DOMAIN I. SIDEROU8. 



spar, or rather felsite ; for Werner has pronounced 

 that the felspar in the ancient porphyries is com- 

 pact. 



The variolites of Turin are of a brownish grey, 

 qf a shining and unctuous appearance, with spots 

 of a lighter grey, and white starry crystals. The 

 variolite of Sesia is of a reddish grey, with spots 

 of a bright brick red. 



Saussure mentions, 1289, a kind of soft vari- 

 olite, seemingly composed of green siderite, with 

 spots of white felspar, sometimes rhomboidal, 

 sometimes circular. 



STRUCTURE II. IRON-STONE WITH IMBEDDED 

 CRYSTALS. 



Iron-stone, with crystals of quartz, from the 

 Surry hills. 



Saussure mentions, 1322, a red and green 

 porphyry, or rather intrite, mixed with felspar 

 and actinote; the base being of granular felspar. 



