242 The American Geologist. October, 1896 
of granitic rock and l)aiKls of lh(^ typical "augen"-gneiss also 
show in the face of the cliir. 
It should be mentioned h(M-e that no field evidences of de- 
trital origin liave been observed. 
PK(iMATITt; V^EINS. 
Within this area many more or less pure veins or masses of 
great size occur. Quarries have been worked in other locali- 
ties, but the best of them seem to be included in the area just 
described. The larger deposits of commercial importance are 
marked on the map (Plate IX, Fig. 6) at F, li and A. Tlie 
size of these pegmatite deposits can be inferred from the view 
of one of the quarry excavations on P, H. Kinkel's farm; see 
Plate VIII, Fig. 2. On A. Hobby's farm (F) a large, well ex- 
posed pegmatite vein is found, where the deep erosion of the 
Mianus river has laid bare large masses of vei'y pure quartz 
and feldspar. Just to the south of this exposure a fairly good 
granite occurs. P. H. Kinkel's quarry (7i) is being worked 
at present principally for feldsjjar, which is ground in a mill 
on the place. The other small outcrops of feldspar and quartz 
are usually so mixed that they are not profitable to work. It 
will be noticed that the longer axes of the pegmatite masses 
follow the general strike of the "augen"-gneiss. 
In these pegmatite deposits the quartz and feldspar occur 
in different conditions. At times they are found quite pure, 
in large, separate masses with sharp contacts; while at other 
times the (piartz and feldspar occur intergrown as a true 
pegmatite, varying from an extremely coarse' structure, with 
lenticular quartz, to a very fine graphic granite. 
The quarries are cut through with veins of mica and veins 
of quartz, feldspar and mica, forming a coarse granitic rock. 
Black tourmaline, of the ordinary elongated type, is very 
common and seems to occur principally in the quartz near its 
contact with the feldspar. Its occurrence has not been noticed 
in the purely feldspathic portions of the pegmatite. In P. H. 
Kinkel's quarry, where an excavation has been made into a 
large mass of pure white ([uartz, the intergrowth of tour- 
maline with the latter is very marked. A close adjoining ex- 
cavation shows chiefly feldspar, either pure or mixed with 
<iuartz as true pegmatite. 
