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 contract, which is ongoing, will also evaluate the effectiveness of copper alloy touch surfaces to prevent the transfer of microbes to patients and the transfer of microbes from patients to touch surfaces, as well as the potential efficiency of copper-alloy based components to improve indoor air quality. The latest results from the studies at the three institutions will be developed into a manuscript for publication. In a separate initiative not funded by the U.S. Department of Defense, clinical trials at an infectious disease outpatient ward consisting of patients with HIV and other infectious diseases are being conducted at North Shore