Five miles up a rugged, dusty gravel road off Highway 28 in Lemhi County, Idaho, rise four preserved remains of what were once 16 clay charcoal kilns. The enormous domed structures were used to turn timber into charcoal that was transported across the Birch Creek Valley to a smelter in Nicholia. The smelter processed silver and lead ore from the nearby Viola mine in the late 1880s.