MINERALOGY 391 147. GERSDORFFITE, NiS 2 + Ni As 2 . Cubic (figs. 74, 30, 26). Cl. cubic, generally granular. H. =5 5 ; G. <= 6 67. Lustre metallic. Silver- white to steel-grey, decrepitates in closed tube. B.B. fuses to a black slag ; partially sol. in n. acid. C.c. : 35 2 nickel, 45 4 arsenic, and 19 4 sulphur; sometimes with cobalt. Craignuir, near Loch Fyne, with 23 nickel and 6 cobalt. The Harz, Sweden, Spain, and Brazil. 148. ULLMANNITE, Cubic (figs. 31, 29, 27) ; often tetrahedral, and in twins as in figs. 328, 329. Cl. cubic, perfect ; fracture uneven. H. = 5 to 5 5 ; G. =62 to 6 5. Lead-grey to tin-white, often with iridescent Fig. 328. Fig. 329. tarnish. B.B. fuses with dense fumes. Sol. in n. acid. C.c. : 27*4 nickel, 57 5 antimony, and 15 1 sulphur. Westerwald, Siegen, Harzgerode, Lolling (Carinthia), Lobenstein, and Bleiberg. 149. RAMMELSBERGITE, NiAs. Right prismatic ; ooP 123 to 124. Chiefly massive, or in radiating and botryoidal aggregates. H. =5; G. =7 2. Colour tin-white. Schneeberg, Reichelsdorf, and Wittichen in Baden. 150. HAUERITE, MuS 2 . Cubic (figs. 30, 30-26, 30-33-37). Crystals single or in spherical groups. Cl. cubic, perfect; H. =4; G. =3 46. Reddish brown to brownish black ; streak brownish red. In closed tube yields sul phur, and leaves a green mass, which is sol. in h. acid. C.c. : 46 manganese and 54 sulphur. Kalinka in Hungary. 151. PYRRHOTITE (Magnetic Pyrites], Fe 7 S 8 . Hexagonal; P 126 48 . Crystals rare, sometimes hemihedral on z, commonly massive or granular. Cl. oP, imperfect ; brittle. H. = 3 - 5 to 4 5 ; G. =4 5 to 4 "6. Colour bronze-yellow with pinchbeck - browu tarnish ; streak greyish black. More or less magnetic. C.c.: Fig. 330. Fig. 331. 63 65 iron and 36 35 sulphur ; sometimes with nickel. Common in primary limestones and diorites of Scotland. Crystallized in above forms at Askaig, on Loch Shin, Sutherland ; Carnarvon, Cornwall, Fahlun, Bodenmais, Andreasberg. Distinguished by its colour and its solubility in h. acid. 152. LINN.EITE, 2(Co, Cu)S + CoS 2 . Cubic (figs. 29, 30) ; often twinned ; twin face ; also massive. Cl. cubic ; brittle. H. =5 5 ; G. =4 9 to 5. Silver- white, with a yellow tarnish ; streak blackish grey. B.B. fuses to a grey mag netic globule, which is bronze-yellow when broken. C.c.: cobalt 43 - 2, copper 14 4, iron 3 5, sulphur 38 5. Bastnaes (Sweden). 153. SIEOENITE, CoS + Ni 2 S 3 (?). Cubic ; generally in crystals like fig. 29 ; also massive. Colour silver- white, inclining to pink. Other features like linnseite. C.c. : cobalt 40 8, nickel 14 6, sulphur 43 1. Miisen near Siegen, Mary land, and Missouri. The American mineral has 30 - 5 of nickel. 154. POLYDYMITE, Ni 4 S 5 . Cubic ; in minute octahedral crystals and flattened twins. Cl. cubic. H.=4 5; G. = 4 81. C.c.: 39 45 nickel, 40 55 sulphur, but generally with 4 of iron. Westphalia. Saynite or grunauite seems to be a bismuthic and cobaltic variety ; it is from Grunau in Sayn Altenkirchen. 155. BYRICHRITE, 3NiS + 2NiS 2 . H. =3 to 3 5; G. = 47. C.c.: 54 23 nickel, 279 iron. 42 86 sulphur. From the Westerwald. 156. HORBACHITE, 4Fe 2 S 3 + Ni 2 S 3 . Crystalline masses. H. = 4 5; G. =4 - 43to47. Colour pinch beck-brown; streak black. C.c.: nickel 11 98, iron 41 96, sulphur 45 87. Horbach in the Black Forest. 