62 
ANALYSES OF ROCKS, IT. S. GEOLOGICAL SURVEY. 
[NO. 
NORTH CAROLINA. 
Rocks A to F collected by Arthur Keith, who furnishes the petro- 
graphic data. Analyses B, C, D, and E by W. F. Hillebrand, record 
No. 1707. Analyses A and F by H. N. Stokes, record No. 1710. 
A. Porphyritic rhyolite, 2 miles west of Banners Elk, Watauga 
County. Adamellose. Contains orthoclase and plagioclase, with less 
quartz, epidote, chlorite, and pyrite. 
B. Quartz-porphyry, 2i miles northwest of Blowing Rock, Watauga 
County. Magdeburgose. Contains quartz and orthoclase, with sub- 
ordinate sericite, chlorite, and biotite. 
C. Diorite, east end of Hump Mountain, Mitchell County. Auver- 
gnose. Contains plagioclase, orthoclase, and hornblende, with less 
quartz, biotite, magnetite, and garnet. 
D. Garnetiferous diabase, If miles southeast of Cranberry. III. 
If. 4- 4-, 5- Contains plagioclase and hornblende, with less garnet, bio- 
tite, and magnetite. 
Si0 2 .. 
A1 2 3 . 
Fe 2 3 . 
FeO.. 
MgO . 
CaO.. 
K 2 
H 2 OatllO°.._. 
H 2 above 110° 
Ti0 2 
PA 
Zr0 2 
Cr 2 3 
v 2 o 3 
CoO,NiO 
MnO 
SrO 
BaO 
Li 2 
S 
62. 35 
13.24 
3.52 
6.33 
.85 
3.34 
2.79 
3.95 
.11 
1.21 
1.18 
.57 
none 
.08 
trace 
.16 
trace 
79.75 
10.47 
.64 
.92 
.13 
.15 
1.36 
6.01 
.08 
.60 
.15 
trace 
.05 
none 
trace 
trace 
.06 
trace 
none 
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 
.03 
.20 
none 
none 
trace 
trace 
99.68 
100. 37 
98 
99.79 
