Silver is one of the precious metals and has been used in jewelry and coinage since ancient times. It is one of the few metals to be found in its pure form in nature as it is relatively ureactive, although some minerals do contain silver. Although considered a precious metal it has numerous practical applications in electronics and medical instruments. This is due to its high conductivity and antibacterial properties. Silver salts, especially silver iodide, are also used in photographic film as they are senstitive to light. Silver is considered in folklore to have mystical properties, and in alchemy was associated with the moon due to its white, shining colouration.