of /&> Pyrites. 345 



thcrto, Found the beft means for that purpofe j 

 and therein the pyrites is the principal inftrument, 

 as by its means the heap-work, wherein the metal 

 lies widely difperfed, is, by procuring the crude' 

 fione^ concentrated or brought within a narrow 

 compafs, and afterwards this ftone duly worked 

 by roafting and fmeking, for procuring the metal- 

 yield ; and after repeated roaftings gives forth its 

 filver by means of the lead-working, amidft leady 

 ores, and the like additions ; but its copper in a 

 crude, ftony form, called lead-ftone ; which Jaft 

 muft by repeated roaftings be reduced to copper- 

 ftom, and this again, by fmeking, to black cop- 

 per, before it can be made pure and fine. This 

 crude-ftone, with us at Friberg, generally contains 

 between 2, 3, and 4 pounds of copper, and four 

 loths of filver, and is accordingly dofed with 

 additions. Now pyrites either lodges already in the 

 ore, thus to be treated in its crude ftate, especially 

 in coarfe veins ; or is added on purpofe, as found 

 necclTary ♦, or is entirely wanting, as generally in 

 noble veins : and here it is fo much the more 

 needful to be added, as where no pyrites is to be 

 had, or proves too expenfive to be conveyed to 

 the ipot, mod of the ore of fuch places, which is 

 commonly interfperfed with metallic fpangles, very 

 thinly fown, and, on that account, neither to be 

 warned nor roafted, lies ufelefs and unworked. 



That the pyrites promotes at lead the flux of 

 ores, or rather of their rocky, ftony, and earthy 

 admixtures •, or briefly, helps to fcorify and reduce 

 them to glafs, is its known effect in the operation 

 of crude [melting. But when fuch rocky admix- 

 tures hold good ores, as of lead, copper, and the 

 like, the ufe of pyrites is fuperfeded, as the above 



are 



