A white-coloured metallic element that is very ductile and malleable. Silver is one of the noble elements as it does not oxidize when heated in air. Silver was usually obtained by cupellation of lead ores, although it may also be extracted directly from silver sulphide deposits. Pure silver is often stated to be 1000 fine and alloys are based on this nomenclature. For example, sterling silver is 925 fine (contains more than 92.5 % by weight silver). The atomic number of silver is 47, and its atomic weight 107.87, with a melting point of 960ºC, and specific gravity 10.50.