Rosiclare Mining Sub-District, Hardin County, Illinois, USAi

Regional Level Types
Rosiclare Mining Sub-District	Mining District
Hardin County	County
Illinois	State
USA	Country

The Rosiclare Subdistrict is located in Hardin County, in southeastern Illinois, and extends from the Ohio River northward through the village of Rosiclare to just north of Illinois Route 146. The Rosiclare Mine, which operated for more than a century, was at one time the largest fluorspar mine in the United States and possibly the world. Several adjacent mines, notably the Argo, Blue Diggings, Daisy, Eureka, and Hillside, were also major producers. The veins are aligned along a set of north-trending normal faults of slight to moderate displacement. Mineralization is predominantly fluorite, along with calcite and lesser amounts of quartz, galena, and sphalerite. Barite in the Rosiclare Subdistrict is not common, in contrast to some other parts of the IKFD. The widest veins in the Rosiclare Subdistrict typically lay where one or both walls of the fault were composed of limestone or highly calcareous units. Fluorspar also replaced an earlier-phase calcite already present within the faults and fractures. Both the fault and vein were usually named the same; thus, the Rosiclare Vein lay along the Rosiclare Fault. From east to west, the major veins are named the Hillside, Rosiclare, Daisy, Blue Diggings, Argo, and Knight. The biggest problem in the Rosiclare Subdistrict was flooding, which forced a number of mines (including the Rosiclare) to shut down temporarily or permanently. In mines at the southern end of this subdistrict, fissures may have channeled water directly from the Ohio River into underground workings.