Bellecombe, Châtillon, Aosta Valley, Italy © D. Preite

Chemical Formula: CaMgSi2O6
Locality: Wide spread occurrence.
Name Origin: From the Greek dis – “two kinds” and opsis – “opinion.”

Diopside is a monoclinic pyroxene mineral with composition MgCaSi2O6. It forms complete solid solution series with hedenbergite (FeCaSi2O6) and augite, and partial solid solutions with orthopyroxene and pigeonite. 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, a Vickers hardness of 7.7 GPa at a load of 0.98 N, and a specific gravity of 3.25 to 3.55. It is transparent to translucent with indices of refraction of nα=1.663–1.699, nβ=1.671–1.705, and nγ=1.693–1.728. The optic angle is 58° to 63°.

Physical Properties of Diopside

Cleavage: {110} Good, {???} Indistinct
Color: Blue, Brown, Colorless, Green, Gray.
Density: 3.25 – 3.55, Average = 3.4
Diaphaneity: Transparent to translucent
Fracture: Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments.
Hardness: 6 – Orthoclase
Luminescence: Sometimes fluorescent.- red-purple
Luster: Vitreous (Glassy)
Streak: white green

Photos :

Diopside Testa Ciarva, Ala valley, Piedmont, Italy Specimen weight:272 gr. Crystal size:13 mm Overall size: 80mm x 50 mm x 50 mm © minservice
Diopside Testa Ciarva (TO), Piemonte, Italy Specimen weight:14 gr. Crystal size:2 cm Overall size:2,9 x 2,5 x 2,5 cm © minservice
Diopside DeKalb, St. Lawrence Co., New York, USA Miniature, 4.3 x 3.3 x 1.9 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Diopside cluster Merelani Mines, Lelatema Mts, Arusha Region, Tanzania Miniature, 4.3 x 1.5 x 1.2 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
DIOPSIDE Konar Valley, Kunar Province (Nuristan), Afghanistan, Asia Size: 3.8 x 1.3 x 1.2 cm (Miniature) Status: Available Owner: Crystal Classics