Tephroite
Mineral Mn2SiO4
About it
The manganese olivine, grey to reddish brown, in manganese ores and skarns such as Franklin, New Jersey, and Långban, Sweden. Named from the Greek for ash grey.
- Type
- Mineral
- Group
- Silicate (nesosilicate), olivine group
- Formula
- Mn2SiO4
- Hardness (Mohs)
- 6
- Specific gravity
- 3.87–4.12
- Streak
- pale grey
- Lustre
- vitreous (glassy), greasy
- Crystal system
- Orthorhombic
- Colours
- grey, olive green, flesh red, red-brown
- Transparency
- transparent, translucent
- Cleavage and fracture
- distinct in two directions
Typical values: real specimens vary. For more, see mindat.org.