Northwest Africa 2998

Algeria

Find: 2006

Achondrite (lunar, anorthositic breccia)

History: Found in the southern Algerian desert in May 2006. Purchased by A. Aaronson in Morocco, June 2006.

Physical characteristics: Medium brown, oriented, nearly complete 163 g stone. The fusion crust is fresh, with very prominent flow lines.

Petrography: (T. Bunch and J. Wittke, NAU) Breccia-in-breccia structure; breccia clasts are granulated or cataclastized with fine-grained to melt matrix. Vesiculated shock-melt veins and isolated glass clumps are common. Consists of partially maskelynitized plagioclase fragments (47 vol%), shock-melt anorthositic clasts (38 vol%), dark glasses (7 vol%), norites and troctolites (6 vol%), and olivine and pyroxene fragments (2 vol%). No mare components were observed.

Mineral compositions and geochemistry: Plagioclase (An_93.6–99; FeO = 0.15–0.35 wt%), olivine (Fa_21.7–34.6; FeO/ MnO = 79–87), orthopyroxene (Fs_22.5–29.5Wo_2.1–3.2; FeO/MnO = 53–59), pigeonite (Fs_49.3Wo_5.2; FeO/MnO = 53), augite exsolution lamellae in pigeonite (Fs_27.4Wo_43.1), ferroaugite (Fs_45.8Wo_38.9; FeO/MnO = 28). Bulk composition: (R. Korotev, WUSL, INAA of 224 mg sample) FeO = 2.7 wt%; Ni =60, Sm = 0.42, and Th = 0.13 (all ppm).

Classification: Achondrite (lunar, anorthositic breccia).

Type specimen: A total of 20.4 g and one thin section are on deposit at NAU. The main mass holder is anonymous.