( 4° ) 



volcanic ftones which, from their greenifh 

 yellow colour, and other circumftances, re- 

 femble that gem, and therefore are called 

 chryfolltes by the Volcanifts, differ from 

 them entirely in their component parts, 

 and feveral of their external characters. To 

 this opinion I can make no objedicn, 

 though, in defcriblng thefe ftones, I have 

 adopted the name by which they are ufual- 

 ly known. It mud be obferved, however, 

 that fome of their properties fhew they can- 

 .not be clafied as fhoerls, among which fome 

 naturalifts generally place the chryfolites of 

 volcanos. 



It remains like wife to fpeak of a ftone 

 which was the laft of the produds that of- 

 fered themfelves to my obfervation, as I 

 proceeded along the declivity of the moun- 

 tain leading to the Stoves. 



This ftone is a porphyry, the bafe of 

 which is the petrofilex, containing feltfpars 

 with feveral faces, and brilliant in the frac- 

 tures, and blackifh irregular fhoerls. The 



bafe 



