A new metal-rich mesosiderite from Antarctica, RKPA79015

• Main Authors: Roy S. Jr. Clarke, Brian Mason
• Format: Report
• Language: English
• Published: Department of Mineral Sciences, Smithsonian Institution 1982
• Subjects: Antarctic; Antarc*; Antarctica; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1380; http://id.nii.ac.jp/1291/00001380/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1380&item_no=1&attribute_id=18&file_no=1

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.