When people mention copper, the first thing most will think of is pennies. They will talk about something not being worth a copper penny. But if by penny, you mean the cent that is the 1/100th part of an American dollar, then that is no longer the case. They stopped making pennies out of pure copper in 1837.
http://www.usmint.gov/about_the_mint/fun_facts/index.cfm?flash=yes&action=fun_facts2
According the U.S. Mint, as linked above, things started out well and went downhill:
The following is a brief chronology of the metal composition of the cent coin (penny):
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The composition was pure copper from 1793 to 1837.
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From 1837 to 1857, the cent was made of bronze (95 percent copper, and five percent tin and zinc).
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From 1857, the cent was 88 percent copper and 12 percent nickel, giving the coin a whitish appearance.
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The cent was again bronze (95 percent copper, and five percent tin and zinc) from 1864 to 1962.(Note: In 1943, the coin’s composition was changed to zinc-coated steel. This change was only for the year 1943 and was due to the critical use of copper for the war effort. However, a limited number of copper pennies were minted that year. You can read more about the rare, collectible 1943 copper penny in “What’s So Special about the 1943 Copper Penny.”)
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In 1962, the cent’s tin content, which was quite small, was removed. That made the metal composition of the cent 95 percent copper and 5 percent zinc.
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The alloy remained 95 percent copper and 5 percent zinc until 1982, when the composition was changed to 97.5 percent zinc and 2.5 percent copper (copper-plated zinc). Cents of both compositions appeared in that year.
The reason that the cent could not possibly be made of copper today is that the amount of copper that it would take is worth a great deal more than one one hundreth of a dollar. The demand for copper has risen steadily over this period of time, and productions has been stepped up.
So what kinds of uses do people make of copper, besides coating zinc coins with? Here are a few:
- as a trace dietary mineral. It is a key constituent of the respiratory enzyme complex cytochrome c oxidase’. In humans, copper can be found in the liver, muscles and bone.
- In compounds, copper can be used as bacteriostatics, fungicides and wood preservatives.
- present in the Earth’s crust at a concentration of about 50 parts per million (ppm), so it’s used to keep the earth together.
- It forms an alloy called brass when mixed with zinc.
- It forms an alloy called bronze when mixed with tin.
- It forms an alloy called cupronickel when mixed with nickel. The US five cent coin is actually made of 75% copper and 25% nickel. Its composition is homogeneous.
- Copper can also form compounds, such as copper oxides, sulfides and halicides.
- The major industrial applications of copper are: electrical wires, roofing and plumbing and industrial machinery.
When the United States economy is doing poorly, people have been known to pilfer copper wiring from other people’s houses, especially when those houses are not being occupied. More than gold and silver, copper is a useful substance found in many industries whose value goes up when other resources are not available.
