ADIRONDACK MAGNETIC IRON ORES 2$ 



are generally considered too refractory for direct smelting; their 

 utilization depends upon concentration, to which they are as a 

 rule very adaptable. There are large bodies of such ores in the 

 Lyon Mountain, Arnold hill and St Lawrence county districts. 

 The lowest grade of milling ore that is worked carries about 35 

 per cent iron. 



According to the percentage of phosphorus present, the mag- 

 netites may be subdivided into low-phosphorus, Bessemer and 

 non-Bessemer grades. There is no well defined connection between 

 the distribution of phosphorus and the nature of the ore occur- 

 rence. In some districts, as instanced by Mineville, both Bessemer 

 and high-phosphorus ores have been produced from contiguous 

 deposits, though generally the ores from any one district show a 

 fair degree of uniformity in respect to the phosphorus. The leaner 

 magnetites are apt to be lower in phosphorus than those having a 

 high percentage of iron. The bulk of the low-phosphorus ores has 

 been produced at Lyon Mountain; the present concentrates from 

 this locality carry less than .01 per cent of that element with 65 

 per cent iron. The non-Bessemer ores range up to about 2 per 

 cent phosphorus, corresponding to 10 per cent of apatite, which is 

 the containing mineral. The Old Bed group of mines at Mineville 

 has furnished most of this grade of ore. 



The magnetites carry a variable proportion of sulfur, due to 

 admixture with pyrite and more rarely pyrrhotite. The part 

 played by these minerals in the composition depends upon the 

 geological associates of the ore bodies, and a sharp line can be 

 drawn generally between the class which carries any considerable 

 proportion of them and the low-sulfur deposits. The presence of 

 sulfur above a fraction of one per cent is confined mainly to the 

 deposits that occur in the banded gneisses and schists of the Gren- 

 ville series, which are themselves impregnated with pyrite. When 

 the wall rock is an acid variety, corresponding to granite or syenite 

 in mineral composition, sulfur exists only in minute quantity. 

 Among the deposits belonging to the former class it is possible 

 to find gradations from ores with fairly low sulfur to those in 

 which the magnetite is replaced largely or almost completely by 

 pyritic minerals. 



Local variations in the ores frequently arise from the association 

 of pegmatite which may carry magnetite in quantity to make it 

 valuable. It has additional interest as affording a number of the 

 rare minerals and many that attain unusual crystallographic 

 development. Mineville and Lyon Mountain have yielded the 