157. SKUTTERUDITE, CoAs 3 . Cubic (figs. 30, 26 with 33, 40) and granular. Cl. cubic ; frac ture conchoidal ; brittle. H. = 6 ; G. = 6 74 to 6 84. Tin-white to lead-grey. Lustre brilliant. In closed tube gives sublimate of metallic arsenic, otherwise like smaltine. C.c.: 79 arsenic, 21 cobalt. Skutterud, near Modum in Norway. 158. GALENA, PbS. Cubic ; crystals chiefly cube, octahedron, and rhombic dodeca hedron ; rarely 20 and 202. Also massive and granular, compact, or laminar, and in pseudomorphs of pyromorphite and other minerals. Cl. cubic, very perfect ; fracture scarcely observable ; sectile. H. = 2 5; G. =7 2 to 7 6. Lead- grey, with darker or rarely iridescent tarnish; streak greyish black. B.B. decrepitates, fuses, and leaves a globule of lead. Sol. in n. acid, .c. : 867 lead, and 13 3 sulphur; but usually contains a little silver, ranging from 1 to 3 or 5 parts in 10,000 ; rarely 1 per cent, or more. Some contain copper, zinc, or anti mony, others selenium, and others (the " supersulphuret ") probably free v . qon sulphur (2 to 8 per cent.). Most common ore of lead in many countries. Leadhills, Pentland Hills, Linlithgow, Inverkeithing, Monaltrie, Tyndrum, Strontian, Islay, Orkney, Cornwall, Derbyshire (Castletown), Cumberland (Alston Moor), Durham (Allenhead), Wales, Isle of Man. 159. CUPROPLUMBITE, 2PbS + Cu 2 S. Cubic. H. =2-5; G. =6-4. Bluish grey. Chili. 160. BEEGERITE, 6PbS + Bi 2 S 3 . Cubic. G. = 7-27. Cl. cubic. Light to dark grey. Lustre brilliant. C.c. : sulphur 15, bismuth 20 - 6, lead 64 - 2, with copper 17. Grant (Park county, Colorado). 161. CLAUSTHALITE, PbSe . Cubic; but massive granular. H. = 2 5 to 3; G. = 8 2 to 8 8. Lead -grey ; streak grey. B. B. fuses, smells of selenium, colours the flame blue, stains the support red, yellow, and white, and volatilizes, except a small residue, without fusing. C.c.: 727 lead, 27 3 selenium ; but sometimes 117 of silver. Zorge, Lerbach, and Clausthal in the Harz. Tilkerodite, or Selen- Cobalt- Blei, containing 3 per cent, of cobalt, from Tilkerode, is a variety. 162. ZORGITE. Massive granular ; like clausthalite, but inclining to reddish, and often tarnished. There are four varieties, (a) Selen-Blci-Kupfer : G. =7 4 to 7 5 ; 5PbSe + CuSe ; with 4 copper, 65 lead, 30 selenium. (b) The same, but with G. =5 6 ; 4Pb, 4Cu, 7Se ; with 15 8 copper, 48 4 lead, and 35 selenium, (c) Selen-Kupfer-Blei : with G. =7; 2PbSe + CuSe; with 8 copper, 57 lead, and 32 selenium. (tf)2PbSe-i- 9CuSe ; with 46 64 copper, 16 58 lead, and 36 59 selenium. From Tilkerode and Zorge in the Harz, and near Gabel in Thuringia. 163. ALTAITE, PbTe . Cubic and granular ; fracture uneven ; sectile. H. =3 to 3 5; G. = 8 1 to 8 2. Tin-white to yellow, with yellow tarnish. B. B. colours the flame blue, fusing to a globule, which almost wholly volatilizes. C.c. : 61-9 lead and 38-1 tellurium. Zavodinski in the Altai, California, Colorado, and Chili. 164. REDRUTHITE (Copper Glance), Cu 2 S. Right prismatic. ooP (o) 119 35 ; P (P) middle edge 125 22 ; ? (a) middle edge 65 40 ; 2poo (d) middle edge 125 40 ; $ Poo (e) middle edge 65 48 . Crystals OP (s), ooP (o), ooPoo (p) (figs. 333, Fig. 333. Fig. 334. 334); with hexagonal aspect; also twins ; and massive. Cl. oP,
imperfect ; fracture conchoidal or uneven ; sectile. H. = 2 5 to 3 ;