Reézamination of American Minerals. 243 
red shale are characterised by containing the ores of copper. But the 
zinc ores, viz., zine blende and calamine, prevail in greater or less pro- 
portions in both sets of veins, existing, perhaps, i ina rather larger rela- 
ue amount in the copper-bearing lodes of the red shale. 
gneissic strata of the tract embracing this group of lead-bear- 
ing veins, seem to differ in no essential features from the rest of the 
thirdly a thicker bedded granitic gneiss, composed not unfrequently of 
little else than the two minerals, quartz and feldspar. 
enetrating this quite diversified formation are innumerable injections 
of various kinds of granite, oS trap, and other genuine igneous 
rocks. The i rsaers as throughout this region generally, consist for 
were i but ofien partially conforming with its planes of bedding for 
a limited space, and then branching through, or expiring in it in trans- 
stronger lead-bearing veins, particularly in their more productive por- 
tions ; but this materia | belongs, in all probability, not to the ancient 
—. which filled long aces Tents in that formation with the lead 
ore es a their associated minerals.” 
h gneissic strata and their Sac injections, throughout this dis- 
trict display’ a_ softened, partially decomposed condition, extending 
many age to a depth of twenty fathoms.” 
“OF the dozen or more lead and copper lodes of greater or less 
size brought to light in this quite limited region of five or six miles 
length and two or three miles breadth, the greater number are remark- 
ably similar in their course, rangin —35° E., and 8. 32°— 
+; and what is equally worthy of note, they dip, ‘with scarcely an 
exception, towards the same quarter, or south- eastwardly, though in 
eethe instances so steeply as to approach the perpendic ney? 
“There is no marked difference in the general character of the vein- 
Stones of the several mineral lodes, nor any seuieet to pamwene asa 
class those of the red shale from those of the gne 
The minerals found bes these — are quite numerous, and 
among them, there are specimens of species hardly equalled 
by those coming from any seni locality. Prof. Silliman, in 
ma 
in lead mining, and tual by 4 any thitg to be seen in the 
cabinets of Buto 
