I am trying to identify a stone structures next to two mine shafts on a historic 
mine site on the Sumter National Forest in Oconee County , SC.  The site was 
probably used in the 1850s and contains a couple of deep vertical shafts (15 x 
15, and 10 x 10) and several adits, trenches and smaller prospecting holes.  
They were probably mining argentiferous galena (silver-lead).  The stone 
sturctures are about 15 feet from the shafts, are mud mortared fieldstone, and 
about six feet square.  They are each located upslope of the shafts on steep 
slopes and do not appear to have associated building foundations.  They look 
like chimneys, but I have not seen soot or any charcoal or slag near the 
chimneys.  Photos are on the attached:

http://www.fs.fed.us/r8/fms/forest/projects/OconeeCountyHistoricMineStructur
es.shtml

Any Ideas?  Thanks, Jim Bates