Iron Ores. 226 Lowland iron ore. $79. Variety 4. Nodular, or kidney form iron ore. This variety, which was mentioned by the ancients, Variety 5. Pifiform or granular iron ore. The oolitic ore found at Creufot, near mount Cenis, 50 lime, 30 ison, 20 alumina. 100 SPECIES 7. Lowland iron ore *. This fpecies of ore is fuppofed to confift of oxyd of Kirw. ii. iron, mixed with clay and phofphuret or phosphat of iron. It is called lowland ore, because it is found only in low grounds; whereas the laft fpecies is more commonly in high grounds; and is therefore called highland 227 G.VI. Salts. Sparry iron ore. ore. This ore occurs in amorphous maffes, and alfo in Variety. Meadow lowland ore. Frequently yields from 32 to 38 per cent. of iron. This variety is generally found under water. It is GENUS VI. SALTS OF IRON. It is found fometimes in amorphous maffes, and fome- Melle times cryftallized. Its colour is white; but it becomes tarnished by expofure to the air, and then affumes various colours. Streak grey or white. External luftre often metallic; internal common or glaffy. Tranfparency 1 or 2; fometimes o. Texture foliated. Fragments rhomboidal. Hardrefs 5 to 7. Brittle. Sp. gr. 3.6 to 3.810. Not magnetic. Soluble in acids with very little effervefcence. Before the blow-pipe decrepitates, becomes brownish black, and magnetic; but is scarcely fufible. Tinges borax fmutty yellow, with some effervefcence. This ore, as Bergman afcertained, confifts of iron, manganefe, lime, and carbonic acid. Que fpecimen, according to his analyfis, contained 24 manganefe, 38 carbonat of lime. 100 Another contained 22 iron, 28 manganefe, 100 acid is ftill a difputed point. The crystals of this ore are rhomboidal parallelopipeds; which is precisely the form of carbonat of lime. This amounts nearly to a demonftration, that the carbonic acid is combined with the lime; and that, as Cronstedt and Hauy have sup, ted with a quantity of the oxyds of iron and manganese. pofed, this ore is merely carbonat of lime, contamina. Whether the iron be combined with the carbonic SPECIES 2. Arseniat of iron. 128 Arfenia: of Mr Prouft has discovered this ore in Spain. Its co-iron. in water and nitric acid. When melted on charcoal, lour is greenish white. Its texture granular. Infoluble the arfenical acid efcapes with effervescence ‡. no + Ann. la Chim, i. SPECIES 3. Sulphat of iron. For a defcription of this falt, fee CHEMISTRY, no 195. 631. in this Suppl. ORDER VII. TIN ORES (H). TIN is employed to cover plates of iron and copper, and to filver the backs of looking glasses: It enters into the compofition of pewter; and forms a very important article in dyeing. the metals which we have already described. They Tin ores are by no means fo common as the ores of are found only in the primitive mountains (1). Hence Werner fuppofes them to be the most ancient of all metallic ores. They occur moft frequently in granite, Almoft This ore is common in Germany, France, and Spain. fometimes in porphyry, but never in limestone. (G) Kirw. II. 190-Bergman, II. 184.-Bayen. Jour. de Phyf. VII. 213.-Razowmowski, Mem. Laufanne, 1783, p. 149. (H) Geoffroy, Mem. Par. 1738, p. 103.—Morveau, Ann. de Chim. XXIV. 127. (1) Geologifts have divided mountains into three claffes; primitive, fecondary, and tertiary. The primitive occupy the centre of all extenfive chains; they are the higheft, the moft rugged, and exhibit the most pointed tops. They are confidered as the moft ancient mountains of the globe. The fecondary mountains occupy the outfide of extenfive ranges. They are ufually compofed of ftrata, more or lefs inclined, and commonly rest against the fides of the primitive mountains.-The tertiary mountains are much smaller than the others, and are often folitary. We use the terms primitive, fecondary, &c. merely as 220 Sulphat of iron. 230 Mince proer > 232 G. II. Oxyd. Brown oxyd of tin. * Kirw. ii. 297. Min N The compofition of this ore, as was firft difcovered by Mr Rafpe. proth's analysis, it is composed of 34 tin, 36 copper, 25 fulphur, 3 iron, 2 earth. 100 $ GENUS II. Klaproth informs us, According to Kla. OXYDS OF TING SPECIES I. Brown oxyd of tin Tinflone-Woodlin. This ore, which may be confidered as almost the only ore of tin, occurs in maffes, in rounded pieces, and cryftallized. Thefe cryftals are very irregular. Hauy 4 Four. de fuppofes, that their primitive form is a cube +; but Romé de Lifle, with more probability, makes it an octohezazii. 