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.
Description
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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