Chromium (III) oxide green (Cr2O3)

Chromium(III) oxide green, with the formula Cr2O3, is an inorganic compound known as chromia or chrome green. It appears as a fine green powder or crystals with a hexagonal corundum crystal structure. The oxide consists of a hexagonal close-packed array of oxide ions with two-thirds of the octahedral holes occupied by chromium(III) ions. It is very hard (Mohs hardness 8-8.5) and brittle, with a melting point of 2435°C and boiling point above 3000°C. It is practically insoluble in water, alcohol, and acetone and slightly soluble in acids and alkalis.​

Chemically, it is amphoteric, dissolving in acids to give chromium(III) ions and in concentrated alkalis to form chromite ions. It is antiferromagnetic up to about 307 K and exhibits excellent chemical stability and resistance to heat, acids, and alkalis, making it widely used as a stable green pigment ('chrome green') in paints, ceramics, glass, and inks. It is also employed in refractory materials and as an electrode material in lithium-ion batteries.​

The compound has a density of approximately 5.22 g/cm³, is odorless, and its green color is highly stable, resistant to fading by light or heat. Natural chromium(III) oxide occurs as the mineral eskolaite