of the Pyrites. 37 



repeated infpe&ion and companion of iamples. 

 The Following circumilances however may help 

 our ob ns thereon; the more* the yellow 



inclines to a iiikin-green, the more dead and lefs 

 glittering it is, and the clofer more clear-grained 

 and firm the (ample, richer the pyrites proves in 

 copper. 



It has been already remarked that the whitenefs 

 of the pyrites is a fign of its arfenic, and I might 

 add of its iron too, but that there is a (ingle, yet 

 rare, inttance Handing as an exception : at Chemnitz 

 or Stolberg in Mifnia, there is a whitiih pyrites- 

 copper- ore, holding at the rate of ,£40 the quintal, 

 plainly diftinguifnable from miftpickel, in its pale 

 colour, compaclnefs and firmnefs, tho' in a man- 

 ner not to be defcribed •, however as its whitenefs 

 is owing to its arfenic, it ftill remains a general 

 propofition, that arfenic imparts that colour; tho' 

 it be difficult to dittinguifh the whitenefs fattened 

 on the copper in this uncommon inilance, from 

 that on iron in the mi fs picket. 



D 3 CHAP, 



