48 
COPPER-BEARING ROCKS OF LAKE SUPERIOR. 
Tabulation of observations on coarse orthoclase-free gabbro and diabase—Continued. 
8 : ; 
E Place. E Masronconis char. 
8 AA Es 
2 a /'o A 
3 Bele| & 
a 6 |ala| & 
Cy pase Sscech Mocsa6 Sechoe NE. | 10 | 53 | 10 W.) Medium- grained; 
brownish, with 
diallage; much 
altered ; seamed 
by laumontite. 
(esecd bereas Gas secrenas- NE. | 10 | 53 | 10 W.| Medinm-grained; 
black; rough- 
textured. 
682....| North shore Lake | SW.| 5 | 54 |8W.| Medium-grained; 
Superior, below black; heavy; 
Split Rock rough-textured. 
River, Minne- S$i0246.17p. cent. 
sota. 
779....| North shore Lake | NW.| 3 | 55 |8 W.| Coarse-grained; 
Superior, one- black, stained 
quarter mile with brown; 
southwest of rough-textured. 
south point of Sp. gr., 2.87. 
Beaver Bay, 
Minnesota. 
785....| North shore Lake | SW. | 12 | 55 | 8 W.| Coarse-grained; 
Superior; south black; rough- 
side of Beaver textured. 
Bay Point, Min- 
nesota. 
PEE Bead oan tetera SE. | 12 | 55 | 8 W.| Coarse-grained; 
dark-gray; 
rough-textured. 
793....| Falls of Beaver | SW. | 12 | 55 | 8 W.| Coarse-grained; 
River, Minne- nearly black; 
sota. rough-textured. 
Sp. gr., 2.93. 
794....| Beaver River, | SW. | 12 | 55 |8W.| Coarse-grained; 
Minnesota. black; rough- 
textured. 
782..-.| Falls of Beaver | SW. | 12 | 55 | 8 W.| Coarse-grained; 
River, Minne- black; rough- 
sota. textured, 
Constituents as determined by 
microscope, in order of age. 
Angle between 
maximum ex- 
tinctions of 
adjacent hemi- 
tropic bands of 
the plagioclase 
in sections cut 
at random in 
the zone O: zi. 
Olivine, wholly altered to green 
substance; labradorite ; titan- 
iferous magnetite in large 
areas; diallage, mostly altered 
to a green substance. 
Olivine, wholly altered to green 
substance; anorthite; titan- 
iferous magnetite ; augite, non- 
diallagic, greatly predominat- 
ing. 
Labradorite ; titaniferous mag- 
netite; augite; diallage; al- 
teration-product of augite and 
diallage. 
Anorthite ; titaniferous magne- 
tite, sparse; augite, in very 
large crystals, rarely dial- 
lagic, very fresh, and greatly 
predominating. 
Olivine, represented by green- 
ish-yellow alteration-product; 
anorthite; titaniferous mag- 
netite, sparse and small; dial- 
lage. 
Labradorite; titaniferous mag- 
netite ; diallagic augite, highly 
altered. 
Olivine, in large areas, largely 
altered to brown ochreous 
substance; anorthite ; titanif- 
erous magnetite; diallagic 
augite in very large areas. 
Olivine, in large areas, much 
altered; anorthite; titanifer- 
ous magnetite; non-diallagic 
augite. 
Labradorite; titaniferous mag- 
netite, notabundant; diallage ; 
viridite as alteration-product. 
Angles on/ ° 5 
opposite | o "Sb 
sides of| 4 
cross-hair.| a 
° ° ° 
21 24 45 
25 25 50 
29 20 49 
33 39 72 
32 31 63 
33 27 60 
30 26 56 
25 27 52 
32 33 65 
35 36 71 
34 28 62 
40 33 73 
31 30 61 
28 31 59 
31 36 67 
20 20 40 
24 29 53 
20 26 46 
27 20 47 
32 32 64 
29 29 58 
25 26 51 
31 31 62 
33 40 73 
33 31 64 
38 35 73 
18 24 42 
17 17 34 
24 23 47 
28 
