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 Romanian leu Coins of the Romanian leu The Coins of the Romanian leu have been issued since the introduction of the Romanian leu in 1867. In 1867, copper 1, 2, 5 and 10 bani were issued, with gold 20 lei (known as "poli" after the French Napoleons) first minted the next year. These were followed, between 1870 and 1873, by silver 50 bani, 1 and 2 lei. Silver 5 lei were added in 1880. Uniquely, the 1867 issue used the spelling 1 "banu" rather than 1 ban. In 1900, cupro-nickel 5, 10 and 20 bani coins were introduced, with holed versions following