Tin was so important that a body of law was developed to deal specifically with stannaries. King John in 1201 gave the tin miners of Cornwall the Stannary Charter: the right to prospect for tin anywhere, to be exempt from standard taxation, and to have their own stannary courts in the case of law-breaking. King Edward I in 1305 confirmed these rights, as did Edward III when he created the Duchy of Cornwall in 1337. Crockern Tor, pictured above, was the site of the Stannary Parliament, representing the tin industry.
Tin mining pre-dated the Middle Ages in Cornwall. When the Romans arrived, it was already thriving. Diodorus Siculus in 44BCE wrote the earliest reference to Cornwall we know:
The people of that promontory of Britain called Belerion [west Cornwall] are friendly to strangers and, from their contact with foreign merchants, are civilised in their way of life. They carefully work the ground from which they extract the tin.
This whole system of special privilege, etc., existed until the Tin Duties Act of 1838.
The history of mining in Cornwall was far more extensive than dealing with tin, even tied to a Biblical legend. I'll tell you more next time.