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NEW YORK STATE MUSEUM 



3 Hematites of St Lawrence and Jefferson Counties 



Hematite, both soft and hard, is found in quantity in the Pre- 

 cambrian of St Lawrence and Jefferson counties, on the outskirts 

 of the main Adirondack Precambrian area. On this side the 

 Precambrian reaches out from the highland into the St Lawrence 

 valley and even extends across the latter into Canada. The hema- 

 tite is associated more particularly with the sedimentary portion of 

 the series, which is classed with the Grenville, and which is distrib- 

 uted in long belts running northeast-southwest. The wall rocks 

 are usually i"usty gneisses or schists, the same beds that contain 

 the pyrite ores, but occasionally they are bordered on one or both 

 sides by limestone. In a few places the bodies have a capping of 

 Potsdam sandstone which rests in horizontal layers upon the highly 

 inclined Precambrian strata, but as a i"ule they are covered only by 

 soil and earth. 



The main hematite mines of St Lawrence-Jefferson counties 



