140 



IRON. 



but in Germany, France, and the Austrian dominions, 

 it is wrought in great abundance. Its most remark- 

 able deposit in the tinted States, is at Salisbury in 

 Conn., where it has been wrought for nearly 100 

 years ; the amount of pig iron yielded annually, at 

 present, is about 2000 tons. The iron which this 

 variety affords is superior in malleability to that 

 yielded by the red ore of iron, and is much esteemed, 

 also, on account of its toughness and hardness. The 

 pig iron obtained from melting its purer varieties with 

 cliarcoal, in particular, may be easily converted into 

 steel. The compact variety of this species is usually 

 found in the same localities with the fibrous hematite, 

 and is equally employed, with that variety for obtain- 

 ing iron. The ochrey brown iron ore, or bog iron 

 ore, is the most recent in its formation of all the ores 

 of iron, its deposition being continually going on, 

 even now, in shallow lakes and in morasses. It is 

 wrought in all countries, more or less extensively; 

 but the iron it yields is chiefly used for castings. The 

 pisiform clay iron stone occurs imbedded in secondary 

 limestone, in large deposits, in France and Switzer- 

 land, where it supplies considerable iron works ; but 

 the iron, like that from the other earthy varieties of 

 the present species, is generally too brittle to be 

 wrought into bar-iron. 



6. Arsenical Iron, or Mispickel, is found crystal- 

 lized in right rhombic prisms of 111 12' and 68 48'. 

 These are often terminated by dihedral summits, and 

 liable to a large number of modifications. It also 

 occurs massive. Lustre, metallic ; colour, silver- 

 white, inclining to steel-gray; streak, dark grayish- 

 black ; brittle ; hardness, nearly that of feldspar ; 

 specific gravity, 6.127. Its chemical composition is, 

 iron 33.5, arsenic 46.5, and sulphur 20. Before the 

 blowpipe, upon charcoal, it emits copious arsenical 

 fumes, and melts into a globule, which is nearly pure 

 sulphuret of iron. It is soluble in nitric acid, with 

 the exception of a whitish residue. It sometimes 

 contains a small proportion of silver ; when it is de- 

 nominated argentiferous arsenical pyrites. Arsenical 

 iron is a pretty abundant substance, and occurs both 

 in beds and veins, often accompanied by ores of silver, 

 lead, and zinc. It is very plentiful in the mining dis- 

 tricts of Saxony, in the silver mines of Joachimsthal, 

 and the tin mines of Schlaggenwald, the Hartz, 

 Sweden, Cornwall, the United States, &c. The ac- 

 cidental admixture of silver renders some varieties of 

 the present species useful as ores of that metal. The 

 common arsenical pyrites, when occurring in large 

 quantities, is employed in the manufacture of white 

 arsenic and of realgar. 



7. Axotomous Arsenical Pyrites ; a species differ- 

 ing from the preceding in the inclination of the lateral 

 faces, which, in the present case, meet under angles 

 of 122 26' and 57 34', and in specific gravity, which 

 hi this species is 7.228. It has not yet been analyzed, 

 but is believed to consist wholly of iron and arsenic. 

 It has been found in beds, in primitive mountains, in 

 Carinthia, Silesia, and Stiria. 



8. Iron Pyrites is the most universally distributed 

 of all the ores of iron, and, from its yellow colour 

 and metallic aspect, is the substance which is so fre- 

 quently mistaken, by ignorant people, for gold. It 

 is not uncommon to find it regularly crystallized, 

 though the dimensions of the crystals are rarely such 

 as to render them very conspicuous. The prevailing 

 figure among its crystals is the cube, parallel to whose 

 faces they may be cleaved, as also parallel to the sides 

 of the regular octahedron. The last is assumed as 

 the primitive form of the species by most mineralo- 

 gists, as leading to an explanation of the numerous 

 secondary forms with the greatest simplicity. The 

 most frequent of these secondaries are the cubo-octa- 

 hedron, the pentagonal-dodecahedron, and the icosi- 



tetrahedron. The surfaces of the crystals are some- 

 times smooth, and sometimes alternately streaked. 

