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which feparate its parts. It is found in de- 

 tached pieces, like the four preceding lavas^ 

 but thefe pieces are rare. It gives but few 

 fparks with fteel, emits a flight argillaceous 

 odour, and ad:s on the magnetic needle at 

 the diftancc of a full line. In confequence 

 of its numerous fifl'ures it is rather light, 

 and when flruck with a hammer is fome- 

 what fonorous. I omit to mention fome 

 fmall fcales of feltfpar incorporated in it, 

 and proceed to the examination of the chiy- 

 folites. 



Thefe, when fituated in the external parts 

 of the lava, which have fuffered by the 

 influence of the atmofphere and elements, 

 readily attract the eye, by their lively" co- 

 lour, which is betv/een a green and a yel- 

 low ; but in the recent fraftures they fliine 

 with much more brilliant colours. The moft 

 confpicuous are the golden-yellow, and the 

 fine grafs-green, with wliich, fometimes, is 

 mixed a fire-red, tempered with a tinge of 

 purple. If thefe chryfolites are expofed to 

 the immediate light of the fun, and viewed 

 D 2 under 



