See also: William and Mary Worth, part of East Cornwall.

Silver Valley Mine, an old silver and lead mine located in a small valley on the southeast slope of Kit Hill, began operations in 1815 and ceased in 1855. Initially known as William and Mary Worth Mine, it operated concurrently with Wheal Brothers. The mine’s workings primarily occupied the eastern side of the valley in Calstock parish, while the western side, known as Ashburton Mine, was also part of its sett. Although its lode was believed to be an extension of Wheal Brothers, its precise position remains uncertain. Development works in 1852 revealed a 4-foot wide lode at the 14-fathom level, containing a 6-inch leader of argentiferous ore yielding 200 ounces of silver per ton. In 1912 and 1918, exploration for tin and tungsten focused on the Goodluck Lode, possibly an extension of Harrowbarrow Mine’s Goodluck Lode. Despite reopening in 1943 due to tungsten demand, the project failed due to uneven ore distribution, with only 9 tons of 77% lead ore recorded as output in 1852.

1851-1855 1912;1918 1943 trial