Mining and Exploration History of the Southeast Missouri Iron Metallogenic Province

Abstract

Mining has been a driving force in the development of Missouri for hundreds of years—a history of feast and famine, success and ruin. In southeast Missouri, the mining history spans times from early crude furnaces and small mines to large modern operations working at depths of more than 730 m below the surface. Eight major iron orebodies and myriad minor deposits are known in the southeast Missouri iron metallogenic province, which is hosted in Mesoproterozoic igneous rocks of the St. Francois Mountains terrane. The first iron furnace west of the Mississippi River was opened in Missouri in the early part of the 19 th century, marking the beginning of a prosperous industry that shaped the fortunes of citizens and the state. The industry persevered through the United States Civil War, including the dramatic battle in 1864 that caused extensive damage to the Pilot Knob ironworks. Earlier discovery in 1844 of banded iron formation ores in Michigan and depletion of easily accessible surface iron deposits in southeast Missouri led to eventual downturn in the local mining industry. Magnetic surveys in the 1950s resulted in discovery of several large subsurface deposits, including the Pea Ridge iron oxide-apatite deposit and the Boss iron oxide-copper-gold deposit ca. 52 km to the south. Iron production in Missouri ceased in 2001, when the Pea Ridge mine closed. Great potential nevertheless exists for renewed production of iron and other metals in the province.