NOME VI. OBSIDIAN. 



44? 



Glasses of 



Lipan. 



The Ptedra de Galmazzo, above mentioned Raven-stone. 

 by M. Patrin, is a kind of obsidian found in 

 Quito and Peru; and is so called, because in 

 blackness it resembles the raven. It seems to 

 have been sometimes polished, and used for 

 mirrors ; but must not be confounded with the 

 stone of the Incas, found in the female tombs, 

 and used for the same purpose j the latter being 

 a compact pyrites, or marcasite of the Arabians, 

 and other early writers on mineralogy. 



In his account of the island of Lipari, after 

 having mentioned several kinds of volcanic 

 glass, as the pumiceous, reticulated, and capil- 

 lary, Spallanzani thus proceeds, having apolo- 

 gised for the prolixity of his description as indis- 

 pensably necessary for the sake of accuracy, in 

 discussions merely scientific. 



" 4. The glasses of the Monte della Castagna, 

 which we have hitherto considered, are those 

 that have a texture more or less porous 3 we will 

 now proceed to those of a compact structure, of 

 which kind is the fourth species, which may be 

 said to compose nearly one half of the mountain. 

 This glass, if viewed superficially, and as it is 

 found on the spot, has rather the appearance of 

 a red earth than a glass, occasioned by a red 

 earthy coating that invests the glass disposed 



account. 



