DOMAIN II. SILICEOUS. 



sand-stone cemented by quartz; so that a chemi- 

 cal and mechanical formation may occur in the 

 same rock. He mentions, in another work*, that 

 there is a vein at Lauterberg, in the Hartz, nine 

 fathoms wide, filled with quartz in the state of 

 sand. Pepits of copper are intermixed, and the 

 miners only use picks. It is crystallised, and not 

 the product of decomposition ; if permeated by a 

 siliceous juice, it would have been sand-stone. 

 Fine examples of siliceous sand-stone may be 

 found in Salisbury Craigs, near Edinburgh. 



Aspect 1. Coarse siliceous sand-stone, from 

 Sweden, &c. 



Aspect 2. Fine, from Stonehenge, &c. 



The same, from Salisbury Craigs, near Edin- 

 burgh. 



Elastic siliceous sand-stone, sometimes called 

 elastic quartz, from Brazil. 



Siliceous sand-stone, like most other rocks, is 

 also found schistose and laminated. 



Add the following varieties, from Saussure : 



A remarkable sand-stone, composed of very 

 small grains of white quartz and felspar, with 

 little specks of greenish mica, which absorbs water 



* Dumfriesshire, from Voigt, 



