416 DESCRIPTIVE MINERALOGY. 



Composition. Oxide of lead 72.47, sulphuric acid 26.09, water 0.12, silica 0.51 {Stro- 

 meyer). Formula PbO.SO^. 



Geological Situation. This mineral, like the last, is almost always associated with 

 galena. 



localities. 



It has already been observed that this mineral, in a pulverulent state, has been found asso- 

 ciated with carbonate of lead, at the Rossie mine in St. Lawrence county. It is, of course, 

 the result of decomposition of galena. It has not been observed in a crystalline form at any 

 of our lead mines. 



This mineral occurs with galena in the Missouri lead mines, and in that of Southampton 

 in Massachusetts. 



YELLOW LEAD ORE. 



Plomb Molybdate. Haiiy. — Molybdatc of Lead. Ckavcland, Phillips and Thomson. — Pyramidal Lead Spar. 

 Jameson. — Pyramidalcr Blei-Baryt. Mohs. — Yellow Lead Ore. Shcpard. — Melinosc. Bciulant. 



^'^- ^^^- Description. Colour usually orange or wax-yellow, passing into 



#grey or brown, rarely green or red. Streak white. It occurs regu- 

 larly crystallized ; also massive, in crusts and cellular. Primary 

 form the octahedron with a square base. Fig. 498. P on P' 131° 

 15' ; P on P and P' on P' 99° 50. Cleavage parallel to the planes 

 of the primary. Fracture uneven and conchoidal. Lustre resinous. 

 Translucent, or translucent on the edges. Brittle. Hardness 3.0. 

 Specific gravity from 6.69 to 6.76. Before the blowpipe on char- 

 coal, it melts, and is absorbed by it, leaving behind some globules of 

 reduced lead. Dissolves in concentrated muriatic acid, under sepa- 

 ration of chloride of lead, producing a green solution, which, on being somewhat diluted and 

 stirred with an iron spatula, acquires a blue colour (Kobel). 



Composition. Oxide of lead 60.86, molybdic acid 39.14 (Berzelius). ' The formula is 

 Pb.MoOj. 



Geological Situation. It is said to occur in compact limestone at Bleiberg at Carinthia, 

 and also in France and Saxony. 



localities. 



The only locality that has been credited to this State, is the Ancram mine in Columbia 

 county, where, if the yellow lead ore does occur, it is associated with galena. It must, how- 

 ever, be of rare occurrence. 



