TIN MINING
http://en.wikipedia.org/Tin is one of the earliest metals to have been exploited in Britain. Chalcolithic metal workers discovered that by putting a small amount of tin (5 – 20%) in molten copper an alloy called bronze was produced that was easier to work and harder than copper. Exploitation of the tin resources in Britain is believed to have started before 2000 BC, with a thriving tin trade developing with the civilisations of the Mediterranean. The strategic importance of tin in forging bronze weapons brought the southwest of Britain into the Mediterranean economy at an early date.
Bronze is an alloy of copper and tin. Since tin was not discovered in Ireland, the bronze age people had to get it from Devon and Cornwall, from Brittany, Spain or further afield. There is a Labbacalle line that goes directly through the port of Dungarvan to the Geevor tin mine in St Justin, Cornwall which was mined during the bronze age.
http://stjustin.co.uk/
Cornwall is justly proud of its ancient tin industry that began nearly 4,000 years ago during the Bronze Age. Tin was mined by our Celtic ancestors and exported to Europe and the Middle East where it was used in making weapons and tools.