1846.] Copper Mines. 6 1 



pyrites. The trap rocks are also very rich in minerals; among 

 them are calcedony, carnelian, jasper, agates, various zeolites, 

 epidote, augite, olivine, green earth, prehnite, fluor spar, satin 

 spar, amethystine quartz, graphite, malachite, copper pyrites, na- 

 tive copper, native silver, green silicate of copper, red and black 

 oxide of copper. 



Extent and Distribution of the Sand-stone and its Conglomerate. 



According to Capt. Bayfield and Dr. Eights, this rock forms 

 the entire shore of the lake; it is rarely removed from its original 

 horizontal position, but is frequently shattered and broken by the 

 disrupted trap which often reposes upon it. It does not extend 

 itself in a continuous mass, but occurs in beds disconnected by 

 igneous, as well as by diluvial action, but still may be traced 

 from the southern to the northern shore, along which it appears in 

 headlands from 30 to 60 feet high. It also appears upon all the 

 islands. 



Hence it is considered as a general formation spreading over 

 the basin of Lake Superior, and resting on granite, excepting 

 when the amygdaloids and trap are interposed, or intruded be- 

 tween them. The height to which it rises is not over 400 feet 

 above the Lake. The greenstones, trap or amygdaloids, associated 

 with the conglomerates, sandstone and sandstone shale, are of an 

 origin entirely different from the latter, and having been ejected 

 from below, they have brought up with them the metals which 

 are the objects of so much attraction; hence the position of the 

 metals must be, in all cases, in the vicinity of these ejected rocks : 

 usually at the junction of the lowest, that is, the conglomerate 

 and the trap or igneous beds, and sometimes the metal is dissem- 

 inated in the trap ; it never, however, extends into the conglome- 

 rate or sandstones by dissemination. One general remark seems 

 to be called for in this place, viz: when metals or ore occur in 

 sedimentary rocks, we may infer, as a general rule, that the igne- 

 ous rocks, or the granites and trap, are not far distant, and the 

 close proximity of all the primary rocks to the sedimentary, is a 



