One - 1 ounce, 99.9% pure copper bar
Copper is what we call any atom containing exactly 29 protons. It is one of the most useful chemical elements to humanity.
Copper was one of the first metals discovered and used by humans, starting at least 10,000 years ago during the Neolithic. During the next few thousand years, human knowledge of metallurgy was developing as there is evidence of copper mining and smelting during this time. We call the transition period from Stone Age to Bronze Age the Chalcolithic, or the Copper Age.
Despite its long history, almost all of the copper ever extracted from Earth has occurred since the invention of the electric motor. The average car contains about 1 mile of copper wire.
Copper has 29 isotopes—these are atoms containing varying numbers of neutrons. Only 2 of these are stable and found in nature, while the remaining are radioactive and have a short half- life, most under 1 minute.