234 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[NO. 228. 
G. Diorite, north fork of Mokelumne River. Amadorose. Con- 
tains quartz, feldspar, biotite, sphene, epidote, and secondary chlorite. 
P. R. C. 771. 
H. Diorite, north fork of Mokelumne River. Andose. Contains 
plagioclase, quartz, hornblende, biotite, apatite, iron ore, epidote, 
and chlorite. P. R. C. 772. 
I. Plagioclase-gneiss, north fork of Mokelumne River. ITessose- 
andose. Contains plagioclase, hornblende, biotite, and apatite. P. R. C. 
768. 
J. Plagioclase-gneiss, north fork of Mokelumne River. Bandose. 
Contains plagioclase, hornblende, brown mica, apatite, epidote, and 
grains of iron ore. P. R. C. 767. 
Si0 2 
AlA 
FeA 
FeO 
MgO 
CaO 
Na 2 
K 2 
H,0 at 110 c 
Ti0 2 
P 2 5 
va 
NiO. 
MnO 
SrO. 
BaO. 
Li 2 
co 2 . 
FeS 2 
69.66 
17.57 
.21 
1.04 
.58 
4.54 
4.91 
.71 
.05 
.50 
.21 
.03 
none 
trace 
.05 
.03 
none 
none 
trace? 
100. 09 
ii. 
55. 86 
19.30 
.91 
4.78 
2.94 
7. 31 
3.52 
1.52 
.19 
1.23 
1.20 
.38 
trace 
.16 
.04 
.13 
trace 
none 
.39 
I. 
52. 21 
18.79 
2.71 
5. 30 
5.11 
8.01 
3.31 
1.60 
.12 
1.35 
1.16 
.36 
trace 
.06 
.08 
trace 
none 
.06 
100. 23 
46.63 
"19. 47 
3.26 
6.63 
5. 37 
9. 15 
3. 19 
1 . 55 
.10 
1.61 
1.82 
.66 
.02 
.02 
.21 
.06 
.14 
trace 
none 
.19 
100. 08 
