THE ADIRONDACK GRAPHITE DEPOSITS 6j 



spar and the latter is orthoclase rather than plagioclase. Still the 

 mica exceeds the amount of graphite present. 



The graphite is not limited entirely to the Bear Pond schist, for 

 frequently the Catamount schist exposed in contact with it contains 

 small amounts. It is the opinion of the writer that igneous activity, 

 in which the metagabbro and the Algoman granite-pegmatites have 

 had a share, the latter being the more important factor, has redis- 

 tributed the graphite, causing some of it to lodge in the adjacent 

 rocks. This is particularly true of the South Side pit and the 

 central bar of the Z-shaped outcrop. 



Bastin regards the bed on the north side of the hill as having 

 a thickness of 40 feet. 1 The writer thinks that this is a little 

 excessive, for the graphitic Catamount schist that lies next to the 

 Bear Pond schist is too low in graphite to be considered as a source 

 of supply. It is thought that possibly the 40 feet includes some of 

 the sillimanite schist. 



Considerable space has been given to the description of the Bly 

 ores, for the quantity is very great, probably equalling the tonnage 

 of the Hooper property. 



Possibilities of exploitation. There are several serious con- 

 siderations to be taken into account in regard to the exploitation of 

 the Bear Pond mountain property. In the first place, there is the 

 high mica content, proportionately larger than that of the graphite. 

 The usual methods of concentration do not make a clean separation 

 of the two. " Most of the graphite plates are bordered on both 

 sides by biotite and lie between the biotite laminae as between leaves 

 of a book. Thus biotite crystals 0.15 to 0.45 millimeter thick may 

 inclose graphite flakes of about one-tenth of this thickness." 2 It 

 would appear to be exceedingly difficult to treat commercially this 

 type of ore successfully by huddling. It has been pointed out that 

 the habit of the plates to bridge different grains interferes with the 

 chance of securing large flakes in the concentrates. 



In the second place, the vertical dip would render mining opera- 

 tions rather difficult. Probably the most economical method would 

 be by open cuts along the strike, starting in at the Eutoka pit, reject- 

 ing the soft, weathered material, with its high clay content, and 

 working up the slope w T hich would enable a gravity tramway to be 

 employed. Offsets at the crossings of the fault lines should be 

 looked for. 



In the third place, the transportation problems are rather serious. 

 The roads from the Eutoka pit to the farmhouse at the junction of 



1 Bastin, E. S., loc. cit. p. 726. 



2 Bastin, E. S., Economic Geology, 5:142. 



