PREFACE. XIX 



ledge, and the great additions recently made to 

 the history of these species, give us reason to 

 hope that the time is not far distant when a system 

 of organic mineralogy (if this term is admis- 

 sible,) will be formed. Whenever that shall hap- 

 pen, a new and independent work will be pro- 

 duced to comprise that department which could 

 not here have been attempted with any prospect 

 of advantage, and which has therefore been in- 

 tentionally passed over. 



The student whose pursuit is chiefly directed 

 towards the mineral characters of rocks, or whose 

 object it may be to forma collection of specimens, 

 may be surprised to find that so many substances 

 are comprised in the present arrangement under 

 so small a number of names. But it has been 

 the constant endeavour of the author, not only 

 to shun technical phraseology where facts can be 

 described in ordinary language, but to avoid in- 

 troducing new terms wherever it was possible to 

 proceed with those which have been long re- 

 ceived or generally acknowledged. However 

 exceptionable these may sometimes be, their in- 



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