168 Copper Mines of Lake Superior. (April, 
found in what has been taken for the other wall. More 
than once, cross cuttings for many fathoms have thus 
resuscitated parts of the mine where it was feared the 
copper had given out altogether. The suddenness with 
which the rock will change and lose its metalliferous 
character is very remarkable, and affects, naturally, the 
productiveness of the mine from year to year. 
Copper-bearing beds alternate, however, with barren trap 
for a distance of 500 feet, as determined by a cross cut 
eastward from the 70 fathoms level of the neighbouring 
Pewabic Mine. In the report of the agent of that mine, in 
1863, he anticipates that the following copper beds would 
be reached at the distances indicated. The results justified 
his predictions. From the Pewabic lode, the distances of 
the adjacent strata were :— 
As ANTICIPATED. As DETERMINED. 
Old Pewabic . . . 148 feet. Old Pewabic -. . . 191 feet. 
Green Amygdaloid . 285 ,, Green Amygdaloid . 275 ,, 
Albany and Boston . 382 ,, Albany and Boston . 380 ,, 
Epidote or Mesnard . 465 ,, Epidote or Mesnard. 448 ,, 
Conglomerate . . . 520 ,, Conglomerate . . . 500 ;, 
To the West of the Quincy and Pewabic lode, little 
mining has been done on the lake shore, the Hancock being 
the only copper-bearing bed extensively worked. 
The heaviest copper lies generally near the foot wall. 
Throughout the region the metal is classed according to its 
size as mass, barrel, and stamp work. Mass copper is 
confined to the other districts; but the Quincy Mine yields 
a certain quantity of barrel work, or copper pieces of such 
size that they can be separated from adhering rock without 
the aid of water dressing. The quantity is, however, small, 
compared with that which is scattered in particles so small 
that machinery and mechanical concentration alone can 
separate them from their matrix. The means used to effect 
the separation are the same in all the mills of the district. 
The equipment of the Quincy Mine above and below 
ground is excellent. The hoisting cars are of heavy boiler 
plate. Here and at other mines the cars discharge themselves 
by means of a very simple device. They are shaped like 
large coal-scuttles, and run on four wheels ; but on the same 
axle, and projecting beyond the back wheels, are wheels of 
smaller diameter, which, when the car reaches the spot 
where it is to be emptied, run up inclines secured on each 
side beyond the track. Thus the back wheels are lifted off 
the track, while the four wheels remain on the rails and the 
body of the waggon, tilted forward, shoots out its contents. 
Heretofore it has been the custom in the Portage Lake 
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