THE ADIRONDACK GRAPHITE DEPOSITS 45 



pure rock but a syntectic. 1 Careful studies indicate that the lower 

 beds of the Hague gneiss have been " soaked " and saturated by 

 igneous solutions of the Laurentian granite. In this syntectic rock 

 the characteristic garnets of the former are absent but the sillimanite 

 is still persistent. This syntectic rock is termed the Trumbull gneiss, 

 from Trumbull mountain. The lower portions of the Trumbull are 

 comparatively free from sedimentary admixture and approach the 

 true Laurentian granite in character. 



The summary of the stratigraphy for this district is as follows : 



AGE ROCK NAME 



Keweenawan Diabase 



Algoman Gabbro 



Laurentian Granite 



' Para-amphibolite Beech Mountain 



Graphite schist Bear Pond schist 



Sillimanite schist Catamount 



Limestone . . 



Grenville J Quartzite Swede Pond 



Limestone Faxon 



Graphite schist Dixon 



Garnet-sillimanite para- 

 gneiss Hague 



^ Syntectic rock Trumbull 



American graphite mine. The great share of the mining is 

 underground and more closely resembles coal mining than operations 

 on a vein deposit. The extensive mining has resulted in very large 

 chambers; the entrance drift driven into the hillside with a south- 

 west direction, follows the strike of the Dixon schist for a distance 

 of probably over one-half cf a mile. At the far end of the open- 

 ing, near the southwestern limits of the mine, the mine tracks are 

 near the surface, but the miners have worked down the dip to the 

 southeast one-fourth of a mile, reaching a depth of 20b to 250 feet. 

 The roof needs little support and for that purpose is left an occa- 

 sional pillar of ore. The floor of the mine is exceedingly uneven as 

 the dip (average about 20 to 25 degrees) is not constant but varies 

 considerably, due to irregularities of the Grenville rocks. Occa- 

 sionally the Hague gneiss and the hanging wall come together, 

 pinching out the ore. The deepest portion of the mine, now 

 abandoned and filled with water, is known as the " big sink." The 

 breast here is said to be barren of graphite and in character abrupt 

 and nearly vertical. The ore here has been cut off by a fault (see 

 below). The present mining is localized in the far south corner of 

 the property close to the Faxon line. 



1 Suggested by Kemp, ibid. Used to indicate a rock composed of the admixture 

 of two or more different rocks. 



