1088 General Notes. [ November, 
in making a geological examination of a portion of what has proved 
to be a very extensive area of anorthosite rocks, which belong to 
what has been called the Norian or Labrador series, occurring 
about Lake St. John and the Upper Saguenay, and which from 
thence strikes far away to the north, I noticed in many of these 
rocks a mineral which weathered to an orange color and which, 
when the weathered surface of a specimen containing it was care- 
fully examined, was invariably seen to be surrounded by a nar- 
row light green border. On my return to Ottawa in the fall a 
large number of thin sections of these rocks were prepared and 
were found on examination to exhibit a most interesting phenom- 
enon, which I propose here to describe briefly. 
The mineral olivine has never heretofore been mentioned as 
occurring in the Norian series in Canada, although Dr. Hunt, I 
believe, has mentioned it as a constituent of certain boulders of 
anorthosite rock, referable to this series, which were found in 
New Hampshire, but which were probably carried thither from 
Canada during the glacial age. The mineral, however, occurs 
abundantly in the anorthosite of many parts of the Saguenay 
area, and I have also found it in a specimen from a little area of 
rocks which has been referred to this series, and which occurs 
near Dolin’s lake, in New Brunswick. 
en thin sections of the massive or nearly massive dark 
violet anorthosite from the shore of Lake St. John, near the Little 
Discharge of the Saguenay, is examined with the microscope, the 
rock is found to be composed of plagioclase, olivine and iron ore. 
The plagioclase occurs in large well twinned individuals, which 
are seldom broken or twisted, and which between crossed trichols 
show nothing of the peculiar, wavy appearance so often seen in 
the feldspar of the Laurentian gneiss. The iron ore which is pres- 
ent only in small amount is probably titaniferous, as in one slide a 
grain of it is seen partially altered to leucoxene. The olivine, of 
which the rock usually contains a large quantity, occurs either 1n 
single individuals, or especially in the larger grains, as several in- 
dividuals united to form one grain. They seldom have any re- 
semblance to proper crystalline forms, but one usually irregular 
in shape, a single individual sometimes forming a very irregular 
elongated string. It is recognized by its bianial character, high 
index of refraction and imperfect cleavage, and although like the 
plagioclase very fresh, by the presence of a little serpentine which 
here and there may be detected along the cracks which traverse 
it. The olivine, as is usually the case in eruptive rocks, crystal- 
lized before the plagioclase and therefore lies imbedded in it; but 
_ although I have examined a very large number of thin sections 
of this rock, I have never been able to find these two minerals in 
contact, there being invariably two zones of certain other silicates 
urrounding - olivine and intervening between it and the 
€, so that since the rock consists almost entirely of these 
r 
