CLARKE.] 
SLATES AND SHALES. 
WISCONSIN. 
345 
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., II. 2 E. 
B. Sec. 1, T. 45 N., R. 1 E. 
C. Sec. 4, T. 44 N., R. 2 W. 
Si0 2 ... 
A1A-- 
Fe 2 3 . 
FeO... 
MgO.. 
CaO... 
p 2 . . 
K 2 0... 
H 2 0... 
PA -- 
MnO . . 
Li 2 .. 
53. 44 
19.62 
11.38 
5. 35 
1.58 
.42 
2.61 
1.73 
4.07 
trace 
trace 
trace 
100. 20 
B. 
59. 73 
22.78 
.11 
5.98 
2.94 
.53 
1.41 
3.48 
3.28 
.09 
100. 33 
52.58 
20.76 
12.17 
4.08 
1. 33 
.30 
.37 
4.87 
3.43 
.21 
trace 
100. 10 
