The ironmaking process resulted in by-products as well. This furnace produced a waste product called slag. This material is formed from other minerals present in iron ore, most notably silicon, and resembles glass. During the years of its operation this furnace produced an enormous amount of slag. The size of the slag heap across the river from the furnace was estimated at 900,000 cubic yards in 1920. Some of the slag was crushed and mixed with cement to make slag concrete. A number of buildings in New England were made with slag exported from this site. Slag was also used as a component in road surfacing, but it did not perform well in that application. Ultimately the slag was abandoned to the forest which has reclaimed the slag piles and made them all but invisible today.
