Epistilbite
Mineral CaAl2Si6O16·5H2O
About it
Small glassy prisms, often twinned, in basalt cavities with other zeolites; Iceland, the Faroe Islands, and India are known sources.
- Type
- Mineral
- Group
- Silicate (tectosilicate), zeolite group
- Formula
- CaAl2Si6O16·5H2O
- Hardness (Mohs)
- 4–4.5
- Specific gravity
- 2.22–2.28
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Monoclinic
- Colours
- colourless, white, pink, yellowish
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect in one direction
Typical values: real specimens vary. For more, see mindat.org.