58 COPPER-BEARING ROCKS OF LAKE SUPERIOR. 
Tabulation of observations on hornblende-gabbro—Continued. 
| Angle between 
maximum eX- 
tinetions of 
adjacent hemi- 
tropic bands of 
a ; the plagioclase 
4 Place. 8 ; Macroscopic char- Constituents as determined by ae aeougre cut 
=| 3 acters. microscope, in order of age. at random im 
EI SI ns the zone O: wt. 
g B a zl Angles on| & |; 
a £2 é E) opposite ice 
2 5B |3|5|6é sides of| 4 8 
nm Clalal & cross-hair. ' 
——————— (asec ase ee ee SS ea ’ 
° ° ° j 
9022 I.| Ashland County, IS. W.| 53 | 45 | 3W. Medium-grained ; Apatite, very abundant, insmall | 20 19 39 f 
Wisconsin. mottled black crystals; labradorite and ortho- j 
| and white; clase, in much rounded parti- 
rough. Sp.gr., cles; diallage, often partly 
2.83. altered to uralite; non-dial- 
lagic augite ; basaltic horn- 
blende; a few large scales of 
biotite; quartz, filling corners 
and apparently primary, 
abundant. 
2020 I.|.---d0 ...------20-|--22°* 2 | 44 | 3W.| Medium-grained; | Apatite; oligoclase and ortho-| 7 | 5 | 12 5 
d neatly black: clase in much-rounded grains; 5 3 8 
rough-textured. magnetite, or titanic tron; 1 4 5 
augite, very abundant, in 
large, rounded grains, attimes 
diallagic; basaltic hornblende, 
not very abandant, secondary, 
and grading into augite; 
quartz, filling corners, not 
abundant. 
106 I..| Ashland County, |N.W.| 17 | 44 5W.| Medium-grained; | Apatite, very large and abun-| 7 P| abe 
Wisconsin, north mottled black, dant, just as in No.1 of this| 11 12 23 
line of white, and yel- group—often in hexagonal sec- 
lowish-pink; | tions which reach .01™™ in 
rough-textured. diameter; oligoclase ; ortho- 
clase; magnetite, or titanic 
iron; diallage almost wholly 
changed to uralite; basaltic 
hornblende, occurring just as 
in 137 W., but very much more 
abundant; biotite, in ® few 
flakes; quartz, ina few spots, 
filling corners, apparently 
original; chlorite and ferrite, 
secondary. 
187 W.| English Lake, at | S.4| 5 | 44 | 3W. Medium-grained; | Apatite, in afew large crystals; | 15 | 13 | 28 
outlet, Ashland black; lustrous. labradorite; magnetite, small | 24 23°) 47 
county, Wiscon- and sparse; augite, mostly | 13 14 | 27 - 
sin. quite fresh; basaltic horn- | 
blende, making up most of the 
section, in a few cases appear- | 
ing to shade into the augite; 
biotite. 
| 06 W..| Ashland County, | S.4 | 15 | 45 | 1 W- Medium-grained | Oligoclase ; orthoclase; magne-| 14 Ww 31 
Wisconsin. 1 to fine-grained; | tite; augite; basaltic horn-| 13 | 16 | 29 
nearly black. blende; biotite. Resembles | 11 13 24 
Sp. gr., 3.08. No.5, but much finer grained. 
