La’gad 003        27.606°N, 8.761°W

Saguia el Hamra, Western Sahara

Find: 2015

Classification: Lunar meteorite (feldspathic breccia)

History: Found in 2015 by nomads on a small hill named Grarat-Zawi, and purchased by Darryl Pitt on behalf of MMGM from Mauritanian dealers in the period August-October 2015.

Physical characteristics: A single, very large stone (27.249 kg) found as a group of many pieces which fit together (but with several missing pieces). The specimen lacks fusion crust, but individual pieces have thin coatings of light-brown weathering products. Fresh interiors exhibit angular, whitish clasts within a dark-gray matrix.

Petrography: (A. Irving and S. Kuehner, UWS) Breccia composed predominantly of mineral clasts plus rare glass clasts and basalt clasts in a finer grained, partly vesicular matrix. Minerals are anorthite, olivine, pigeonite, orthopyroxene, exsolved pigeonite, subcalcic augite, Al-rich chromite, ilmenite and baddeleyite. Minor amounts of secondary calcite and barite are present.

Geochemistry: Olivine (Fa_30.0-52.6, FeO/MnO = 84-110, N = 4), pigeonite (Fs_28.2-38.2Wo_9.8-14.7, FeO/MnO = 50-54, N = 3), orthopyroxene (Fs_19.3Wo_4.5, FeO/MnO = 57), subcalcic augite (Fs_49.6Wo_28.3, FeO/MnO = 59), plagioclase (An_95.2-97.1Or_0.1-0.2, N = 3). Bulk composition (R. Korotev, WUSL) INAA of 10 subsamples from different portions of the reassmbled mass gave the following mean abundances: (in wt.%) FeO 5.95±0.88, Na₂O 0.34±0.02, BaO 0.51; (in ppm) Sc 13.6±2.6, Cr 930±210, Ni 140±160, La 2.3±0.6, Sm 1.0±0.2, Eu 0.75±0.06, Yb 0.85±0.14, Lu 0.13±0.02, Hf 0.65±0.13, Th 0.37±0.11.

Classification: Lunar (feldspathic regolith breccia). Based on closely similar bulk chemical compositional data (determined by Dr. R. Korotev at WUSL utilizing the same INAA methods), it is likely that the NWA 10509 stone and the material classified as NWA 10798 are paired portions of the same disaggregated meteorite. Another lunar feldspathic meteorite from a different location in the same dense collection area received the name La’gad, but analyses by Dr. Korotev demonstrate that the La’gad stones differ from the material described here, especially in having much higher (by a factor of 6) abundances of Th and other lithophile elements.

Specimens: 33.21 g including two polished endcuts at UWB; main mass at MMGM.