44 



ECONOMICAL MINERALOGY. 



ORES OF LEAD, ZINC AND COPPER. 



Although these ores liave been for a long time known to occur in various parts of this State, 

 they have, for a few years past, in some counties at least, been objects of peculiar interest. 

 It lias, indeed, been supposed, that lead, zinc, and perhaps copper, would be ranked among 

 our most important mineral productions. Whether these anticipations are well founded, will 

 probably appear from the facts about to be presented. 



SULPHURET OF LEAD, or GALENA. Cleaveland. 



Plomb sulfur*;. Hany. — Heiahedral Galena, or Lead-glance. Jameson. — Hexaedrischer Bleiglanz. Mohs. — Gaidne. Beudant. 



Description. This mineral, which, here as in other parts of the world, is the common 

 ore of lead, has a bluish grey colour, usually called lead-grey ; streak unaltered. The colour 

 is liable to tarnish, and the mineral then becomes iridescent. 



It occurs massive and crystallized. When massive, it is granular or compact, and some- 

 times striated or fibrous. When crystallized, it is foliated, and has a threefold cleavage 

 parallel to the faces of the cube, which is the primary form. Sometimes the cube is trun- 

 cated on its angles and edges, and sometimes it is elongated. It occurs also in octahedrons, 

 cubo-octahedrons, &c. 



The following crystalline forms have been observed in this State : 



F.g. 8. 



Fis. a. 



RnssiR, St. Lawrpnne Cn. 

 MartiDsburgh, Lewis Co. 



RoGsie, Si. T.awrciirp Co. 



Rnsslp, St. Lawienfe Co. 



