Kerman 254        30°45.299’N, 57°48.005’E

Kerman, Iran

Find: 2017 Jan 9

Classification: Ordinary chondrite (H5)

History: Meteorite (11 samples, 534.28 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. All fragments of the meteorite were observed on the hard surface (probably, the place of fall).

Physical characteristics: Total mass is 534.28 g. All fragments 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. Some small cracks are totally filled with Fe-hydroxides and sulfates.

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 600 to 1000 µm. They have BO, POP and GOP texture and some of them consist of Ol+Opx+Cpx+Pl±Crt or Ol+Opx+Pl±Crt. Olivine, low-Ca-pyroxene and plagioclase are main minerals in middle-grained 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. Fresh FeNi metals and troilite are very rare due to intensive alteration. Relics of taenite grains (up to 50 µm) were observed only. Weathering products (goethite, "hydrogoethite", akaganeite, droninoite and other Fe-hydroxides, rarely siderite and anhydrite) are very abundant and occur as veins and in situ alteration of FeNi-metals and troilite and fill all microfractures in minerals from matrix and chondrules (weathering grade – W3-4). Clinopyroxene, chromite, chlorapatite and merrillite (up to 150 µm) occur locally in the matrix; K-feldspar is found in the BO chondrules. Pyrrhotite and hydrated sulfide FeS•nH₂O (alteration after troilite?) form grains up to 20-50 µm. Association of anhydrite and natrojarosite is occasionally present in alteration products.

Geochemistry: EDS-WDS analyses (Victor V. Sharygin, SIGM and UrFU). The primary chondrite paragenesis includes olivine 19.32±0.19 (N=33), low-Ca pyroxene Fs_17.29±0.28Wo_1.45±0.21 (N=28)), plagioclase Ab_81.2An_12.3Or_6.5 (N=15), K-feldspar Ab_8.6An_4.7Or_86.7 (N=1), Cr-bearing clinopyroxene En_46.2Fs_7.2Wo_46.6 (Cr₂O₃ – 0.9 wt.%, N=4), chromite Crt_80.5Spl_14.3 (N=12), chlorapatite, merrillite, FeNi-metals and troilite. Chlorapatite contains F (0.8 wt.%) and Cl (5.2 wt.% ,N=4). Merrillite is poor in FeO (0.4-0.8 wt.%, N=6). Composition of taenite (in wt.%, N=4): Fe 74.51, Ni 25.26, Co 0.25. Pyrrhotite bears up to 7.6 wt.% Ni. Fe-rich serpentine-group mineral contains NiO (up to 1.1 wt.%). Goethite and "hydrogoethite" contain 2.5-13.4 wt.% NiO, up to 0.8 wt.% CoO.

Classification: (Victor V. Sharygin, SIGM and UrFU). Ordinary chondrite. H5, S2, W3-4.

Specimens: 521.54 g (10 samples) – UrFU; 12.74 g (1 sample) and thin section – SIGM.