Tin of protons. It has two main allotropes: at room temperature, the stable allotrope is β-tin, a silvery-white, malleable metal, but at low temperatures it transforms into the less dense grey α-tin, which has the diamond cubic structure. Metallic tin does not easily oxidize in air. The first tin alloy used on a large scale was bronze, made of tin and copper, from as early as 3000 BC. After 600 BC, pure metallic tin was produced. Pewter, which is an alloy of 85–90% tin with the remainder commonly consisting of copper, antimony, and lead, was used for flatware from the Bronze
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