Of Maimanse J L. Superior. 7 



former is unproductive ; but the latter, which, is six inches in 

 ■width, contains small bunches of purple copper, in a veinstone of 

 quartz and calc spar. A few small crystals of copper pyrites 

 have also been observed in it. About 30 yards eastward from 

 the second opening, is another vein, runniug E., 20*^ N., apd 

 wider than either of the others. Its principal mineral con- 

 tents are green carbonate of copper with a little vitreous copper 

 and copper pyrites. A few minute specks only of native cop- 

 per have been observed in it. It appears to be very irregular in 

 its width, and at the place where it has been opened, the wall on 

 one side consists of amygdaloid, and that on the other, of com- 

 pact trap, probably in consequence of a fault. 



It would appear that this ridge is traversed by a multitude of 

 fissures, containing copper and copper ores, and as is generally the 

 case with such veins in trap, very irregular in course and dimen- 

 sions. Those above described, are the most considerable yet dis- 

 covered. Their value as deposits of copper, is not yet deter- 

 mined ; but the indications are of sufficient promise to warrant 

 works of exploration. The quality of the veins will, no doubt, 

 change as they penetrate the underlying tufa and conglomerate, 

 though, whether in the direction of greater or less value, is uncer- 

 tain. 



As the mode of deposition of native copper has been a subject 

 of much eontrovei-sy, I examined with care, with the aid of Mr. 

 Borron, of the Bruce Mine, the veins exposed at Maimanse ; 

 and shall state the results at which I have arrived for that 

 locality, with the facts on which they are based, without mean- 

 ing to assert that the mode of occurrence and formation of 

 native copper must, in all cases, have been of similar character. 

 The veins traversing the trap of Maimanse have been filled with 

 successive deposits of mineral matter on their sides, in the manner 

 of ordinary mineral veins. In the larger veins, these are alter- 

 nate layers of quartz and calc spar, the latter often moulded on 

 the crystalline surfaces of the former, and vice vers&. In several 

 cases, the first deposit of quartz is of an sgatiform character 

 and stained by peroxide of iron, but the greater part both of the 

 quartz and calc spar is crystalline and colourless. 



The deposition of the native copper has evidently been con- 

 temporaneous with or subsequent to that of the quartz and calc 

 spar. The larger masses are imbedded in calc spar, occupying 

 tlie cavities left in the wider parts of the vein, after its sides had 