476. dron ; and in this opinion Mr Day agrees with him . + Crystallog. iii. 413. The octohedron is compofed of two four-fided pyra. Philof mids, applied base to bale. The fides of the pyramids Mag. iv. are ifofceles triangles, the angle at the vertex of which is 70°, and each of the other angles 55°. The fides of the two pyramids are inclined to each other at an angle of 95 f. This primitive form, however, never occurs, but cryftals of tinftone are fometimes found, in which the two pyramids are separated by a prifm. For a complete defcription of the varieties of the cryftals of SUPPL. VOL. II. Part I.. 152. Romé de Life, ibid. tinftone, we refer the reader to Romé de Life and Mr Metallic Day*. Its colour is commonly brown. Streak grey. Hard. nefs 9 to 10. Sp. gr. 6.9 to 7.0. Brittle. Variety 1. Common tinftone. Colour dark brown; fometimes yellowish grey, and 6.9 to 6.97. Before the blow pipe it decrepitates, and THE ufeful purposes to which lead in its metallic flate is applied, are too well known to require description. Its oxyds are employed in painting, in dyeing, and fometimes alfo in medicine. Ores of lead occur in great abundance in almost every part of the world. They are generally in veins; fometimes in filiceous rocks, fometimes in calcareous rocks. GENUS I. SULPHURETS OF LEAD. Ores. Pbilof. Mag. ibid. + Beiträge, ii. 256. 233 G. I. Sul. phurets. Galena, or pure ful SPECIES 1. Galena, or pure fulphuret of lead t. This ore, which is very common, is found both in maffes and cryftallized. The primitive form of its cry-phuret of ftels is a cube. The moft common varieties are the cube, lead. fometimes with its angles wanting, and the octohedron, Kirw. ii. compofed of two four-fided pyramids applied base to bafe: The fummits of these pyramids are fometimes cuneiform, and sometimes their folid angles are wanting. Romé de Its colour is commonly bluish grey, like lead. Streak Life, ini. 364. bluish grey and metallic. Luftre metallic. Sometimes Hh ftains proper names, without affirming or denying the truth or falsehood of the theory on which thefe names are founded. That the reader may have a more accurate idea of the compofition of thefe different classes of mountains, we have fubjoined a list of the subftances which, according to Werner, enter into the compofition of each. I. PRIMARY MOUNTAINS. 7. Shittofe porphyry, 8. Quartz, 216. to. Serpentine, 11. Topaz rock. 3. Micaceous fhiftus 6. Porphyry, 9. Primitive limestone, 7 235 Blue lead ore. *Kirw. ii. 220. + Gellert. 236 Black lead ore. Kirw. ii. 225. Hard Colour light bluish grey. Streak light bluish grey, and brighter. Luftre metallic. Texture compact. Before the blow pipe partly evaporates, and leaves a filver bead on the charcoal, furrounded by yellow dust. According to Klaproth, it contains. 48.06 lead, 20.40 filver, 7.88 antimony, 12.35 fulphur, 2.25 iron, 7.00 alumina, .25 filica. 98.09 + Variety 2. Dark grey filver ore. Colour iron grey, verging on black. Powder black, and ftains the fingers. Luftre o. 'Texture earthy. According to Klaproth, it contains 41.00 lead, 21.50 antimony, 29.25 filver, 22.00 fulphur, 1 75 iron, 1.00 alumina, 75 filica. 97.25 SPECIES 3. Blue lead ore This ore, which is found in Siberia, Germany, and Hungary, and is very rare, occurs fometimes in maffes, and fometimes cryftallized in fix-fided prifms. Colour between indigo blue and lead grey; fometimes inclining to black. Internal luftre metallic. Streak brighter. Texture compact. Hardness 6. Sp. gr. 5.461 t. Before the blow pipe melts with a low blue flame and a fulphureous fmell, and is easily reduced. SPECIES 4. Black lead ore . This ore, which is found in Germany and Brittanny, Ores. and which is fuppofed to be common galena decayed, Metallic is fometimes in ftalactites of various forms, and fometimes cryftallized in fix fided prifms, which are generally truncated and confufed. Colour black, often with fome ftreaks of red. Streak light bluish grey. Internal lure metallic. Hardness 5 to 6. Brittle. Sp. gr. from 5.744 || to 5.77 *. Be- 1 Brides. fore the blow-pipe decrepitates, melts cafily, and is reduced. According to the experiments of Laumont, this ore is a fulphuret of lead (or rather fulphuret of oxyd of lead), mixed with fome phofphat of lead. This ore, which is a mixture of the oxyd of lead ochre. with various earths, is