294 PLUMBOSTIB. 



Analysis, from Nussifere, by Ihtfrenoy: 

 Oxide of lead . , " . 43'42 

 Chloride of lead „ . .2-11 

 Alumina .... 34-23 

 Phosphoric acid . . . r89 

 Water 16-14 



97-79 



BB decrepitates strongly, turns white, 

 swells up, and fuses partially under a strong 

 blast ; on charcoal, with carbonate of soda, 

 yields globules of lead. 



Soluble in nitric acid. 



Localities. — Foreign. Huelgoet, in Brit- 

 tany, in clay-slate. Nussiere, near Beaujeu, 

 in France. " Mine La Motte, Missouri, U.S. 



Name. , From its composition, and its re- 

 semblance to gum-arabic. 



Brit. Mus., Case 19. 



Plumbostib, Breithaupt. Boulangerite 

 from Nertschinsk, in Siberia. 



Plumose Mica. The name given to 

 the variety of Mica composed of scales 

 arranged in a plumose form. 



Plumose Ore of Antimony, or Plu- 

 MOSIT, Haidinger, Nicol. Capillary forms of 

 Heteromorphite. 



Plush Copper. The name given in 

 Cornwall to Chalcotrichite. 



PocuAMu. The name given to Axe- 

 stone by the natives of New Zealand. 



PoDAR. Mundic. Also an old Cornish 

 name for Copper Ore. 



Poix MiNERALE Elastique, Brocliant. 

 See Elaterite. 



Poix Minerals Scoriacee, Brochant. 

 See Asphalt. 



Poix Minerale Terreuse, Brochg^nt. 

 See Earthy Bitumen. 



PoLiANiTE, Breithaupt. A variety of 

 Pyrolusite. Rhombic. Occurs in short, 

 verticalh' striated, right rhomboidal prisms : 

 also in granular masses. Colour pale steel - 

 grev. Opaque. Lustre sub-metallic. H. 

 6-5 to 7. S.G. 4-84 to 4-88. 



Analysis, by Plattner : 

 Proto-peroxide of manganese 87*27 

 Alumina and peroxide of 



iron 0-17 



Oxygen .... 12-11 



Quartz 0-13 



Water .... 0-32 



100-00 

 Localities. Maria Theresa Zeche, near 

 Platten, in Bohemia. Schneeberg, Geyer, 

 and Johanngeorgenstadt, in Saxony. Prus- 

 sia, at Eiserne Haardt, in Siegen. II- 

 menau, in Thuringia. 



POLYBASITE. 



Name. From ^oXiocvos, grey; because of 

 its colour. 



Brit. Mus., Case 13. 



Pollux, Breithaupt, Plattner. Massive. 

 Resembles Quartz in appearance. Colour- 

 less. Transparent. Lustre splendent-vitre- 

 ous. Cleavage none, or scarcely perceptible. 

 Fracture conchoidal. H. 6 to 6*5. S-G. 

 2-87 to 2-89. 



Comp. 3K si + 3Na Si + 3M Si + 2H. 



Analysis, by Plattner : 



Silica 46-20 



Alumina .... 16-39 

 Peroxide of iron . . .0-86 



Potash 16-51 



Soda 10-47 



Water .... 2-32 



92-75 



BB turns white, and when in thin 

 laminffi becomes rounded at the edges, the 

 fused portions resembling a blistered enamel. 

 Colours the outer flame reddish-vellow. 



Entirely soluble in muriatic acid, wath the 

 aid of heat, with separation of gelatinous 

 silica. 



Locality. Elba, associated with Castor in 

 granite. 



Pollux appears to contain a larger quan- 

 tity of alkali than any other known silicate 

 mineral. (L. Gmelin.) ' 



Polyadelphite, Thomson. A brownish- 

 yellow Garnet, from the Franklin Furnace, 

 New Jersey, IJ. S. 



Analysis, bv Baumann : 



Silica / . . . . 35-47 



Alumina . . . . 3*10 



Peroxide of iron . . . 28-55 



Protoxide of manganese . 5-41 



Magnesia . . . .2-13 

 Lime ..... 26-74 



101-40 



Name. From rroXv?, many, and eihX(pos, a 

 brother, because it consists of a union of 

 five different silicates. 



Brit. Mus., Case 36. 



PoLYARGiTE, Svanberg. An altered form 

 of Anorthite. Granular-massive, the form 

 of the grains somewhat similar to those of 

 granular Quartz. Colour gax-net-red, pass- 

 ing into violet. Fracture vitreous, more 

 shining that that of Garnet, and like that 

 of Quartz. Scratches glass easily. S.G. 

 2-76. 



Brit. Mus., Case 28. 



PoLYBAsiTE, ^. i?ose. Hexagonal. Occurs 

 in short tabular, six-sided prisms striated 



