08 1>OMAIN XII. VOLCANIC. 



by a grey lava, which itself contains a number 

 of sandy grains of black lava. 



" 9. Bricia of a yellowish base, with very 

 large fragments of a black compact basaltic 

 lava, filled with vitreous grains of chrysolite of a 

 yellowish green, and a number of smaller frag- 

 ments of black lava with small pores, some of 

 which are vitrified. The yellowish and rather 

 earthy lava, which cements this bricia, contains 

 some grains of black pyroxene, which seem to 

 have been melted ; and of flaky felspar, changed 

 and of a dirty white. 



" Division 2. Bricias, or volcanic tufos, form- 

 ed by the concurrence of fire and water, carried 

 to the highest degree of temperature : the water 

 introducing itself by some subterranean communi- 

 cations into the burning centre ofvolcanos, has pro- 

 duced results and particular combinations, which 

 partake of the contrary properties of those two 

 . elements. 

 From fire i. Bricia of an ashv grey base, formed of a 



and water. 



number of fragments, rather porous, of black 

 basaltic lava, mixed with many grains of chry- 

 solite, of large fragments of quartzose sandstone 

 with parallel zones, white and red, irregular 

 pieces of hard grey marl, reddish in many parts,, 



