98 DOMAIN I. SIDEROUS. 



into the Mode of Iron-stone, as appears from its 

 action on the magnet. 



The stone which serves as a gangart to the 

 quartz crystals called Bristol diamond, may also 

 be ranked in this division ; but it seems to be only 

 a vein-stone passing through limestone. Various 

 kinds of iron-stone, siliceous and argillaceous, 

 often occur in mines, but have not been found to 

 constitute rocks. 



The following substance may also be added to 

 this division. 



Iron clay of ct Tiv\n ^Ta-tr 

 Werner. lron cla j- 



" Eiseathom. Werner. 



" External Characters. 



" Its colour is commonly brownish red, which 

 seldom approaches to blood red, but more often 

 to reddish brown. 



" Occurs almost always vesicular, sometimes 

 with empty, sometimes with filled vesicles. 



" Internally it is dull. 



" Fracture fine, earthy, sometimes inclining to 

 conchoidal. 



" Fragments indeterminately angular. 



" Is soft, but sometimes passes into semi-hard. 



" Is not particularly difficultly frangible. 



" Not particularly heavy, in a middling degree. 



