Analysis of some Steatites. 141 



From this analysis it follows, that of the three varieties 

 of talc here mentioned, two only must continue to be so 

 called ; namely, the laminar talc, and the compact rose-co- 

 loured talc. The third, the speckstein, should be removed 

 to the genus of alkaliniferous stones. 



It deserves particular remark, that those two varieties, 

 which most resemble each other, and which have always 

 been classed together, should now be separated by analysis : 

 which shows, that minerals should never be classed accord- 

 ing to their external appearance, since the most striking 

 analogies in this respect are the most deceitful. In fact, the 

 speckstein and compact rose-coloured talc have the same 

 softness, the same fineness of particles, the same fracture, 

 nearly the same specific gravity ; and certainly, if there were 

 any room to suppose that one of the three substances 

 ought to be separated from the" talc species, we should be 

 more inclined to suppose it the laminar, than either of the 

 others. 



Note. I analysed at the same time that species of talc 

 known by the name of crate de Briangon, or French chalk, 

 and I found it to contain the same principles, and nearly in 

 the same proportions, as the laminar talc, and the compact 

 rose-coloured talc. These proportions were, 



Silex 61-25 



Magnesia 26*25 



Water 6 



Alumine 1 



Oxide of iron 1 



Lime 0*75 



Loss 3*75 



100 



XXIII. Me- 



