Silver is an element with the chemical symbol Ag and atomic number 47. Opaque and bright silvery white with a slightly pink tint, it readily tarnishes to either gray or black. Natural crystals of silver are uncommon, but when found they are cubic, octahedral, or dodecahedral. It is usually found in granular habit and as wiry, branching, lamellar, or scaly masses. Widely distributed in nature, it is a primary hydrothermal mineral. It also forms by alteration of other silver-bearing minerals.