diopsiidi

Diopsidi is a mineral belonging to the pyroxene group, with the chemical formula (Ca,Na)(Mg,Fe,Al)Si2O6. It is a solid solution series, meaning its composition can vary within certain limits. The most common end-member is hedenbergite, rich in iron, and augite, which is also a pyroxene. Diopsidi itself is often considered to be near the calcium-magnesium end of the series, though it commonly contains significant amounts of iron. It crystallizes in the monoclinic system, typically forming prismatic or stubby crystals, but can also occur in granular or massive forms.

Diopsidi is characterized by its vitreous luster and a hardness of 5.5 to 6.5 on the Mohs scale. Its color can range widely, from colorless, white, and pale green to dark green, brown, and even black, depending on the presence and oxidation state of iron and other trace elements. Some varieties exhibit asterism, producing a star-like effect when cut en cabochon. Gem-quality diopsidi, particularly the vibrant chrome-rich diopsidi from Pakistan and Siberia, are highly prized for their intense green color and brilliance.

This mineral is a common constituent of various igneous rocks, particularly those that are mafic and ultramafic, such as basalts, gabbros, and peridotites. It is also found in metamorphic rocks, especially in calcium-rich skarns formed by contact metamorphism. Diopsidi plays a role in understanding the geological conditions under which rocks form, as its composition can reflect the temperature, pressure, and chemical environment of its genesis. Its presence can also indicate specific tectonic settings.