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The Eiiganeari mountains, which form 

 maffes, for the moft part conical, fome de- 

 tached, and others coiitij2,uoii« at their bafes, 

 are principally compofed of lavas, with 

 which, in feverai of them, are mixed cal- 

 careous carbonates. Thefe two kinds of 

 ftones arc of fome value to the Venetians, 

 who ii^e the lavas, which they call mafegne^ 

 to pave the ftreets, and the carbonates to 

 make lime. There are therefore here fe- 

 veral quarrie?, fomie of which are now 

 worked, while others, that are either ex- 

 haufl(d, or become iefs produdlve, are 

 abandoned. 



I entered two of thefe quarries, the one 

 at Monte RoiTo, and the other at Monte 

 Ortone ; and, having continued there fome 

 time, determined to go down into fome 

 others, as I found they were extrem.ely 

 convenient for obferving in their fides the 

 ilony fubftances 1 wiflied to examine. I 

 therefore proceeded to Monte Merlo, where 

 there is a very large excavation of this kind 

 within the lava. To extrad the ftones, 



which 



