Green Sand

The Green Sand Beach in Hawaii is one of only a few in the world. The sand consists of spheres of olivine, or peridot. Each grain is a clear olive green. White sand primarily is quartz, which is an uncolored silicate (SiO₂), and other light-colored minerals (white sand beaches in Hawaii, on the other hand, are almost entirely made from smoothed shells, or calcium carbonate, rather than inorganic minerals). Olivine is another silicate, though with magnesium and iron in its crystal matrix. The metals are responsible for the characteristic color.