Diopside

Diopside is found in ultramafic (kimberlite and peridotite) igneous rocks, and diopside-rich augite is common in mafic rocks, such as olivine basalt and andesite. Diopside is also found in a variety of metamorphic rocks, such as in contact metamorphosed skarns developed from high silica dolomites. It is an important mineral in the Earth's mantle and is common in peridotite xenoliths erupted in kimberlite and alkali basalt.

Due to its rarity and beauty, diopside is commonly used as a gemstone in jewelry, and can be found in mineral collections. Its gorgeous green color makes this mineral a great alternative to emeralds. Diopside has shown promise in the glass and ceramics industries, but specimens are rarely large enough for any industrial use.

Diopside comes from the Greek words "di" and "opsis," meaning "double vision." Ancient Greek peoples would place a chunk of diopside on their forehead to encourage good dreams. People would also bury their dead with this crystal to ensure their reincarnation back into the Earth.

Diopside derives its name from the Greek dis, "twice", and òpsè, "face" in reference to the two ways of orienting the vertical prism. Diopside was discovered and first described about 1800, by Brazilian naturalist Jose Bonifacio de Andrada e Silva.

Diopside is a precursor of chrysotile (white asbestos) by hydrothermal alteration and magmatic differentiation; it can react with hydrous solutions of magnesium and chlorine to yield chrysotile by heating at 600 °C for three days. Some vermiculite deposits, most notably those in Libby, Montana, are contaminated with chrysotile (as well as other forms of asbestos) that formed from diopside. At relatively high temperatures, there is a miscibility gap between diopside and pigeonite, and at lower temperatures, between diopside and orthopyroxene. The calcium/(calcium+magnesium+iron) ratio in diopside that formed with one of these other two pyroxenes is particularly sensitive to temperature above 900 °C, and compositions of diopside in peridotite xenoliths have been important in reconstructions of temperatures in the Earth's mantle. Chrome diopside ((Ca,Na,Mg,Fe,Cr)2(Si,Al)2O6) is a common constituent of peridotite xenoliths, and dispersed grains are found near kimberlite pipes, and as such are a prospecting indicator for diamonds. Occurrences are reported in Canada, South Africa, Russia, Brazil, and a wide variety of other locations. In the US, chromian diopside localities are described in the serpentinite belt in northern California, in kimberlite in the Colorado-Wyoming State Line district, in kimberlite in the Iron Mountain district, Wyoming, in lamprophyre at Cedar Mountain in Wyoming, and in numerous anthills and outcrops of the Tertiary Bishop Conglomerate in the Green River Basin of Wyoming. Much chromian diopside from the Green River Basin localities and several of the State Line Kimberlites have been gem in character.

Gemstone quality diopside is found in two forms: black star diopside and chrome diopside (which includes chromium, giving it a rich green color). At 5.5–6.5 on the Mohs scale, chrome diopside is relatively soft to scratch. Due to the deep green color of the gem, they are sometimes referred to as Siberian emeralds, although they are on a mineralogical level completely unrelated, emerald being a precious stone and diopside being a semi-precious stone.

Violane is a manganese-rich variety of diopside, violet to light blue in color.

Diopside is a stone of empowerment and is often used by those whose inner sorrow has been held back too long. It encourages love for others and enables better understanding of the physical and spiritual self. It boosts creativity and stimulates the intellect, allowing for greater learning and a higher level of discipline. It works on the Heart chakra and encourages the user to be more appreciative of life.