found maffive, and of various de- ‡ Kirw L. of hardness. grees Its colour is either yellow, grey, or red. Luftre c. Transparency o to 1. Hardness 6 to 8; fometimes in powder. Sp. gr. from 4.165 to 5.545. Textures Kirwa compact. Effervefces with nitric and muriatic acids. Eafily reduced by the blow-pipe, leaving a black flag, unless the lead be mixed with too great a proportion of earth. This ore of lead, which is very common, is fometimes, Kiru. in masses, and fometimes cryftallized. But the crystal 203. lization is in general fo confufed, that the primitive form of the crystals has not yet been afcertained (K). Its colour is white. External luftre, waxy or filky, from to I; internal 1 to 2. Generally fomewhat transparent. Hardness 5 to 6. Brittle. Sp. gr. from acids when they are heated. Soluble in fat oils. Black-§ Gellert. 5.349 to 6.92 §. Effervefces with nitric and muriatic Kirwan. heated. Before the blow-pipe, in a filver fpoon, it be- de ened by fulphuret of ammonia *. Decrepitates when * Postier, comes red by the yellow cone of the flame, while the blue cone renders it yellow +. On charcoal it is imme-Ribbendiately reduced. Clin. is 56. trapp, A. It contains from .60 to .85 of lead, and from .18 to de Chim. XXV. 189. .24 of carbonic acid. It is generally contaminated with carbonat of lime and oxyd of iron. (x) See Hauy, Four, de Min. No XXXI. 502. and Romé de Lifle, III. 380. SPECIES Ores of SPECIES 2. Phofphat of lead +. -Ores. According to Fourcroy, from whom the whole of Metallic Lead. This ore, which is found in Siberia, Scotland, Eng. this defcription has been taken, it is compofed of land, Germany, Carinthia, Brittany. &c. is fometimes Pofphat amorphous, and fometimes cryftallized. The primitive 240 of lead. 207. form of its crystals, according to Romé de Lifle, is a +Kirw. ii. dodecahedron, contifing of a lix-fided rectangular prifm, terminated by fix fided pyramids, the fides of which are ifofceles trianglea (L). Sometimes the pyramids are truncated, and even altogether wanting. The cryftals of this ore are often acicular. Its colour is commonly green; fometimes yellowish or brownish, or greyish white. Streak commonly greenish white. Powder yellowish. External luftre, waxy, 2 to 3. Somewhat transparent, except when its colour is greyish white. Hardness 5 to 6. Brittle. Sp. gr. from 5.86 to 6.27 . Infoluble in water and fulphuric acid, and nearly infoluble in nitric acid; foluble in Fourrey, hot muriatic acid, with a flight effervefcence 1. Before the blow-pipe it eafily melts on charcoal, and cryftallizes on cooling: with foda the lead is in fome measure Briffon. ↑ Klaproth Ain, de Chim. it. 207. Ibid. 241 Arfeniat of lead. Kirw. ii. 259. * Proust, Four, de Fbyf.xxx. 394. 242 Phosphat and arfe. niat of lead. ↑ Kiaro. iì. 210. Briffon SPECIES 3. Arfeniat of lead §. This ore, which has hitherto been found only in Andalufia in Spain, and always in quartz or feldfpar, is in fmall maffes. Colour meadow green, often paffing into wax yellow. Luftre waxy, 2. Tranfparency 2. Before the blow-pipe it melts, and retains its colour, and does not crystallize on cooling. When heated to whitenefs, the arfenic acid escapes, and the lead is reduced *. SPECIES 4. Phosphat and arfeniat of lead. Arfenio phofphat of lead †. This ore, which has been found in Auvergne in France, is either in males, or cryftallized in small fix-tided prifms, with curvilineal faces. Colour yellowish green, or fhews alternate layers of pale and light green. Powder yellowish. The cryftals are fomewhat tranfparent; but when maffive, this ore is opaque. Hardnefs 5 to 7. Brittle. Sp. gr. 6.8465. Soluble in hot muriatic acid, but not in nitric. When heated it decrepitates. Before the blow-pipe melts eafily, effervefces, emits a white smoke, with an arfenical fmell. Some particles of lead are reduced, a brown fluid remains, which cryftallizes on cooling like phofphat of lead. hills in Scotland, was first mentioned in 1781 by Me This ore, which is found in Carinthia and at LeadJacquin (N). It occurs either in mafles, or cryftallized in cubic, or rhomboidal, or o&tohedral plates. Its colour is yellow. Streak white. Luftre waxy. Generally fomewhat tranfparent. Texture foliated. Fracture conchoidal. Hardnefs 5 to 6. Sp. gr. 5.486+; †Macquart. when purified from its gangue by nitric acid, 5.706 t. Hatchett. nicates a blue colour to hot fulphuric acid. Soluble