Page:Encyclopædia Britannica, Ninth Edition, v. 16.djvu/401

Rh MINERALOGY 383 California ; and more recently New Soutli Wales and Queensland in Australia, Tasmania, and New Zealand. Some of the largest single masses of gold found in recent times are the following: one of 22 oz. in Transylvania, of 28 Ib in North Carolina, of 20 Ib in California, one of 96 Ib troy near Miask in the Urals, and one of 184 Ib 8 oz., which yielded 8376, 10s. 6d., at Ballanit, Australia. The annual produce of gold from Australia is about 5 millions of pounds sterling, of the United States about 15 millions, and the whole earth about 23 millions. The following sub-species may be noticed : 1. Elect-rum. This name for the alloys of gold and silver was applied by Pliny, whenever the proportion of the latter metal was one-fifth. An alloy of 2 gold and 1 silver contains 21 per cent, of silver; this is found in Sutherland. One of 1 to 1 contains 86 per cent, of silver, this last being the most usual proportion. It occurs in Transylvania, in the Altai, and in Colombia. Its colour is brass-yellow to yellowish white. G. =12 &quot;5 to 15 5. 2. Porpezite, or Palladium Gold (ouro-poudrc), from Porpez in Brazil, contains 9 85 per cent, of palladium and 4 17 of silver. 3. Rhodium Gold, from Mexico (G. =15 5 to 16 8), contains from 34 to 43 per cent, of rhodium. 26. PLATINUM, Pt. Cubic ; rarely in small cubes or octahedrons, usually in minute scaly grains, sometimes cohering, and also in rounded lumps. No cl. H. = 4 to 4 5; G. = 17to 19. Lustre metallic. Colour and streak pale steel-grey. Malleable and ductile -with difficulty, having a hackly fracture. When containing much iron, magnetipolar. B. B. in fusible. Sol. in aqua regia, but only when heated ; solution red ; corrodes the skin. C.c. : platinum, but never to a greater extent than 86 5 per cent. The remainder consists of iron, iridium, rhodium, palladium, osmium, gold, copper, and a mechanical mixture of irid- osmine. The iron exists in quantities varying from 4 3 per cent, to double that amount. Occurs in Brazil in syenite ; near Popayan (Colombia) in alluvium, associated with chromite, iridium, palla dium, gold, and copper ; in the Urals in alluvium derived from crystalline rocks ; and at Nijni-Tagilsk in serpentine along with cliromite. It is also found in Borneo, California, and Carolina, and is said to have been found in the county of Wicklow in Ireland. The sands of many rivers yield it in small amount. Platinum docs not occur in large masses. A mass in the Madrid Museum from Condoto weighs 26i oz. ; masses have been found in the Urals from 11 to 21 Ib. Iron Platina is a sub-species. This, which has a composition FePt 2, and contains from 11 to 13 per cent, of iron, is found at Nijni-Tagilsk. G. = 14 6 to 15 8 ; H. =6. It is magnetipolar, and attracts iron much more strongly than an ordinary magnet. 27. PLATINHUDIUM. In minute silver-white grains. H. =6 to 7 ; G. = 16 - 94 to 22 8. Contains 55 44 platinum, 2779 iridium, 6 86 rhodium, 4 14 iron, 3 3 copper, 49 palladium. Is found in Brazil. 28. IRIDIUM, Ir. Cubic (fig. 27). H. = 6 to 7 ; G. = 21 57 to 23 46 Cl. cubic, traces. Very slightly malleable. Silver-white to steel-grey. B.B. un changed. Insoluble in all acids. C.c. : 76 &quot;8 iridium, 19 64 platinum, 89 palladium, 178 copper. Found at Nijni-Tagilsk, generally in minute grains. Is the heaviest known substance. Avaite, sub-species. From Ava in India. C.c.: 60 iridium, 20 platinum (according to Pnnsep). 29. PALLADIUM, Pd. Cubic ; in minute octahedrons, and in grains. H. = 4 5 to 5; G. = 11-3 to 11 8. Malleable. Light steel -grey. B.B. infusible. Slowly dissolves in n. acid, forming a brown-red solution. C.c.: palla dium, with a little platinum and iridium. From the gold sands of Brazil, often in small plumose crystalline lumps. Also from St Domingo, and the Urals. Does not tarnish with sulphurous fumes. 