GEOLOGICAL SOCIETY OF PENNSYLVANIA. 297 



It has a dark brown colour, giving a jet black powder. 

 Its texture is fibrous and silky, very soft to the touch, 

 and pulverizes into an impalpable powder with the 

 slightest effort burns and incinerates with facility, leav- 

 ing a lilac-coloured ash which does not effervesce. 



Composition per cent. 



Carbon, , 83.3 



Volatile matter, 10.7 



Ashes, 6.0 



100.0 



