PYROLUSITE. 

 Kinahan, of the Geological SurA-ey of Ire- 

 land, in the loAver bed of the Coal Measures, 

 just above the limestone, about three miles 

 N.W. of Cahermoyle, in Limerick. 



Pyrolusite, Allan, Haklinger, Dufrenoy. 

 Rhombic: primary form a right rhombic 

 prism. Occurs crystallized, but generally 

 in botryoidal and' reniform masses, with a 

 radiating librous or columnar structure; or 

 in granular masses. Colour steel-grey in- 

 clining to iron-black; often bluish. Opaque. 

 Lustre metallic. Streak black and soiling. 

 Rather brittle, or friable. H. 2 to 2'5. S.G. 

 4-7 to 4-97. 



Fig. 351. 



Camp. Mn= manganese 63-64, oxygen 

 36-36-100. 



Analysis, from Elgersburg, by Turner ; 

 Protoperoxide of manganese 84-06 

 Oxygen .... 11-78 

 Barytes .... 0-53 



Silica 0-51 



Water . . . • . . 1-12 



98-00 



BB in the inner flame, under a strong 

 heat, becomes brownish -red, but does not 

 fuse : with borax, effervesces strongly, and 

 forms an araethj'st-coloured globule, in the 

 outer flame. 



Soluble in muriatic acid, with evolution 

 of chlorine. 



Localities. — English. Cornwall, at some of 

 the mines near Launceston and St. Minver. 

 Creva Wood, Callmgton. Hartshill, War- 

 wickshire; crystallized, j?^. 351. — Fore'tgn. 

 Elgersburg. in Saxe-Coburg-Gotha. Ilme- 

 nau, in Thuringia. Vorderehrensdorf, near 

 jMahrisch-Triiban in Moravia. Hirschberg, 

 in Westphalia. Near Giessen, in dolomite. 

 Crj^stallized at Ihlefeld, and near Goslar in 

 the Harz, and at Johanngeorgenstadt in 

 Saxony. Bohemia. Hungary. France. 

 Villa Rica, in Brazil. 



Brit. Mus., Case 13. 



M.P.G. Principal Floor, Wall-case 13 

 (British). 



Name. From ■^v^, fire, and Ais-;?, decom- 

 position; in allusion to its being extensively 

 employed in glass manufactories. 



Pyrolusite is the most valuable of the 

 ores of manganese, in consequence of the 



PYROMORPHITE. 307 



large amount of oxygen it contains, which 

 renders it of great value in the preparation 

 of chloride of lime and in bleaching. It 

 is also employed in the manufacture of 

 glass, for discharging the brown and green 

 tints and other colouring matters (on which, 

 account it is termed by the French, le savon 

 des verriers) ; in enamel and glass painting, 

 and in colouring pottery. 



It may always be distinguished from 

 Psilomelane, with which it is associated, by 

 its inferior degree of hardness, being so soft 

 as to soil the lingers when handled. From 

 Manganite, Limonite, Hematite, and Spe- 

 cular Iron it differs in having a blackish 

 streak or powder ; and from certain ores of 

 antimony it is distinguished by its infusi- 

 bility at the blowpipe, Avhile the latter may 

 be melted in the flame of a candle. 



Pyromeline, T. S. Hunt, v. Kobell. A 

 hydrated sulphate of nickel, occurring in 

 interlacing capillary crystals, but chiefly as 

 a greenish-white etflorescence, at Wallace 

 Mine, Lake Huron, on sulphide of iron and 

 nickel. It is also met with, forming a pale 

 yellow earthy crust, at the Friederichs Mine, 

 near Bayreuth, with Native Bismuth and 

 Arsenical Nickel. 



Name. It derives its name from ^v^, 

 fire, and !^v,\Uog, bright yellow ; because the 

 green mineral becomes bright yellow when 

 first heated BB. 



Pyromorphite, Beudant, Greg §• Lettsom, 

 Hexagonal. Primary form the regular six- 

 sided prism, in which it also occurs crystal- 

 lized, general!}', however, modified on the 

 edges. Commonly striated horizontally. 

 Cleavage parallel to the planes of a six- 

 sided pyramid. Also occurs globular, bo- 

 tryoidal, reniform, and massive. Colour 

 green, yellow, grey and brown of various 

 shades. Subtransparent to translucent at 

 the edges. Lustre resinous. Streak white 

 or yellow. Brittle. Fracture imperfect- 

 conchoidal and dull. H. 3-5 to 4. S.G. 

 6-58 to 7. 



^ 



Fig. 352. 



Chlorophosphate of lead, or SPb^ 



P + PbCl, but sometimes the chloride of 

 lead is partly replaced by fluoride of calcium, 

 and the triphosphate of lead by triphosphate 

 of lime, or triarseniate of lead!! 



x2 