 Fracture, conchoidal, uneven ; lustre, metallic ; 

 colour, passing through a few shades of a character- 

 istic bronze yellow; streak, brownish-black ; brittle; 

 hardness, such ns to be impressed with the knife, and 

 scratched by feldspar ; specific gravity, 4.1)8. The 

 crystals, are liable to be much grouped, often penetrat- 

 ing each other so as to form globular masses. It occurs, 

 also, in granular, columnar, and impalpable masses ; 

 and often cellular, in consequence of forming upon 

 crystals of galena, which have subsequently become 

 decomposed. Iron pyrites consists of iron 45.74, 

 and sulphur 54.26. In the exterior flame of the 

 blowpipe, it becomes red upon charcoal, the sulphur 

 is driven off, and oxide of iron remains. In heated 

 nitric acid, it is partly soluble, and leaves a whitish 

 residue. Some varieties are subject to decomposi- 

 tion, when exposed to the action of the atmosphere. 

 With regard to its geological relations, much diver- 

 sity obtains ; it constitutes beds by itself of consider- 

 able magnitude, in gneiss, mica-slate, and primitive 

 argillite, and is often an important ingredient of those 

 beds which contain ores of lead, iron, copper, &c. 

 It is frequently mixed with coal seams and the beds 

 of clay which accompany them. It is also met with, 

 in considerable quantities, in veins, associated with 

 blende, arsenical iron, galena, and copper pyrites. 

 It is found, likewise, with ores of silver, and is con- 

 tained in many organic remains, both of vegetable 

 and animal origin. Its localities are too numerous to 

 admit of being noticed with particularity. Some of 

 the most beautiful crystallizations which adorn mine- 

 ralogical cabinets, are brought from the island of 

 Elba, Piedmont, Saxony, Hartz, Norway, and Corn- 

 wall. Vast deposits of iron pyrites, intermingled, 

 in some instances, with magnetic iron pyrites, are 

 found in the United States, and also abound in the 

 gold region of the Southern States, being wrought 

 extensively in many places for the sake of the gold me- 

 chanically mixed with it, from the presence of which 

 it receives a golden-yellow tinge. The uses of this 

 species are as follows : it is roasted for extracting 

 sulphur; after having been exposed to the oxidating 

 influence of the atmosphere, it yields sulphate of iron, 

 or copperas, and sulphuric acid ; the remaining oxide 

 of iron is used as a coarse pigment ; it is an impor- 

 tant agent in several metallurgical operations, and was 

 formerly considerably employed instead of flints in 

 gun-locks, from whence the name pyrites was derived. 

 9. White Iron Pyrites differs from the preceding 

 species in its crystalline characters, as well as in some 

 other respects, though, in chemical constitution, the 

 two appear to be perfectly identical. Its crystals 

 are in the form of modified rhombic prisms, and of 

 very flat crystals, having the appearance, at first 

 sight, of dodecahedrons with triangular planes, but 

 which, however, are macles, consisting of similar 

 portions of five crystals. The primary form is a right 

 rhombic prism, of about 106 and 73<>, parallel to the 

 planes of which it yields to mechanical division. 

 The faces of the crystals are deeply streaked, in a 

 vertical direction. Lustre, metallic ; colour, pale 

 bronze-yellow, inclining to gray ; streak, grayish- 

 black ; hardness, equal to that of feldspar ; specific 

 gravity, 4.67. It occurs massive, and in various 

 imitative shapes, in consequence of which, and the 

 composition of its crystals, it has been distinguished 

 into several varieties, as radiated pyrites , spear pyr- 

 ites, cock's-comb pyrites, hepatic pyrites, and cellu- 

 lar pyrites. Before the blowpipe, it behaves like 

 common iron pyrites. Some of its varieties are 

 peculiarly subject to decomposition. It is less fre- 

 quently met with in nature than the preceding species, 

 though very often found accompanying it. It occurs 



