ABSTRACT
Natural inorganic pigments have been used as colorants since prehistoric times. Inorganic pigments can be classified according to a number of different criteria, three of which are chemical structure, crystal form, and color. The primary particles of inorganic pigments are individual crystals, which can be cuboid, spherical, rodlike, or plate-shaped, depending on the chemical type of pigment and its preparative history. Among the synthetic colored inorganic pigments, iron oxides account for a high proportion of the market in volume terms. The colors yielded by these pigments range from yellow to orange, red, brown, and black. The leading position held by the iron oxides among colored inorganic pigments is due not only to their low cost but also to their excellent fastness properties. The cadmium pigments combine a number of the advantages of both organic and inorganic pigments. Colored inorganic pigments can be manufactured in a wide range of transparent shades.
