30 



composed apparently of the injected gangue of the ore, consisting 

 of hornblende or blackjack and mica, with a variable proportion 

 of ore in an irregular crystalline or granular form. The mine is 

 drained by an adit which passes out through the side of the hill 

 next the east. 



Upon the second or middle range of mines, the most north- 

 eastern excavation is the Hihernia Mine. The situation of this 

 mine, which is upon the top of an elevated hill, adjacent to the 

 Hibernia Forge, renders it somewhat difficult of access. The 

 ore here also sometimes shows itself upon the surface, though it 

 more frequently requires an excavation of moderate depth before 

 it can be reached. 



The dimensions of the vein are quite variable, though its 

 average thickness is perhaps about eight or nine feet. The ore, 

 containing much foreign mineral matter, and being at the same 

 time highly magnetic, affords an opportunity for using the mag- 

 netic separating machine, by which it is economically freed from 

 its impurities. 



About half a mile to the west of Dover is Jackson's Mine, 

 yielding an ore similar to the last. This is inferred, by its 

 position, to lie upon the same vein or string of veins. 



The vein is here seven feet in widlh. There is a shaft leading 

 down to the ore forty feet deep. The excavation is about two 

 hundred feet in length. 



The next, and by far the largest vein of the range, is half a 

 mile further towards the southwest, at General Dickerson's, near 

 Succasunny. Here the enclosing rock is a variety of gneiss, 

 composed chiefly of quartz and felspar, with occasionally a little 

 mica and oxidulated or magnetic iron ore, disseminated through 

 it. The dip is about 60° to the southeast. The mine has been 

 wrought to a depth of about eighty feet. In the horizontal drift, 

 along which the vein has been chiefly worked, the quantity 

 removed has been very great. Here the average thickness may 

 be stated at about twelve feet, though near the entrance of the 

 mine, in consequence of an irregularity, the mass of ore seems to 

 have been at least thirty feet across. This being in a disturbed 

 portion of the vein, the presumption is, that it does not continue 

 far of this dimension. 



The general structure of this ore is highly granular, showing a 



