120 Of the Copper 



in fome ores, namely, in the glajfy and red-goldifh 

 iort, is confiderable, or at lead fo far conftant, as 

 that the former, when pure, and without any rocky 

 admixture, affords always above a half, and com- 

 monly about two thirds : the latter alfo, when pure 

 and fine, ufually above a half in filver, and never 

 lefs. But then we mud here regard the proper and 

 effential characters of fuch ores ; as no ore is to be 

 accounted a glajfy fort, that will not bear the be- 

 ing cut, -hammered, i£c. A red-goldijh fort may 

 alfo happen to have fome foreign admixture, as 

 appears from its dark caft at Braunfdorff: and thus 

 in proportion to fuch admixture, its yield falls 

 fbort of half. But in mod ores, the yield in noble 

 metals is fo variable, that there is no coming at 

 near fo much certainty for thefe, as for the glajfy 

 and red-goldijh ores. 



'Lead-glitter ■, or galena, holds fometimes a half, 

 fometimes a whole loth, fometimes two, three, ten, 

 and more loths of filver ; not to mention a fort, that 

 rifes to Marks* the quintal ; among which there 

 break noble veins, in particular of white goldijh ore, 

 tho' often very unobfervable. Copper-oreaKo, in re- 

 gard of its River-yield, greatly rifes and falls : and 

 here I have obferved, that when it comes to laths, 

 it is of a dark-grey caft, and then called fallow 

 copper-ore -, and when to marks, this dark-grey hue 

 remitting fomewhat, it comes to be called fallow 

 ere: nay, the white-goldifh ore, which, fo far as 

 I could learn, is certainly a copper-holding fort, only 

 fo fat' differs from fallow ore, that fometimes in 

 &[ver-yield it has nfen very high, namely, to ten, 

 twenty, thirty, and more marks the quintal, and 

 on the contrary, falls in copper : and thus the white- 

 goldifi) ore cannot, like the red-goldijh fort, properly 



con- 

 * A mark in the language of affayers is half a pound. 



