Alizarin red

Originally a bright red pigment, also called madder lake, made from madder, derived from the root of the plant Rubia tinctorum. Alizarin now generally refers to a pigment and a class of dyes derived from anthraquinone — synthetic coal-tar — and is used in the manufacture of blue, brown, green, red, violet, and yellow pigments.  (Artlex.com)  Also see “Pigments through the Ages on cerulean blue” http://www.webexhibits.org/pigments/indiv/overview/alizarin.html

Canadian Heritage University of Regina Mackenzie Art Gallery Mendel Art Gallery Sask Learning