The inhabitants of Britain who dwell about the headland of Belerium are unusually hospitable and have adopted a civilized manner of life because of their intercourse with foreign traders. It is they who work the tin, extracting it by an ingenious method.
Another Cornish tradition is to the effect that Joseph of Arimathea came in a boat to Cornwall and bought the boy Jesus with him: and the latter taught him how to extract tin and purge it of the wolfram. When the tin is flashed, then the tinner shouts, "Joseph was in the trade".
(Baring Gould. Cornwall)