Claromecó        38°48.264’S, 60°07.386’W

Buenos Aires, Argentina

Find: 1963

Classification: Ordinary chondrite (L5/6)

History: Two reddish brown meteoritic stones of 13 kg each were found in 1963 by Mr. F. Massigogge. The stones were leaning against a windmill in his farm at Argentine Pampas, and were reported a few years ago to geologist Rogelio Daniel Acevedo. The farm owner knew the exact location where he had found the stones. No other specimens are known.

Physical characteristics: The meteorites have a rusty appearance that is indicative of having experienced significant terrestrial weathering and the matrix is oxidized. About 90% of the original specimens were covered by a fusion crust. The degree of weathering is variable on the cm-scale of the thin section. The sample is moderately weathered and about half of the metals have been destroyed. Close to the surface most of the metal is gone. Once cut the metal grains are barely oxidized by terrestrial alteration, but the matrix is significantly colored by iron staining.

Petrography: Rogelio D. Acevedo (CONICET), J. M. Trigo-Rodriguez (CSIC-IEEC), A. Bischoff and S. Ebert, (IfP), I. Subías, J. Reche and A. Bergara Pinto (UAdB). The sample is well equilibrated and recrystallized. Thus, in some area, the meteorite looks like a type 6 chondrite, and in other areas chondrules can be clearly observed indicating a type 5 classification. Thus, a Type 5/6 classification is most appropriate. The olivines show planar fractures in olivine, clearly indicating shock stage S3.

Geochemistry: Mineral compositions: Olivine: Fa_24.9±0.4 (n =10); Pyroxene: Fs_20.7±0.4Wo_1.5±0.4 (n = 10).

Classification: L5/6 Ordinary chondrite

Specimens: 459.2 g at CONICET and 20 g plus two thin sections at Institute of Space Sciences (CSIC-IEEC).