A warm reddish gold in colour, copper is the most easily recognized of all metals. It is quite soft, and sometimes found pure in nativeform - which is why it was one of the first metals people learned to use. The oldest knives found, dating back 6,000 years, are made of copper. Pure copper is often found in sulphide-rich veins in warm desert areas, or in cavities in-ancient lava flows. Like silver, it often grows in branching masses and tarnishes quickly. Yet the tarnish is bright green, not black, and a copper deposit is often revealed by bright green stains on rocks called copper bloom. As a
nativeelement, copper is quite rare, so most of the copper used today comes from ores such aschalcopyrite.