296 
ANALYSES OF ROCKS, IT. S. GEOLOGICAL SURVEY. 
[NO. 228. 
F. Potsdam sandstone, Ablemans, Sauk County, Wisconsin. 
Described by Diller in Bull. 150, p. 80. Analysis by Schneider, record 
No. 1280. P. R. C. 15. 
(I. Banded sandstone, Peoa, Utah. Described by Diller in Bull. 
150, p. 80. Analysis by Schneider, record No. 1280. P. R. C. 16. 
H. Brown sandstone, Flagstaff, Arizona. Analysis by T. M. 
Chatard, record No. 1141. 
1. Sandstone, Robinson mine, Summit County, Colorado. Analysis 
by L. G. Eakins, made in the Denver laboratory, partial. 
,]. Sandstone from the Logan mine, Rico district, Colorado. Con- 
sists mainty of quartz and sericite. 
K. Altered sandstone, in contact with J. Same constituents, plus 
limonite, anglesite, and a lrydrous magnesian mineral. Analyses J, 
K, by W. F. Hillebrand, record No. 191-1. Described by Ransome, 
22d Annual, Part II, p. 287. 
F. 
G. 
H. 
I. 
J. 
K. 
Si0 2 
99.42 
} ■« 
96.60 
\ 2.02 
"79.19 
1.30 
2.45 
56. 33 
.77 
.97 
83. 95 
8.92 
.48 
.13 
.97 
.12 
.06 
3.09 
| &1.90 
none 
none 
} 
} 
62.88 
Al 2 O s 
21.38 
Fe 2 3 
1.09 
FeO 
MgO 
.08 
.04 
.23 
7.76 
7.30 
14.01 
undet. 
undet. 
undet, 
undet. 
''19.04 
2.00 
CaO 
.40 
Na 2 
.07 
K 2 
6.59 
H 2 at 100° 
} ■» 
.11 
.29 
.32 
2.94 
5.77 
H 2 above 100° 
C0 2 
5.49 
P 2 5 
SO, 
.53 
MnO 
a little 
CuO...._ 
trace 
trace 
.04 
PbO 
.34 
Ag 
none 
99.91 
99.14 
99. 96 
98.42 
99.66 
100. 77 
<' Silica and insoluble matter. 
(> Loss on ignition. 
c Calculated to satisfy bases. 
