Crosby Garrett Helmet some point the helmet was repaired using a bronze sheet which was riveted across two splits. Only two other Roman helmets complete with visors have been found in Britain – the Newstead Helmet and Ribchester Helmet. The helmet and visor were cast from an alloy consisting of an average of 82% copper, 10% zinc and 8% tin. This alloy was probably derived from melted-down scrap brass with a low zinc content, with which some tin had been added to improve the quality of the casting. Some of the fragments show traces of a white metal coating, indicating that the visor
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