Río Cuarto 001                                   32°52.3′′S, 64°13.4′ W

Río Cuarto, Cordoba Province, Argentina

Find: 11 October 2000

Achondrite (eucrite, polymict basaltic)

History: A single stone was found in a deflation hollow (formed within a parabolic dune) during an expedition to the Pampean Plain of Argentina by P. A. Bland (ICL), C. R. de Souza Filho (UEdeC), and J. Coniglio (UNdeRC).

Physical characteristics: The 62.7 g meteorite is largely covered with a matte black, slightly weathered fusion crust. Broken surfaces and thin sections are bright gray in color with clasts clearly visible.

Petrography: (J. Levine, UChi; P. A. Bland, ICL) The meteorite consists of larger (up to 1 mm) mineral and lithic clasts set in a fine-grained matrix composed of 10–50 µm size plagioclase and pyroxene fragments. Polycrystalline clasts occur from a variety of sources, reflected in the large range of pyroxene compositions. Areas with fine-grained recrystallized melt are commonly seen. Pigeonite clasts with augite exsolution lamellae are observed. Larger fragments include plagioclase, Ca pyroxene, and basaltic clasts; plagioclase contains pigeonite and troilite inclusions. Accessory minerals, including olivine, troilite, spinel (mostly chromite), ilmenite, metal, and a silica polymorph, have been observed.

Mineral compositions and geochemistry: Plagioclase (An_92.9; range An_89.7–96.6), orthopyroxene (Fs_37.2–77.1Wo_0.3–4.8), pigeonite (Fs_62.6–85.8Wo_5.3–16.6), and augite (Fs_35.4–72.6Wo_21.3–43.5).

Classification: Achondrite (polymict basaltic eucrite).

Type specimen: 50.67 g is on deposit at UNdeRC. A 5.09 g specimen and polished thin section are on deposit at ICL. Fragments totaling 1.79 g, a polished thin section, and polished epoxy mount are on deposit at UChi.