This hybrid system operates where CO2- and HF-bearing magmatic volatiles condense into basinal brines that replace carbonate with fluorspar ± barite, REE, Ti, Nb, Be as in the Illinois-Kentucky Fluorspar district and Hicks Dome.
Denny, F.B., Devera, J.A., and Seid, M.J., 2016, Fluorite deposits within the Illinois-Kentucky Fluorspar District and how they relate to the Hicks Dome cryptoexplosive feature, Hardin County, Illinois, in Lasemi, Z., and Elrick, S., eds., 1967-2016--Celebrating 50 years of geoscience in the mid-continent, Guidebook for the 50th Annual Meeting of the Geological Society of America North-Central Section, April 18-19, 2016: Illinois State Geological Survey Guidebook 43, p. 39-54.