The fault systems of the Levias-Keystone and Dike-Eaton areas, in the
Kentucky-Illinois fiuorspar district, are a complex northeastward-trending sys-
tem and a simple northwestward-trending system of steeply dipping normal
faults, associated in part with a lamprophyre dike. Fluorspar mining started
in the area about 1900 and, as of 1945, more than 200,000 tons of crude ore
probably has been mined; most of the ore was from the Levias-Keystone area.
A small quantity of zinc and lead ore also is present in the Dike-Eaton area.
The deposits are localized along faults that displace fiat-lying or low-dipping
limestones, sandstones, and shales of the Meramec and Chester series of Missis-
sippian age. Movement along most of the faults was principally vertical, with
displacement as much as 600 feet. Some horizontal movement occurred along
at least one fault. Geologic mapping of the surface and data from underground
workings have revealed 13 faults in an area of four-fifths of a square mile.
Only a few of these faults are known to contain economically important deposits
of fiuorspar.
The most abundant vein minerals are calcite and fiuorite with subordinate
quantities of sphalerite, galena, barite, and quartz. Some weathering products
of sphalerite and galena are present also. The veins are dominantly calcite
that contains fiuorite lenses but in places are mainly fiuorite having lesser
quantities of calcite. Sphalerite- and galena-bearing deposits are present in the Dike-Eaton area. The ore bodies mainly are the result of fissure filling and replacement of calcite by fiuorite; in addition a small amount of limestone
wallrock probably has been replaced. Residual concentrations of high-grade
fluorspar in the overburden above faults have yielded some so-called gravel
fiuorspar. The position of the veins within the faults may be related to one
or more factors such as type of wallrock, change in dip of the fault, and amount of displacement.
