MAGNETIC IRON ORE OF NIJNY TAGILSK. 
371 
more laid open at the period of our visit than when they were inspected by Baron 
Humboldt and his associates. On the summit and slopes of the Vissokaya-gora 
patches of the ore (usually compact and with a conchoidal fracture) have been ex- 
tracted from a very remote period ; but whether these metallic masses are merely 
the upper portions of veins which traverse the surrounding rock, like those in the 
magnetic hill of Blagodat. described as dykes by Colonel Helmersen 1 , or mere 
adherent superficial patches which occupied cavities and clefts in the greenstone, 
we could not ascertain. However this may he, the chief mass of the ore is now 
seen to occupy the valley on the western side of the hill, for it has been deeply 
cut into by open quarries. The refuse stuff or capping of decomposed felspar and 
mixed matter with hydrate of iron having been cleared away, an enormous body of 
the iron ore (fer oxydule), rudely bedded and traversed by numerous joints, is ex- 
posed by great works along a face which, including the useless overlying materials, 
has a height of nearly a hundred feet and a length of several hundred. When on 
the spot it seemed to us possible to account for the appearance presented by this 
metallic accumulation, most of which is now but little solidified, either by supposing 
it to have been of plutonic origin, and that, issuing from fissures on the hill side, 
it had flowed, when in a molten state, into the hollow where it lies ; or that it was 
formerly a mass of sedimentary materials which had been altered and mineralized 
by heat and vapours, which making use of parts of the surrounding limestones as 
a flux, had elaborated this metallic substance. A feature pointed out to us by 
M. Schwetzoff may serve to throw some light upon the question of the origin of 
the iron. In opening out the side of the valley nearest to the hill of greenstone, 
irregular knobs or points of that rock were met with, on stripping which it was 
found, that the iron ore had accommodated itself to the inequalities of their sur- 
face, and that at such points of contact the ore was not only harder and more 
crystalline than usual — in fact almost unmanageable by the workmen but also 
much more magnetic than at a short distance from the greenstone. Now, if the 
observer were furnished with no other data than these, he might, reasoning from 
the countless analogies of metamorphism which result from the eruption of igneous 
though sedimentary matter, infer that the greenstone intruding into ancient ma- 
terials had, in producing a change throughout their whole mass, rendered those 
' Der Magnetberg Blagodat am Nordlichen Ural, von G. Helmersen, 1837. Colonel Helmersen in this 
memoir has very properly corrected the errors of previous authors, one of whom had spoken of the iron 
ore at Nijny Tagilsk as overlying the limestone, a second as associated with grauwacke, and a third as a 
mass in chlorite schist. 
