Inorganic colors (pigments) are composed of insoluble metallic compounds which are either derived from natural sources (e.g. china clay, carbon deposits) or are synthesized. Based on the composition pigments are divided into iron oxides, zinc oxides, carbon blacks, chromium oxide greens, and ultramarines. Since inorganic pigments are not considered to be irritant to mucous membranes, they do not require certification as do organic pigments. Because inorganic pigments are not water soluble, they are utilized preferentially in solid makeups such as lipsticks, lip glosses, powders, and eyeliners. Inorganic colors are not available in the range of shades as organic colors which limits a bit their range of applications. However, they are the colors of choice for eye shadows, mascara, and other products used in close proximity to the eye.