CLARKE.] 
SLATES AND SHALES. 
285 
WISCONSIN. 
Slates of the Penokee-Gogebic series, collected by C. R. Van Hise. 
A and C are described in Mon. XIX, p. 306, as magnetitic clay slates. 
Analyses by L. G. Eakins, record No. 392. 
A. Sec. 6, T. 45 N., R. 2 E. 
B. Sec. 1, T. 45 N., R. IE. 
C. Sec. 4, T. 44N.,R. 2 W. 
Si0 2 .. 
A1 2 3 
Fe 2 3 
FeO. 
MgO 
CaO., 
Na 2 
K 2 0. 
H 2 0. 
PA- 
MnO 
Li 2 
A. 
53. 44 
19.62 
11.38 
5.35 
1.58 
.42 
2.61 
1.73 
4.07 
trace 
trace 
trace 
100. 20 
59. 73 
22.78 
.11 
5.98 
2.94 
.53 
1.41 
3.48 
3.28 
.09 
100. 33 
c. 
52. 58 
20.76 
12.17 
4.08 
1.33 
.30 
.37 
4.87 
3.43 
.21 
trace 
100. 10 
