iv? 
a ee ee oe 
ORTHOCLASE-BEARING GABBRO. 
55 
Tabulation of observations on orthoclase-bearing gabbros—Continued. 
Angle between 
maximum ex- 
tinctions of 
adjacent hemi- 
4 tropic bands of 
5B el, the plagioclase 
2 Place. a Macroscopic char- | Constituents as determined by in sections cut 
g 3 acters. microscope, in order of age. at random in 
A S . the zone O: ii. 
g 4 | | ; Angles on| 2 
: a ISlel § eppeste| 3 
a B 2 | ° S 0 a 
n Clnla!] & cross-hair.| & @ 
° ° ° 
10. Near Duluth, | NE. | 33 | 50 |14W.| Very coarse-grain- | Apatite ; labradorite; orthoclase; | 23 22 45 
Minn., 1,980 ed; light-gray;| titaniferous magnetite; diallage 9 10 19 
north, 0 west. much pinkish | mostly changed to wralite. 
titanic iron; 
very rough-text- 
ured. 
3...... Near Duluth, | N.4 | 28 | 50 |14W.| Coarse-grained; | Apatite in a few large crystals; | 22 21 43 
Minn., 1,970 light-gray ; very labradorite; titanic iron, | 27 20 47 
north, 680 west. rough-textured. abundant; diallage, highly | 27 23 50 
fibrous and largely altered to 
uralite. | 
teen Near Duluth, | NW.| 28 | 50 }14W.| Very coarse-grain-| Oligoclase; orthoclase; little | 12 11 23 
Minn., 2,000 ed; light- gray; titaniferous magnetite; dial- 8 13 21 
north, 1,300 west. very rough-text- lage mostly altered to uralite. 
' tured. | 
(Heeaas Near Duluth, |NW.| 28 | 50 |14W.| Very coarse-grain- | Apatite, in quite large crystals; | 13 16 | 29 
Minn., 1,800 ed; light-gray; oligoclase ; orthoclase; titani- | 11 13 24 
north, 2,000 west. very rough-| ferous magnetite; diallage,| 12 13 25 
textured. partly fresh, partly altered to 
uralite; ochre; biotite. 
509....| Top of bluff, Du- | SW. | 27 | 50 |14W.| Very coarse-grain-| Labradorite; titaniferous mag-| 20 24 44 
luth, Minn. ed; dark-gray. netite; diallage, partly fresh, | 25 24 | 49 
partly altered to wralite and | 21 25 46 
chlorite. | 
BLL: soe| sees COs seeccccscse SW. | 27 | 50 | 14 W.| Very coarse-grain-| Apatite in large crystals; labra- | 20 19 | 39 
ed; light-gray; dorite, much altered; titani- | 26 24 50 
rough-textured. Jerous magnetite; diallage, | 23 23 46 
much altered; chlorite. 
508....| Near quarry, Du- | SW. | 27 | 50 |14 W.| Very coarse-grain-| Labradorite or anorthite, much | 31 31 62 
loth, Minn, ed, the plagio- clouded; titaniferous magne- | 19 21 40 
clases running| tite; diallage, mostly altered 
from ahalfinch| to uralite. 
to an inch in 
length. 
Sie => Lester River, Min-|NW.| 4 | 50 |13W.) Medium-grained;| Apatite abundant; oligoclase | 14 15 29 
nesota, near red - black-and- much clouded; orthoclase; 8 10 18 
northwest cor- green - mottled; titaniferous magnetite; non-| 13 13 26 
ner. muchweathered.| diallagic augite; alteration- 
product of augite. 
At, os Near Lester River, | NE. | 29 | 51 |} 13W.| Clese to 39, less ; Labradorite, orthoclase, in the | 19 21 40 
Minnesota. weathered. characteristic twins; titani-| 29 320 59 
ferous magnetite; augite in| 16 14 30 
long, twinned blades; dial- 
lage; a green alteration-pro- 
duct of augite; secondary 
quartz. 
18 15 33 
