82 GRANITE. 



ferent combinations, of two, three, or four. If this 

 were merely a question of mineralogy, the distinc- 

 tions thus condemned might be conceded without in- 

 convenience. But as the nomenclature of rocks is a 

 nomenclature for the purposes of Geology, it is easy to 

 see what fallacies may intrude from an improper use 

 of terms : as has happened from that of Syenite, thus 

 making a distinct geological rock of any granite which 

 happens to contain hornblende. Thus have the latest 

 been confounded with the older unstratified rocks ; 

 not only producing inextricable confusion, but per- 

 mitting trifling observers to impose on their 

 readers by false or flimsy statements founded on 

 mere terms. 



The minerals of granite, both essential and acci- 

 dental, are united by a confused crystallization ; the 

 endless variety of proportions, sizes, and colours, in 

 the ingredients, producing corresponding differences 

 of aspect and of texture ; while many different tex- 

 tures often unite in one mass. Though, in general, 

 uniformly granular, the felspar is sometimes separately 

 crystallized, so as to form " porphyritic" granite ; as is 

 the case much more rarely with the quartz and the 

 mica. Occasionally, it splits in one direction prefe- 

 rably to another, though the ingredients are still uni- 

 formly confused ; there being a slight tendency to the 

 parallel position, as in gneiss, while when this is not 

 visible in the mica, an acute eye will discover that the 

 felspar has crystallized under a common polarity, so 

 as to produce this effect. 



Did the mineral history of granite terminate here, 

 its character would be sufficiently defined; and we 

 should not be compelled to adopt a conventional one 

 in distinguishing it for the purposes of Geology. But, 

 as formerly shown, its mineral characters are often 



