Prof. Naumann on Mineralogical Classification. 33 



although some of ita groups, as, tor example, the micas, ex- 

 hibit, along with similar cleavage, a similarity of the mass. 

 It is unnecessary to explain, that a classification founded on 

 the crystallographic indications of the cleavage planes, would 

 coincide with an arrangement founded on crystallographic 

 systems, and would have just as little physiographical value. 



It therefore results, from what has been said, that it is the 

 formless masses, or, that it is the masses without reference to the 

 form, which must in reality form the immediate object of 

 every general arrangement of mineral species. Hence we 

 must entirely give up the moi'phological and morphological- 

 physical properties, and thus gain the great advantage, that 

 all the varieties of a species, the perfectly crystallized, as well 

 as the crystalline, the isolated fully developed individual, as 

 well as massive and compact aggregates, will receive 

 equal consideration. This feature gives rise to a striking 

 distinction between inorganic and organic nature, for, in the 

 latter, classification is, and must be, founded on the resem- 

 blance of the morphological habitus. 



If, however, the inorganic mass, without reference to its 

 form, is to be regarded as the true principal object in the 

 systematic arrangement of mineral species ; and if, accord- 

 ingly, morphological properties, and the physical properties 

 directly connected with them, can only in certain cases throw 

 into the scale an accessory, and, so to speak, a superfluous 

 weight, it is self-evident, that, in the determination of phy- 

 siographical resemblance, it is only certain physical proper- 

 ties, and the chemical properties represented by chemical con- 

 stitution, which can receive consideration. 



We must above all assign a great degree of importance 

 to the distinction of the metallic habitus, for its characters can 

 be recognised at the first glance. Opacity, metallic colour, 

 and metallic lustre, the three characters whose union pro- 

 duces that appearance which we designate by the expression 

 " metallic habitus," can be perceived and recognised with 

 equal certainty in the smallest particle, and in the largest 

 mass of a mineral ; so that we can instantaneously determine 

 with great confidence whether a mineral possesses the 

 metallic habitus or not. Now, as the presence or absence 



VOL. X.XXIX. NO. LXXVII. — JFLV 1845. C 



