PREFACE. VH 



figures represent the combinations, where they are 

 quoted themselves ; others are only similar to them, 

 in so far as they have the same general appearance, 

 but different angles. 



To distinguish the compound varieties from the 

 simple ones, is a matter of the highest importance ; 

 and they must therefore be kept perfectly separate. 

 This is the point where Mineralogy ends and Geo- 

 logy begins, two sciences which have nothing com- 

 mon with each other. Geology presupposes Mine- 

 ralogy ; but it considers the productions of the Mine- 

 ral Kingdom in quite another point of view, and 

 according to different principles ; without which 

 it would not be a distinct science. 



With the enumeration of the compound varieties, 

 the General Description of the species is completed. 

 But there exists besides, a great variety of informa- 

 tion in regard to the productions of the Mineral 

 Kingdom, belonging in part to Natural History, 

 but partly also foreign to this science ; the latter 

 nevertheless is generally deemed an essential part 

 of a work on Mineralogy. Something of this in- 

 formation is contained in the Observations added 

 to every species, and which may require here a few 

 explanations. 



The first of them properly belongs to the pro- 

 vince of Natural History. It comprehends some re- 



