Copper is a soft and malleable metal with a reddish-orange color. It is commonly used as a constituent of various metal alloys, and is sometimes used alone in making chain, wire, and findings. It is also possible to find items with some other base metal, such as zinc, that have been plated in copper.
Most people have had the experience of having copper turn their skin green. This is not an allergic reaction; in fact, very few people are allergic to copper. The color change is due to the oxidization of the copper, which occurs faster when exposed to oils, sweat, or high acidity. Keeping your copper jewelry clean and dry can help minimize this reaction.
Copper has antimicrobial properties, and is used in many applications, especially in hospitals. It is biostatic, meaning bacteria and other life cannot grow on it.