Various obsolete lead based pigments ranging in color from yellow through orange to red. It is a mark of the lack of good quality reds and yellows on the palette until the 19th century that these impermanent pigments were ever used. In paintings they always had a reputation for darkening and were totally replaced by Cadmiums as they became available. These colors are to be avoided if found in a tube, as strangely despite health problems and other issues their low price makes them tempting for unscrupulous manufacturers to use. Not to be confused with the excellent Chromium Green Oxide, a totally unrelated color.