Lintzgarth Smelt Mill, located on the south side of the Rookhope Burn, was the smeltmill for all the leadmines in the Rookhope Valley from 1740. It was built by the Blackett family in 1737 to replace an older mill. It was recorded in 1821 that the mill had one roasting furnace, three ore hearths and one slag hearth. The smeltmill used orehearths, with an air blast powered by a waterwheel to smelt the ore. The mill was taken over by the Weardale Lead Company in 1883 and by 1884 it was made bigger to incorporate an extra roasting furnace and a reverbatory smelting furnace.