
About it
White to salmon fibrous spheres and tufts of the natrolite family, in basalt cavities; first described from Puy-de-Dôme, France, and known near Rome, Italy.
- Type
- Mineral
- Group
- Silicate (tectosilicate), zeolite group
- Formula
- Na2CaAl4Si6O20·7H2O
- Hardness (Mohs)
- 5
- Specific gravity
- 2.25–2.36
- Streak
- white
- Lustre
- silky
- Crystal system
- Tetragonal
- Colours
- white, yellowish, salmon red
- Transparency
- transparent, translucent
- Cleavage and fracture
- not distinct; fibrous
Typical values: real specimens vary. For more, see mindat.org.