The Lonaconing Iron Furnace (officially, the George's Creek Iron and Coal Company Expermental Furnace Number One) is an 1840 metallic-iron production blast furnace, the first commercially-successful iron smelting furnace to produce commercial-quality cast iron (in the form of pig iron), using inexpensive coal as the fuel rather than charcoal. The first ingot was cast, May 17, 1839, initiating the modern "age of iron and steel production." The basic process and basic furnace design is still used today world-wide. The furnace was used until 1855, when the local deposits of iron ore were exhausted. The furnace structure is almost intact and open to visitors year around. The construction notes still exist and are reprinted as the Lonaconing Journals.