Distribution of minor elements in ore and host rock, Illinois-Kentucky fluorite district and Upper Mississippi Valley zinc-lead district

This paper presents data on the distribution of minor elements in ore and gangue minerals and in adjacent host rock from the Illinois-Kentucky fluorite district and Upper Mississippi Valley zinc-lead district. Comparisons are made of the minor-element abundances between districts and within the paragenetic sequence in individual districts.The ore of the Illinois-Kentucky fluorite district is characterized by greater abundance of minor elements than in other Mississippi Valley deposits, by large fractionation of silver between galena and sphalerite, and by a low ratio of antimony to silver in galena. Silver and antimony are concentrated in the galena and show a marked zonal pattern within the district. Sphalerite is high in cadmium, gallium, and germanium.The Upper Mississippi Valley zinc-lead district differs markedly from the Illinois-Kentucky fluorite district in minor-element concentrations and distribution. The minor elements are much less abundant, and silver is slightly more concentrated in sphalerite than in galena.Several analyses of minor elements in ore minerals from the Southeast Missouri lead district are given for comparison.It is concluded that the minor elements were largely leached from the basement by convective circulation of heated oilfield brine.