310 DOMAIN XII. VOLCANIC. 



some naturalists have found in other mo- 

 dern lavas ; and the great difference ought 

 to be remembered between these scarce 

 trifles, and the vast masses of prisms, groups 

 of columns, and fascicular assemblages, of 

 which even the fragments tend to regular 

 divisions, which constitute their charac- 

 teristic quality/'* 



Even the amorphous lava of the prime- 

 val period is very compact, sprinkled with 

 filiform crystals of felspar, and some of 

 siderite, with grains of chrysolite. That 

 of Cape Passaro takes a beautiful polish. 

 " The prismatic lavas are very hard and 

 compact, and always of a dull ashy colour, 

 or a bluish black ; and I have never ob- 

 served any pores in prismatic lava/'-f- 

 Among these primeval products is also 

 found black or blue obsidian, sometimes 

 in fragments, sometimes in tables in the 

 slits of the lava, and sometimes concave, 



* P. 144. He had before said, p. 112, " In generale posso dire 

 che le lave prismatiche, le lave basaltine, i basalti, che sono intorno 

 alia base dell' Etna appartengono agli ANTICHI VOLCANI, e non 

 mai alle eruzione inoderne di questo volcano." 



t P. 176. 



