78 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[BULL. 1( 
H. Dark vitreous quartzite. Contains quartz, a little red feldspai 
some chlorite, some green mica, a few scales of biotite, and grains c 
magnetite. P. R. C. 1007. 
I. Lighter interbedded quartzite. Feldspar in it much alterec 
P. R. C. 1004. 
J. Epidotic quartzite. P. R. C. 1023. 
K. Unaltered quartzite. P. R. C. 1006. 
Analyses by R. B. Riggs, record Nos. 569, 571, 572, 575. Materia 
dried at 105°. 
H. 
I. 
J. 
K. 
Si0 2 
74.22 
10.61 
7.45 
.85 
1.48 
.56 
2.12 
1.08 
1.79 
.16 
none 
73.65 
11.08 
7.24 
.77 
1.52 
.40 
1.67 
1.65 
1.88 
trace? 
trace 
73.14 
12.60 
7.57 
1.31 
1.67 
.43 > 
1.78 
1.00 
.83 
.04 
trace 
73. 64 
11.25 
6.24 
1.04 
1.57 
.36 
3.04 
1.42 
1.98 
trace 
none 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 0.. 
Ism ... ..... .-_ . -. 
Ti0 2 
MnO 
100. 32 
99.86 
100. 37 
100. 54 
Ba and Sr not looked for. 
