THE MINING AND QUARRY INDUSTRY IQII 53 



ville series of gneisses, schists and crystalline limestones. The 

 principal deposits thus far found occur in the belts of these rocks, 

 which are regarded as metamorphosed sediments, on the western 

 border in St Lawrence and Jefferson counties. One large belt ex- 

 tends from near Antwerp, Jefferson county, across Gouverneur, 

 De Kalb and Hermon townships of St Lawrence county, a distance 

 of over 40 miles. It is the same belt which carries the red hematite 

 ores of that region. The pyrite is disseminated through the schists 

 and gneisses, but here and there it occurs segregated in bands or 

 lenses so as to constitute mineable deposits, though of rather low- 

 grade character. The bodies are arranged in conformity with the 

 major structural features of the county rocks, so far as can be de- 

 termined, having usually a northeast-southwest strike and a north- 

 erly dip as are prevalent throughout the region. They show local 

 modifications in the way of folding, swells and pinches and were no 

 doubt accumulated before the final period of regional compression 

 which has affected the wall rocks. 



The ore as mined consists normally of a granular aggregate made 

 up of crystals and irregular particles of pyrite distributed through 

 a gangue of which quartz is the chief component. The texture and 

 grade of the ore is quite variable. Considerable masses of prac- 

 tically pure pyrite are found as an intergrowth of large-sized 

 crystals, but the chief part of the output is represented by a mix- 

 ture of medium to fine-grained pyrite showing no crystal develop- 

 ment, with fairly large amounts of gangue materials. Besides 

 quartz the accompanying minerals include hornblende, biotite, feld- 

 spar and alteration products of chloritic nature. Zinc blende and 

 chalcopyrite are found occasionally in small amounts in the ore. 



In some parts of the belt pyrrhotite occurs as an associate of the 

 pyrite or in separate bodies of closely related features. It is found 

 for instance at High Falls or Pyrites in distinct shoots though in 

 the same mineralized zone with the pyrite. It has not been con- 

 sidered, hitherto, of any economical value, yet recent progress in 

 the use of low-grade sulfides may be regarded as affording some 

 prospect for its future industrial employment. The sulfur content 

 is naturally lower than that of the pyrite, the theoretic, amount be- 

 ing a little under 40 per cent and the average of the usual grade of 

 material probably not over 25 per cent. The pyrrhotite gives a 

 slight reaction for nickel. 



The mines at Stellaville operated by the St Lawrence Pyrite Co. 

 are opened on a parallel series of deposits, of which the largest is 

 known as the Stella. A second important deposit, the Anna, is 



