T1IK ADIRONDACK CKAl'lIITK DEPOSITS 135 



flake into thin, bent plates which under rolls or burr-stones would 

 be reduced in size. This would lead the writer to suggest that ore 

 near pegmatites be carefully examined before being sent to the mill, 

 as any fraying of graphite should cause its rejection. 



It is quite possible that a preliminary roasting of the ore prior 

 to crushing will have a very beneficial effect, both upon the 

 quantitative results of separation and upon the quality of the 

 graphite that is recovered. The object of such a treatment would 

 be the disintegration of the ore by chemical and physical changes in 

 modifying the pyrite and the quartz, so that the amount of severe 

 crushing would be lessened and therefore the attrition of the flake 

 be reduced to a minimum. 



The lack of uniformity in the ore is a factor frequently over- 

 looked. The concentration processes are very sensitive to any 

 change in the character of the ore. " To a certain extent the 

 problems encountered by each operator are unique, as slight dif- 

 ferences in the mineralogical composition of the ore may compel 

 operators in near-by mines to instal decidedly different types of 

 machinery. In some instances, even in the same mine, the ore may 

 vary sufficiently as the work is extended to make it necessary to alter 

 the concentration process. The fact that those companies that have 

 a rather uniform kind of ore in their mines are also frequently 

 making changes in the methods of concentration, is further evidence 

 of unsolved problems." 1 



Most of the bedded deposits carry pyrite; the normal schists about 

 4 per cent, the Bly ores 7 per cent, and the Rowland-International- 

 Sacandaga class 11 per cent by weight, while the Rock Pond ore is 

 exceedingly rich in this sulphide, which runs from 15 to 40 per cent 

 of the rock. As the rock is crushed for the graphite content, it 

 would seem that perhaps this could be saved without adding mater- 

 ially to the milling cost. Pyrite might be a profitable by-product. 



The amount of graphite is perhaps the first matter that interests 

 the average graphite man. While this is of vital importance, it is 

 not the only factor. The writer has not taken the time to make 

 chemical analyses of the different ores collected, the microscope 

 enabling him to obtain a far better opinion of values. The example 

 of the " rich " Rowland ore, illustrates this point. In St Lawrence 

 county, where metamorphism has not been so severe, the crystalliza- 

 tion of the carbon content of the old sediments to graphite has not ■ 

 proceeded so completely, and the percentage of " amorphous " 



Miller, B. L., Topo. and Geol. Surv. of Pa. Rep't 6, p. 82. 



