Smith.] LEAD, ZINC, AND FLUORSPAR OF WESTERN KENTUCKY. 213 
or less extent, but they have had comparatively little effect as yet on 
the fluorite and barite. The galena has not been oxidized to any con- 
siderable extent, and is still found near the surface. The fine-grained 
sphalerite has been largely removed from the veins, having been in 
part altered to smithsonite (zinc carbonate), which in turn is being 
slowl} x dissolved and removed by the surface waters. At the Old Jim 
mine the zinc salts in solution, reacting with limestone, have replaced 
it here and there with zinc carbonate. The result of the leaching out 
of the calcite and limestone fragments has been to leave the fluorite in 
a more or less honeycombed condition. Where it was not originally 
associated with these substances it is usually found in lumps. Wher- 
ever the grains have been loosened or separated it is found in a sand} 7 
or gravelly form known as gravel spar. In all these cases it is usu- 
ally associated with red clay formed as a residual product on the solu- 
tion of the adjacent limestone. 
The depth of oxidation along the course of the veins is variable and 
may be as much as 100 feet or more. In a few cases fresh, unaltered 
vein matter and country rock come nearly or quite to the surface. 
Descending surface waters have occasionally formed channels along 
a fissure, thus carrying oxidation and oxidized products considerably 
below the normal level of underground water. 
Vertical distribution of vein minerals. — As far as the deposits have 
been developed it can not be proved that the fluorite, on the whole, 
actually decreases with depth, though it is said to do so in some cases. 
This assumed decrease may be merely comparative, since the associ- 
ated calcite in many instances appears to increase with depth, 
although it is quite probable that in general this is due merely to the 
fact that it has been removed by surface waters at the higher levels. 
Galena, in general, appears to be most abundant near the surface, 
and on the whole to decrease with depth, though in many instances 
it is not apparently more abundant at one level than at an another. 
Above the level of underground water fine-grained sphalerite lias 
been generally removed or changed to carbonate. Below this level it 
seems probable, from what has been observed, that it does not materi- 
ally increase in amount with depth. The coarser occurrences of the 
sphalerite may be due to secondary enrichment, the finer-grained 
mineral having been oxidized and carried downward in solution 
below ground-water level, where it was redeposited in the coarser 
form. Connected with these deposits there appears to have been 
also some secondary concentration of the galena. No positive state- 
ment can be made on this point, as none of the mines yielding coarse 
sphalerite were accessible below ground-water level at the time the 
region was visited by the writer; but if this is the true interpreta- 
tion of the facts, these deposits of coarser sphalerite will be found to 
be most abundant just below ground-water level, and will tend to 
decrease with depth till only the finer-grained ore is found, the latter 
representing the primary concentration. 
