Chemical elements
    History of Iron
      Native Iron
      Iron Minerals
      Sources of Iron
    Physical Properties
    Chemical Properties
    Iron Salts
    PDB 101m-1aeb
    PDB 1aed-1awd
    PDB 1awp-1beq
    PDB 1bes-1c53
    PDB 1c6o-1ci6
    PDB 1cie-1cry
    PDB 1csu-1dfx
    PDB 1dgb-1dry
    PDB 1ds1-1e08
    PDB 1e0z-1ehj
    PDB 1ehk-1f5o
    PDB 1f5p-1fnp
    PDB 1fnq-1fzi
    PDB 1g08-1gnl
    PDB 1gnt-1h43
    PDB 1h44-1hdb
    PDB 1hds-1i5u
    PDB 1i6d-1iwh
    PDB 1iwi-1jgx
    PDB 1jgy-1k2o
    PDB 1k2r-1kw6
    PDB 1kw8-1lj0
    PDB 1lj1-1m2m
    PDB 1m34-1mko
    PDB 1mkq-1mun
    PDB 1muy-1n9x
    PDB 1naz-1nx4
    PDB 1nx7-1ofe
    PDB 1off-1p3t
    PDB 1p3u-1pmb
    PDB 1po3-1qmq
    PDB 1qn0-1ra0
    PDB 1ra5-1rxg
    PDB 1ry5-1smi
    PDB 1smj-1t71
    PDB 1t85-1u8v
    PDB 1u9m-1uyu
    PDB 1uzr-1vxf
    PDB 1vxg-1wri
    PDB 1wtf-1xlq
    PDB 1xm8-1y4r
    PDB 1y4t-1ygd
    PDB 1yge-1z01
    PDB 1z02-2a9e
    PDB 2aa1-2azq
    PDB 2b0z-2boz
    PDB 2bpb-2ca3
    PDB 2ca4-2cz7
    PDB 2czs-2dyr
    PDB 2dys-2ewk
    PDB 2ewu-2fwl
    PDB 2fwt-2gl3
    PDB 2gln-2hhb
    PDB 2hhd-2ibn
    PDB 2ibz-2jb8
    PDB 2jbl-2mgh
    PDB 2mgi-2o01
    PDB 2o08-2ozy
    PDB 2p0b-2q0i
    PDB 2q0j-2r1h
    PDB 2r1k-2spm
    PDB 2spn-2vbd
    PDB 2vbp-2vzb
    PDB 2vzm-2wiv
    PDB 2wiy-2xj5
    PDB 2xj6-2ylj
    PDB 2yrs-2zon
    PDB 2zoo-3a17
    PDB 3a18-3aes
    PDB 3aet-3bnd
    PDB 3bne-3cir
    PDB 3ciu-3dax
    PDB 3dbg-3e1p
    PDB 3e1q-3eh4
    PDB 3eh5-3fll
    PDB 3fm1-3gas
    PDB 3gb4-3h57
    PDB 3h58-3hrw
    PDB 3hsn-3ir6
    PDB 3ir7-3k9y
    PDB 3k9z-3l4p
    PDB 3l61-3lxi
    PDB 3lyq-3mm8
    PDB 3mm9-3n62
    PDB 3n63-3nlo
    PDB 3nlp-3o0f
    PDB 3o0r-3p6o
    PDB 3p6p-3prq
    PDB 3prr-3sel
    PDB 3sik-3una
    PDB 3unc-4blc
    PDB 4cat-4erg
    PDB 4erm-4nse
    PDB 4pah-8cat
    PDB 8cpp-9nse

Native Iron

As has already been mentioned, iron seldom occurs in the free state in nature on account of the readiness with which it oxidises on exposure to a moist atmosphere. Native iron is frequently of meteoric origin, and contains varying quantities of alloyed nickel. Usually the nickel ranges from 1 to 10 per cent., but the metallic particles contained in the meteorite which fell near Middlesbrough in 1881 possessed no less than 21.32 per cent, of nickel, whilst the Santa Catharina siderite contained 34 per cent., and Oktibbeha County siderite 60 per cent, of nickel. Owing largely to the presence of this element, meteoric iron presents a whitish fracture, and resists corrosion extraordinarily well.

