Calama 009        22°24.200’ S, 68°37.632’ W

Antofagasta, Chile

Find: 2017 Oct 13

Classification: Ordinary chondrite (L6)

History: The 13.5 kg meteorite was found 13 October 2017 by the UrFU meteorite expedition-2017 in Chile (Pastukhovich A.Yu., Larionov M.Yu., Kruglikov N.A., Kolunin R.N.) near Chiu-Chiu, Calama region.

Physical characteristics: The meteorite has angular shape. Exterior of the stone is desert polished. The interior of the meteorite is light gray in color with red-brown spots due to Fe-hydroxides around metal and troilite. Fusion crust is present.

Petrography: Classification (V. V. Sharygin, SIGM and UrFU). Petrographic observation of a polished thin section shows very rare chondrules in a coarse recrystallized matrix. Chondrules are very poorly delineated with apparent size to 1 mm. The porphyritic and olivine- or orthopyroxene-barred chondrules are common and mainly consist of olivine, low-Ca-pyroxene and plagioclase, diopside, and ±chromite and blebs of troilite and FeNi-metal. Olivine, low-Ca-pyroxene and plagioclase are main minerals in matrix. Plagioclase grains are larger than 50-100 µm. This indicates a petrological type of 6 for the meteorite. Undulatory extinction, irregular and planar fractures in olivine, as well as the presence of opaque melt pockets and twinning in low-Ca-pyroxene, troilite and ilmenite, indicate a shock stage of S3/4. Majority of grains of FeNi metal (kamacite, taenite, tetrataenite, up to 1.5 mm) and troilite (100-500 µm) are fresh. Weathering products (goethite and other Fe-Ni-hydroxides) occur as in situ partial alteration of FeNi-metals and troilite and fill microfractures in minerals from matrix and chondrules (weathering grade W1/2). Grains of copper (up to 50 µm) are occasionally found in kamacite-taenite-tetrataenite aggregate. Pentlandite (±Ni-rich pyrrhotite, 4.4-6.1 wt.% Ni, up to 10 µm) is rarely observed in troilite. Ni-free pyrrhotite sometimes fills fissures in troilite and seems to be an intermediate phase of troilite alteration to goethite and other Fe-hydroxides. Clinopyroxene, chromite, ilmenite, chlorapatite and merrillite (100-300 µm) occur locally in the matrix. Opaque melt pockets (up to 100 µm) are rarely located near large FeNi-metal grains and contain abundant metal blebs in fine-grained olivine-pyroxene aggregate.

Geochemistry: EDS-WDS analyses (V. V. Sharygin, SIGM and UrFU). The primary chondrite paragenesis includes olivine Fa_25.68±0.43 (N=40), orthopyroxene Fs_21.46±0.32Wo_1.43±0.31 (N=32), plagioclase Ab_83.9An_10.5Or_5.6 (N=25), Cr-bearing clinopyroxene En_45.8Fs_8.6Wo_45.8 (N=2), chromite Crt_81.2Spl_13.3 (N=11), ilmenite Ilm_84.9Gkl_12.9 (N=16), chlorapatite, merrillite, FeNi-metals and copper. Chlorapatite contains F (up to 0.9 wt.%); Cl – 5.33 wt.% (N=11). Merrillite is poor in FeO (0.5-0.7 wt.%, N=11). Composition of metals (in wt.%): kamacite (N=22) – Fe 94.38±1.59, Ni – 4.77±1.52, Co – 0.84±0.24; taenite (N=40) – Fe 66.78±3.53, Ni 32.75±3.49, Co 0.42±0.08; tetrataenite (N=16) – Fe 44.65±1.24, Ni 55.07±1.26, Co 0.22±0.05; copper (N=10) – Cu 93.13±0.69, Fe 4.46±0.66, Ni 2.37±0.18.

Classification: Ordinary chondrite. L6, S3/4, W1/2.

Specimens: 12.512 kg at UrFU; 960 g at The Catholic University of the North, Antofagasta, Chile; 19 g and thin section – SIGM.