Chug Chug 003        22°29.931’S, 69°8.683’W

Antofagasta, Chile

Find: 2018 Apr 5

Classification: Ordinary chondrite (H4)

History: Meteorite (1 piece 8700 g and 5 small fragments) was found April 5, 2018, by Mikhail Nepomiluev during a meteorite search organized by Timur Kryachko.

Physical characteristics: Total mass is 8918 g. Meteorite has roughly rounded and slightly elongated shape. The surface and interior of the meteorite is light, with dark brown fusion crust up to 2 mm. No fresh glass in fusion crust was observed. Outermost slightly fractured zone is up to 5 mm width. Cracks (up to 0.1 mm in thickness) form a network in this zone.

Petrography: (Pavel Yu. Plechov, FMMR). Petrographic observation of a polished section shows that main part of the meteorite contains well-formed chondrules in the matrix. Chondrules sizes vary from 200 to 600 µm. They have quenched or porphyritic texture, rarely cryptocrystalline, and consist of Ol, Ol+Opx, Ol+Opx+Cpx+Pl. Matrix consists of olivine grains (50-150 µm) and less low-Ca-pyroxene, which is surrounded by cryptocrystalline matrix with a significant amount of tiny (about 1 µm) round drops of metal (kamacite and taenite), chromite and plagioclase. Plagioclase grains (An_18.5-41) are less than 5 µm. These features indicate a petrological type of 4. Fresh Fe-Ni metal blebs (up to 300 µm) and troilite (up to 20 µm) occurs in matrix. Metal consists of kamacite surrounded by relatively small grains of taenite and troilite on the boundary with matrix. One elongated area (4 × 7 mm) in the thin section have sharp boundaries with main part of the meteorite. It also consists of chondrules (about 500 µm) and coarse-grained (200-400 µm) Ol-Px matrix. Less metal is in the matrix of the area of a large (2 × 2 mm) metal blob. Olivine has no undulatory extinction, and opaque shock veins and melt pockets are absent, indicating a shock stage of S1. Weathering products (goethite, "hydrogoethite") occur as veins and in situ alteration of FeNi-metals and troilite near meteorite surface. Olivine, pyroxene, chromite, metal and troilite are fresh and not weathered (weathering grade W1). Clinopyroxene, chromite and merrillite (up to 200 µm) occur locally in the matrix.

Geochemistry: Mineral composition and Geochemistry: EDS-WDS analyses (Pavel Yu. Plechov, FMMR). The primary chondrite paragenesis includes olivine Fa_19.9±1.6 (N=34), orthopyroxene Fs_14.1±3.5Wo_1.42±1.26 (N=34), plagioclase Ab_62.6An_28.8Or_6.7 (N=3), Cr-bearing clinopyroxene En_48.1Fs_6.4Wo_45.4 (N=1), chromite Crt_77.8±5.93Spl_13.2±0.78 (N=3) and merrillite. No Cl-apatite occurred in the meteorite. Merrillite contain (in wt.%, N=6) FeO - 0.28-1.71 wt.%, MgO - 3.52-3.83 and Cl - 0.01-0.02. Composition of kamacite (in wt.%, N=2): Fe 93.3-94.0, Ni 6.2-6.7, Co 0.88. Taenite contain 39.8 wt.% of Ni. Troilite is close to ideal FeS. Rare goethite contains 1.9 wt.% NiO and 0.4 wt.% CoO.

Classification: (Pavel Yu. Plechov, FMMR). Ordinary chondrite. H4, S1, W1.

Specimens: 8700 g, Mikhail Nepomiluev; 198 g (4 pieces), Timur Kryachko, type specimen at FMMR.