Stock Photo - Carglaze tin mine, near St Austell, Cornwall, England, c1825, (1837). 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. Carglaze was a huge opencast mine worked for china clay after the tin reserves were exhausted. In the 20th century, the dicovery of extensive, more accessible reserves of tin ore overseas began the demise of the tin industry in Cornwall. In the 1980s, the global price of tin collapsed, and by the end of the century the last commercial Cornish mine had closed. After a painting by Thomas Allom (1804-1872).