IN! ADIRONDACK GRAPHITE DEPOSITS I \J 



Reasoning based upon the work of H. Dixon 1 indicates thai the 

 following reactions are reversible: 



CCX + 2H 2 -> 2H,0 + C 

 2CO + 2H 2 -> 2H 2 + 2C 



But the intermediate steps appear to be : 



Above 900 C. 2C0 2 + 2H 2 -> 2CO + 2H.O 



Below ooo° C. ] 



AU on 2CO +2H 2 0-»2CO, + 2H 2 



Above 500° C. J - - 



Below 500 C. CO, — 2H 2 -* 2H;,0 + C 



This goes to show that the oxides of carbon (gases) in the 

 presence of gaseous water react to form graphite. Much of this 

 w<iter is probably magmatic, while some of it may be derived from 

 the sediments. Available analyses of such rocks give from 1 to 2 

 per cent of water. This may partly explain the occurrence of 

 graph ; te at the margins of pegmatites; the heat of the intrusive 

 releasing it from the sediments and acting as one of the reagents. 

 In a similar manner the CO L , from limestones (CaC0 3 ) may have 

 been liberated and thus there is furnished another reagent for the 

 process. 



Applying the theories outlined above it is reasonable to expect 

 that " any magma which contains sufficient water, upon coming in 

 contact with bituminous (sediments) may be expected to convert 

 all that portion of the carbon which is heated above . . . 6oo° C. 

 to the oxide state. The resulting gases are soluble in water and 

 silicate melts. When this solution cools below 6oo° C. graphite 

 may be expected to crystallize out . . ." 2 If this explanation of 

 the origin of graphite is correct, then certain contact deposits may 

 have a complex origin ; the carbon being derived from organic re- 

 mains in sediments was picked up by the intrusive (as oxides) and 

 redeposited. Such a process may possibly be the one responsible for 

 the contact pud vein types on Lead hill. This is suggested upon the 

 basis that in the Barrett Construction Company's abandoned spar 

 quarry, on the eastern slopes of Lead hill, there is shown the Hague 

 gneiss enveloped by the same pegmatitic-granite mass that forms 

 Lead hill. If the stratigraphy of the Grenville, as here developed, 



1 Pixon. H.. Jour. Chem. Soc, 1886, 49: 94. 

 - Winchell. loc. cit. 



