Native copper was used by prehistoric humans as early as 6000 B.C. for beads and tools. It was shaped by being hammered while unheated until it was discovered that heated metal is easier to work. Some early peoples melted copper into molds to get a variety of shapes. Around 4500 B.C. the peoples of Mesopotamia became the first to extract copper from ores by smelting (a heating process), marking the beginning of the art of metallurgy. About 3000 B.C. the Mesopotamians began combining copper with tin to make bronze, which is stronger and easier to cast than copper. The name copper comes from Kupras, Greek for Cyprus, a major source of copper in ancient times.
The Romans worked copper mines in central Europe, Spain, and Britain. The Indians of North and South America knew and used copper at a very early date. Small shipments of copper ore were sent from America to Europe in the 18th century, but it was not until the middle of the 19th century that copper became important in the mineral production of the United States.
For the world's leading producers, see graph. In the United States, Arizona is by far the leading producer.
Symbol: Cu. Atomic number: 29. Atomic weight: 63.546. Melting point: 1,981.4 F. (1,083 C.). Boiling point: 4,653 F. (2,567 C.). Specific gravity: 8.96. Copper belongs to Group I-B of the Periodic Table and has a valence of +1 or +2.