The image of a lamb carrying the flag of St Piran is a device which was used to signify the purity of Cornish tin. It was presed onto the molten ingots after smelting as proof that they had been properly asayed and the appropriate duty had been paid to the Duchy of Cornwall. Tin mining was practised in Cornwall since the Bronze Age, but reached its peak in the 19th century, when the county was one of the world's leading producers. In the 20th century, the dicovery of extensive, more accesible reserves overseas began the demise of the industry. In the 1980s, the global price of tin collapsed, and by the end of the century the last commercial Cornish mine had closed. Produced by the Cornish Tin Smelting Company, Redruth, Cornwall.
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