OVERLYING ROCKS. 503 



B. Hornblende and common felspai 

 a. In nearly equal proportions. 



As already noticed under F, c, Division First, 

 it is sometimes uncertain, from the minuteness of 

 the parts and the state of mixture, whether com- 

 mon felspar is not the mineral present, instead of 

 compact felspar, in some of the preceding varie- 

 ties. 



In other cases, the nature of the felspar is 

 abundantly evident, and it is even confusedly, or 

 more regularly crystallized, and intermixed with 

 the hornblende. The hornblende is also at times 

 crystallized in a manner considerably distinct. 

 The rocks of this variety also, are classed under 

 the very loose term of greenstone ; but they ge- 

 nerally differ in appearance from most of the 

 varieties of A in this division, into which they 

 however pass. Some mineralogists are inclined 

 to place them with the syenites. They pass into 

 those in a perfect manner, by the increase of 

 the felspar. When the felspar is red, they have, 

 in a considerable degree, the general aspect of 

 some varieties of granite ; and similar rocks 

 are found connected with ordinary granite, un- 



