PIOTINE. 

 colourless or black Avben a large proportion 

 of iron is present. 



Only imperfectly decomposed by muriatic 

 acid. 



Localities. — English. Cornwall : Lamorna 

 Cove, in small dark brown crystals,)?^. 335 ; 

 in granite, near Breage, and at Toi Pedn 

 Penwith, near tbe Land's End ; near St. 

 Just; Mulvra Hill, near Sancreed. — Scotch. 

 Aberdeenshire. — Foreign. Auvergne, at tbe 

 Puy-de-D6me, in a felspathic porphyry. 

 Penig, in Saxony, The Harz. United States. 



Name. After Pini, the name of the mine 

 near Scbneeberg, in Saxony, where it was 

 first discovered in granite. 



Brit. Mus., Case 32. 



PiOTiNE. From Tnof/ig, fat. See Sapo- 



MITE. 



Pipestone, Thomson. A variety of clay- 

 slate, or Argil lite, of a dull greyish-blue or 

 black colour, found in Northern Oregon, 

 and carved by the Indians into the bowls 

 of tobacco-pipes. Tender and soft to the 

 touch. Easily moulded and cut. H. 1"5. 

 S.G. 2-6. 



Comp. 5A1 Si2 T 2Ca Si + 2H, or 2A1 Si^ 

 + (XaCaMg) Si + H.. 

 Analysis, by Thomson : 



Silica 56-11 



Alumina .... 17-31 

 Peroxide of iron . . . 6-96 



Soda 1248 



Lime 2-17 



Magnesia .... 0*20 

 Water 4-58 



99-81 



PiRENEiTE. See Pyreneite. 



PiROP. See Pyrope. 



PisoPHALT. (From *'V«v, a pea, and as- 

 phalt.) A soft Bitumen, forming a passage 

 between Petroleum and Asphalt. 



PiSSASPHALT. 'nicnrxa-tftx.XTOi, Dioscorides. 

 (From ^'B-B-a,, pitch, and ka-c^ci-kro',, asphalt.) 

 See Earthy Bitumen. The ancient Greeks 

 gave the name to the liquid as well as 

 the solid Bitumen, both of which, according 

 to Dioscorides, they obtained from the 

 Ceraunian mountains, near Apollonia. 



PissoPHANE, Breithaupt. Stalactitic, or 

 amorphous. Colour olive-green to liver- 

 brown. Lu-stre vitreous. Transparent. 

 Streak greenish- white topale yellow. Kather 

 sectile. Easily frangible. Fracture con- 

 choidal. H. 1-5. S.G. 1'93 to 1-98. 



PISTACTTE. 289 



Comp. Sulphate of alumina, and per- 

 il T 2 

 oxide of iron, or -^^ J- -^ ^^^-^^ 



Analysis, of green variety, by Erdmann : 

 Alumina .... 35'301 



Peroxide of iron . 

 Sulphuric acid . 

 Water 

 Gang-ue and loss 



9-799 

 12-487 

 41-700 



0-709 



99-996 



BB blackens, and with the fluxes gives a 

 reaction for iron. 



Dissolves readily in muriatic acid. 



Localities. Garnsdorf, near Saalfeld, and 

 at Reichenbach, in Saxony, on alum-slate. 



Name, From ^ifftra,, pitch, and ipoi/v^, to 

 seem. 



Probably Pissophane is not a simple mine- 

 ral, but a mixture of various salts, formed 

 by the decomposition of alum-slate. 



PiSTAClTE. PiSTAZiTE, Werner. Occurs 



in prismatic crystals, also granular, earthy, 



I and in crusts. Colour pistachio-green, pass- 



' ing to olive- and blackish-green, also brown 



or yellow. Transparent. Easily frangible. 



S.G. 3-35 to 3-5. 



Fig. 336. 



Comp. L-on-and-lime Epidote, in which 

 a large quantity of the lime is replaced by 

 protoxide of iron, and a large proportion of 

 the alumina by peroxide of iron. 



Analysis, from Dauphiny, by Descotils : 

 Silica . . . . . 37-0 

 Alumina . . , . 27-0 

 Peroxide of iron v . . 17r0 

 Peroxide of manganese . . 1-5 

 Lime . . . . , 14-0 



96-5 

 BB fuses at the edges, and subsequently 

 swells up, forming a dark brown mass, 

 which, by exposure to a more powerful 

 blast, becomes black and somewhat rounded. 

 Localities. — Scotch. Shetland, in syenite. 

 Rona, in Quartz. Mull and Skye, in trap rock. 

 Arran. — Foreign. Arendal, in Magnetic Iron 

 (Arendalite), in very fine crystals. The 

 IJral. Finland. Greenland. Mont Blanc, 

 and other parts of the Alps. The Pyrenees. 

 Bourg d'Oisans, in Dauphiny. Grossarl, in 

 Austria. The Fichtelgebirge. The Harz. 

 North America. 



u 



