DR T. THOMSON on Abestus, Chlorite, and Talc. 357 



Amianthus, then, appears not to constitute a particular species, 

 but to be merely a variety of amphibole. 



2. Amianthus, from Bleyberg, in Carinihia. 



This variety has a greenish-white colour. Its lustre is some- 

 what silky, but less so than the preceding variety. It feels soft 

 and unctuous, and consists of fine threads, which are flexible, 

 but too easily broken to be capable of being spun into threads. 

 It is opaque, and its specific gravity is 1.892. Its constituents 

 were found to be, 



Silica, . >, Vv ^ TV nVx - . 52.512 



Magnesia,. ... . 19.112 



Protoxide of iron, . . 13.652 



Lime 7.960 



Alumina, ..... 4.808 



Water, 4.080 



102.124 

 This is equivalent very nearly to 



58 atoms silica, 

 17 atoms magnesia, 



6^ atoms protoxide of iron, 



5 atoms lime, 



4f atoms alumina, 



8 atoms water. 



Now, if we make an allowance for a slight over estimate of 

 the quantity of magnesia, indicated by an excess of 2^ per cent, 

 in the analysis, we shall find that these constituents may be 



vy 2 



