46 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
2. CRYSTAL FALLS DISTRICT, MICHIGAN. 
Rocks described by J. Morgan Clements and H. L. Smyth, in Mon. XXXVI. A,B, 
C, and D by Smyth, p. 274. Analyses by H. N. Stokes, record No. 1721. 
A. Granite, sec. 2,T.41N.,R.30W. Magdeburgose. Contains quartz, orthoclase, 
microcline, plagioclase, biotite, muscovite, magnetite, hematite, titanite, and occa- 
sional apatite. 
B. Gneiss, sec. 35, T. 42 N., R. 29 W. Same minerals as in A. 
C. Mica schist, sec. 35, T. 42 N., R. 29 W. Contains biotite, quartz, some micro- 
cline, and magnetite. . 
D. Amphibolite, sec. 32, T. 42 N., R. 28 W. Contains hornblende, plagioclase, 
biotite, and quartz, with a little rutile and magnetite. 
A B Cc. D 
SiO serine wsnsecncedienas ete SRSA aisee tes WAP VAR RA ERLE a EPO 76.10 | 74.37] 64.71 50. 36 
Al2O3 12.95 | 13.34] 16.43 13. 26 
Fe203 65 92 1.83 6.30 
FeO. 09 21 3.84 9. 34 
MgO 14 27 2.97 5. 55 
CaO. 12 50 08 7.85 
Naa) oj: atts oaceecindsisinnigecanins Aesmeinss aicumstates ade suenen 2. 36 2. 50 ll 2.11 
eee meen ern oe cop MB) a) Se) Ae 
OP BE ME «fogs eademe ce eee Mateo se Rieke wes Ria HER Rhea eeRKaR: ate . * . . 
T{120 above 110°. eoscisiniinibis ss 3 ceieeerebreieieeieto isis 48 44 2.79 1.55 
iO ae 07 07 ota 1.77 
02 01 02 20 
trace | trace | trace trace 
99.65 | 99.45 | 99.44 99. 59 
Ba, Sr, Cl, F, S, SO3 not looked for. 
The following rocks, with one exception, are described by Clements in his portion 
of Mon. XXXVI: 
E. Mica diorite, sec. 28, T. 42 N., R. 32 W., southeast of Crystal Falls. Shoshonose. 
Contains plagioclase (andesine), orthoclase, quartz, biotite, hornblende, and titanifer- 
ous magnetite. Analysis by Stokes, record No. 1721. 
F. Hornblende gabbro, sec. 29, T. 42 N., R. 31 W., west bank Michigamme River, 
east of Crystal Falls. Hessose. Contains labradorite, hornblende, and iron oxide, 
with subordinate pyroxene, biotite, and orthoclase. Analysis by George Steiger, 
record No. 1712. 
G. Bronzite norite, same locality as F. Auvergnose. Contains bronzite, horn- 
blende, and labradorite. Analysis by Steiger, record No. 1712. 
H. Wehrlite, sec. 29, T. 42 N., R. 31 W., on Michigamme River, east of Crystal 
Falls. Rossweinose. Contains hornblende, pyroxene, olivine, biotite, and iron 
oxide. Analysis by Stokes, record No. 1721. 
