146 NEW YORK STATE MUSEUM 



repeatedly cuts across at all angles and wanders about quite inde- 

 pendently. Thus it is evident that at least a part of the pyrite has 

 been deposited in its present position quite late in the history of the 

 formation. The pyrite ranges from tiny scattered grains up to large 

 masses, and may be irregular in shape or bounded by its own crystal 

 faces. Crystals an inch or more in diameter are common, not in 

 cavities but wholly imbedded in the country rock. 



Intimately associated w^ith the pyrite is graphite in sufficient 

 abundance to be conspicuous in the tailings from the separator. 



\\ hile the gangue is ordinarily the normal country rocks, the dump 

 affords many lumps of quartz whose relations to the ore and other 

 rocks are not shown in the flooded pit. This material appears to be 

 vein quartz, in spite of its carrying considerable graphite. 



The ore body is perhaps ten feet thick as an average and conforms 

 in a general way with the strike and dip of the surrounding rocks. 

 That the latter are, with the exception of the pegmatite before men- 

 tioned, apparently sedimentary in origin is the most striking fact 

 exhibited at this locality with reference to the origin of the pyrite 

 deposits in general. 



While the sedimentary character of the immediately adjacent 

 rocks is apparent, it must not be overlooked that everywhere the 

 Grenville is cut by intrusives which, in this vicinity, are abundantly 

 represented by the white granite which is the common phase of the 

 granite-gneiss when intrusive in limestone. With these intrusions, 

 the pegmatite associated with the pyrite must be connected, and quite 

 possibly too the quartz mentioned above, in spite of its graphite, the 

 latter mineral being frequent and sometimes abundant in very acid 

 pegmatites elsewhere associated with pyrite. A quarter of a mile 

 south of the mine the crystalline limestone contains large quantities 

 of quartz, probably of vein origin, but quite free from both pyrite 

 and graphite. 



Passing to the more detailed features of the deposits we find 

 a fine-grained, gray banded schist of the wall containing considerable 

 scattered pyrite strung out parallel to the foliation, while a minor 

 cross fracture is filled with calcite and a little pyrite, the latter per- 

 meating the wall of the fissure and thus showing a very late circu- 

 lation of pyrite in the rock. A thin section shows abundant quartz, 

 kaolinized feldspar, chloritized mica, some sericite and graphite. 

 There are also many grains of colorless tourmalin. Pyrite, in 

 moderate amount, occurs in crystals and rodlike and branched aggre- 

 gates, which run between and very commonly project into the other 

 minerals as shown in figure 3. Sometimes pyrite separates and 



