g2 NEW YORK STATE MUSEUM 



magnetite is finely divided, having the form of lenticular and irregu- 

 lar granules that may be distributed evenly throughout the rock 

 mass, but are more commonly grouped into parallel bands which 

 alternate with the other constituents. It occurs not infrequently 

 in considerable bodies and then has a much coarser texture. Feld- 

 spar, which is next in importance to magnetite, is represented by 

 orthoclase, microcline and oligoclase, the latter being white while 

 the others are of reddish color. 



Pegmatite frequently accompanies the ore bodies and sometimes 

 carries enough magnetite to be commercially valuable. So far as 

 observed it rarely, if ever, takes the form of dikes with well defined 

 walls. Its composition usually is similar to that of the gneiss, but 

 it somtimes contains secondary minerals like scapolite and epidote 

 that replace the feldspar. 



Mining operations at present, and for some time past, have been 

 confined to the southwestern section between shaft i6 and the Bur- 

 den mine. The workings are very extensive and include about 20 

 inclined shafts or slopes driven on the dip of the ore. Most of the 

 shafts are driven on the front or main " vein " which has been 

 chiefly exploited. Among those recently operated are, in order from 

 north to south, nos. 14, 12, 7, 5, 4, 3, and the Hall shaft. The 

 deepest are no. 4 which is down t6oo feet, or 800 feet vertically, 

 and no. 3 and the Hall, nearly to the same level. 



The thickness of the ore body on the front vein, as shown near 

 the surface, averages about 20 feet. The workings which extend 

 along the strike widen, however, in depth, so that on the bottom level 

 of the Hall slope there is a breast of ore measuring over 200 feet 

 from wall to wall. This widening is due in part at least to the- 

 change of dip which decreases with depth. It has been suggested, 

 also, that the three parallel ore bodies, separated at the surface by 

 many feet of wall rock, may unite below, but there is little reason 

 for believing this to be the case. 



The only portion of the back " vein " that has been worked to any 

 extent is at the extreme southwest on the east-west wing of the fold. 

 The main openings are the Weed, Cannon and Burden. The shafts 

 are now dismantled, and ore is mined by open cutting along the 

 outcrop. The Burden and Cannon open cuts have recently supplied 

 a large output. The ore is broken down by drilling and blasting 

 and hoisted to the surface by derricks. As a result of these excava- 

 tions, a much greater width of ore has been uncovered than had 

 been supposed to exist from the nature of the underground workings. 



