BREECE HILL. 507 



shaft in order to reach it, no mine owner has yet had the enterprise to 

 attempt its exploration. It is difficnlt to pi-edicate the probalde thickness 

 of a sheet of porpliyry from the width of its outcrops or even from an 

 observed thickness at some point bnt little removed, since it is liable to 

 change rapidly, both in thickness and in horizon, from causes which are not 

 apparent at the surface. The depths given for the Blue Limestone horizon 

 under the P}ritiferous Porphyry by the various sections which pass through 

 this area cannot be expected to be so close an approximation to the actual 

 facts as when the proportion of sedimentary beds is greater. Thev have, 

 however, by no means been given at hap-hazard, but are the result of 

 most careful weighing of probabilities, based on a studv of the whole region. 

 The nearest approach to an actual development of ore in the Blue 

 Limestone under Pyritiferous Porphyry is in the Mike mine, and the indi- 

 cations afforded b}' this favor the supposition that it will be found to be 

 ore-bearing when reached farther east. Another favorable sign is found 

 in the numerous evidences of mineral concentration in the porphyry itself 

 Scattered bodies of ore have also been found in the beds of the Weber 

 horizon, which ai'e sufficient to show considerable mineral action. 



GREEN MOUNTAIN. 



Li the shales and sandstones of the Weber formation and in the adjoin- 

 ing Pyritiferous Porphyry bodies numerous small deposits of ore have been 

 struck, but of somewhat different character from those developed at the 

 Blue Limestone horizon. The most important of these have been found on 

 Green Mountain, in regard to which the following information has been 

 obtained. 



The Ontario mine is opened by a tunnel 380 feet long and a shaft 70 

 feet deep, run through Pyritiferous Porphyry into micaceous sandstone and 

 black shale. The deposit is found in a vein running north and south, and 

 traceable from about one hundred feet from the mouth of the tunnel through 

 the porphyry into the overlying sandstones. A body of coarse-grained 

 galena 20 feet long by 3 feet in width was found in the porphyry, but 

 in the sandstone the vein proved barren. A similar deposit in the porphyry 

 is found in the adjoining Tiger (E-22) mine. It is a gash vein six to eight 



