124 Of the Copper 



folely relying on the colour. The fureft way there- 

 fore of judging of thefe ores, where the ftructure 

 affords no light, is, together with their colour, to 

 take their weight, denfity, and glittering, fhining 

 appearance into the account. True it is, the above- 

 mentioned copper-ore, which yields to the quantity 

 of 40 pounds in the centner, appears very pale, 

 and almoft like a white pyrites ; but, on the other 

 hand, from its denfity and clofenefs, it mud be of 

 a more metallic nature, and not barely a white 

 pyrites or mifspickel, but a body only invefted with 

 arfenic, and thence ought to be imagined to be 

 more coppery. But what judgment then are we to 

 form of the fallow-ore, fallow copper-ore, copper - 

 glafs, and copper-laful? Fallow-ore is a grey fort, 

 darker than the white-goldifh -, containing between 

 1 and 2 marks of filver, ufually breaking, as we 

 fee at the Croner and the Halfebruck, with yellow 

 copper- ore. Fallow-copper-ore is darker than fallow- 

 ore, and therefore exprefsly denominated from cop- 

 per, as containing more of that metal, and much 

 iefs filver. 



Copper-glafs is (till darker, inclining much to a 

 black, as being highly irony. Copper-laful diftin- 

 guifhes itfelf by its fteel-blue colour, though mif- 

 ufe has introduced the calling a yellow- greenifh 

 eopper-ore, a copper-laful. Among the ancients 

 copper-glafs denoted only a copper-laful. But here 

 to obviate much difficulty, thefe ores, but jiift 

 mentioned, may well be excluded the clafs of py- 

 rites, as not properly belonging thereto •, though I 

 thought it neceffary to mention them, as they 

 ferve to clear up the bufinefs of ore-colours ; and, 

 in particular, to find out the marks of copper-yields. 

 That the iron in the pure iron-pyrites appears not 

 black, or as' an iron-ftone, but yellowifh, is folely 



owing 