It will be observed that all of the meteorites contain, in addition to nickel, a small quantity of cobalt, whilst the carbon content is extremely small. Carbon is sometimes present in meteoric iron in the form of minute diamonds. The Rowton specimen is interesting as being the first siderite observed to fall in Great Britain, and may be seen in the Natural History Museum, South Kensington. The Perryville siderite is the first recorded instance of the presence of ruthenium in meteoric iron. In addition to traces of this element, traces of iridium, palladium, and platinum were detected.

The largest known meteoric mass is the Ahnighito, brought by Peary from Western Greenland in 1895. It now lies in the New York Museum, and weighs 36| tons.

In 1870 Nordenskidld found some large masses of iron containing 1 or 2 per cent, of nickel at Ovifak in Western Greenland. They weighed 9000, 20,000, and 50,000 lbs. respectively, and, though formerly regarded as meteoric, are now believed to be of terrestrial origin, having been reduced from basalt by some natural process.

Grains of Awaruite, an alloy of nickel and iron, have been found in the sands of certain New Zealand and Canadian rivers, containing as much as 67.6 per cent, nickel. Souesite and Josephinite are names given to similar alloys, the former from British Columbia, and the latter found enclosed within water-worn pebbles in Josephine and Jackson Counties, Oregon, U.S.A. An alloy containing some 7 per cent, of nickel is frequently termed kamasite; one corresponding to the formula Fe5Ni3 (38 per cent. Ni), taenite; and FeNi (60 per cent, nickel), octibbehite.

Native iron has been found in the coal measures of Missouri, at depths ranging from 35 to 51 feet, which preclude the possibility of meteoric origin. Most probably the metal has been formed by reduction. The fragments of iron weighed on the average 0.5 gram, but a larger mass of 45.4 grams was also discovered. The metal was soft (hardness on Mohs' scale 4), malleable, and, on fracture, silver-white in appearance. Different specimens yielded the following analyses: -

Fe99.16 %99.39 %97.10 %
SiO20.37 %0.31 %1.65 %
C0.065 %??
P0.207 %0.13 %0.176 %

In no case was cobalt, nickel, or copper present. The densities ranged from 7.43 to 7.88.

The dust showers which at various times have fallen in Italy and Sicily frequently contain grains of metallic iron. Similar grains are found in the sands of the Sahara desert, and it is not improbable that the dust showers referred to are terrestrial phenomena, the sand being transported from the desert by cyclones. In numerous other places small grains of iron have been found, and a terrestrial origin is ascribed to the metal in all of these cases.

Traces of metallic iron have been found in basaltic rocks, such as those from the Giant's Causeway. They were detected by pulverising the rock, separating the magnetic grains, and subjecting them to the action of an acidulated solution of copper sulphate in the field of a microscope. Small depositions of copper in crystalline bunches indicated the presence of traces of native iron. Grains of native iron mixed up with limonite and organic matter have been found in petrified wood. Iron crystallises in the cubic system, its cleavage being octahedral. Hardness 4.5; density, when pure, 7.86 (mean value).

A specimen of what may be termed " native cast iron " is stated by Inostzanzeff to have been obtained from Russian Island, Vladivostok. Analysis showed it to contain

Iron93.87 %
Carbon (free)2.87 %
Carbon (combined)0.33 %
Silicon1.55 %

and small quantities of manganese, sulphur, etc. In micrographical structure, as well as in composition, the metal resembled cast iron, and it is supposed to have been formed by the interaction of coal and iron ore in a sedimentary rock induced by the heat from an intruded igneous rock.

A carbide of iron occurs as Cohenite (Fe, Co, Ni)3C, in meteorites in distorted crystals, probably belonging to the cubic system. It possesses a metallic lustre, is tin-white in colour when pure, becoming bronze-yellow upon exposure to air. Hardness 5.5 to 6; density 6.977.

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