260 METALS. 



Composition : essentially binoxyd of manganese with on« 

 per cent, of water, and also some baryta or potassa. The 

 compound is somewhat varying in its constitution. Before 

 the blowpipe like pyrolusite, except that it affords water. 



Obs. This is an abundant ore, and is associated usually 

 with the pyrolusite. Prof. Silliman, jr., has lately detected 

 oxyd of cobalt mixed with this ore. It occurs at the differ- 

 ent localities mentioned under pyrolusite; and the two are 

 often in alternating layers ; it has been considered only an 

 impure variety of the pyrolusite. The name is from tha 

 Greek psilos, smooth or naked, and melas, black. 



Uses. Same as with pyrolusite. 



Heteroclin and marceline are similar ores, containing 10 to 16 pet 

 cent, of silica. 



wad. — Bog manganese. 



Massive, rftniform or earthy ; also in coatings and dendri- 

 tic delineations. 



Color and streak black or brownish-black. .Luster uu,., 

 earthy. H=l. Gr=3-7. Soils. 



Composition. Consists of peroxyd of manganese, in vary- 

 ing proportions, from 30 to 70 per cent, along with peroxyd 

 of iron, 20 to 25 per cent, of water, and often several pet 

 cent, of oxyd of cobalt or copper. It is a hydrated peroxyd, 

 mechanically mixed with other oxyds, organic acids and 

 other impurities, and like bog iron ore, is formed in low places 

 from the decomposition of minerals containing manganese. 

 Gives off much water when heated, and affords a violet glass 

 with borax. 



Obs. Wad is abundant in Columbia and Dutchess coun- 

 ties, N. Y.j at Austerlitz, Canaan Center, and elsewhere ; 

 also at Blue Hill Bay, Dover, and other places in Maine ; at 

 Nelson, Gilmanton, and Grafton, N. H. ; and in many othei 

 parts of the country. 



Uses. May be employed like the preceding in bleaching, 

 but is too impure to afford good oxygen. It may also be 

 used for umber paint. 



triplite. — Ferruginous Phosphate of Manganese. 

 Massive, with cleavage in three directions. Color black 

 ish-brown. Streak yellowish-gray. Luster resinous ; near 

 ly or quite opaque. Ii— 5 — 5*5. Gr=3'4 : — 3*8. 



What is wad ? its composition 1 its origin ? For what may it br 

 used ? What is triplite I 



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