Mineral description : Diopside

Diopside from Persberg.
Chromian diopside from Outokumpu, Finland.
Diopside in wollastonite from Snösjön.
Chromian diopside in limestone from Elsfjord, Norway.

Mineral class Silicates : Inosilicates : Diopside - Augite group.
Chemical formula CaMg(Si2O6)
Crystal system Monoclinic.
Habitus Often as well formed crystals with squarish or octaedric cross section, often twinned. Other habits are grainy, columnar, massive and lamellar aggregates.
Cleavage Good, with two cleavage planes in 87 degrees angle. Fracture uneven.
Hardness 5.5-6.5
Density 3.22-3.38
Color Colorless, white, gray, green, greenish black, yellowish brown, reddish brown. Transparent to nearly opaque.
Streak White to gray.
Luster Vitreous.
Occurance Often in contact metamorphic limestones and dolomites. In many metamorphic rocks and in basic igneous rocks.
Associates Garnet, Wollastonite, Forsterite.
Notes Insoluble in acids.
Locations A common mineral in Sweden. Good crystal localities are old limestone and marble quarries. Also in scarn in many iron mines.
  • Nordmark mining field, Värmland. As nice dark green crystal groups.
  • Persberg area (Gåsgruvan, blankagruvan), Värmland.
  • Norberg area (Åsgruvan), Västmanland.
  • Kaveltorpsgruvan, Kopparberg, Västmanland.
  • Malsjö limestone quarry, Värmland.
  • Los area. As a greenblue grainy type, called mansjöite.
  • Outokumpu, Finland. As green masses or crystals of chromian diopside.

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Last changed : 1998-03-07