176 Prof. Chapman on the Classification of Minerals. 



fications may necessarily have to be introduced into the general 

 plan by the natural progress of discovery. In no case, however, 

 do the most important of these modifications, any more than the 

 slight differences of opinion which prevail in regard to some of the 

 minor subdivisions, invalidate the general fact, that there exist 

 for these sciences certain primary or fundamental groupings of 

 universal recognition. In Mineralogy, on the contrary, we have 

 nothing of the kind. No broad, well-marked and acknowledged 

 divisions, which strike the mind at once as being natural and true. 

 No agreement, indeed, amongst the cultivators of the science as to 

 what should constitute the basis of a mineral classification. This 

 arises principally from the double nature, so to say, possessed 

 by minerals ; or perhaps, more correctly, from the prominence 

 and individuality of each of these natures in every mineral 

 species. For if animals and plants admit also of being considered 

 both as chemical and as physical bodies, their respective chemical 

 natures either offer merely a few inessential points of dissimi- 

 larity, or where a real difference of the kind does actually exist — 

 as in the solid parts of the Vertebrata compared to those of the 

 Articulata, Mollusca and Radiata — the difference affects not indi- 

 viduals only, but whole classes, and is in conformity with the 

 physical differences exhibited by the same ; so that in the classi- 

 fication of plants and animals, it is to their physical attributes 

 solely — in contradistinction at least to their chemical qualities — 

 that we have to look. In the classification of minerals, on the 

 contrary, both natures must be taken into consideration, and it 

 is here that the principal difficulty lies ; because, as a general 

 rule, no immediately perceptible relations can be traced between 

 the two. 



That a satisfactory classification cannot be founded solely upon 

 chemical characters is becoming daily more and more evident ; 

 whilst, at the same time, the so-called "natural-historical" 

 divisions of Mohs and his followers are seen, in numerous in- 

 stances, to be equally unsatisfactory. In affecting to deny the 

 right of chemical characters to be considered a classification- 

 element in Mineralogy, it is yet very obvious that many of their 

 groupings have been influenced by, if not entirely based upon, a 

 consideration of these characters. The incongruous union in the 

 order " Ore," for example, of specular iron, magnetic iron ore, 

 ruby copper, and tinstone — minerals which have really no affi- 

 nities in common, is a striking case in point. The separation, 

 again, of apatite from pyromorphite, of siderose (carbonate of 

 iron) from calcite, of barytine from anglesite, amongst numerous 

 other equally salient examples, are amply sufficient to show how 

 little the system merits the appellation of a natural one. If the 

 chemical nature of minerals, on the other hand, be only taken 

 into account, it is as yet impossible, with all the assistance to be 



