A naturally occurring dark brown earth named for a city in central Germany. Cassel earth, also known as Vandyke brown and Cologne earth, contains organic humus or coal material mixed with iron oxides, alumina and silica. When ignited, the pigment leaves a soft grey residue. The colorant is fugitive and fades on exposure to strong light. It is listed among the pigments used for colouring stucco marble in the nineteenth and twentieth century. Synonyms: Cassel earth; Cassel's earth; Kassel earth; Cologne earth; Pigment Brown 9; CI 77430; Vandyke brown; Castle earth; Castile earth; Cullens earth; Colens earth; Collens earth. Wittenburg (1999); Museum of Fine Arts, Boston (2000). [J. Cassar, R; de Angelis]