Gabbroid Rocks of Minnesota. — Wi?ichell. 231 
Thus labradorite from Kamenoi Brod, Russia, possesses 
an unusually easy cleavage parallel to g'^{oi6), but both cleav- 
ages are rather uneven; the images are nearly as good as 
those fromi the Minnesota feldspar. The Russian locality fur- 
nished the following series of measures i/^Xooi) A (oio)=93' 
57'. 94° 7', 93° 49'. 93''58'. 94 ''7'- 94^ 2', 94° 5', 93^ 56', 94^ 
15', 94^ o', 93*^ 44',94'' o', 94° 0', 93^^40', 94° 8 ', 93° 55 '. 
93'' 50 ^ 93* 56 ', 93^^ 50 ', 94*^ 14 ', 93'^ 45 ' or an average of 
93^ 58' with variations between 93° 35' and 94° 15'. The 
extinction angle on/(ooi) varies from 6^° to 11°, averaging 
nearly 9°; on g\oio) the extinction varies between 20° and 
24'' with an average about 213^°; the specific gravity is 
2.697-2.700; the composition must therefore be very near 
Ah- Ans, and the only analysis known from this locality gave 
very nearly that composition. 
Another specimen of labradorite from Kamenoi Brod (near 
Kiew), Russia, gave images, bright, but often blurred. About 
fifty crystals were examined from this locality and the follow- 
ing measures taken :/^'-'(ooi) A(oio)=94'^' 12', 93*^ 37', 93'-^ 
52 ', 93^ 57 ',93^^ 40', 94'' 14, 93^^ 57< 93'' 47'- 93"^ 52', 93° 5°', 
93"^ 53'. 93^^ 14', 93"* 36,' 93° 55- 94"" 9 - 94° 10 , 94^ 13'. 93^ 
54'. 93'' 57'. 93'' 48 ',93° 5^ '- 94* 4^93° 42^93° 55'. that is 
an average of 93° 56', with variations between 93° 36' and 
94° 14'. The extinction angle on/'(ooi) varies from 21° to 
24° with the average about 23°; on ^'(010) it varies* from 
6° to 9°, averaging about 7>^°; the specific gravity varies be- 
tween 2.696 and the composition is therefore again very near 
AbiAns. 
Labradorite from the classic locality on the east coast of 
Labrador occassionally gave good images; the measures re- 
sult: /'/(ooi)A(oio) = 93°59',93°52',94° 14' ,93° 45'. 93° 44', 
94^4 ', 93°39 '- 93''59 '. 93° 58', 93° 42', 93° 45'. 93° 59'. 93''45 '. 
94° 13', 94° o', which furnish an average of 93"" 543^'. The 
extinction angle on/ (001) varies from 22° to 25°, but averages 
very nearly 23°; on g\oio) it runs from 6^ to 10" averaging 
about 7>2°; the specific gravity varies from 2.696 to 2.698. 
The composition is again very near AbiAns perhaps slightly 
more acid than the preceding. 
Finally a single cleavage crystal f from Poulkouka valley, 
*This angle very rarely is about 2°; also about 12°. 
tOther crystals from the same locality were more acid. 
