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NEW YORK STATE MUSEUM 



up a large proportion of the rock at Graphite, while on Bear Pond 

 mountain they are entirely absent. Whereas the Graphite occur- 

 rence is massive, the Bear Pond mountain variety consists of thin 

 layers interbedded with sandy quartzite. There has been much 

 shearing and crumpling, and the whole series is impregnated with 

 iron oxids. The bedded nature of this sillimanite gneiss is certain. 



At Graphite, limestone has been found in a prospect boring, 

 beneath the sillimanite gneiss. At Bear Pond mountain the silli- 

 manite gneiss overlies the hornblende gneiss, no limestone being 

 present. These relations suggest the possibility of an unconformity 

 between the sillimanite gneiss and the limestone series, although the 

 limestone is so patchy in its general distribution as to prevent too 

 confident drawing of conclusions. 



The graphitic sandstone occurs in a small area about North pond. 

 It is a gray variety, weathering red, dipping steeply west, and 

 containing abundant flakes of graphite and of mica. On the north- 

 east bay of Rock pond a small mine has been opened. The 

 graphite occurs along a fault line, associated with iron pyrites. 

 Slickensides are abundant in the opening. The country rock is the 

 above described quartzose gneiss, of probably sedimentary origin. 

 The biotite schist, commonly interbedded with the limestone, appears 

 near the mine. The sillimanite gneiss is present on the neighboring 

 mountain. The strike of the graphitic sandstone is n. 5 e„ its dip 

 70 w. i 



The sandstone is similar to the layer bearing the graphite at the 

 mine of Graphite. The chief difference is that whereas at the 

 Graphite exposure flakes of graphite form the principal constituent 

 of the rock and the only scaly constituent, at North pond mica is 

 also present. The North pond rock is hence less valuable econom- 

 ically, since it not only contains a smaller percentage of graphite, 

 but the process of concentration would be complicated by the 

 presence of two scaly minerals. Both rocks contain much accessory 

 pyrite, and weather yellow or red. 



Geologically the two rocks probably represent the same formation, 

 and both are intimately related to the sillimanite gneiss. The silli- 



