NOME VI. OBSIDIAN. 443 



HYPONOME II. VESICULAR PUMICE. 



From Lipari, Santorin, Hecla, Ternate, &c. 



Micronome 1. Fibrous fdsite. 



This kind of pumice, described by Dolomieu, 

 assumes the form of distinct elongated fibres, and 

 sometimes occurs with minute crystals of felspar. 



NOME VI. OBSIDIAN. 



This division will include all the Volcanic 

 Glasses and Amels* ; which are nearly connect- 

 ed, and often pass into each other. 



The volcanic glass called obsidian, appears in 

 such quantities as to constitute rocks. 



" In the Isle of Lipari, the mountain della patrm's 

 Castagna is wholly composed of glass and amels. ... 

 It forms a promontory which extends 800 fa- 

 thoms into the sea., and which is more than 3000 

 in circumference. Spallanzani says, that this 

 mass of vitrified substances cannot be better 

 compared than to a great river, which, dividing 

 itself into a thousand branches, should be preci- 



* See Johnson, as before mentioned : enamel is properly the ap- 

 plication of the amel to another substance. 



