DOMAIN II. SILICEOUS. 



mountain which contains the copper mines of St. 

 George. 1201. 



Werner has a large piece of massive granite, 

 inclosing rolled pebbles of gneiss. 2143. Saus- 

 sure gives, 661, examples of granite imbedded 

 in mica slate, or rather gneiss. 



In the mountains on the south-east of the valley 

 of Chamouni, the inferior parts are gneiss, while 

 the summits are granite. 677. 



Mount Rosa is wholly composed of veined gra- 

 nite, gneiss, and schistose rocks, from the base to 

 the highest summits. 2 1 38, 



MODE XII. PITCH-STONE. 



Characters. Texture, impalpably fine, resinous. 



Hardness, basaltic, sometimes felsparic. Frac- 

 ture, conchoidal; if impure, splintery or coarse- 

 grained. Fragments, irregular and sharp. 



Weight, carbonose. 



Lustre, from glistening to splendent, resinous. 

 Somewhat translucent; but the black only on 

 the edges. 



The colours are various shades of black, and 

 sometimes grey, brown, red, seldom green ; but 

 the tints are commonly pale, 

 sues. Pitch-stone forms entire mountains in Mis- 



