105 
marketed. The main pit was worked from time to time 
between 1890 and 1896. The ore was first roasted in 
kilns and then treated with water to make it more readily 
crushable, and the graphite was separated by a wet process. 
ANNOTATED GUIDE—(Continued. 
Miles and 
Kilometres. 
142-8m. The road from Buckingham is followed back 
228 km. to McFall’s Corners, and from there a westward 
direction is taken. The first rock exposed in 
the road is impure Grenville limestone immedi- 
ately followed by a rock so rich in garnets that, 
in the hand specimen this mineral is the most 
conspicuous constituent. This rock has the 
character of an altered norite. It is followed 
by a more normal gabbro, similar in some of its 
aspects to the diorite which caps the hill above 
the main pit at the Walker mine. This gabbro 
is cut by two broad, parallel dykes to which the 
convenient field name, “blue quartz veins,” 
has been applied. The first one has a width of 
200 feet (67 m.), and the second a width of 60 
feet (18-2m.). From this hill to the Dominion 
mine black and rusty weathering gneisses 
alternate with Grenville limestone. 
THE GRAPHITE DEPOSITS AT THE DOMINION 
MINE. 
In the vicinity of the Dominion mine, Grenville 
limestone and a small amount of associated sillimanite- 
gneiss have been intruded by mica-syenite-gneisses. These, 
in their turn, have been intruded by quartz-pyroxene- 
gneisses comparable to the hypersthene-granite-gneisses of 
the Emerald mine, and by diorites, pegmatites and gabbros. 
The age relations of these various intrusives are not always 
clear; the nearest approach to a chronological order, at 
present possible, is shown in the legend of the map. Many 
small pegmatite and diorite dykes occur in the gneisses 
of the area. 
The rocks that command attention most are the var- 
ieties of gabbros with which the graphite ore-bodies are 
associated. These have intruded the Grenville limestone 
and older gneisses and have caught up masses of limestone 
