of the P Y R I T E s. 3 1 



nifefl caufe of the whitenefs of the mifspickel, or 

 arfenic-pyrites -, alfoof certain copper- ores, in which 

 it exceeds the fulphur in quantity. 



The three above mentioned capital colours of 

 the pyrites are to be taken in a comparative, not 

 a feparate view : for, the fulphur -pyrites being 

 viewed apart, mews white or grey -, but placed near 

 the mifspickel, its yellow call mews to greater ad- 

 vantage : in like manner the yellow ceales to be 

 diflinguifhable, unlefs compared with the yel- 

 lowifh. The reafon is, that thefe are three not 

 very oppofite colours, but eafily running into each 

 other, without deflroying, tho' lowering or heigh- 

 tening, one the other : again, they Hand in fuch 

 a degree of mutual affinity, that many others dif- 

 ferent cannot be placed between them. Thefe co- 

 lours are to be underftood as entirely penetrating 

 into the fubflance and body of the pyrites ; con- 

 fequently they are not owing to the adjoining mi- 

 neral, which indeed often ftrikes the eye in fuch a 

 manner, that the pyrites, efpecialiy if lying inter- 

 fperfed therein, cannot well exhibit its natural co- 

 lour •, fome caution alfo is neceffary to prevent 

 being deceived by the variegated, the red and 

 green, the gold-yeilow, the blue, &c. colours, 

 which fometimes fettle upon, without penetrating 

 into the fibres or firings of the veins, and are ufu- 

 ally called copper-blooms : to which muft be added, 

 th&tpyrit* being long expofed in the weather, change 

 their external colour •, whence it is poflible to be 

 milled by that powdery coloured fubflance, which 

 is either ochre or verdigreafe, arifing in part from 

 the deftrudtion of tht pyrites, and lying externally 

 upon it, without making a part of its effence or 

 compofition. 



This divifion taken from the colour will, upon 

 trial, be found not only eafy and diftinc~l, but com- 

 prehenfive of all the variety of t\is pyrita. There 



may, 



