ment which can even be said to approach to that 

 which is considered a classification in the organic 

 departments of Natural History. The difficulties 

 which have been experienced, even by mineralo- 

 gists, in their attempts to produce a perfect, or a 

 commodious classification of minerals, have hi- 

 therto proved insuperable ; but to the obscurity 

 and doubt pervading that department, in which 

 it necessarily shares, the classification of rocks 

 adds others peculiar to itself. I do not pretend 

 to accomplish that in which others have failed ; 

 but, in adopting the present as a temporary ar- 

 rangement, have been guided by the principle of 

 utility; chusing that method which, while it 

 seemed most applicable to those researches for 

 which the study of rocks is peculiarly desirable, 

 appeared also to be the most susceptible of future 

 improvement. 



A critical examination of the different arrange- 

 ments which have already been proposed, would 

 doubtless be of utility to the reader, by display- 

 ing minutely the merits and faults of each, and 

 by thus pointing out, in a practical manner, the 



