Pennyweight Act of 1878; only the Troy ounce and its decimal subdivisions remained official. The Troy ounce enjoys a specific legal exemption from metrication in the UK. The pennyweight is the common weight used in the valuation and measurement of precious metals. Jewellers use the pennyweight in calculating the amount and cost of precious metals used in fabricating or casting jewellery. Similarly, dentists and dental labs still use the pennyweight as the measure of precious metals in dental crowns and inlays. Pennyweight and grains are still used to weigh gooseberries in competitions in Cheshire, northwest UK. Over the Pennines in Yorkshire
Synthesis of precious metals Synthesis of precious metals The synthesis of precious metals involves the use of either nuclear reactors or particle accelerators to produce these elements. Ruthenium and rhodium are precious metals produced by nuclear fission, as a small percentage of the fission products. The radioisotopes of these elements generated by nuclear fission with the longest half-lives have half-lives of 373.59 days and 45 days for ruthenium and rhodium, respectively. This makes their extraction from spent nuclear fuel possible, although they must be checked for radioactivity before use. Each kilogram of the fission products of U will contain 63.44 grams of ruthenium isotopes