Tin mining to trace metal content in the copper ore It was soon discovered that the addition of tin or arsenic to copper increased its hardness and made casting much easier, which revolutionized metal working techniques and brought humanity from the Copper Age or Chalcolithic to the Bronze Age around 3000 BC. Early tin exploitation appears to have been centered on placer deposits of cassiterite. The first evidence of tin use for making bronze appears in the Near East and the Balkans around 3000 BC. It is still unclear where the earliest tin was mined, as tin deposits are very rare and
Antimicrobial copper-alloy touch surfaces Copper (Cu) is a logo/mark required by the U.S. E.P.A. in order for bulk metal fabricators and manufacturing companies to make public health claims about antimicrobial copper in the U.S. market. The logo/mark indicates that the products have strong efficacies as sanitizers, residual self-sanitizing efficacies after multiple wet-dry cycles, and continuous reductions of bacterial contaminants. A list of bulk alloy suppliers that offer E.P.A.-registered antimicrobial copper to manufacturers is available. A list of approved manufacturers and retailers offering antimicrobial copper products to the regulated U.S. market is also available. These firms have completed all legal requirements to sell antimicrobial copper