III 
Miles and 
Kilometres. 
192 m. An exposure of Grenville limestone at this 
307 km. point is followed by granite-gneiss, which is in- 
truded by pegmatite, and, still later, by two 
dykes of diorite. South of the post office at 
194.7 m. Cantley, a series of black and rusty-weathering 
312 km_ gneisses make a slight rise to the west of the 
road. Turning in at the road to the mine a 
small outcrop of limestone is passed and the 
north hill of the Nellis mine is reached. 
THE MICA DEPOSITS AT THE NELLIS MINE. 
GEOLOGICAL RELATIONSHIPS OF THE DEPOSITS. 
The veins worked at the Nellis mine occur on two 
“hills”? separated from each other by a clay filled hollow, 
in which a small post-glacial creek has cut a deep valley. 
On the north hill, which is shown on the map, the 
Ottawa gneiss is intruded by a small stock of scapolite 
gabbro, and by an elliptical intrusion of gabbro-pegmatite. 
Mica-bearing veins cut all of these rocks. The Ottawa 
gneiss is an augite gneiss similar to the granite-gneiss seen 
along the road, except that the gneissic banding is more 
strongly developed. It is cut, without regard to the 
direction of the gneissic banding, by mica-bearing veins. 
The greater part of the gabbro contains an important 
amount of scapolite in addition to augite and minor amounts 
of plagioclase, phlogopite, sphene, apatite and sulphides. 
A sugary anorthosite phase occurs at two points. Another 
variation from the average type occurs at the east central 
part of the stock. It is a black amphibolite, in some 
specimens of which epidote can be seen in the hand- 
specimen, though hornblende is the sole constituent of 
importance. The gabbro-pegmatite is composed of felds- 
par with a little quartz. The feldspar is chiefly micro- 
perthite with some microcline and plagioclase. 
CHARACTER OF THE VEINS. 
Mica-bearing veins occur more abundantly in the gabbro 
area than in the gneiss or gabbro-pegmatite. They forma 
parallel series, striking N. 68° E. (mag.) at the northern 
end of the hill, and swinging round to N. 23° E. (mag.), 
