diopsiid

Diopside is a mineral belonging to the pyroxene group, with the chemical formula CaMgSi2O6. It is a common constituent of many igneous and metamorphic rocks, particularly in mafic and ultramafic rocks. Diopside can be found in a variety of colors, including green, yellow, brown, and colorless, depending on the presence of impurities. Gem-quality diopside is often a vivid green.

Crystallographically, diopside is a monoclinic mineral. It forms prismatic crystals, often with a square or rectangular cross-section. Cleavage is typically perfect in two directions, intersecting at angles close to 90 degrees, a characteristic feature of pyroxenes. Diopside has a hardness of 5.5 to 6.5 on the Mohs scale and a specific gravity of around 3.25 to 3.38.

Diopside is an important indicator mineral in metamorphic petrology, providing clues about the temperature and pressure conditions under which rocks formed. It is particularly common in metamorphosed carbonate rocks and in calcium-rich, silica-poor metamorphic environments. In igneous rocks, it is found in rocks like basalt, gabbro, and kimberlite.

Varieties of diopside include chrome diopside, which is known for its intense green color due to chromium content, and star diopside, which exhibits asterism. Diopside is not a major ore mineral, but it can be a minor source of calcium, magnesium, and silicon. It is also sometimes used as a gemstone, especially the chrome diopside variety.