72 ANALYSES OF EOCKS, U. S. GEOLOGICAL SURVEY. [bull. 108. 
3D. UPPER QUINNESEC FALLS, MENOMINEE RIVER. 
Described by Williams, Bull. 62, pp. 104, 113, 114, 121. 
A. Light greenstone. Contains hornblende, feldspar much altered 
to saussurite, ilmenite with leucoxene border, and some secondary 
quartz. 
B. Mica-diorite-porphyry. Mainly andesitic feldspar and biotite, 
with apatite, zircon, sphene, and some calcite. 
C. Biotite-gneiss, Michigan side. Contains biotite, soda-orthoclase, 
and quartz. Sphene common, zircon and apatite present. 
D. Schistose quartz-porphyry. Contains quartz, feldspar, sericite, 
some chlorite, anatase, and tourmaline, with zircon and apatite sparingly. 
A, B, and D are from the Wisconsin side of the river. 
Analyses by R. B. Riggs, record Nos. 392, 393, 394, 395. Material 
dried at 105°. 
A. 
B. 
c. 
D. 
Si0 2 
48.35 
15. 40 
4.04 
4.63 
11.61 
10.38 
1.87 
.35 
3.60 
.08 
54.83 
25. 49 
1.61 
1.65 
1.96 
6.08 
5.69 
1.87 
1.18 
.18 
67.77 
16.61 
2.06 
1.96 
1.26 
1.87 
4.35 
2.35 
1.69 
.19 
66.69 
16.69 
2.06 
.93 
1.15 
1.40 
2.46 
5.23 
1.70 
1.42 
A1 2 3 
Fe 9 Oo 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 
co 2 
t 
100. 31 
100. 54 
100. 11 
99.73 
4th. schist from the aragon iron mine. 
Talcose-schist. Description, hitherto unpublished, furnished by 
W. S. Bayley. Analysis by George Steiger, record No. 1835. Con- 
sists mainly of talc and quartz, with a little limonite and other iron 
oxides. 
Si0 2 
49.56 
10.12 
5.87 
.13 
20.53 
• .72 
none 
H 2 OatllO° 
4.50 
7.66 
.60 
.04 
trace 
none 
A1,0, 
H 2 above 110° 
Fe 2 3 
Ti0 2 
FeO 
P 2 5 
MgO 
MnO 
CaO 
co 2 
Alkalies 
99.73 
