furnace, about ‘twelve per cent. of iron sede sednced fom: is 
k 
and we know, from the experiments of Dr. Locke, that e 
fragments of the trap rock are both magnetic and polar. It eo 
mains to be proved that there are any electric currents in the native 
copper veins, for such currents are by no means proved by devia- 
ae * eo" OF. Lanes on ae ane = ee ly 
tions of the magnetic needle, which are iit produced by. 
the magnetic polarity of the trap rock its 
The occurrence of bright scales and natlact crystals of native * 
per in —— erystals of prehnite, datholite, cale spar, and 
cop 
quartz, would seem to indicate a simultaneous deposition of the 
copper and i cigatallined minerals including it, or that they 
re impregnated with native copper by sublimation immediately 
before the injection of the principal copper vein took place. 
we could admit the igneous formation of zeolites, and of cale 
spar, there would be less difficulty in accounting for the veins by 
sublimation or injection, or by both methods, but this chemists 
will not readily admit, for the zeolitic minerals are generally 
hydrous. 
It is also a question whether the native copper in the: amygda- 
loid was derived from the interfused sandstone, or was mechanic- 
ically brought up with the trap rock. It has been imagined, that 
rocks which might have contained copper ores, that the copper 
ore being deposited with the sand was reduced by the action of 
the trap. This idea would be plausible, if it could be shown 
that the sandstone in the vicinity of the trap contained copper in 
a sufficiency to account for that in the amygdaloid; but such is 
not the case. It has been said that local deposits of the ore might 
have taken place in portions of the sandstone strata, and that the 
trap rocks came up and reduced it. This would be imputing a 
most remarkable degree of intelligence to the trap rocks, that 
they should know exactly where the copper ore was deposited, 
and come up at those places expressly to smelt it! I must con- 
fess that I cannot attribute the origin of the copper to any other 
causes than those which produced the trap rocks themselves, and 
that the copper came from the molten interior of the earth seems, 
at least from what we know of igneous agencies, to be most prob- 
able. There are veins in the conglomerate rocks which are filled 
with calcareous spar, containing crystals of copper, some of which 
will weigh half a pound, and are generally in the rhombic dode- 
cahedral form. One of the calc spar veins at Agate Harbor has 
yielded masses of copper weighing several hundred pounds. 
At Copper Harbor, a large vein of solid black oxyd of copper 
was found in the conglomerate rock. This ore is not known to 
exist in any considerable quantity elsewhere. The ore in the 
vein was fourteen inches wide, and for a short se the mine fur- 
nished a good supply of copper ore, yielding abo sixty or sev- 
’ 
ba 
tan 
ee 
“ 
