252 THE METALS IN CANADA. 
veins, and are both very thin and do not hold out in depth, though ex- 
ceedingly rich in some places. In 1855, at the depth of eighteen feet 
a mass of native copper weighing 630 lbs. was extracted, and the whole 
yield of a shaft twenty -seven feet deep and without galleries was about 
three tons of metallic copper. 
On Michipicoten Island, where copper mining has been carried on 
for many years, the metal is deposited in the native state in beds of 
amygdaloid trap and volcanic ash, overlaid by compact trap and under- 
laid by a coarse red quartzose sandstone ; the cupriferous bed proper 
being from one to two feet thick, and sufficiently rich to pay for work- 
ing. The metal also pervades to some extent the rocks lying above and 
below the copper-bearing belt, being distributed through the former in 
bunches, and through the latter disseminated in grains. It occurs also in 
veins traversing the beds at nearly right angles. It seems that when a 
metalliferous belt has been broken up by the intrusion of igneous rocks 
and rearranged under metamorphic action, rich deposits of ore may be 
expected. 
At the western locations on Lake Superior, the rocks consist of 
argillaceous shales or slates overlaid by a flow of trap ; both formations 
being cut by numerous parallel trap dykes, and by transverse veins of 
quartz, barytes, and calc-spar, carrying ores of copper and native copper. 
We are not aware of the extent to which these veins have proved pro- 
ductive. The amazing development reached by the copper workings on 
the south shore, situated in corresponding positions, will be best judged 
by the fact that in 1850 the aggregate value of exports was 266,000 dols., 
while in 1860 it had attained the sum of 3,000,000 dols. Masses of 
nearly pure native copper have been there discovered weighing from 300 
to 400 tons. 
Copper in Lower Canada. — We have already remarked that the 
Quebec group of rocks are the equivalents of the upper copper-bearing 
rocks of Lake Superior ; and accordingly we find them characterised by 
similar features, as regards their metallic contents. Towards the line of 
junction between the Laurentian rocks and the Quebec group of the 
Lower Silurian system a few discoveries of copper ore have been made 
and recorded by the Provincial geologists. In the Report for 1852-53, 
Sir William Logan states, that in the seignoiry of La-Norraye, in the 
county of Berthier, on the north side of the St. Lawrence, a point situ- 
ated in the above geological horizon, a vein of calc-spar and pearl-spar 
occurs carrying copper pyrites, though in small quantity. He remarks 
that " though the vein does not appear by any means a promising one, 
it yet bears too many of the characteristics of a regular lode to be passed 
over without notice." Recently, a report which, however, wants con- 
firmation, has been made of an important discovery of copper ore at St. 
Irenee Malbaie, which, as will be seen by reference to the Report for 
1849-50, is also situated at this point in the geological series. 
In this connection also we have shortly to notice the discovery as re- 
