CLARKE.] 
IGNEOUS AND CRYSTALLINE HOCKS. 
75 
The following analyses, by W. F. Hillebrand, of separations from 
the gabbro of Ashland County, Wisconsin, were made for the late R. 
D. Irving, but were never published by him: 
H. Magnetite, record No. 687. Partial analysis. 
I. Feldspar, record No. 688. 
J. Diallage, record No. 686. 
For convenience I also include here, although it is decidedly out of 
classification — 
K. Graywacke, Hurley, Wisconsin. Described by Bayley in Bull. 
150, p. 84. Analysis by H. N. Stokes, record No. 1314. Contains 
quartz, feldspars, iron oxides, and probably kaolin. In the cement 
are chlorite, quartz, magnetite, pyrite, rutile, occasionally biotite, and 
either muscovite or kaolin. P. R. C. 20. 
H. 
I. 
J. 
K. 
Si0 2 
53. 30 
29.03 
.55 
.23 
.13 
11.40 
4.87 
.40 
.23 
trace 
trace 
none 
trace 
trace 
none 
49.80 
2.86 
2.48 
10.82 
15.33 
16.50 
.51 
.12 
.33 
1.29 
trace 
.37 
none 
none 
trace? 
76.84 
11.76 
.55 
2. a: 
1.39 
.70 
2.57 
1.62 
1.87 
A1 2 3 
Fe 2 3 
50.29 
30.70 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 
Ti0 2 
8.77 
P 2 5 
MnO 
trace 
SrO 
BaO 
Li 2 
89.46 
100. 14 
100. 41 
100. 18 
