502 DOMAIN IV. TALCOUS. 



rocks, in particular, have never been described 

 with that attention which their curiosity and 

 importance authorise. 



STRUCTURE I. COMMON TALC. 



Characters. Texture, finely foliated, and of a glassy appear* 

 ance ; level, undulated, or involved. 



Hardness, cretic. Fracture, slaty. Fragments, 

 amorphous, rather sharp, but the corners easily 

 crumble into white powder. 



Weight, pumicose. 



Lustre, shining. Translucent, semi-transparent, 

 sometimes transparent. 



The colour is commonly a silvery grey, but 

 often also light brown ; and specimens of this co- 

 lour are found, though very rarely, with beautiful 

 metallic veins, or illinitions. It is also found of 

 various beautiful tints of green, sometimes change* 

 able, being reflected as it were through a white 

 surface. 



sites. It abounds in the Uralian mountains; and it 



appears, from the accounts of Gmelin and Pallas, 

 that it sometimes may be said to form whole 

 mountains, while a mountain of quartz appears on 

 one hand, and a mountain of felspar on the other, 

 so as to present elements of granite on a vast 

 scale. Fine talc is also found in the mountains 



