PUTORANO : Terrestrial Native Iron
 

The samples were first identified not as meteorites but as fine-grained basaltic breccia with basalt, fine-grained "anorthosite" and feldspathic dunite clasts, lacking the cosmogenic radionuclide 26Al. Plagioclase, olivine and rare ilmenite co-crystallized, followed by pigeonite.

 

The rock contains Ni-bearing native iron (essentially, but not quite, kamacite, generally found only in meteorites) but despite this unusual metal, it is not a meteorite - in addition to the evidence above, oxygen isotope ratios appear terrestrial, and some of the silicate mineral-chemical details are not appropriate to meteorites. This "Putorana" rock is presumed to be related to Siberian Trap basalt magmatism. The metallic copper can be seen in hand specimen, or within kamacite. There is no taenite, the typical nickel-rich alloy complement of kamacite in meteorites. Iron carbide (Fe3C, cohenite) encloses kamacite. Comparison with native iron on Earth (e.g., Disko Island, west Greenland) and with planetary basalt suites and mesosiderites identifies Putorana as terrestrial (Treiman et al., 2002). Electron microprobe analysis of Putorana iron reveals that the iron contains minor amounts of Ni (2.31%), Co (0.54%) and Cu (0.12%)