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NEW YORK STATE MUSEUM 



furnace ore and concentrates. The ore is of a most desirable quality 

 on account of the low proportions of phosphorus and sulphur. The 

 run of concentrates averages around 65 per cent iron, with from 

 .005 to .01 phosphorus and an average of about .008 phosphorus. 



Benson Mines. Large deposits of low grade magnetite inclosed 

 by a banded gametiferous pyritic gneiss are the basis of mining at 

 this place which has recently been resumed after several years 

 inactivity. The deposits are found along a zone that lies near the 

 base of a low ridge and that begins apparently about a mile west 

 of the railroad station and trends first to the southeast and then 

 swings around to the northeast and east-northeast which direction 

 it follows for most of its course. At the pits by the station the 

 trend is N. 60° E. Beyond there it can be traced by magnetic 

 readings for some distance across the highway and brook, but seems 

 to die out within a few hundred feet of the brook. The ore at the 

 pits has a dip to the southeast of about 45° and the open cut is 

 about 200 feet wide and over 1200 feet long (1915). No underground 

 mining has been undertaken. 



Ore Gromre 



Benson Mines. Section across the ore bodies, near middle of quarry 



The occurrence belongs to the disseminated type like the Lyon 

 mountain, but differs materially from the latter in many respects. 

 The country rock is a mixed gneiss, of which the base seems to be 

 a part of the Grenville or sedimentary series, while it contains much 

 granitic material injected and diffused through the mass. The 

 magnetite is fine grained and held in a matrix of garnet, feldspar, 

 quartz, sillimanite and pyrite. The granite injection is accompanied 

 by pegmatite phases which also carry magnetite. 



The ore carries about 30 per cent iron on the average. In crude 

 state it has too much sulphur to be desirable for the furnace, but 

 this is removed partly in concentration, while the phosphorus is 

 also reduced by the process. The concentrates after agglomeration 

 in the kiln yield an excellent Bessemer product. A process of wet 

 magnetic concentration has been employed in the recent work. 



