GNEISS. 257 



limitation of a given rock to one place, when it 

 exists in two. 



As in granite, many minerals are found im- 

 bedded in gneiss, in greater or less abundance : 

 and these, as in the former case, are enumerated 

 in an appended list. 



The colours of gneiss vary from the same 

 causes which influence those of granite ; and to 

 repeat these would be superfluous. It may only 

 be added, that the peculiar structure of this rock, 

 by frequently causing the several colours to be 

 disposed in stripes, produces a much greater diver- 

 sity of aspect in a series of specimens, than can be 

 found in a collection of granites. 



SYNOPSIS OF GNEISS. 



FIRST DIVISION. 



OF regular composition, containing at least 

 three of the four minerals, quartz, felspar, mica, 

 and hornblende. 



