OUTLINES. 
129 
between the forks of New River, in Ashe and Watauga counties, in the 
Rich Mountains, Elk Knob, &c., to Negro Mountain, near Jefferson. 
Very large veins of a very coarse granite abound along the median 
parts of the tract, especially in Mitchell and Yancey. The quartz, mica 
and feldspar are found in huge masses instead of small crystals. These 
veins are extensively wrought for mica, which is obtained in large plates, 
10 to 20 and even 30 inches in diameter. Some single veins have yielded 
hundreds of tons within the last 3 or 4 years. And these mines are not 
now opened for the first time. On the contrary, they were wrought on 
a much larger scale by the Mound-Builders ages ago; and most of these 
veins are honey-combed with ancient tunnels and shafts, which were 
located and excavated with more skill and success than the modern 
workers have yet attained. Their market was evidently the populous 
regions north of the Ohio, whose numerous mounds contain, in their 
multitudes of ornaments and utensils of this mineral, the evidence of the 
extent of this curious ancient commerce. 
One of the most remarkable and interesting features of the geology of 
this belt is the line of chrysolyte ledges, ( dunyte ), which occur along the 
median zone of it, outcropping in massive dikes, which form rough, 
jagged hills at intervals of half a score of miles, more or less, from the 
Rich Mountains of Watauga through Mitchell, and the intervening 
counties to Clay. Some of these ledges are nearly a mile long and sev- 
eral hundred yards wide. They are notin line with one another, but are 
scattered over a zone 10 to 20 miles in breadth. It is worthy to be noted 
that they occur in the middle zone, where the rocks are most disturbed 
and irregular in position ; that they are associated with the most massive 
outcrops of hornblendic rocks, — syenytes, schists and actinolyte rocks, 
and with heavy veins of coarse porphyroidal granite, and that they thus 
claim a very low horizon. 
The masses of chrysolyte are more or less distinctly granular, and are in 
fact, a chrysolytic sandstone, of a yellowish to dull, or dark olive-green 
color. The composition of this rock Dr. Genth finds to be as follows : 
Silica, 41. SO 
Protoxide of iron, 7.39 
Nickel oxide, 0.35 
Magnesia, 49.13 
Lime, 0. 6 
Loss by heat,., 0.S2 
Chromic iron, 0.58 
100.22 
