OVERLYIXG ROCKS. 515 



H. Augit, felspar, and chalcedony, or quartz. 

 I. Augit, felspar, chalcedony and prehnite, or 

 inesotype. 



These are varieties of augit rock, and they 

 occur in different parts of the Western Islands of 

 Scotland. 



K. Hornblende, felspar, and olivin. 

 L. Hornblende, felspar, and epidote. 



These varieties are accidental, or very limited: 

 they may not possibly deserve a place in a cata- 

 logue of rocks formed on this principle; as the 

 last ingredient in each, may be supposed an acci- 

 dental imbedded mineral. 



M. Hornblende, felspar, and prehnite ; or horn- 

 blende, felspar, prehnite, and mica. 



This variety occurs in Dumbartonshire, the 

 prehnite appearing rather to form a constituent 

 part of the rock, than to be an imbedded mineral. 



N. Hornblende, common felspar, compact felspar ? 

 quartz, and steatite apparently containing augit also. 



Occurs near Edinburgh. 



O. Hornblende, and greenish compact felspar 

 forming the chief part of a mixture in which are inter- 

 mingled glassy felspar, opake white felspar, augit in 

 distinct prisms, and mica, together with pyrites. 



L L 2 



