Old Market House (Galena, Illinois) Old Market House (Galena, Illinois) The Old Market House, currently being operated as the Galena Welcome Center, is a brick building built in the Greek Revival style in 1845 in Galena, Illinois. It is owned and operated by the Illinois Historic Preservation Agency as an Illinois State Historic Site. The Old Market House was built by the city of Galena to serve as a city hall and enclosed public farmer's market. A rapid increase in population in the Galena area in the 1830s and 1840s, largely a result of the discovery of galena, a kind of lead ore found in
Broken Hill ore deposit hornblende schists. The ore consists of massive, recrystallised sphalerite-rich, galena-sphalerite and galena-rich sulfide lenses in folded horizons, known as No. 2 Lens Formation and No.3 Lens Formation. Both have distinctive metal ratios and gangue minerals. The ore boundaries are parallel to the bedding planes. According to Gustafson, "There is evidence that the ore has been introduced into an old, already folded, rock and has replaced certain favourable layers of that rock, particle by particle, with large tonnages of garnet, rhodonite, fluorite, marmatite (and wurtzite), galena, and other minerals that constitute the orebodies." The Potosi-Footwall Gneiss is found on both sides