Kerman 253        30°45.353’N, 57°48.126’E

Kerman, Iran

Find: 2017 Jan 9

Classification: Ordinary chondrite (H5)

History: Meteorite (one sample, 29.4 g) was found 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. This meteorite was observed on the hard surface (probably, the place of fall).

Physical characteristics: Total mass is 29.4 g. Meteorite has 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. Fusion crust was locally observed (60-150 μm). Some small cracks are totally filled with Fe-hydroxides.

Petrography: Classification (Victor 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 200 to 700 μm. They have BO, POP and RP texture and some of them 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 the main minerals in matrix. Plagioclase grains are less than 50 μm. This indicates a petrologic 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 450 µm) and troilite (up to 200 µm) are rare due to intensive alteration. Weathering products (goethite, "hydrogoethite", akaganeite, droninoite and other Fe-hydroxides, rarely siderite and 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 by serpentine is occasionally fixed in outer zones of grains (weathering grade – W3). Clinopyroxene, chromite, chlorapatite and merrillite (up to 200 µm) occur locally in the matrix. Pyrrhotite and hydrated sulfide FeS•nH₂O (alteration of troilite?) form grains up to 100 µm. Fusion crust (60-150 µm in thickness) is fine-grained and contains skeletal crystals of olivine (10-50 µm), mafic glass and metal-sulfide blebs (martensite or taenite and troilite, 1-20 µm).

Geochemistry: EDS-WDS analyses (Victor V. Sharygin, SIGM and UrFU). The primary chondrite paragenesis includes olivine Fa_19.51±0.13 (N=24), low-Ca-pyroxene Fs_17.37±0.38Wo_1.29±0.15 (N=26), plagioclase Ab_83.0An_11.5Or_5.5 (N=7), Cr-bearing clinopyroxene En_47.0Fs_6.7Wo_46.3 (Cr₂O₃ – 0.8 wt.%, N=1), chromite Crt_80.4Spl_14.3 (N=8), chlorapatite, merrillite, FeNi-metals and troilite. Chlorapatite contains F (0.9 wt.%) and Cl (4.4 wt.% ,N=1). Merrillite is poor in FeO (0.4-0.7 wt.%, N=7). Composition of metals (in wt.%): kamacite (N=16) – Fe 92.51±1.21, Ni – 6.80±1.10, Co – 0.57±0.08; taenite (N=3) – Fe 68.73, Ni 31.03, Co 0.27; tetrataenite (N=6) – Fe 49.92±3.95; Ni 49.89±3.96, Co 0.22±0.02. Troilite is close to ideal FeS. Composition of pyrrhotite (in wt.%, N=8): Fe 59.54±1.44, Ni 1.44±1.08; S 39.04±0.53. Fe-rich serpentine-group mineral contains NiO (up to 1.1 wt.%). Goethite and "hydrogoethite" contain 3.9-16.1 wt.% NiO, up to 0.6 wt.% CoO. Droninoite bears NiO (47.4), FeO (19.4) and Cl (8.6 wt.%).

Classification: (Victor V. Sharygin, SIGM and UrFU). Ordinary chondrite. H5, S2, W2-3.

Specimens: 14.7 g (cut-off) – UrFU; 7.2 g (cut-off) and thin section – SIGM.