31 



would be impossible to distinguish all those 

 which, as specimens of mineralogical composi- 

 tion and structure, would require distinction. To 

 be consistent, as formerly remarked, a nomen- 

 clature on a mineralogical principle must neces- 

 sarily be large as well as appropriate. 



The numerous combinations, and the endless 

 varieties of aspect which rocks present, render it 

 impossible to apply distinct names to all ; nor 

 is it easy to see, on this system, where the line is 

 to be drawn. The inutility of such a nomencla- 

 ture, even could it be rendered complete, is ne- 

 cessarily comprised in the inutility, already point- 

 ed out, of this mode of classification. 



If such names be thus contrived according to 

 some principle either of structure or of composi- 

 tion, it is obvious that the greatest confusion of all 

 the natural analogies of mixed rocks must ensue. 

 In this case, as well as in the geological method, 

 the same substances would recur more than once, 

 whether the principle of the integrant minerals, 

 or those of the structure, were made the basis of 

 the nomenclature ; as the same circumstances and 



