187 



TAB. CXCIX. 



S I L E X Quartzum. 

 Crystallized Quartz. 



Div. 1. Crystallized. 



1 hese curious specimens were lent me by Philip Rash- 

 leigh, Esq. of Menabilly, and are said to contain Arsenical 

 Cobalt. They came from Poulteney mine, and are rare 

 specimens, on account of the mine having been destroyed 

 by the overflowing of a river. The Quartz is more regularly 

 eighteen- sided than usual, although it is as it were clogged 

 up with such abundance of a metal, that it otherwise 

 would be nearly obliterated in its character ; and that it 

 should crystallize under such circumstances, distinctly and 

 regularly at both ends, merely as if heaped on each other, 

 as in the top figure, is very remarkable. There appears to 

 be little else than Arsenical Iron among them, but 

 capillary Silver and flowers of Cobalt are sometimes to be 

 seen very distinctly about the gangue. 



VOL. II. 



