THE ADIRONDACK GRAPHITE DEPOSITS IQ. 



3 Limestone succeeded by a biotitic schist. 



4 Amphibolite. 



5 The limestone ore, varying greatly in thickness, as lime- 

 stone is easily molded and stretched by dynamic disturbances. 



6 A thick mass of pegmatite. 



7 More granite which continues to the shore of Eagle lake. 

 The granite has absorbed considerable amounts of the sed- 

 imentary rocks and is cut by frequent pegmatites. 



All the rocks dip at an average -angle of 55 ° to the south. 



The ore. The ore is nearly pure limestone, in places charged with 

 dark minerals (augite), the workable portion being from 3 to 7 feet 

 in width. It can be traced along the strike (north 65 ° to 70 

 east) for a distance of a thousand feet. There is a second bed 375 

 feet south of the main bed that can not be followed for so great a 

 distance. 



Most of the graphite flake " ranges from 0.9 to 3.0 millimeters in 

 length and from 0.15 to 0.3 millimeter in thickness. . . . 

 A composite sample of the ore selected ... so as to 

 represent approximately the run of the mine was analyzed in the 

 laboratory of the United States Geological Survey and showed 2.97 

 per cent of graphitic carbon." * 



In places the pegmatite comes in direct contact with the lime- 

 stone without affecting it in any appreciable way, and again there is 

 a development of large feldspar crystals set in a groundmass of 

 finer grains. A " porphyry " of this type is shown near a dam not 

 far from the main shaft. 



" The even distribution of the graphite through the crystalline 

 limestone renders it probable that the carbon formed an original 

 constituent of the limestone. Its conversion to the graphite 

 state, the recrystallization of the limestone, and the development in 

 it of the mineral pyroxene are the result of metamorphism, possibly 

 in part dynamic but due to some extent to the contact effects of the 

 neighboring masses of granite." 2 



The term " metamorphism," especially that denoted as dynamic, 

 refers to the changes taking place under the action of heat and pres- 

 sure set up by stresses during mountain-making periods. 



Future prospects. The future of the Crown Point graphite 

 property is extremely doubtful. The limestone ore is uncertain in 

 distribution, and the lack of mill water, the high dip, the necessity 



1 Bastin, E. S., Mineral Resources, U. S. G. S.,~i9o8, 2:72* 



2 Loc. cit., p. 729. 



