52 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SUKVEY, 
NORTH CAROLINA. 
[BULL. 16* 
Rocks A to F collected by Arthur Keith, who f .rnishes the petro 
graphic data. Analyses B, C, D, and E by W. F. Hillebrand, recoi*( 
No. 1707. Analyses A and F by H. N. Stokes, record No. 1710. 
A. Porphyritic rhyolite, 2 miles west of Banners Elk, Wataugi 
County. Contains orthoclase and plagioclase, with less quartz, epidote 
chlorite, and pyrite. 
B. Quartz-porphyry, 2i miles northwest of Blowing Rock, Wataugj 
County. Contains quartz and orthoclase, with subordinate sericite 
chlorite, and biotite. 
C. Diorite, east end of Hump Mountain, Mitchell County. Con 
tains plagioclase, orthoclase, and hornblende, with less quartz, biotite 
magnetite, and garnet. 
D. Garnetiferous diabase, If miles southeast of Cranberry. Con 
tains plagioclase and hornblende, with less garnet, biotite, anc 
magnetite. 
A. 
B. 
c. 
D. 
Si0 2 
62.35 
13.24 
3.52 
6.33 
.85 
3.34 
2.79 
3.95 
.11 
1.21 
1.18 
.57 
79.75 
10.47 
.64 
.92 
.13 
.15 
1.36 
6.01 
.08 
.60 
.15 
trace 
.05 
46.91 
15.85 
2.86 
9.95 
7.01 
9.62 
2.65 
.69 
.24 
1.62 
2.03 
.26 
none 
.01 
.03 
.03 
.22 
trace? 
trace? 
trace 
none 
52.11 
13.70 
1.22 
9.86 
8.08 
12.16 
1.31 
.16 
.06 
.53 
.32 
.05 
none 
A1 2 3 
Fe 2 3 . 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatll0° 
H 2 above 110° 
Ti0 2 
RO, 
Zr0 2 
Cr 2 3 
none 
VoOo 
CoO, NiO 
* none 
.08 
trace 
.16 
trace 

none 
trace 
trace 
.06 
trace 
none 
.03 
.20 
none 
none 
trace 
trace 
MnO 
SrO 
BaO 
Li 2 
S 
99.68 
100. 37 
99.98 
99.79 
