POLYCHROILITE. 

 parallel to their bases. Colour and streak 

 iron-black. Opaque ; cherry - red in thin 

 crystals by transmitted light. Lustre metal- 

 lic. Yields to the knife. Fracture uneven. 

 H. 2 to 3. S.G. 6-214. 



Camp. Sulphantimonite of silver, in 

 which part of the silver is replaced by cop- 

 per, and part of the antimony by arsenic, or 



Agl 9 fsb 



Ciij Ias 

 Analysis, from Durango, by H. Rose : 



Silver 64-29 



Sulphur ..... 17-04 



Copper 9-93 



Antimony .... 5-09 

 Arsenic " . . . .3-74 

 Iron 0-06 



100-15 



BB decrepitates slightly, fuses easily, 

 yielding sulphurous acid and a film of anti- 

 jnony; with soda, fumes of arsenic; with 

 fluxes gives a copper reaction. 



Localities. Mexico, in the mines of Guan- 

 axuato, and Guadalupe e Calvo, and Gua- 

 risame, in Durango. Mine of Morgen- 

 stern, near Freiberg, in Saxony. Schemnitz, 

 in Hungary. 



Name. From froxh;, much, and /3«<r/?, base, 

 in allusion to the large proportion of silver 

 present compared with the other sulphides 

 of that metal. 



Brit. Mus., Case 11. 



Polybasite is distinguished from Brittle 

 Sulphide of Silver by the arsenical odour 

 which it gives oflBB ; and from Bournonite, 

 by yielding a button of silver instead of 

 copper. 



PoLYCHROiLiTE, Weihye. Occurs in six- 

 sided prisms, with flat summits ; also reni- 

 form and massive. Colour blue, green, 

 brown, red, or white. Lustre greasy. Frac- 

 ture subconchoidal to even. 



Fig. 340. 



Analysis, by Dahl ; 



Silica 52 



Alumina 37 



Peroxide of iron . . .3 



Magnesia 7 



Lime and water . . . „ 



' 99 

 Locality. Krageroe, in Norway, in gneiss. 



POLYHALITE DE VIC. 295 



Name. From ■^roXv;, many, y.^oitx.^ colour, 

 and >.iQo;^ stone. 



PoLYOHROMATic Felspar, Mohs. See 

 Labraborite. 



PoLYCRASE, Dana. Rhombic. Occurs in 

 six-sided tables. Colour black; in thin 

 splinters bi'ownish. Opaque. Lustre bright. 

 Streak greyish-brown. Fracture conchoidal. 

 H. 5-5. S.G. 5-09 to 5-15. 



Comp. Near Polymignite, with the ad- 

 dition of columbic acid and protoxide of 

 uranium, but no manganese, and only a 

 small quantity of lime. 



Locality. Hitteroe, in Norway. 



Name. From s-aAyr, many, and x^^(ri;, mix- 

 ture, in alhxsion to the numerous substances 

 entering into its composition, viz. Titanic 

 and columbic acids, zirconia, yttria, per- 

 oxide of iron, protoxide of uranium, prot- 

 oxide of cerium, with a small quantity of 

 alumina, and traces of lime and magnesia. 



Brit. Mus., Case 37. 



PoLYHALiTE, Stromeyer. POLYHALLITE, 

 Phillips. Generally occurs in compact fibrous 

 masses, with the fibres parallel, and mostly 

 curved. Colourless, but usually brick-red or 

 flesh-coloured. Slightly translucent. Lustre 

 resinous or pearly. Taste faintly bitter and 

 astringent. Streak white. Brittle. Fracture 

 uneven. H. 2-5 to 3. S.G. 2'77. 



Comp. (K, Mg, Ca) S+iH. 



Analysis, from Aussee, by Rammelsberg : 

 Sulphate of lime . . . 45-43 

 Sulphate of magnesia . . 20-59 

 Sulphate of potash . .28-10 

 Chloride of soda . . .0-11 

 Peroxide of iron . . . 0-33 

 Silica . . . . . 0-20 

 Water 5-24 



100-00 



BB fuses instantaneously; in the flame 

 of a candle forms an opaque brownish mass. 



Localities. The mines of Ischel, Aussee. 

 Hallstatt, and Ebensee, in Upper Austria. 



Name. From TcAy?, many, and aA?, salt, 

 in allusion to the number of salts Avhich 

 enter into its composition. 



Brit. Mus., Case 55. 



PoLYHALiTE DE Vic. Glauberlte from 

 Vic, Dept. de la Meurthe, in France, where 

 it occurs in whitish or greyish crystals dis- 

 seminated in Common Salt, or saliferous 

 clays, or in compact and reddish kidney- 

 form masses in saliferous clays ; also at 

 Villa Rubia, near Ocana, in Spain. See 

 Glauberite. 



u4 



