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NEW YORK STATE MUSEUM 



been opened, it also occurs along a line of movement in a gneiss 

 which is probably of sedimentary origin but is not graphitic. In 

 various other localities prospect holes have been opened, and where- 

 ever successful there is evidence of shearing. The sandstones and 

 limestones which are charged with small amounts of graphite are not 

 far from all of these openings, but the wall rock is apparently never 

 a markedly graphitic one. Less than half a mile east of the Rock 

 pond locality the graphitic sandstone occurs on North pond ; the 

 drill cores at Graphite went through graphitic limestone. It there- 

 fore appears as though the graphite deposits were a result of impreg- 

 nation along a line of weakness by some products, possibly volatile 

 hydrocarbons, originating from the distillation of originally fossilif- 

 erous sediments. 



Thin sections of the shear zone at the western front of the cliffs 

 of Treadway mountain reveal flakes of graphite. The bounding 

 rock is the quartzose gneiss of probable sedimentary origin, and the 

 graphite flakes appear secondary and are evidently related to an 

 infiltration of iron-charged solutions. Pyrite invariably occurs asso- 

 ciated with the graphite, and sometimes limonite and magnetite as 

 well. Any theory of the origin of graphite must explain its associ- 

 ation with these iron compounds. 



Dr Ernst Weinschenk has recently published a series of papers 

 entitled " Zur Kenntniss der Graphitlagerstatten," in which he takes 

 up occurrences of graphite in various European localities. He finds 

 that graphite may occur either as a result of contact metamorphism 

 from a large intrusion of any kind into a calcareous formation, or 

 from injection in gaseous condition along planes of weakness in a 

 disturbed area. He finds that graphite is never to be regarded as 

 the final step in the process of coal formation, and that at least in 

 the Alps and in Ceylon the graphite is not due to regional or to 

 dynamic metamorphism. 



The Adirondack graphite is plainly of two kinds : that present as 

 an accessory constituent of the limestone and quartzite, and that 

 occurring in a secondary position along fault lines. The latter 

 occurrence appears analogous to that described by Weinschenk as 



