Diopside
Diopside is a
monoclinic pyroxene mineral with composition MgCaSi2O6. It forms solid solution series with hedenbergite and
augite. It forms variably colored, but typically dull green crystals in the
monoclinic prismatic class. It has two distinct prismatic cleavages at 87 and 93? typical of the pyroxene series. It has a Mohs hardness of six and a specific gravity of 3.25 to 3.55. It is transparent to translucent with indices of refraction of na=1.663 - 1.699, n?=1.671 - 1.705 and n?=1.693 - 1.728. The optic angle is 58? to 63?.
Encyclopedia
Diopside is a
monoclinic pyroxene mineral with composition MgCaSi
2O
6. It forms solid solution series with hedenbergite and
augite. It forms variably colored, but typically dull green crystals in the
monoclinic prismatic class. It has two distinct prismatic cleavages at 87 and 93° typical of the pyroxene series. It has a Mohs hardness of six and a specific gravity of 3.25 to 3.55. It is transparent to translucent with indices of refraction of na=1.663 - 1.699, nß=1.671 - 1.705 and n?=1.693 - 1.728. The optic angle is 58° to 63°.
Diopside is found in mafic to
ultramafic igneous rocks. It is also found in a variety of
metamorphic rocks. It often occurs in contact metamorphosed skarns developed from high silica
dolomites. It is also a constituent of the
Earth's
mantle.
Gemstone quality diopside is found in two forms: the black star diopside and the chrome diopside . At 5.5-6.5 on the Mohs scale, chrome diopside is relatively soft to scratch. Mohs scale of hardness does not measure tensile strength or resistance to fracture.
Chrome diopside is found near
kimberlite pipes, and as such is a prospecting indicator for
diamonds. Occurrences are reported in Canada, South Africa, Russia and a wide variety of other locations.
Diopside was first described about 1800 and derives its name from the Greek
dis - "two kinds" or "double" and
opsis - "opinion" or "appearance" in reference to the two ways of orienting the vertical prism.
References
- Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., Wiley, pp 403-404, ISBN 0-471-80580-7
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- Handbook of Mineralogy, Mineral Data Publishing, 2001,
