CORUNDIFEROUS NEPHELINE-SVENITE 443 
surface, but mottled bright blue and white where broken. Under 
the microscope the rock is found to consist of scapolite, soda- 
lite and biotite with a very little orthoclase. The scapolite 
forms the greater part of the rock, the spaces between its 
anhedra being filled with sodalite; the latter blue throughout 
when in small portions, but only on the edges when in large 
ones, the center being colorless and isotropic. The bowlders are 
said by Miller to be blue only after being burnt in the lime- 
kiln. 
The biotite is deep red-brown in color, has a high absorption 
and a wide axial angle, perhaps the result of heating; just 
as many dark biotites turn brown by weathering and have a 
wider angle between the optical axes. 
There are small quantities of an unknown mineral present, 
white, transparent and having a low double refraction, so as to 
give only dull blue or purple tints between crossed nicols. Two 
or three sections of it show an axial image consisting of a black 
cross opening out about as far as in many biotites, but without 
colored rings. It is optically positive. 
About eleven years ago the writer collected a considerable 
number of specimens of nepheline-syenite from drift bowlders 
in the neighborhood of Cobourg, Ontario, which lies about 
south-southwest of the localities referred to above and from 
fifty to a hundred miles distant from them. At that time neph- 
eline-syenite had not yet been reported from the province.? 
In a general way these specimens correspond in appearance and 
composition to those that have been described, though a num- 
ber of additional minerals occur in them, the more important 
being hornblende, augite and garnet, both of the ordinary kind 
and melanite, the brown variety. Only one of the specimens 
collected then contains corundum; and it, though closely like 
the others in appearance, shows little or no nepheline and 
resembles in mineralogical constitution, one of the specimens 
from Methuen. The purplish-gray corundum crystals are quite 
large, and thin sections show the same needlelike inclusions 
* Trans. Roy. Soc. Can., 1890, pp. 14-18. 
