Page:Encyclopædia Britannica, Ninth Edition, v. 16.djvu/413

MINERALOGY 395 Fig. 352 (sp. 225). Fig. 353 (sp. 226). Schneeberg, Marienberg, Przibram, Schemnitz and Kremnitz, Kongsberg, Mexico, Nevada, &c. 226. PROUSTITE, 3Ag 2 S + As 2 S 3 . Rhombohedral, like pyrargyrite, except R 107 50 (fig. 353). G. *=5 5 to 5 6. Semi- trans- edges. transparent to lucent on the Cochineal to crimson-red. C.c. : 65 5 silver, 15 1 arsenic, and 19 4 sulphur. Streak aurora-red. B. B. arsenical odour, and difficultly reduced to metallic silver. At the same localities as pyrar- gyrite ; both are valu able ores of silver. Red orpiment has a lower specific gravity, and yellow streak ; cinnabar volatilizes before the blowpipe. 227. BOULANGERITE, 3PbS + SbS 3 . Fine granular, columnar, radiating, or fibrous ; slightly sectile. H. =3 ; G. = 5 8 to 6. Silky, metallic. Blackish lead-grey, with darker streak. B. B. like jamesonite. C. c. : 59 lead, 22 8 antimony, and 18 2 sulphur. Molieres in France, Oberlahr (Rhenish Prussia), Lapland, and Siberia. Plumbostib or Embrethite, from Nertchinsk, is only a variety. 228. KOBELLITE, 3PbS, Bi 2 S 3 + 3PbS, Sb 2 S 3 . Radiated columnar ; soft. G. = 6 2 to 6 3. C. c. : 53 lead, 20 bis muth, 10 antimony, and 17 sulphur. Hvena in Nerike (Sweden). 229. WITTICHENITE (Cupreous Bismuth), 3CuS + Bi 2 S 3 . Right prismatic ; in tabular crystals like bournonite. Wittichen in the Black Forest. 230. BOTTRXONITE (3CuS + Sb 2 S 3 ) + 2(3PbS + Sb 2 S 3 ). Right prismatic. ooP (d) 93 40 ; Poo (71) 96 13 ; Poo (e) 92 34 ; OP (r); coPoo(s); oop~oo(&) (fig. 354). ci. brachydiagonal, im perfect; fracture uneven to conchoidal; rather brittle. H. =2 5 to 3; G. =57 to 5 9. Lustre brilliant metallic. Steel- grey. C.c. : 42-4 lead, 13 copper, 25 antimony, and 19 6 sulphur. Redruth and Beeralston ; Harz (Neudorf), Brauns- dorf, Kapnik, Servoz; Alais and Pontgi- baud in France. Wolchite from Welch in Carinthia is only a variety. 231. AIKINITE (Needle-ore), 2(3PbS + Bi a S 3 ) + 3(CuS + Bi 2 S 3 ). Right prismatic ; long thin crystals imbedded in quartz, often bent or broken- f rather brittle. H. = 2 5 ; G. = 6 7 to 6 8. Fi g- 354 ( S P- 230 )- Blackish lead-grey or steel-grey, with a brownish tarnish. C.c. : 36 lead, 11 copper, 36 bismuth, and 17 sulphur. Berezoff (Siberia), Georgia. 232. STYLOTYP, 3(CuAgFe)S + Sb 2 S 3 . Right prismatic. OP 92 30 . H. =3;G. =4 8. Black. Copiapo, Chili. 233. ANNIVITE, 4CuS + (As 2 S 3 , Sb 2 S 3 , Bi 2 S 3 ). Massive, similar to the foregoing. From Anaiver in Valais. Studerite is similar, but with 15 5 of antimony. 234. JULIANITE, 3Cu 2 S + As 2 S 3 . Cubic. G. =5-12. Metallic. Reddish grey. Rudelstadt in Silesia. 235. MENEGHINITE, 4PbS + Sb 2 S 3 . Oblique prismatic, C 72 8 . ooP 140 24 ; Poo 70. Crystals small, acicular, chiefly of ooP c oo, ooPoo , o>P ; rare- mostly fibrous. H. = 3 ; G. = 6 -4. Bottino in Tuscany, Schwarzenberc in Saxony. 236. JORDANITE, 4PbS + As 2 S a . Right prismatic ; ooP 123 29 . Cl. brachydiagonal, perfect. Streak black. G.-6-38. C.c.: lead 68 9, arsenic 12 "5, sulphur 18 - 6. Binuen and Nagyag. 