Cassel earth or Cologne brown is an organic brown pigment made of lignite. As a color, it is also called Van Dyck or juicy brown; it has a dark, coffee-brown shade. Cassel earth consists of humus and humic acids with bitumen and manganese content. Therefore it is also known as the earth of Kassel. Cassel earth is considered a mixed form of pigment and dye. It is one of the vegetable colorants. Cassel earth is not to be confused with the colorant Cologne umber or Cologne earth. The latter differs from the true mineral umber by a much lower specific weight, it also smells peaty when heated and cannot be burnt, because it would burn to ashes. Real umbra, on the other hand, remains stable.