602 MANUAL OF NATURAL HISTORY. 



1. Family. — Molibdides. Minerals containing lead, 



either native or in combination. Occurs 1, 

 native, monometric, H. 1*5, sp. gr. 11*381 ; 

 very rarely ; 2, as Sulphuret or " Galena/' 

 monometric, H. 2*5, sp. gr. 7*5, colour and 

 streak lead-gray, easily fused, frangible, in 

 beds and veins in crystalline and uncrystalline 

 rocks ; 3, as Oxide or " Minium/' pulverulent, 

 in minute rhombic prisms ; sp. gr. 4*6, in 

 veins of galena and calamine ; 4, as Car- 

 bonate or " Cerusite/' in right rhombic 

 prisms, H. 3-3*5, sp. gr. 6 "4, lustre adaman- 

 tine, colour white or gray, very brittle, in 

 many lead mines ; 5, as Phosphate or "Pyro- 

 morphite/' in hexagonal prisms, H. 3*5-4, 

 sp. gr. 7 ; colour green, yellow, or brown ; 

 lustre resinous, brittle, in veins with other lead 

 ores ; 6, also less frequently combined, with 

 selenium, tellurium, antimony, arsenic, va- 

 nadic, chromic, molybdic, and tungstic acids. 

 Metallic lead fuses at 612°F., its soluble salts 

 give a black precipitate with hydrosulphuric 

 acid. Symb. Pb. 



2. Family. — Baryides. Minerals containing com- 



pounds of Barium. Occur 1, as Sulphate of 

 Baryta or " Heavy-spar/' tabular, H. 2*5-3*5, 

 sp. gr. 4*7, white or grayish-blue, in metallic 

 beds, or in distinct veins in secondary lime- 

 stone ; 2, as Carbonate or " Witherite/' 

 trimetric, in large masses, H. 3'5, sp. gr. 4*30, 

 white, brittle, with lead ore, in coal formations. 