237. TETRAHEDRITE (Fahlerz), 4Cu,S + Sb 2 S 3 . Tesseral and tetrahedral. In crystals , - -P-, 0,0, (figs. 355 to 358, also 65, 66, 206). Twins (figs. 164, 207); generally massive. Cl. octahedral ; fracture conchoidal ; brittle. H. =3-44 ; G. -4-5 to 5-2. Steel-grey to iron-black; streak black (dark red when containing zinc). B.B. on charcoal boils slightly, and fuses to a steel-grey slag, usually magnetic, and with soda gives copper. C.c. essentially Cu 2 S in combination with Sb 2 S 3 . Airthrey near Fig. 355. Fig. 356. Fig. 357. Fig. 358. Stirling, Sandlodge in Shetland, Tomnadashin on Loch Tay, Kirk cudbright; Crinnis and other Cornish mines near St Austell; Harz, Miisen, Freiberg, Camsdorf, Alsace, Kremnitz, and Kapnik. Those with 17 to 31 silver are the Silver Fahlore (Freiberg). Ore of copper and silver. 238. TENNANTITE, (CuS, FeS) As 2 S 3 . Cubic (like fig. 237). Cl. 0. Brittle. H. =4; G. =4 3 to 4 5. Iron-black ; streak dark red, grey. C.c. : 49 copper, 4 iron, 19 arsenic, and 28 sulphur. Redruth and St Day (Cornwall), and Skutterud. Copper-blende, with brownish red streak; G. =4 3; con tains 8 9 zinc ; Freiberg. 239. POLTTELITE ( Weissgiltigerz), 4RS + Sb 2 S 3 . Like tetrahedrite. H. = 2 5 ; G. = 5 4 to 5 7. C.c.: silver 6 to 22, lead 38 to 52, antimony 8 5 to 22, sulphur 13 to 22 5. Freiberg. 240. STEPHANITE, 5Ag 2 S + Sb 2 S 3 . Right prismatic. ooP (o) 115 39 ; P (P) middle edge 104 20 ; 2?oo(d) middle edge 107 48 ; OP (s); oop_oo(p) (figs. 333, 334). Cl. d and p, both imperfect ; fracture conchoidal or uneven ; sectile. H. =2 to 2 -5; G. =6 2 to 6 3. Iron-black to blackish lead-grey. C.c. : 68 5 silver, 15 3 antimony, and 16 - 2 sulphur. Cornwall, Freiberg, Schneeberg, Annaberg, Joachimsthal, Przibram, Schem nitz, Mexico, Peru, and Siberia. Valuable ore of silver. 241. GEOCRONITE, 5PbS + (Sb, As) 2 S 3 . Right prismatic. Fracture conchoidal ; sectile. H. = 2 to 3 ; G. = 6 45 to 6 "54. Pale lead-grey. C.c. : 67 lead, with 1 to 2 copper and iron, 16 antimony, with 4 7 arsenic, and 17 sulphur. Sala in Sweden, Meredo (Oviedo) in Spain, and near Pietrosanto in Tuscany. 242. KILBRICKENITE, 6PbS + Sb 2 S 3 . Massive ; granular or foliated. C.c. : 70 01 lead, 1376 antimony, and 16 23 sulphur. County Clare in Ireland. 243. POLYBASITE, 9(Ag 2 , Cu 2 )S + (Sb, As) 2 S 3 . Hexagonal ; P 117. Crystals OP. ooP ; and OP, P, tabular. Cl. basal, imperfect; sectile, and easily frangible. H. = 2 to 2 5; G. = 6 to 6 25. Iron-black, in very thin lamella?, translucent, red. C.c. : 64 to 72 silver, 3 to 10 copper, 16 to 17 sulphur, 2 to 8 antimony, and 1 to 6 arsenic. Freiberg, Joachimsthal, Schem nitz, Guanajuato, Nevada, and Idaho. Rich ore of silver. 244. POLYARGYRITE, 1 2 AgS -f Sb.jS 3 . Cubic. Typical form 0, ooOoo, ooO,mOni. Cl. cubic. H.=2 5; G. = 6 97. Metallic, iron-black; streak black. Malleable. C.c.: 78 2 silver, 7 4 antimony, 14 - 5 sulphur. Wolfach in Baden. 245. ENARGITE, 3Cu.jS + As 2 S s . Right prismatic. Cl. oP 97 53 perfect, brachydiagonal 100" 58 and macrodiagonal less so. Typical form ooP, OP, oopoo, ooPoo. Brittle. H. =3; G. =4 3 to 4 5. Iron-black. C.c. : 48 3 copper,

19 1 arsenic, and 32 "6 sulphur. Morococha in Peru.