Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 148,095 pages of information and 233,633 images on early companies, their products and the people who designed and built them.
1844, the phenomenally-rich Wheal Maria was discovered. From then until 1920 Wheal Maria produced copper, lead and arsenic. It was part of the Devon Great Consols Mine - at one time the world's largest producer of copper.
Copper production reached its peak in 1857, but by the 1880's Devon Consols relied upon arsenic for its business.