viridian

thumb|right|Chromium(III) oxide sample thumb|Viridian (Pigment Green 18), left 3 smears; and Phthalocyanine Green (Pigment Green 7), right 3 smears Viridian is a blue-green pigment, a hydrated chromium(III) oxide, of medium saturation and relatively dark in value. It is composed of a majority of green, followed by blue. The first recorded use of viridian as a color name in English was in the 1860s. Viridian takes its name from the Latin , meaning "green". The pigment was first prepared in mid-19th-century Paris and remains available from several US manufacturers as prepared artists' colors in all media.

== History == Viridian pigment was first prepared in 1838 in Paris by Parisian color chemist and painter Pannetier alongside his assistant Binet as a hydrated form of chromium oxide. The preparation process was demanding, expensive, and shrouded in secrecy. The French chemist C. E. Guignet developed and patented a cheaper manufacturing method in 1859 that enabled larger distribution and use of the pigment. This method involved calcining a combination of boric acid and potassium bichromate, then washing the material.