in the Pyrites. 221 



or, by means of a mercurial admixture, over- 

 pale, but to break and crumble the fample which 

 is commonly quartzy, and thereby to expofe to 

 view more fides of veins, where the gold common- 

 ly lodges •, and the pyrites, for which the gold, be- 

 ing fo'crude, cannot always be diftinguifhed, be- 

 coming dark, the gold muft needs mew to the 

 greater advantage : (2.) amalgamation, on which 

 the mod fkilful hands mould be employed, as the 

 gold, being in fuch tender fpangles, is apt to float 

 on the water: (3 ) aqua regis, which is (till better, 

 taking the ore crude and unroafted : laftly, the re- 

 peating the proof-, when the difference of yield 

 muft at leaft fhew the gold either accompanying, 

 or lodged in the -pyrites. 



The following remarks may here be juftly 

 made ; (1.) that as no great ftrefs is to be laid oa 

 the cubical or marcafitical, as little is there on 

 the round figure of the pyrites, for their gold-yield: 

 (2.) that the pale-white colour of pyrites mould be 

 no prejudice againit our examining them for gold $ 

 nor its yellow colour, either that efTential to its 

 mixtion (fuch as the copper-pyrites) or fuperficial 

 only, from an external weathering, be any preju- 

 dice againft their gold: (3.) among all the forts of 

 pyrites, I have never met with any containing gold 

 alone (namely, in an cry, pyrity ftate) without 

 filver, a circumflance worth our greateft atten- 

 tion j and it may be doubted, whether there is an 

 inftance of a fingle gold-ore in nature: (4.) that 

 there is no pyrites whofe filver does not considerably 

 exceed its gold- yield : laftly, that the gold-yield, of any 

 confequence in pyrites, generally amounts to a penny 

 weight in the centner, or alittleover or under; which 

 conftant proportion makes it highly probable, the 

 gold-yield is procured from the pyrites as fuch, and 



not 



