Metallurgical assay and the U.S. Mint continue to produce precious metal bullion coins for collectors and investors. The precious metal purity and content of these coins is guaranteed by the respective mint or government, and, therefore, the assay of the raw materials and finished coins is an important quality control. In the UK, the Trial of the Pyx is a ceremonial procedure for ensuring that newly minted coins conform to required standards. Metallurgical assay A metallurgical assay is a compositional analysis of an ore, metal, or alloy. Some assay methods are suitable for raw materials; others are more appropriate for finished goods.
Coins of the New Zealand dollar koru; with the words "Eleventh Hour of the Eleventh Day of the Eleventh Month". It was issued to commemorate the 100th anniversary of Armistice Day. It is the second circulating coin to feature colour. The coins are limited to 2,000,000 and were minted by the Canadian Mint. Changes to coinage in 1990 and 2006 has resulted in several demonetised coins. Coins have been demonetised for various reasons. This is a list of demonetised coins: Numerous mule coins have been accidentally minted, at least two of which have ended up in circulation. The first instance occurred in 1967, when the two