THE CHEDER IRON METEORITE ( Tuva ): MINERAL COMPOSITION, STRUCTURE, AND PGE AND REE CONTENTS
L.V. Agafonova, V.A. Popovb† , G.N. Anoshina,c, L.N. Pospelovaa, V.I. Zabelinb, and V.I. Kudryavtsevb†
aV.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
bTuva Institute for Exploration of Natural Resources (TuvIKOPR), Siberian Branch of the Russian Academy of Sciences, ul. Internatsional'naya 117a, Kyzyl, 667007, Russia
cNovosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
Keywords: Kamacite, taenite, meteorite, regmaglypt, plessite
Pages: 620-630
Abstract
The Cheder meteorite, found 23 km south of Kyzyl, has been studied in terms of mineral composition and internal structure. Structurally, it is a medium octahedrite, which measures 26 × 9 × 8 cm and weighs 5.39 kg. Its surface is streamlined and features flow lines. One of the sides, probably that facing the flight direction, features regmaglypts and a sinuous cavern (9 × 1.5 cm). The meteorite consists of kamacite admixed with taenite. The inside of Widmanstatten bands is of complex kamacite-taenite composition and flanked by taenite lamellae. Phosphides are present in kamacite in small amounts as variously sized and shaped bodies. They are divided into three types depending on the Ni/Fe ratio. Small shapeless wormlike grains, which are usually assigned to rhabdites, consist of nickelphosphide (Ni-rich variety). All the minerals in the meteorite contain Co (up to 67 wt.%) and, sometimes, Cu and P (slightly above the detection limit). The total PGE content of the meteorite is several times higher than that of chromitites, which are one of the terrestrial PGE sources. The REE in the meteorite are dominated by HREE. The total REE content of the meteorite is lower than that of chondrite C 1 by two orders of magnitude.
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