408 DOMAIN XII. VOLCANIC. 



lustre has become agglutinated, and compressed 

 by a kind of calcination. 



" Its origin similar to the last. 



" No. XV. A black lava with a base of felspar 

 and chrysolite, to which fire has imparted dif- 

 ferent colours ; it comprehends rhomboidal crys- 

 tals of felspar, and crystals of vitreous schorl 

 and mica. 



" From the eruption of the west-south-west. 



" No. XVI. Lava in beds of different sub- 

 stances : one of them is compact, very hard, of a 

 fine grain, with laminae of felspar ; the other has 

 regular pores, with laminae of felspar which 

 cross each other, and vitrified grains of a green- 

 ish hue and semi-transparent ; this lava, on 

 being moistened, yields a strong smell like 

 clay. 



" It is a product of the same eruption as the 

 lava of the preceding article. 



" No. XVII. A compact and very hard lava, 

 with a vitreous fracture ; its black base contains 

 small laminae of felspar, with a few crystals of 

 vitreous schorl. 



" From the same current of lava as the pre- 

 ceding. 



" No. XVIII. A very hard and compact lava, 

 black, and sprinkled with points varying in size, 



