Copper (Cu)

Copper ([Ar]3d¹⁰4s¹) is reddish, lustrous, ductile, malleable metal. It is second only to silver in electrical conductivity and is also a good conductor of heat. Copper is one of the earliest known metals and is believed to have been mined for over 5,000 years. Though it occasionally occurs native, copper is often found in other minerals including cuprite, malachite, and chalcopyrite.