Wheal Unity Wood mine, between 1815 and 1843 produced large tonnages of copper ore, but by 1843 its output had reduced considerably, although it still employed 200 workers. Unusually for this district, the mine also produced some tin at depth.
During the second half of the nineteenth century the mine opened and closed frequently, and was operated under a number of different, including West Poldice (1880-85) and Tolgullow United Mines (1886-1903). However Wheal Unity Wood is the name that appears to have been used for it most often.
A 70-inch pumping engine at Magor's Shaft was purchased, in about 1869, from Prosper United near Marazion. It seems probable that the 20-inch whim engine at Wheal Bush was bought from Prosper United too. This engine operated both a whim and the stamps.
Killifreth, at the northern end of the woods, started to become more important, and before the end of the the 1900's had returned to being principally a tin mine. It was a model of a small-scale mine, with safety features on its skips, a shiftboss system underground and a new and efficient tin stamps and dressing plant. Old Sump Shaft (Engine Shaft) was fitted with a 50-inch cylinder pumping engine, a 32-inch stamps engine installed, with buddles and calciner, and a steam whim. In the early 1890s an 80-inch pumping engine was installed at Hawke's (Richard's) Shaft. However by 1896, with the tin price dropping, the mine was not profitable. In 1897 the underground was leased to Truro School of Mines for the training of students, and most of the machinery and plant was sold off.
When the tin price picked up,the owners installed a second-hand 85inch engine in Hawke's engine house in 1912 (there had been an 80-inch steam engine). Shafts were examined and put in order, but no actual mining took place the First World War intervened. After the War preparations the tin price slump of 1920/21 closed it again.
During the middle of the 1920s Killifreth took over Wheal Busy to mine arsenic, but this brief revival was over by 1927, and mining ceased.
Trevithick Society, Wheal Unity Wood
Gwennap Area Mines.