30. ALLOPALLADIUM, Pd 3. Hexagonal ; in small flat hexagons. Cl basal, perfect. Lustre bright silvery. Colour pale steel-grey. From Tilkerode in the Harz, with gold. 31. NEWJANSKITE (Osmiridium), IrOs (iridium 4978, osmium 50-22) and Ir 3 0s. Hexagonal ; P 124. OP, P, ooP. Generally in flat scales. Cl. basal perfect. H. =7; G. =18 8 to 19 47. Lustre metallic. Colour tin-white. B. B. unchanged. Insoluble in all acids. The analyses of this mineral give quantities of iridium varying from 44 to 77 per cent. , and of osmium from 21 to 49. Ruthenium, rhodium, and platinum make up the 100 parts. F. ,. The largest quantity of ruthenium is 8 49, and one variety from New Granada was found to contain no ruthenium, but 12 - 3 of rhodium, which is more than double its usual amount. Occurs with platinum in Choco (Colombia) ; at Newjansk and several localities in the Urals, in Australia, in northern California (somewhat abundantly in gold sands), also in Canada. 32. SISSEHSKITE (Iridos-mium), Ir0s 4 (iridium 19 9, osmium 80 1) and IrOs 3 (iridium 24 8, osmium 75 2). Rhombohedral ; R = 84 28. H. =7 5 ; G. =21-12. Colour lead- grey to bluish. B.B. becomes black, with strong odour of osmic acid ; in flame of spirit-lamp shines strongly, and colours flame yellowish red. Occurs in small quantity with newjanskite at all its localities, and in proportionally larger quantity at Sissersk in the Urals. It is used for pointing gold pens, and in the United States sells at 50 dollars an ounce. COMPOUNDS OF FLUORINE, CHLORINE, BROMINE, AND IODINE (HALOID SALTS). 33. FLUORITE (Fhcor-spar), CaF. _ Cubic (figs. 267 to 270, also figs. 31, 33, 36, 55, 56, 57, 58) ; also divergent crystalline, granular, and compact. Cl. octahedral; fracture conchoidal ; brittle. H. =4; G. = 3 lto3 2. Transparent to pellucid. Lustre vitreous. Colourless, but generally coloured purple, blue, green, yellow, white, black, and pink. Sometimes two or three colours disposed in layers in one crystal. Frequently Fig. 267. Fig. 268. Fig. 269. phosphoresces with different tints of light, when heated. B. B. de crepitates and fuses to an opaque bead. Sol. in s. acid with evolution of hydrofluoric acid. C.c.: 51 - 3 calcium, 48 7 fluorine. Common in veins, generally associated with metallic ores. Shetland, Suther land, on the Avon, and Ballater in Scotland; Cumberland, Northumberland, Derbyshire, and Cornwall; Saxony, Bohemia, Freiberg. Used to be turned into vases and other ornaments (&quot;blue John &quot;) ; formerly employed as a flux, now for etching and obscuring glass. 34. YTTROCEIUTE. In crystalline crusts. H. = 4 to 5 ; G. =3 4 to3 5. Translucent ; vitreous. Violet-blue to grey or white. B.B. infusible. Evolves fluorine when heated with sulphuric acid. C.c : fluorides of cerium, yttrium, and calcium. Finbo and Broddbo near Falun (Sweden), Massachusetts and New York. 35. FLUOCERITE, CeF + Ce 2 F 3. Hexagonal. H. =4 to 5; G. =47. Opaque or translucent on the edges. Pale brick-red or yellowish ; streak yellowish white. B. B. infusible. In closed tube gives out hydrofluoric acid. C.c.: 82 64 peroxide of cerium, 1*12 yttria, 16 24 hydrofluoric acid. Finbo and Broddbo. 36. FLUOCERINE, Ce 2 F 3 + (Ce 2 3 + H. i O). Massive ; fracture conchoidal. H. =4 5 to 5. Opaque ; resinous. Bright yellow to reddish brown ; streak brownish yellow. B. B. infusible, darkens with the heat; colour restored on cooling. C.c.: cerium 17 6, fluorine 10 9. sesquioxide of cerium 66 4, water 5 1. From Finbo. 37. BASTNAESITE, Ce 2 F 3 + Ce 2 3 -t-4H 2 0, and 38. HAMARTITE, 2(LaO, CeO)3C0 2 + CeF 3, are similar. The first is from Bastuaes in Sweden, the second from Pike s Peak in Colorado.