136 CLASSIFICATION. 



the object, and of consequence, is useless except to those who are 

 already acquainted with the names ;* chemical arrangements, where 

 minerals have been studied more with regard to their relations to 

 their chemical than to their natural properties, and which involve 



that there exist species, between which there is a similar degree of re- 

 semblance, and which are more allied to each other than to any other 

 species out of the groupe, a discovery which lies at the foundation of the 

 idea of the genus. A demonstration of these remarks may easily be 

 acquired by any person familiar with the species in mineralogy. 



The mineral kingdom is, therefore, represented by a series of genera, 

 exactly as in the animal and vegetable kingdoms, and like them it does 

 not contain a series of single species. Each of these genera contains 

 similar species, (if it contains more than one,) every one of these again 

 being the assemblage of homogeneous individuals. Their succession in 

 the series is made to depend upon their greater or less agreement, or 

 similarity. 



'The order is, in respect to the genera, what the genus is to the spe- 

 cies. The idea of it is therefore obvious from the preceding remarks. 

 A few observations will illustrate its mode of application. 



The genus Iron Pyrites, in the peculiar place it occupies in the gen- 

 eral series of genera, is surrounded by several other genera, which ex- 

 hibit so high a degree of resemblance to each other, that they seem to 

 have been formed after a common type or original. These are the ge- 

 nera Nickel Pyrites, Cobalt Pyrites, Arsenical Pyrites and Copper Py- 

 rites. There is not another genus to be found in the whole mineral king- 

 dom, as hitherto known, which could be enumerated along with these, 

 without destroying the idea produced by the assemblage of the above 

 mentioned genera. In a similar manner, the genus Iron-Ore is connect- 

 ed, on one side with the genus Manganese-Ore, on the other side with 

 the genera Chrome-Ore, Cerium-Ore, Uranium-Ore, Tantalum-Ore, 

 Copper-Ore, Scheelium-Ore, Tin-Ore, Zinc-Ore and Titanium-Ore. 

 Thus, likewise, around the genus Feld-Spar are assembled the other 

 genera of Spars, under similar circumstances. Every groupe of this kind, 

 which is an assemblage of genera similar to each other, is an order. 



The class is an assemblage of similar orders; what the genus is to the 

 species, or the order to the genus, the class is in respect to the order. 

 The idea of the class is so comprehensive, that it becomes difficult to 

 judge of its applicability, without the direct inspection of the objects 

 themselves. This inspection proves that every one of the three classes 

 of the natural system in mineralogy does contain orders, which are con- 

 * Brooke, 



