Pound (mass) a legal unit for trade (it was abolished in the United Kingdom on 6 January 1879 by the Weights and Measures Act of 1878), but the troy ounce, of a troy pound, is still used for measurements of gems such as opals, and precious metals such as silver, platinum and particularly gold. The system called Tower weight was the more general name for King Offa's pound. This dates to 757 AD and was based on the silver penny. This in turn was struck over Arabic dirhams (2d). The pound was based on the weight of 120 Arabic silver dirhams, which
Wheaton Precious Metals Corporation (18,600 oz). When converted to silver equivalent using the gold to silver ratio, gold from 777 accounted for 40.5% of the increase in total production in 2012. Wheaton Precious Metals Corporation Silver Wheaton Corp. is a no longer pure play silver mining company but still the largest in the business of silver streaming. It produces over 26 million ounces and sells over 29 million ounces of silver mined by other companies (including Barrick Gold and Goldcorp) as a by-product of their main operations. In 2016 Silver Wheaton reported attributable production totaling 30.4 million ounces of and 353,700 ounces of .