On Crystallized Native Terrestrial Tron, &. 141 
Olmsted’s catalogue of the collection, which was published in the 
fifth volume of this Journal. It is described as distinetly plated ; 
hard ; assuming under the file the lustre of steel; highly magnetic ; 
breaking under the hammer, with the lustre of steel; and having the 
specific gravity of 7.4. Its weight is a little short of two pounds. 
{t was found in the vicinity of a bed of Iron ore, of the argillaceous 
kind. The smaller specimen, which weighs seven ounces, is pos- 
sessed of the same characters in the main, though a little less brittle ; 
but is a distinet crystal, in the form of an octahedron. Prof. Olm- 
sted informs me that it comes from Guildford county, ten or fifteen 
miles distant from the locality of the first specimen, which was found 
in Randolph county. The individual from whom he obtained it, in- 
formed him, that it was detached from a mass weighing twenty eight 
pounds, which was wrought by a blacksmith of the neighborhood, into 
horse-nails. The crystalline structure of this specimen is what par- 
ticularly interested me ; for, although the existence of native terres- 
trial iron may now be considered as established beyond all doubt, yet 
it had hitherto been observed only in a massive state. The axis of 
the crystal measures three inches. The angle at the summit is 60°, 
that at the base 120°. It is, therefore, a regular octahedron. Its 
structure is distinctly foliated, the lame being pretty uniformly one 
twentieth of an inch in thickness, and arranged parallel with the 
planes of the octahedron, which must consequently be considered as 
the primary form of the species. On one or two of the planes, the 
lamine extend beyond the edges ofithe adjoining and opposite faces, 
or those which are external do not in all cases cover the layers upon 
which they rest; but stopping somewhat short of their borders, en- 
able us to discover the internal structure of the erystal with great 
distinctness. 
In farther examining fragments freshly detached from these mass- 
es, I was struck with their resemblance to the native iron from Penn- 
sylvania, of which I gave some account in Vol. XIV. p. 183, of this 
Journal, and which was found to contain a trifling per-centage of 
arsenic. Having satisfied myself, by forming a solution in nitric acid, 
that the brittleness and want of malleability in the on en ee 
hot owing to the presence of carbon, no carbonaceous discoloration 
taking place; and, moreover, being assured, by the applications of 
the customary tests, of the absence of silver, copper, and nickel, J 
felt no hesitation in concluding that it was identical with that sub- 
stance. Had the compound blow-pipe been in operation, it would 
