( ^71 ) 



hard ; it has not, however, the brilliancy of 

 the former. Both thefe rocks produce ia 

 the furnace a greyifli enamel, with an entire 

 fufion of the feltfpars, but not of the micas, 

 which leave black points within the enameL 



The other product of which I went in 

 fearch, according to the directions given 

 me by Father Terzi, was, in like manner, 

 in his opinion, a volcanic glafs, but detached 

 and fcattered. It is found near the Church 

 of Valfanzibio, Having taken a fpecimen 

 of this into my hands, and examined it care- 

 fully on every fide, I perceived that in this 

 inftance he was not miftaken, and congra- 

 tulated him and myfelf on the difcovery. It 

 exhibited, in fad, the moft indubitable cha- 

 radlers of a true glafs. It was black, and 

 gave fparks with fteel. I was, therefore, 

 very anxious to examine the place where it 

 was found, and repaired without delay to 

 Valfanzibio ; where I found more than one 

 piece of it, not infixed in the earth, nor in 

 the mid ft of any rock or ftony vein, but 

 loofe, and fcattered over the ground, like 



ftones^ 



