( 3f> ) 



under certain angles, their colours become 

 much more lively and bright. Many of 

 them- are amorphous, butfome are quadran- 

 gular prifms. Their furface, In the fradtures, 

 fhlnes with a glafly brilliancy, and is fome- 

 times fmooth, and fometlmes rough, accord- 

 ing as the plates of which the chryfolites 

 are compofed may have been broken. The 

 fmall fragments of them are angular and 

 femi-tranfparent. Thefe chryfolites give 

 fparks with fteel, and cut glafs nearly like 

 rock- cry ftal. The largeft are not lefs than 

 three lines and a half in length, but the 

 fmalleft can fcarcely be difcerned by the 

 naked eye. They are fo firmly Infixed in 

 the lava, that only fragments of them can 

 be detached. 



The fire of the furnace, and that of the 

 blow-pipe, not only will not fufe thefe mi- 

 nute Hones, but are unable to injure them 

 either in their^colours or texture. Oxyge- 

 nous gas (dephlogifllcated air) alone dlfco- 

 lours them, and melts them into a globule, 

 of a white colour, but without brilliancy. 



Though 



