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.
Commemorative coins of the United Kingdom Commemorative coins of the United Kingdom Commemorative coins have been issued by the Royal Mint in the United Kingdom since 1935. Initially they only came out to mark events of great interest, but since the turn of the millennium have been minted yearly. Until decimalisation crowns (five shilling coins) were used for this purpose as they were the highest denomination of the time, but due to inflation this rôle has been transferred to higher value coins. Crowns, £5 Coins and (until 1996) £2 Coins are non-circulating, although they are still legal tender. These denominations are only used for commemoratives. During