THE CANADIAN NATURALIST. [Feb. 



Alkalies 1 .97 by difference. 



Water 2.78 



100 



It is probably a variety of green-earth. Some of the amygdules 

 are altogether filled with it, in which case it frequently contains 

 small isolated grains of metallic copper. Sometimes calcspar is 

 found along with the green-earth, the two minerals generally occu- 

 pying separate parts of the cavity. Very frequently the green 

 mineral merely lines the cavities, and the rest is filled up with 

 calcspar. The foregoing description is of a specimen of the bed 

 exceedingly rich in copper. At other places the matrix is more 

 compact and darker coloured, and the amygdules are exclusively 

 filled with calcspar, without any enclosing film of green-earth. 

 Sometimes quartz, delessite, laumontite and prehnite occur 

 filling the cavities. In many parts of the bed, large irregular 

 patches and veins of calcspar are seen, through which and 

 through the adjoining rock, run huge irregular masses of copper 

 frequently weighing several tons, with which small quantities of 

 native silver are associated. Epidote is also often met with in the 

 bed, generally unconnected with the amygdules, and forming small 

 irregular masses in the chocolate-coloured rock. The foregoing 

 description applies equally to the cupriferous bed as developed in 

 the Pewabic and Franklin mines. These are situated on the north 

 side of Portage Lake. The continuation of the bed to the south- 

 east was sought for a long time fruitlessly, until at last it was dis- 

 covered accidentally at a distance of about four miles south-west of 

 Portage Lake. At this point, on the property of the South Pewa- 

 bic Mining Company, it is being opened and presents the following 

 characters. The rock is of the same colour as on the Quincy 

 Mine, but it is finer grained, and in places a conchoidal fracture 

 is even observable. The amygdules are smaller, and the metallic 

 copper seems altogether confined to them, forming solid rounded 

 pellets. It is accompanied by delessite, calcspar, laumontite and 

 prehnite, which minerals also occur in the cavities alone. The 

 matrix of this bed is also fusible to a black magnetic glass. 



The rock which underlies the copper-bearing bed of the 

 Quincy Mine is distinctly amygdaloidal. The matrix is fine 

 grained, but it is crystalline and is seen to consist of different consti- 

 tuents. Its colour is dark reddish-grey, and it is fusible to a black 

 glass. The cavities, which seldom exceed the size of a pea ; are 



