Mineral description : Tephroite

Grayish tephroite on the lower part of the rock.
From Harstigen.

Mineral class Silicates : Nesosilicates : Olivine group.
Chemical formula Mn2(SiO4)
Crystal system Orthorombic.
Habitus Crystals prismatic but very rare. Mostly as fine grained quartz like aggregates.
Cleavage [010] indistinct, brittle, fracture conchoidal.
Hardness 6
Density 4.11-4.39
Color Gray to grayish red, red, bluish red and yellowish green.
Streak Gray.
Luster Vitreous to greasy, transparent to translucent.
Occurance Occurs in mangan scarn.
Associates Richterite, Rhodonite, Schefferite.
Notes Named after the Greek word "tephros" meaning ash gray.
Locations An international rare mineral with a few good localities in Sweden.
  • Långban, Värmland. Grainy to dense aggregates with grayish red color.
  • Harstigen, Värmland. Commonly as bluish gray masses.
  • Jakobsberg and Brattforsgruvan, Nordmark, Värmland.

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Last changed : 1998-09-21