GEOLOGY OF THE FLUORSPAR DEPOSITS OF ILL ILL GEOL SUR BULL 7BAXTER J W DESBOROUGH G A ILL GEOL SURVEY CIRC 385 PART 2 19ILL STATE GEOLOGIC SURVEY BULL 41BASTIN EDSON S THE FLUORSPAR DEPOSITS OF HARDIN AND POPE COUILL ILL STATE GEOL SURVEY BULL 58 1931 P 77