On .Metallic Minerals. 367 



yeilds to the nail and soils the fingers ; specific gravity, 

 2-8. It rapidly cflervescc* and in a great niea>ure dis- 

 solves in muriatic acid. Blackens in the exterior llanie of 

 the blow-pi|)e and fuses in the interior into a black scoria, 

 which is generally magnetic Sometimes, however, it 

 requires to be roasted on charcoal with grease to ren- 

 der it so. — It is used as a flux for the other ores. 



I observed another excellent variety of this ore cropj)lng 

 out of the ground near the works, but I cannot say whether 

 it was a loose mass or otherwise, it had a crystalline structure 

 and its colour was a mixture of brown and white. If in 

 abundance it deserves to be explored. 



RED AND YELLOW OCHRE. 



These ores, or rather pigments, are too well knoxvn to 

 refpiire a particular description. They occur forming the 

 sides of the vein. The yellow ochre is of an indurated 

 description of that substance. 



ARGILLACEOUS OXIDE OF IRON. 



In the excavation a large mass of this may be seen ; a 

 passage has been opened through it, in order to extract the 

 other ores. It is the |)redominating ore, but of too poor and 

 infusible a character to be worked. It looks like some 

 varieties of trap or shale, and although very tough and 

 difficult to remove, when first exposed, the action of the 

 atujospliere renders it very brittle, and even friable. 



Colour, greenish black, with seams of a reddish and 

 lighter green, — opaque, — structiu'c imperfectly foliated, 

 Miuietimes curved j fracture, uneven. It is easily scratched 

 by the knife, even when hardest ; powder, yellowish green 

 — no lustre; specific gravity, 3-J ; insoluble in acid; 

 iafilitible before the blow-pipe, after exposure to which, 



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