Gandom Beryan 011        31°52.659’ N, 57°02.920’ E

Kerman, Iran

Find: 4 January 2017

Classification: Ordinary chondrite (LL3)

History: The meteorite was found on 4 January 2017 by the UrFU meteorite expedition-2017 in Iran (Pastukhovich A. Yu., Larionov M. Yu., Kruglikov N.A., Zamyatin D.A.) 5 km north-east from the middle part of the road Ravar – Dige-e-Rostam hot springs, Tabas (northern sandy part of the Lut desert).

Physical characteristics: The meteorite has roughly rounded shape. Exterior of the stone is desert polished. The surface and interior of the meteorite is light to dark brown in color due to Fe-hydroxides. Fusion crust is present.

Petrography: Classification (V. V. Sharygin, SIGM and UrFU). The meteorite shows a chondritic texture. The amount of chondrules and their fragments is up to 90 vol.%. Their sizes vary from 30-50 µm to 2 mm and they are well delineated. They have barred, porphyritic or cryptocrystalline texture and mainly consist of olivine, low-Ca-pyroxene and glassy matrix, diopside, and ±chromite and blebs of troilite and FeNi-metal. In all chondrules the matrix does not contain fresh glass, now it is fine-devitrified aggregate. Olivine and sometimes low-Ca-pyroxene form skeletal/dendritic crystals and contain silicate-melt inclusions in some chondrules. In addition the crystals of these minerals sometimes show evident zonation. All these indicate the high rate of quenching. The exotic porphyritic chondrules containing olivine, spinel, plagioclase and cryptocrystalline Pl-Cpx matrix (former glass) are very rare. Olivine and low-Ca-pyroxene are main minerals in fine-grained matrix; plagioclase was not observed. All petrographic features indicate a petrological type of 3 for the meteorite. Undulatory extinction and irregular fractures in olivine reveal a shock stage of S2. Majority of grains of FeNi-metal (100-500 µm) are mainly represented by kamacite, taenite and tetrataenite; but individual grains of kamacite also occur. The Neumann lines were locally observed in kamacite. Rare copper grains (up to 10 µm) were found in tetrataenite-taenite-troilite association. Sizes of troilite grains are 50-200 µm. Weathering products (goethite and other Fe-Ni-hydroxides, calcite, Fe-Ni-carbonate) are not very abundant and occur as in situ partial alteration of FeNi-metals and troilite and fill microfractures in all minerals (weathering grade – W2). Pentlandite+Ni-rich pyrrhotite (up to 10 µm) is rarely observed in troilite. Clinopyroxene, chromite and chlorapatite (50-100 µm) occur locally in the matrix. Merrillite was found only as rounded inclusions (up to 5 µm) in FeNi-metal and troilite. The fine-grained fusion crust (occasionally vesicular) is up to 100 µm and contains zoned olivine, Fe-rich or Fe-poor glass, magnetite and sulfides, rare low-Ca pyroxene. In the chondrules, which were in fusion crust zone, the matrix turned into glass and individual metal-sulfide blebs appeared. The blebs consist of troilite, Ni-rich metal and Ni-rich sulfides.

Geochemistry: EDS-WDS analyses (ViV. ctor V. Sharygin, SIGM and UrFU). The primary chondrite paragenesis includes olivine, low-Ca-pyroxene, Cr-bearing clinopyroxene, plagioclase, spinel-supergroup minerals, chlorapatite, merrillite, FeNi-metals and copper. The main minerals vary widely in composition. The averaged olivine is Fa_23.94±7.36 (N=141). However its zoned crystals in chondrules show more contrast compositions: core (min) – Fa_0.80, rim (max) – Fa_31.53; grains from matrix indicate more homogeneous composition - Fa_29.4±0.61 (N=31), outlining the LL group. The same situation is with low-Ca-pyroxene: average - Fs_14.91±8.12Wo_1.96±1.85 (N=70); chondrules: core (min) – Fs_1.97, rim (max) – Fs_36.93; matrix – Fs_19.10±6.07Wo_1.35±0.32 (N=8). Plagioclase is rare: anorthite An_72.9Ab_24.3Or_2.8 (N=6) occurs in spinel-containing chondrules, whereas albite Ab_93.2An_3.7Or_3.1 (n=1) – in matrix of some POP chondrules. Spinel-supergroup minerals are represented by chromite Crt_87.1Spl_6.5 (N=15, common in matrix), spinel Spl_98.8Crt_0.3 (N=6, in some chondrules) and intermediate chromite-spinel Crt_49.9Spl_47.5 (n=5, in some chondrules). Composition of metals (in wt.%): kamacite (N=35) – Fe 93.16±0.59, Ni – 5.88±0.58, Co – 1.00±0.17; taenite (N=22) – Fe 65.55, Ni 34.02, Co 0.48; tetrataenite (N=19) – Fe 48.43, Ni 51.25, Co 0.34; copper (N=5) – Fe 5.42, Ni 3.02, Cu 91.61. Pentlandite (in wt.%, N=5): Fe 46.42, Ni 19.83, Co 0.42, S – 33.49. Former glasses in chondrules also show contrast compositions: with moderate alkalis (Na₂O 5.3-9.7, K₂O 2.2-4.1, SiO₂ 60.1-77.4, Al₂O₃ 10.6-16.3 wt.%) and nepheline-normative (Na₂O 10.2-15.2, K₂O 0.2-3.5, SiO₂ 47.5-60.7, Al₂O₃ 18.0-27.4 wt.%).

Classification: Ordinary chondrite. LL3, S2, W2. Estimated subtype 3.4/3.9 based on variations of Fa in olivine and Fs in low-Ca pyroxene.

Specimens: 2056.6 g sample – UrFU; 6.53 g cut-off and thin section – SIGM.