MICACEOUS SCHIST. 277 



The varieties of this are endless, and it passes 

 both into quartz rock and into gneiss. 



D. The mica greenish, and more tender ; thus 

 approximating- to chlorite schist, yet forming large 

 tracts of country without passing decidedly into that 

 rock. 



In point of disposition, this variety comprises 

 all the modifications above named. 



E. The mica grey, but tender ; and thus approxi- 

 mating to talcose schist, a rock which appears to be 

 frequently subordinate to the present, and to occupy 

 very limited spaces among its beds. 



F. Modifications similar to the preceding two^ 

 but the passage being, in this case, into clay slate. 



The chief instances of contortion are found 

 in this subdivision. 



SECOND SUBDIVISION. Granularly laminar. 



A. Granular quartz uniformly mixed with scales 

 of mica in a parallel position, by which the laminar 

 fracture of the rock is determined. 



B. Granular quartz, occupying distinct laminae, 

 which are separable, in consequence of the interposi- 

 tion of scales of mica congregated into distinct spots. 



C. Granular quartz divisible into laminae, between 

 which distinct, and often distant, scales of mica are 

 interspersed. 



