138 



IRON. 



mineralogist, in consequence of the complicated forms 

 ot its crystals, and the diversified appearance of its 

 compound varieties. It is crystallized in a great 

 number of forms, whose fundamental figure is a 

 slightly acute rhomboid of 86 10' and 93 50'', 

 which may be derived from its crystals by cleavage. 

 The general tendency of its secondary forms is to 

 hexagonal prisms and irregular octahedra. Lustre, 

 metallic ; colour, dark steel-gray, iron-black ; streak, 

 cherry-red, or reddish brown ; surface of the crystals 

 frequently tarnished; opaque, except in very thin 

 lamime, which are faintly translucent, and show a 

 deep blood red colour ; brittle ; hardness, the same 

 with the preceding species ; specific gravity, 5.251. 

 Its action upon the magnet is feeble ; it never 

 attracts iron filings, or offers magnetic polarity. 

 Besides occurring in distinct crystals, and in la- 

 melliform and compact masses, with a metallic 

 lustre, it also presents itself in reniform, botryoidal, 

 and stalactitic shapes, and earthy-looking masses, 

 where, from the smallness of the individuals, no signs 

 of the metallic appearance are discernible. These 

 varieties have received distinct names, and have often 

 been treated of, in mineralogical systems, as belong- 

 ing to a distinct species, which, on account of their 

 colour, has been designated red iron ore. But this 

 distinction is now given up, as an uninterrupted tran- 

 sition has been noticed between all the varieties of 

 the red iron ore and the crystalline specular iron. 

 The following are some of the varieties of the pre- 

 sent species, according as they have acquired distinct 

 appellations in mineralogical books, and among man- 

 kind in general : that in distinct crystals is called 

 tpecular iron; that in thin, lamellar concretions, 

 with a metallic lustre, is called micaceous iron ; the 

 rest, with a metallic lustre, is denominated common 

 specular iron. Those varieties which have lost their 

 metallic appearance, are included within, 1, the red 

 iron ore, divided into fibrous red iron ore, or red 

 hematite; compact and ochrey red iron ore, which 

 are massive, and consist of impalpable granular indi- 

 viduals, more or less firmly connected ; aud scaly red 

 iron ore, or red iron froth, consisting of very small, 

 scaly, lamellar particles, which, in most cases are 

 but slightly coherent : 2. clay iron ore, divided into 

 reddle, which possesses an earthy, coarse, slaty frac- 

 ture, and is used as a drawing material ; jaspery 

 clay iron ore, which has a large, flat, conchoidal frac- 

 ture, and considerable hardness when compared with 

 the other varieties of red iron ore ; and columnar 

 and lenticular clay iron ore, which are distinguished, 

 the first by the columnar form, the latter by the flat- 

 tish, granular form of its particles. The micaceous 

 iron, analyzed by Bucholtz, and the red hematite, 

 analyzed by D'Aubuisson, have been found to consist 

 of 



Peroxide of iron, . 100.00 90.00 94.00 

 Oxide of manganese, 0.00 a trace a trace 

 Silica, . . . 0.00 2.00 2.00 

 Lime, . . . 0.00 a trace 1.00 

 Water, . . . 0.00 2.00 3.00 

 The proportion of metal to that of oxygen, in the 

 species, is as 69.34 : 30.66. The clay iron ores, be- 

 ing more or less mixed with earthy substances, vary 

 in their contents, and several of their properties are 

 dependant upon the nature of these admixtures. The 

 specular iron is infusible before the blowpipe, but 

 melts with borax, and forms a green or yellow glass, 

 like pure oxide of iron. It is likewise soluble in 

 heated muriatic acid. The specular iron (in the cry- 

 stalline, lamelliform, and compact varieties, with 

 a metallic lustre) forms very powerful beds, and even 

 entire mountains, which are traversed by a multitude 

 of fissures, and cavities lined with small, but exceed 

 iiigly brilliant crystals of this substance. It yields, 



in the ordinary operations of reduction, sixty per cent, 

 of metal. Its most celebrated locality is the island 

 of Elba, which has afforded iron for sixteen centuries. 

 Its mines are still believed to be inexhaustible. They 

 annually yield 32,000,000 of French quintals of ore, 

 which are transported for reduction into Tuscany, the 

 Roman states, Liguria, and the kingdom of Naples. 

 It is also found at Framont in the Vosges (where its 

 exploration occupies 200 miners), in Saxony, Bohe- 

 mia, Sweden, Siberia, and in the United States of 

 America. Wherever it exists, it is explored with 



Erofit. It deserves to be mentioned, also, that specu- 

 ir iron, in exceedingly brilliant crystals and scales, 

 occurs very frequently among the ejected matter of 

 volcanoes, as in the lavas of Vesuvius and Auvergne, 

 where it is, undoubtedly, a product of sublimation. 

 The red hematite is found in beds and veins, in pri- 

 mitive and secondary countries. It occurs abundantly 

 in Saxony, the Hartz, Silesia, and in England. It 

 affords excellent iron, and often in the large propor- 

 tion of sixty per cent. Most of the plate iron and 

 iron wire of England are made of it. In Scotland, 

 it is used, along with the ore of that country, at the 

 Carron and Glasgow works. The ochrey red iron 

 ore usually accompanies the other varieties of this 

 species, and is treated conjointly with them. In 

 places where it is found in considerable quantities, it 

 is sometimes collected, washed, and employed as a 

 polishing substance. The compact red iron ore is 

 found in France and some other European countries, 

 where it is reduced, and affords a good soft iron, 

 yielding fifty per cent, of metal. But its most im- 

 portant use is as a polisher. It forms, when perfectly 

 compact, the burnisher of the button-maker, by means 

 of which he imparts to gilded buttons the highest 

 polish of which they are capable. The best speci- 

 mens for button-polishers command a very high price, 

 and usually come from little pebbles and rolled masses 

 of this ore, found in secondary countries. The fol- 

 lowing table exhibits a mineralogical analysis of nine 

 specimens of iron ore found in the district of Clydes- 

 dale. 



(a) From Crossbasket, about seven miles south-east from 

 Glasgow. Colour light-greyish, or greenish-black. Fracture, 

 from fine-grained even to coarse-grained, uneven, very easily 

 frangible, soft, easily scratched by the knife. Specific gravity 

 taken in distilled water at the temperature of 60", 3.1793. 



This ia the highest and also the least valuable of the Cross- 

 basket .strata of ironstone, which are at present raised for the 

 use of the blast furnace. The thickness of the stratum is from 

 three to three and a half inches. 



(b) From Crossbasket. Colour light greyish-black. Fracture 

 fine-grained, earthy, slightly uneven. Rather tough. Not 

 particularly soft. Specific gravity 3.3801. 



This ore is found at a distance of four feet under the preced- 

 ing one. It constitutes a stratum of about nine inches in thick, 

 ness, and is esteemed the purest and most valuable of the 

 Crossbasket ores. 



(c) From Crossbasket. Colour light greyish black. Fracture 

 fine-grained, earthy, slightly uneven. Rather tough, but more 

 easily frangible, and softer than the last-mentioned ore. Spe- 

 cific gravity 3.2699. The average thickness of the stratum ia 

 fi-oiii six to eight inches. 



(d) From Crossbasket. Colour brownish-black. Fracture 

 earthy, fine-grained, uneven. Easily frangible and soft. Spe- 

 cific gravity 3.1175. 



'J his 8ti"atum of ironstone is situated next under that from 

 whirl) the preceding specimen was taken, and forms thelowett 



