IGNEOUS AND CRYSTALLINE ROCKS. 45 
LAKE SUPERIOR REGION. 
1. MARQUETTE REGION, MICHIGAN. 
Rocks mostly described by Van Hise and Bayley. When not otherwise specified 
the descriptions have been published in Mon. XXVIII, and partly in 15th Ann., 
p. 485. 
A. Peridotite, near Opin Lake, E. } sec. 27, T. 48 N., R. 27 W. Marquettose. 
Contains diallage, olivine, magnetite, and plagioclase. The diallage is partly chlori- 
tized, and the olivine is partly serpentinized. Analysis by W. F. Hillebrand, record 
No. 1452. P. R. C. 996. 
B. Altered greenstone, Marquette district. Camptonose. Analysis by George 
Steiger, record No. 1586, hitherto unpublished. P. R. (. 988. 
C. Griinerite-magnetite schist, sec. 11, T.47N., R.27W. Mainly impure griinerite, 
with magnetite and quartz. Analysis by W. H. Melville, record No. 1403. P. R.C. 
984. 
D. Like C, from sec. 18, T. 47 N., R. 28 W. Analysis by Melville, record No. 1403. 
P.R. C. 980. 
E. Like C and D, from sec. 20, T. 46 N., R. 30 W. Analysis by H. N. Stokes, 
record No. 1546. ©, D, and E are similar schists, and alike in mineralogical compo- 
sition. P. R. C. 981. 
\ B Cy D E 
SiO ss. a xeieneseentde Mn us ao ota a iad Rome eee 39.37 | 48.85 | 46.94] 49.70 46. 25 
Al2O3 4.47 | 15.83 - 66 1.35 92 
Fe203 4.96 2.50 4.51 3.10 30. 62 
FeO 9.13 | 10.79 | 33.72] 37.19 16.92 
MgO 26. 53 5. 82 6.64 5.72 2.13 
CaO 3. 70 6. 20 3. 22 68 1.69 
IN820 acts ncnramasmie 2 agriqodacwns acieenaueinetierst eae eee - 50 2.79 -16 | trace none 
RO acteyecess asarsterctaguises cigioueieinciemaicinis Ge ceteris a ene aeemep eke - 26 PSST? | evestesiertencs |Patcxeccrored none 
H20 at 110°. . see 
H20 above 110 
F. Green schist, sec. 34, T. 48 N., R. 27 W., near center of section. Contains 
plagioclase, chlorite, and quartz. Analysis by George Steiger, record No. 1447. 
P.R. C. 986. 
G. Sericite schist associated with the preceding. Mainly sericite and quartz. 
Analysis by Steiger, No. 1447. P. R. C. 985. 
H. Dark-gray, foliated schist, southeast corner of sec. 30, T. 47 N., R. 30 W.  Con- 
tains quartz, plagioclase, orthoclase, and biotite. Analysis by Steiger, No. 1525. 
P.R. C. 991. : 
I. Schistose gneiss, NW. } sec. 35, T. 47 N., R. 26 W. Contains quartz, kaolin, 
sericite, plagioclase, chlorite, magnetite, and apatite. Analysis by Steiger, No. 1525. 
J. Novaculite from Marquette. Described by Williams in Bull. 62. Contains 
quartz and sericite. Analysis by W. F. Hillebrand, record No. 759. 
