280 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[BULL. 168. 
J. Slate from Guilford, collected for the Educational Series of Rock 
Specimens. Analysis by L. G. Eakins, record No. 1316. 
K. Slate from the Lakeshore quarry, Hydeville. Analysis by 
Eakins, record No. 1159. 
Si0 2 . 
A1 2 3 
Fe 2 O g 
FeO. 
MgO 
CaO. 
Na 2 
K 9 0. 
Ti0 2 . 
PA- 
MnO 
S0 3 -. 
C ... 
J. 
60.72 
22.59 
6.03 
2.05 
.41 
.86 
3.69 
3.01 
.13 
trace 
.57 
100. 06 
58.15 
18.93 
2.91 
5.64 
2.70 
.60 
1.17 
3.92 
4.56 
.93 
.12 
.07 
.16 
99.86 
