A new metal-rich mesosiderite from Antarctica, RKPA79015

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A 10.0kg iron-rich meteorite (RKPA79015) and four silicate-rich fragments (RKPA80229,80246,80258,and 80263) are individuals from a new Antarctic mesosiderite. The silicate minerals present are orthopyroxene of uniform composition ((Wo)_2(En)_<74>(Fs)_<24>) and calcium-rich plagioclase of somewhat variable composition ((An)_<86>-(An)_<94>). Pigeonite and olivine have been looked for and not found. Chromite containing (Al)_2O_3 7.0%, MgO 1.8%, MnO 1.6%, and TiO_2 0.5% is present, as is merrillite. Analysis of the metallic component gave 9.87% Ni, 0.52% Co, 0.15% P, and 2.14% FeS. Metallic areas consist of polycrystalline kamacite with grain boundaries containing cloudy taenite and schreibersite. Cloudy taenite areas have thick borders of tetrataenite. These metallographic associations indicate a low-temperature cooling history identical to that of well known mesosiderites.
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