Kerman 203        30°45’14.76"N, 57°48’1.32"E

Kerman, Iran

Find: 9 Jan 2017

Classification: Ordinary chondrite (H5)

History: The meteorite was found on 9 January 2017 by the UrFU meteorite expedition-2017 in Iran (Pastukhovich A.Yu., Larionov M.Yu., Kruglikov N.A., Zamyatin D.A.) in the northwest part of the Kalout region of the Lut desert.

Physical characteristics: Total mass is 59.32 g. All fragments of the meteorite have angular to roughly rounded shape. The surface and interior of the meteorite is light to dark brown in color due to abundant Fe-hydroxides. Some parts have glassy-like surface due to desert weathering. No fusion crust was observed. Some small cracks are totally filled with with natrojarosite or aggregate of anhydrite+natrojarosite and Fe-hydroxides.

Petrography: Classification (V. V. Sharygin, SIGM and UrFU). Petrographic observation of a polished section shows chondrules in a recrystallized matrix. Chondrules are readily delineated and their sizes mostly vary from 300 to 600 μm. They have barred or porphyritic texture and consist of Ol+Opx+Cpx+Pl±Crt or Ol+Opx+Pl±Crt. Large chondrules (1.5-5 mm) also occur. Olivine, low-Ca-pyroxene and plagioclase are main minerals in matrix. Plagioclase grains are less than 50 uµm. This indicates a petrological type of 5 for the meteorite. Undulatory extinction and irregular fractures in olivine, as well as the absence of opaque shock veins and melt pockets, indicate a shock stage of S2. Relics of fresh FeNi metals (kamacite, taenite, tetrataenite, up to 100 μm) and troilite (up to 70 µm) are rare due to intensive alteration. Weathering products (goethite, "hydrogoethite", akaganeite, droninoite ? and other Fe-hydroxides, rarely anhydrite) occur as veins and in situ alteration of FeNi-metals and troilite and fill all microfractures in minerals from matrix and chondrules. The replacement of olivine and low-Ca pyroxene by serpentine/chlorite is ocasionally fixed in outer zones of grains (weathering grade W3 to W4). Clinopyroxene, chromite, chlorapatite and merrillite (up to 500 μm) occur locally in the matrix. Pyrrhotite and hydrated sulfide (alteration of troilite?) form grains up to 100 uµm. The relics of Cu-rich sulfide (chalcopyrite or bornite) were observed in goethite aggregate. The secondary association (anhydrite + natrojarosite ± goethite ± celestine ± monazite-(Ce)) is common in the meteorite.

Geochemistry: EDS-WDS analyses (V. V. Sharygin, SIGM and UrFU). The primary chondrite paragenesis includes olivine Fa_19.49±0.38 (N=61), orthopyroxene Fs_17.06±0.47Wo_1.34±0.17 (N=52), plagioclase Ab_82.8An_11.1Or_6.1 (N=39), Cr-bearing clinopyroxene En_47.1Fs_7.6Wo_45.3 (N=15), chromite Crt_80.4Spl_14.4 (N=35), chlorapatite, merrillite, FeNi-metals and troilite. Chlorapatite contains F (up to 1.2 wt.%); Cl up to 5.9 wt.% (N=13), but some grains are richer in F (2.0-2.8 wt.%) and poorer in Cl (2.0-3.8 wt.%) to be fluorapatite. Merrillite is poor in FeO (0.4-1.6 wt.%, N=28). Composition of metals (in wt.%): kamacite (N=20)  Fe 92.51±1.09, Ni  7.12±1.08, Co  0.41±0.04; taenite (central part, N=10)  Fe 68.09±3.94, Ni 31.71±3.96, Co 0.20±0.16; tetrataenite (N=9) Fe 49.75±1.26; Ni 50.27±1.31, Co 0.07±0.10. Troilite is close to ideal FeS. Composition of pyrrhotite (in wt.%, N=7): Fe 58.82±1.42, Ni 1.36±1.0; Co 0.12±0.11; S 39.36±0.57. Fe-rich serpentine-group mineral contains NiO (up to 1.1 wt.%). Goethite and "hydrogoethite" contain 1.3-15.0 wt.% NiO, up to 0.8 wt.% CoO. Akaganeite is rich in NiO (5.6-6.2) and CoO (0.6-0.7 wt.%); Cl 5.7-6.1 wt.%. Natrojarosite NaFe₃(SO₄)₂(OH)₆ (in wt.%, N=9): Fe₂O₃  46.29; Na₂O  4.32; K₂O 1.93; SO₃ 32.95.

Classification: (Victor V. Sharygin, SIGM and UrFU). Ordinary chondrite. H5, S2, W3. In chemical composition of olivine and low-Ca pyroxene this meteorite seems to be similar to nearby H5 meteorites: Kerman 001, Kerman 003, up to Kerman 203.

Specimens: 6 samples (8.15, 16.86, 8.76, 15.7, 3.98, 0.15 g) at UrFU; 5.72 g and thin section at SIGM.