Like cobalt, chromium is a chameleon metal.
The method of its manufacture was patented in 1859.
Chromium Oxide Green, also known as chromium sesquioxide is one of four oxides of chromium.
It is a rather leaden opaque green more in the direction of olive green. Its value is in its good tinting, high stability and tonal equivalence to the iron oxides.
Its more vibrant cousin is hydrated chromium oxide, known as Viridian. In French it is called vert émeraude (Emerald Green), not be confused with the the highly poisonous copper-acetoarsenite Schweinfurt green (also called emerald green) which was used until the early 1900’s.
Viridian soon replaced Emerald Green, particularly in industrial printing processes and quickly became a popular artists’ pigment due to its excellent perma- nence and lack of toxicity.
A cold transparent green with limited tinting strength it is still popular for glazing although superseded by Phthalocyanine Green in the second half of the 20th century.