The keg of nails with a "X" marked on it can be seen in the cabin scene. This same keg was in the previous episode (S1, Ep11 The Boy from Pittsburgh) which supposedly blew up.
The lead mine is in Galena, Illinois. There are also Galenas in Ohio, Indiana, Maryland, New York, and 10 other States. Galena is the principle ore for smelting lead, and a significant ore for silver.