Human skin color protect them from genetic damage. One melanocyte supplies melanin to thirty-six keratinocytes according to signals from the keratinocytes. They also regulate melanin production and replication of melanocytes. People have different skin colors mainly because their melanocytes produce different amount and kinds of melanin. The genetic mechanism behind human skin color is mainly regulated by the enzyme tyrosinase, which creates the color of the skin, eyes, and hair shades. Differences in skin color are also attributed to differences in size and distribution of melanosomes in the skin. Melanocytes produce two types of melanin. The most common form of biological melanin is
Earth pigment Earth pigment Earth pigments are naturally occurring minerals containing metal oxides, principally iron oxides and manganese oxides, that have been used since prehistoric times as pigments. The primary types are ochre, sienna and umber. Earth pigments are known for their fast drying time in oil painting, relative inexpensiveness, and lightfastness. Cave paintings done in sienna still survive today. After mining, the mineral used for making a pigment is ground to a very fine powder (if not already in the form of clay), washed to remove water-soluble components, dried, and ground again to powder. For some pigments, notably sienna and umber,