<P> Copper has excellent brazing and soldering properties and can be welded; the best results are obtained with gas metal arc welding . </P> <P> Copper is biostatic, meaning bacteria and many other forms of life will not grow on it . For this reason it has long been used to line parts of ships to protect against barnacles and mussels . It was originally used pure, but has since been superseded by Muntz metal and copper - based paint . Similarly, as discussed in copper alloys in aquaculture, copper alloys have become important netting materials in the aquaculture industry because they are antimicrobial and prevent biofouling, even in extreme conditions and have strong structural and corrosion - resistant properties in marine environments . </P> <P> Copper - alloy touch surfaces have natural properties that destroy a wide range of microorganisms (e.g., E. coli O157: H7, methicillin - resistant Staphylococcus aureus (MRSA), Staphylococcus, Clostridium difficile, influenza A virus, adenovirus, and fungi). Some 355 copper alloys were proven to kill more than 99.9% of disease - causing bacteria within just two hours when cleaned regularly . The United States Environmental Protection Agency (EPA) has approved the registrations of these copper alloys as "antimicrobial materials with public health benefits"; that approval allows manufacturers to make legal claims to the public health benefits of products made of registered alloys . In addition, the EPA has approved a long list of antimicrobial copper products made from these alloys, such as bedrails, handrails, over-bed tables, sinks, faucets, door knobs, toilet hardware, computer keyboards, health club equipment, and shopping cart handles (for a comprehensive list, see: Antimicrobial copper - alloy touch surfaces #Approved products). Copper doorknobs are used by hospitals to reduce the transfer of disease, and Legionnaires' disease is suppressed by copper tubing in plumbing systems . Antimicrobial copper alloy products are now being installed in healthcare facilities in the U.K., Ireland, Japan, Korea, France, Denmark, and Brazil and in the subway transit system in Santiago, Chile, where copper - zinc alloy handrails will be installed in some 30 stations between 2011 and 2014 . </P> <P> Copper is commonly used in jewelry, and according to some folklore, copper bracelets relieve arthritis symptoms . In one trial for osteoarthritis and one trial for rheumatoid arthritis no differences is found between copper bracelet and control (non-copper) bracelet . No evidence shows that copper can be absorbed through the skin . If it were, it might lead to copper poisoning . </P>

Where is copper found in the earth's crust