The Tassan Mining Company was established in the late 1840s. Total production from the mine was reported at 742 tonnes of ore, including 546 tonnes of lead and 37.478g of silver. The mineralization was hosted by two lodes each striking Northwest and dipping Eastwards. The mine appears to have extended to a depth of 160 m below surface, the site contained a combined engine and crusher house as well as mine offices, workshops and at least five shafts. The lead mine continued in operation until 1865-1866, after which production statistics are unavailable. It provided much needed work locally in the aftermath of the Great Famine (1845–1849). The captains' mine offices remain standing, and the site is largely grassed over with spoil heaps visible near Tassan Lough Natural Heritage Area.