Iron, IVC, ataxite
(Iron-ung in MetBull)
51° 3′ 30′ N., 94° 24′ 0′ E. Many flattened, shrapnel-like iron masses having a combined weight of ~210 kg were found along the Chinge stream bed in Tannu Tuva, which at the time was a small independent country between Mongolia and Siberia. A search for an associated crater was conducted in 1963 but none was found as the fall is estimated to have occurred 10–20 t.y. ago. Because the meteorite contains an average of 16.75 wt% nickel, it forms a macroscopically featureless surface structure (micro-plessite). Small inclusions are present, including kamacite spindles, mm-scale troilite, daubreelite, and schreibersite, and schlieren bands occur in the metallic groundmass. Various features of shearing and plastic deformation are related to a violent event in space.
(µ notation denotes deviation from terrestrial standards in parts per million)
mouseover for alternate view Diagram credit: Worsham et al., EPSL, vol. 467, p. 165 (2017)
‘Characterizing cosmochemical materials with genetic affinities to the Earth: Genetic and chronological diversity within the IAB iron meteorite complex’
(https://doi.org/10.1016/j.epsl.2017.02.044) Mo vs. Ru Isotope Compositions of Irons
Diagram credit: Bermingham et al., EPSL, vol. 487, p. 226 (2018)
‘New insights into Mo and Ru isotope variation in the nebula and terrestrial planet accretionary genetics’
(https://doi.org/10.1016/j.epsl.2018.01.017) HSE Abundances of IVB and Ungrouped Irons
Diagram credit: Honesto et al., 37th LPSC, #1374 (2006) Importantly, Litasov et al. (2018) determined that Chinga shares compositional similarities with six other ungrouped irons: ALH 77255, Alikatnima, Babb’s Mill (Blake’s), Deep Springs, Onello, and Shingle Springs. In addition, they demonstrated that these seven irons plot between the IVA and IVB groups on all elemental diagrams utilized in their study, and therefore they proposed that these irons be combined together into a new transitional subgroup termed IVC. Trace Element Distribution
Classification Diagrams (Chinga is the star symbol)
click on diagrams for a magnified view
click on diagrams for a magnified view Diagrams credit: Litasov et al., Doklady Earth Sciences, vol. 478, #1, pp. 64–65 (Jan. 2018)
‘Trace Element Composition and Classification of the Chinga Iron Meteorite’
(https://doi.org/10.1134/S1028334X18010063) A sculpture made from an iron meteorite that is petrologically and geochemically consistent with that of Chinga was transported from Tibet to Germany in 1938–39 (see below). This carved figure, weighing ~10.6 kg (3rd largest Chinga mass known), is probably a portrayal of the Hindu (or Buddhist) god of both wealthiness and war, Kubera (or Vaiśravana), but it could also be a deity associated with the 11th century Bon religion of western Tibet. An estimated date for the sculpture is 8th–11th century, but a more recent date cannot be ruled out.
Photo credit: Buchner et al., MAPS, vol. 47, #9, p. 1496 (Jan. 2012)
‘Buddha from space—An ancient object of art made of a Chinga iron meteorite fragment’
(https://doi.org/10.1111/j.1945-5100.2012.01409.x) Further geochemical and isotopic analyses are required to better resolve the potential relationships that may exist among the members of the proposed IVC subgroup. The specimen of Chinga shown above is a 43.3 g polished partial slice, beautifully photographed by KD Meteorites.