DOMAIN XII. VOLCANIC. 



vius, the Isle of Bourbon, the Puy-de-Dome, 

 &c. 



The same, with spangles of felspar. 



Vesicular lava of a violet colour, from the extinct 

 volcanoes of Provence: seeSaussure, 1485, 1495* 



The other kinds are sufficiently remarkable to 

 form regular subdivisions. 



Micronome 1. With Leucite. 

 Lava, with unimpaired leucite, from Vesuvius. 

 The same, from Albano near Rome. 

 The same, with decomposed leucite, from the 

 same places*. 



Micronome 2. With Zeolite. 



Black vesicular lava, with fibrous zeolite. 



According to Dolomieu, this is sometimes co- 

 lumnar. 



" A porous black lava, the pores being exactly 

 round, and one or two lines in diameter ; distant 

 from each other more than six lines, and some- 

 times one or two inches ; the interior of the sphe- 

 rical cavities being blue, while they commonly 

 contain zeolite and calcareous spar. This lava is 

 crystallised in prismatic columns, more or less 

 regular, in the mountains of Trezza and of the 

 castle of Jaci."t Is not this an original rock ? 



* See Volcanic Intrites. 



f Etna, 303. Jaci is the Aci of Ferrara. 



