Omphacite
Mineral (Ca,Na)(Mg,Fe,Al)Si2O6
About it
Grass-green sodium-calcium pyroxene that, with red garnet, makes up eclogite, a rock formed at great depth in subducted crust; Norway and the Alps are well known.
- Type
- Mineral
- Group
- Silicate (inosilicate), pyroxene group
- Formula
- (Ca,Na)(Mg,Fe,Al)Si2O6
- Hardness (Mohs)
- 5–6
- Specific gravity
- 3.16–3.43
- Streak
- white to pale green
- Lustre
- vitreous (glassy), silky
- Crystal system
- Monoclinic
- Colours
- green, dark green
- Transparency
- transparent, translucent, opaque
- Cleavage and fracture
- good in two directions at nearly 90°
Typical values: real specimens vary. For more, see mindat.org.