GNEISS. 261 



grains compacted together into a dense and some- 

 what granular aggregate, and having often a 

 glassy lustre. The rocks of this character are 

 more easily recognized than described ; and they 

 abound on the west coast of Sutherland and Ross- 

 shire. 



With respect to the first division I may add, 

 that the several varieties enumerated under it are 

 occasionally found passing into each other, in all 

 situations where gneiss occurs; notwithstanding 

 the leading prevalence of one or other of the sub- 

 divisions. 



SECOND DIVISION. 



Of irregular composition, containing compact 

 felspar, and consisting of that substance united to 

 some or all of the ordinary ingredients of gneiss. 

 In structure it sometimes resembles common 

 gneiss, but more frequently its fracture is like that 

 of the non-fissile schists; presenting no indica- 

 tion of laminae. 



A, Compact felspar with hornblende. This also 

 occurs as a variety of hornblende schist. 



