( 3^4 ) 



great an analogy the lavas of the Euganean 

 hills have with thofe eje(fled by other vol- 

 canos more knov/n to be fuch, as thefe 

 are not fimple flones, but compound ; I 

 mean what are called rocks. The lavas of 

 Etna, which ufually have for their bafe the 

 horn-ftone or Ihoerl in the mafs, contain 

 feltfpars, cryftallized fhoerls, or chryfolites. 

 Feltfpars, garnets, and cryflallized fhoerls 

 are incorporated in Jthe lavas of the volcanos 

 of the Eolian ifles, in a bafe of petrofilex, 

 horn-ftone, and ihoerl in the mafs. Petro- 

 filex, horn-ftone, and garnets are conftantly 

 accompanied by fhoerls, feltfpars, and mi- 

 cas in the lavas of Vefuvius *. Thofe of 

 Ifchia with a horn-ilone bafe abound in 

 feltfpars t. The iflands of Ponza afford 

 both granitous and filiceous lavas, accom- 

 panied with fhoerls, feltfpars, and micas ; 

 and St. Flora in Tufcany is compofed of 

 granitous lavas J. 



* Gloeni, ubi fup. 



f See Chap, V. 



4: Dolomieu, ubi fup. 



The 