in muriatic acid, and decompofed by it. Before the blowpipe decrepitates, melts into a yellowish grey mass, and globules of lead are reduced . Soluble in fixed alkalies and in nitric acid. Commu. SPECIES 6. Sulphat of lead ‡. This ore, which is found in Anglefey and in Anda lead. lufia, is generally cryftallized. The crystals are regular * Kirw. octohedrons §, and very minute. Min ii. 211. Colour white. Luftre 4. Transparency 4. Before Hay, the blow-pipe it is immediately reduced. Jour, de The compofition of this ore was firft afcertained by Min. No xxxi. 508. Dr Withering. ORDER IX. ORES OF ZINC. HITHERTO Zinc has not been applied to a great variety of ufes. It enters into the compofition of brafs; it is ufed in medicine; and Morveau has fhewn that its Hh2 oxyd (1) Cryftal. III. 391. See alfo Hauy's remarks on the fame subject in the Four. de Min. N2 XXXI, 5c6. Ores of oxyd might be employed with advantage as a white paint. Zinc. 243 G 1. Sulphurets. Common fulphuret of zinc. Kirw. ii. ii. 319. Orea of zinc are very abundant; they generally accompany lead ores, particularly galena. Calamine, or oxyd of zinc, has never been difcovered in the primitive mountains. GENUS I. SULPHURETS OF ZINC. This ore very commonly accompanies fulphuret of lead. It occurs both in amorphous maffes and cryftal238.-Berg.lized. The primitive form of its crystals is a rhomboidal dodecahedron, confifting of a fix-fided prifm, terminated by three-fided pyramids. All the faces of the crystals are equal rhombs. This dodecahedron may be mechanically divided into four equal rhomboidal parallelopipeds, and each of these into fix tetrahedrons, whose faces are equal ifofceles triangles. The figure of its integrant particles is the tetrahedron, fimilar to thefe * Hauy, Four.de Min. N° xxiii. 669. Fig. 40. + Fig. 41. The principal varieties of its cryftals are the tetrahedron; the octohedron; the octohedron with its edges wanting; a 24 fided cryftal, 12 of whofe faces are tra pezoids, and 12 elongated trianglest; and, laftly, a 28 fided figure, which is the laft variety, augmented by + See Hawy, four equilateral triangles +. ibid and Colour yellow, brown, or black. Streak reddish, Romé de brownish, or grey. Luftre commonly metallic. GeLifle, iii. nerally fomewhat tranfparent. Texture foliated. Hard65. Gellert. nefs 6 to 8. Sp. gr. 3.93 to 4.1665. Before the Briffon. blow-pipe decrepitates, and gives out white flowers of zinc, but does not melt. Borax does not affect it. When breathed upon, lofes its luftre, and recovers it very flowly. Hauy, Four de Min. ibid. Variety 1. Yellow blende. Colour commonly fulphur yellow, often paffing into olive green or brownish red. Powder pale yellow. Streak yellowish or reddish grey, not metallic. Luftre metallic. Tranfparency 2 to 4. Often phosphoresces ✦ Bergman, when scraped or rubbed *. .345. According to Bergman, it is compofed of 64 zinc, 20 fulphur, 5 iron, 4 fluor acid, 1 filica, Ores nifhed blue; tips of the eryftals often blood red. Pow. Metallic der brownish black. Streak reddish, brownish, or grey. Luftre common or metallic. Tranfparency o to i; the red parts 2. Hardnefa 8. A fpecimen of this variety, analyfed by Bergman, contained 52 zinc, 26 fulphur, G. II. Oxyds. White of yd of zine, This ore is either found loofe, or in maffee, or cry-zint ftallized. The primitive form of its crystals appears, 2:3-B from the mechanical divifion of one of them by Mr. 31. Hauy, to be an oftohedron composed of two fourfided pyramids, whofe fides are equilateral triangles +.+Tour, de But the cryftals are minute, and their figure not very diftinct. They are either four or fix fided tables with bevelled edges, fix-fided prifins, or three-fided pyra mids. Colour commonly white, grey, or yellow. Luftre often o, fometimes 2 or 1. Opaque. The crystals Hardness from 4 to 9, are fomewhat transparent. fometimes in powder. Sp. gr. from 2.565 to 3.674. Kirwan, When heated, becomes electric, without friction, like the tourmaline. Not blackened by fulphuret of ammonia. Soluble in fulphuric acid. Before the blowpipe decrepitates, and does not melt. This ore confifts of oxyd of zinc more or lefs contaminated with iron, filica, lime, and other foreign ingredients. In one fpecimen Bergman found the folfowing ingredients: 84,oxyd of zinc, 33 filica. 99 Colour black, or brownish black; furface often tar han or ore of Tutenago. Variety 418. |