500 OVERLYING ROCKS. 



SECOND DIVISION. 

 Compound : formed of two substances. 



FIRST SUBDIVISION. 



Granitiform mixtures. 



A. Hornblende and compact felspar. 



a. In nearly equal proportions, or the 

 hornblende predominant, and the 

 two minerals distinctly visible. Green- 

 stone. 



This rock is important from its extent, and 

 it occurs both in veins- and in mountain masses. 

 Like some of the preceding, it is also at times 

 columnar, as well as laminar! The horn- 

 blende is either black or dark green, and is 

 sometimes distinctly crystallized. The felspar is 

 white, or yellowish, or of different hues of red, 

 or pale greenish, or grey of different degrees of 

 intensity down to nearly black. The greenish 

 varieties alone, have been distinguished by some 

 mineralogists by the name of greenstone, the 

 grey by that of greystone ; but the former term 

 has been in this country applied to the whole, of 

 whatever colour. It presents a great - variety of 

 aspects, according to the relative proportions of 



