304 PYKNOTEOP. 



Fluoric acid . 



•84 



98-27 



BB infusible ; with borax fuses slowly to 

 a transparent glass. 



Localities. Altenberg, in Saxony. Schlack- 

 enwald and Zinnwald, in Bohemia. 



Name. Frbm -^vxvo:, dense. 



Brit. Mus., Case 58. 



31. P. G. Horse-shoe Case, No. 996. 



Pyknotrop (from ^vKvore,(f^os, compact). 

 A kind of Serpentine. 



Pyrallolit, NordensMold. Pyrallo- 

 LITE, Phillips. An altered form of Augite, 

 in which magnesia takes the place of hme. 

 Usually occurs massive, with a cleavage 

 parallel to the planes of a rhombic prism ; 

 also crystallized in flat rhombic prisms. 

 Colour greenish-white to yellowish -grey. 

 Opaque, or subtranslucent in thin laminge. 

 Lustre resinous ; on cleavage-planes pearl}'. 

 Somewhat brittle. Fracture uneven, splin- 

 tery. H. 3-5. S.G. 2-65 to 2-6. 



Comp. Mg3 Si3 + H. 



Analysis, by Nordenskiold ; 



Silica 56-62 



Alumina .... 3-38 

 Peroxide of iron . . . 0-99 

 Magnesia . . . .23-38 

 Lime ..... 5*58 

 Protoxide of manganese . 0*99 



Water 3*58 



Bituminous matter and loss . 6-38 



100-00 



BB turns blackish, then becomes white 

 and fuses at the edges to a white enamel ; 

 with borax fuses readil}' to a diaphanous 

 glass. 



Localities. Finland, at Storgard, in Par- 

 gas ; in limestone, with Pyroxene, Felspar, 

 and Scapolite. 



Name. From tu^, fire, (x.xxo;, another, and 

 xiQo;, stone ; in allusion to its change of co- 

 lour BB. 



Pyramidal Adiaphane. Spar, Mohs. 

 See Gehlenite. 



Py'rainiidal Cerium Baryte, 3Iohs. See 

 Yttrocerite. 



Pyramidal Copper Pyrites, 3Iohs. See 

 Chalcopyrite. 



Pyramidal Euchlorb Malachite 

 Mica, 3Iohs. See Uranite. 



Pyramidal Felspar, 3Iohs. See Scapo- 

 lite. 



Pyramidal Garnet, 3Iohs. See Ido- 

 crase. 



Pyramidal Kouphone Spar, Mohs. See 

 Apophtllite. 



PYRARGYKITE. 

 Pyramidal Lead Baryte, 3fohs. See 



WULFENITE. 



Pyramidal Manganese Ore, 3Iohs. See 

 Hausmannite. 



Pyramidal Mellichrome Resin, 3fohs. 

 See Mellite. 



Pyramidal Pearl Kerate, 3Iohs. See 

 Calomel. 



Pyramidal Scheelium Bary'te, 3Iohs. 

 See Scheelite. 



Pyramidal Tellurium Glance, 3Iohs. 

 Black Tellurium. See Nagyagite, 



Pyramidal Tin Ore, 3Iohs. See Cas- 

 siterite. 



Pi'KAMiDAL Titanium Ore, 3Iohs. See 

 Anatase. 



Pyramidal Zeolite. See Apophyl- 

 lite; also Ichthy'ophthalmite, Ox- 



HAVERITE, TeSSELITE. 



Pyramidal Zircon, 3Iohs. See Zircon. 



Pyrantimonite, Brochant. Red Anti- 

 mony Ore. See Kermesite. 



Pyrargillitb, Dana, Nicol; or Pyrar- 

 GYLLITE, Nordenski'old, Phillips. According 

 to Bischof, an altered form of lolite. Occurs 

 massive and in prismatic forms with an in- 

 distinct cleavage. Colour partly black and 

 shining, or partly bluish and without lustre ; 

 also liver-brown or dull red. Opaque or 

 translucent at the edges. Lustre dull resin- 

 ous. Fracture uneven. H. 3-5. S.G. 2-5. 



Comp. RSi + AlSi + 6H. 



Analysis, by Nordenskiold ; 



Silica 43-93 



Alumina .... 28-93 

 Protoxide of iron . . . 5-30 

 Magnesia .... 2-90 



Soda 1-85 



Potash 1-05 



Water 15-47 



99-43 



BB alone infusible. 



Entirely soluble in nitric acid. 



Locality. Near Helsingfors, Finland ; in 

 granite. 



Name. From ^i^?, fire, and H^yiXXos, day 

 in allusion to the argillaceous odour given 

 out by it when heated. 



Brit, Mus., Case 31. 



Pyrargyrite, Glocker. Hexagonal. 

 Generally occurs in prismatic crystals. 

 Twins. Is also found dendritic, massive, and 

 micaceous. Colour lead-grey to iron-black ; 

 sometii-nes approaching to cochineal-red. 

 Opaque to translucent at the edges. Lustre 

 in dark varieties submetallic ; in lighter 

 varieties adamantine. Sectile ; yields readily 

 to the knife. Streak cochineal-red. Frac- 



