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
Copper toxicity the interaction of fruit acid with copper, permitting the use of the metal for its efficient thermal transfer properties. OSHA has set safety standards for grinding and sharpening copper and copper alloy tools, which are often used in nonsparking applications. These standards are recorded in the Code of Federal Regulations 29 CFR 1910.134 and 1910.1000. Note: The most important nonsparking copper alloy is beryllium copper, and can lead to beryllium poisoning. With an of 30 mg/kg in rats, "gram quantities" of copper sulfate are potentially lethal in humans. The suggested safe level of copper in drinking water for humans varies