It is a dense, malleable, ductile, precious, gray-white transition metal. Even though it has six naturally occurring isotopes, platinum is one of the rarest elements in the Earth's crust. It exhibits a remarkable resistance to corrosion, even at high temperatures, and as such is considered a noble metal. Only a few hundred tons are produced annually, it is a scarce material, it is highly valuable and a major precious metal commodity. Being a heavy metal, it leads to health issues upon exposure to its salts, but due to its corrosion resistance it is not toxic as a metal.