26 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[BULL. 168. 
M. Basic segregation in diorite. Contains hornblende, augite, bio- 
tite, plagioclase, magnetite, apatite, zircon, and a little quartz. 
N. Diabase. Contains plagioclase, augite, and magnetite. 
O. Camptonite. Contains brown hornblende, plagioclase, a little 
augite, olivine, magnetite, and apatite. 
P. Phyllite. Contains quartz, sericite, graphite?, magnetite, pyrite, 
rare orthoclase, plagioclase, sphene, and rutile. 
Q. Microperthite-hornfels. Contains biotite, quartz, red garnet, 
corundum, magnetite, iolite, microperthite, and rarely pleonaste. 
R. Cordierite-hornfels. Contains quartz, biotite, pleonaste, corun- 
dum, iolite, magnetite, plagioclase, red garnet, and epidote?. 
M. 
N. 
0. 
P. 
Q. 
R. 
Si0 2 
55.28 
17.23 
1.54 
6.23 
2.69 
5.60 
5.42 
2.12 
.20 
.71 
1.64 
.73 
trace 
.24 
(?) 
.06 
.04 
49.63 
14.40 
2.85 
8.06 
7.25 
9.28 
2.47 
.70 
.27 
1.47 
1.68 
.25 • 
trace? 
.17 
.04 
trace? 
1.36 
48.22 
14.27 
2.46 
9.00 
6.24 
8.45 
2.90 
1.93 
.28 
1.66 
2.79 
.64 
.03 
.20 
.03 
.04 
.15 
90.91 
4.18 
.22 
1.27 
.37 
.22 
.77 
.58 
.06 
.74 
.28 
.05 
.02 
trace 
none 
trace 
.18 
.10 
none 
58. 35 
21.30 
.03 
6.41 
2.10 
.85 
1.60 
5.63 
.31 
.86 
.87 
.18 
. none 
.13 
.03 
.05 
45. 30 
30.51 
.24 
8.80 
3.11 
.90 
1.65 
4.84 
.26 
1.05 
1.48 
.12 
none 
.20 
.02 
.03 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatll0°... 
H 2 above 110° 
Ti0 2 
P 2 5 
Zr0 2 
MnO 
(NiCo)O 
BaO 
CO., 
c 
.40 
none 
.03 
(?) 
.58 
.17 
.04 
.04 
.04 
1.07 
S0 3 
none 
.07 
.28 
.07 
none 
.07 
trace 
.22 
none 
.10 
.05 
.36 
CI 
F ' 
trace 
.11 
FeS 2 
Less 
100. 15 
.13 
100. 17 
.02 
99.80 
.04 
100. 06 
99.71 
99.87 
100. 02 
100. 15 
99.76 
In these rocks the sulphur is all reckoned as pyrite, although pyr- 
rhotite also is probably present. The carbonic acid represents either 
dolomite or side rite; not calcite. Traces of lithia and strontia occur 
in nearly all. Samples H, L, O, and Q contain traces of copper. In 
N there is 0.03 V 2 O s , a supplementary determination by Hillebrand. 
