This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Both metal and copper oxidize when exposed to oxygen and this is a natural process. Copper that is exposed to the outside environment is more likely to turn green and that is why copper vases and decorative pieces in gardens are often green.
Copper is a pinkish colour when it is new, but soon turns a reddish orange color after it is exposed to air. Copper is one of the few coloured metals. Most metals are gray or silver. Gold, copper, caesium and osmium are the only four coloured metals. Copper is green as copper(II) carbonate and copper(II) hydroxide.