Geology of Lake Superior. 39 
river’s mouth. ¢Schoolcraft.) We also 
found it on Tle Royale, in considerable 
quantities, disseminated through tabular 
masses on the beaches, (which have been 
noticed in describing He Royale,) in 
membranes, plates, and wires, associated 
with prhenite; quartz, and calespar. It 
also occurred in Ile Rogale, and its islets, 
in veins, and nests in amygdaloid. In 
one instance a wire of copper passed 
through the centre of x fortification agate. 
This agate was split in extracting it, bue 
the copper wire held the parts together. 
Small masses of native copper are 
found occasionally on the beaches of 
Point Keewawonan. (Schoolcraft.) 
Norte.—Copper pyrites, green ca:bonate of copper, and 
plumbago, were found iu the amygdaloid of Point Mamaiuse. 
( Bigsby.) 
Copper pyrites incrasting the sides of an empty vein in 
greenstoue, near Michipicoten. ( Bigsby.) 
CLASS TIIRD.—METALLIFEROUS MINERALS, 
Ocury Rep.—Iron Oxe.—Iron ore was the only metallife- 
rous mineral found besides copper. It occurs in 
veins im greenstone floor island, where it coats 
the veins which contain fluor spar. In amygdae 
Joid it often coats the agates and other nodules. 
In the sandstone it is very plentiful, being proba- 
bly derived from the disintegrated trap rocks. Ina 
the couglomerate of the old sandstone it fre- 
quently coats the imbedded fragments, 
Baown Inon One,—(crystallized and otherwise.) —Was met 
with on the Islets of Gargantua, 
Prumsaco, 
