Stone of the Week - Copper

Tuesday, May 27, 2008
Copper is an elemental metal, represented as Cu on the periodic table. It is a very ductile metal, making it easy to shape and work with. Copper does not react with water (H2O), but does react to the oxygen in the air, forming a layer of brown-black copper oxide on copper metal. The green layer of copper carbonate (sometimes called a patina) that can form actually slows the corroding process. One of the most famous examples of this process is the green patina that has formed on the Statue of Liberty in the U.S. Copper can be found in mineral form as native copper, as well as in minerals such as chalcopyrite, azurite, malachite, and cuprite. Copper is very malleable as well as ductile, conducts heat well, and if near pure conducts electricity too.

Copper is mined and has a vareity of uses, particularly as jewelry components.

Due to the properties of Copper, it has a variety of uses, including copper pipes, copper wire, copper pans, and electronics. A special property of Copper is that it also can be used as an antibacterial and antifungal agent! Copper kills germs due to the toxic effect the metal ions has on bacteria, fungus, and mold spores. For this reason Copper has become more integrated particularly with hospital equipment. One example of this is brass doorknobs, which become disinfected within about eight hours or so.

This is what Copper looks like in a more 'raw' form as nuggets. Notice the green patina and the beginnings of oxidation occuring on the nugget to the left.

Copper exists in various locations through out the world, and has been used since ancient times. It has been in use for over 10,000 years, with the oldest known Copper pendant dating to 8700 BCE. Numerous artifacts comprised of Copper have been found world-wide, mainly as the alloy Bronze. Several copper alloys have been developed for different uses; common alloys with copper include bronze (copper and tin) and brass (copper and zinc). Today the world's largest mine for Copper is located at the Bingham Canyon Mine, located in Utah (U.S.), and is actually so large it is viewable from space!

Copper is a great alternative metal to use in jewelry work and is useful for practicing techniques as it is cheaper than Sterling Silver or Gold filled metal.

Copper has made a popular entrance into jewerly work recently as well. Although a slight greenish tint can occur when wearing Copper, numerous people have no reaction to it or don't wear the jewelry long enough for this to be a concern. Should this occur it can be easily washed off; additionally, some also try to coat the metal to protect both it and the person wearing it such as clear nail polish.

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Copper Facts:
Chemical composition: Cu, plus various alloy compounds
Color: Brown to coppery red
Habit: Branching and dendritic, can be massive
Fracture: Rough
Cleavage: None
Luster: Metallic
Hardness: 2.5-3
Specific Gravity: 8.9
Streak: Red-brown
Occurrence: Worldwide, some of the largest deposits in N. America and the UK

A Guide to Rocks and Fossils by B. Busbey III, R. R. Coenraads, P. Willis, and D. Roots. Published 2002 by Fog City Press. ISBN: 1877019518

Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966

Wikipedia – Copper.