. 23G. NOMENCLATURE. 357 



sume its name. They are therefore compelled as it were, by 

 their natural-historical properties, to part with their former 

 names. 



No other name has been subject to more ambiguities, and 

 to abuses, than the name of Spar. The word Spar is ge- 

 nerally said to signify a certain structure which has been 

 called the spathose one. We should never derive a name 

 a word, which designates a very general idea, from this 

 property ; for no property is less constant in a determined 

 signification, as its constancy does not extend beyond the 

 species, if we except the tessular system. In a more com- 

 prehensive or indeterminate signification, again, it is so ge- 

 neral, that it occurs not only in all the systems of crystal- 

 lisation, but also in many different orders. 



The name of Felspar or Fcld-spar is almost generally re- 

 ceived in many languages, and may be useful on that ac- 

 count in deriving the name of an order. Hence only those 

 minerals are said to be Spars, -which belong with Feld-spar to 

 one and the same natural order, and not those species only 

 which shew the so called spathose structure. 



Mica signifies a mineral, which may be cleaved with fa- 

 cility into thin shining laminae. Common Mica (rhombo- 

 hedral Talc-mica), Uran-mica (pyramidal Euchlore-mica), 

 Copper-mica (rhombohedral Euchlore-mica), are of this kind. 

 Although this relation of structure alone is not sufficient 

 for determining a natural order ; yet the order Mica con- 

 tains only such species as present it in a high degree of 

 perfection, and it bears therefore deservedly this name. 



A mineral which may with propriety bear the name of a 

 Metal, must really be a metal, or it must present the pro- 

 perties peculiar to metals. Hence this name must not 

 be given to species belonging to the orders Pyrites, 

 Glance, Blende or Ore, because they do not possess the 

 properties of metals, although metals actually may be 

 extracted from them. The classification of metallic sub- 

 stances in the greater part of the systems hitherto pub- 

 lished, regard much more the rcguli obtained by chemical 

 aid, than the productions of nature ; and thus they betray 



