24 The American Geologist. January, 1901. 
veyed by Dr. A. E. Barlow and which embraces a territory of 
over 4000 square miles, three quarters of which is Laurentian, 
crystalline limestone was found in only a few small areas.* 
Since this rock was of so rare occurrence in the district which 
has been mapped, it was not expected that it would be found 
in abundance just outside this area. On discovering' the out- 
crop of nepheline rock, however, the writer stated to those 
accompanying him that it was very likely they would find 
crystalline limestone not far off. On proceeding up the river 
a short distance, the limestone was found in place. 
From the discovery of outcrops of nepheline syenyte over 
such an extensive territory in Ontario and Quebec, it would 
appear that no Laurentian area of any great size in central 
Canada, which contains much crystalline limestone or in other 
words which belongs to the Grenville series, is without the 
presence of nepheline syenyte and related rocks. This is or 
economic importance, in addition to any scientific interest it 
may have, as very promising deposits of corundum have been 
found at different points, in certain facies of these rocks, some 
of which are now being worked on a comparatively large 
scale. 
The reason why these rocks have not been discovered in 
many places in this part of Canada in earlier years are no 
doubt the non-familiarity of many observers with the appear- 
ance of nepheline in the field, owing to its comparative rare- 
ness in most countries, and its resemblance under some condi- 
tions to other light colored minerals. Two instances can be 
cited in which rocks containing nepheline were examined meg- 
ascopically years ago and in which the mineral wsa mistaken 
for quartz. One of these is the case of the syenyte of Montreal 
mountain, in which it is said the nepheline was mistaken for 
quartz for years. The other is the case of centain outcrops 
along the York (Shawashkong) river in Hastings county, 
which were examined in 1853 by the late Alex. Murray, and 
described by him in his reports as "hornblende rock" and 
mica slates."'!" These outcrops while they are more or less 
schistose in character, still contain the nepheline in distinct 
grains, some of which are of considerable size. 
*Report Geol. Surv. Can. I, p. 89, 1897. 
fGeo/. Surv. Can. 1843-6, Map No. 17. 
