Chromium(III) oxide is an inorganic compound. It is one of principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite.
Because of its considerable stability, chromia is a commonly used pigment and was originally called viridian. It is used in paints, inks, and glasses. It is the colourant in "chrome green" and "institutional green." Chromium(III) oxide is a precursor to the magnetic pigment chromium dioxide, according to the following reaction:
Cr 2O 3 + 3 CrO 3 → 5 CrO 2 + O 2
It is one of the materials that are used when polishing (also called stropping) the edges of knives, razors, etc. on a piece of leather, balsa, cloth, or other material. In this context it is alternatively known as "green compound".