GRAPHITE 303 



garnetiferous gneiss, and light colored quartzite entirely free 

 from graphite. 



There are numerous limestone deposits in Essex and 

 neighboring counties of New York which contain graphite 

 disseminated throughout the mass, or in small lenses of very 

 rich ore. While a number of these deposits are being promoted 

 and developed, the only ones of apparent promise are on 

 Lead hill, back of Ticonderoga, and on Warner hill, between 

 Ticonderoga and Crown Point. It is probable that if any 

 more valuable mines are opened in this section they will be 

 in the graphitic quartzite, as the lenticular bodies in the 

 limestone have proved uncertain. 



In Pennsylvania the principal graphite mine is one mile 

 east of Chester Springs, Chester county. The mineral oc- 

 curs in two layers of disintegrated mica schist, one 4 feet and 

 the other 6 feet in thickness. Adit levels have been run in on 

 the hillside, following the layers, and the rock is so disinte- 

 grated that most of the ore can be removed by pick and 

 shovel without recourse to blasting. At the mill the ore is 

 crushed in rolls and cleaned in a log washer of the type com- 

 monly used at clay w^orks. After being washed it is again 

 ground, refined by pneumatic concentration, and screened 

 into different grades. There are other graphite properties 

 in the state, notably at Byers, several miles below Chester 

 Springs, and at Pikeland, both in Chester county, and also at 

 Mertztown and Boyertown, Berks county. These properties 

 have been productive at various times, but for the most part 

 are now inoperative. The existence of graphite throughout 

 a large part of the ridge extending from Phoenixville to the 

 Brand\-^vine river seems very probable. Occasionally pockets 

 are found which yield nuggets and masses of nearly pure 

 graphite, such as formed the basis of the producing mines 

 in this region, but more often the mineral is associated with 

 iron oxides, quartz, and feldspar, so that the extraction of 

 the graphite involves considerable difficulty. 



The increased demand for crystalline graphite has led 

 to a careful study of the concentration of low grade graphite 

 dissemhiated in flakes. Operative plants have changed and 



