Epidote
Mineral Ca2(Al2Fe)(SiO4)(Si2O7)O(OH)
Also called Pistacite
About it
Pistachio-green to nearly black striated prisms with one perfect cleavage, common in altered rocks; fine crystals from Green Monster Mountain, Alaska, Pakistan, and Austria's Knappenwand.
- Type
- Mineral
- Group
- Silicate (sorosilicate), epidote group
- Formula
- Ca2(Al2Fe)(SiO4)(Si2O7)O(OH)
- Hardness (Mohs)
- 6–7
- Specific gravity
- 3.38–3.49
- Streak
- greyish white
- Lustre
- vitreous (glassy)
- Crystal system
- Monoclinic
- Colours
- pistachio green, yellow-green, brownish green, black
- Transparency
- transparent, translucent, opaque
- Cleavage and fracture
- perfect in one direction
Typical values: real specimens vary. For more, see mindat.org.