Melanin is a non-hematogenous endogenous pigment, a group of pigments ranging in color from light brown to black, which are commonly found in the substantia nigra and hair follicles of the skin, eyes, and brain. Melanin has a remarkable physical property of being completely insoluble in most organic solvents. ---- This is almost certainly due to the fact that the melanin that has been formed in the melanosomes binds tightly to proteins, and that the melanin binds to proteins. Melanin binds to proteins and these complexes are called “melanin granules” in the cytoplasm. Another physical property of melanin is its ability to be bleached by strong oxidizing agents, although this process is slow, and in pathological cases this pigment can also be found in benign nevus cell tumors and malignant melanomas.