Northwest Africa 11223 (NWA 11223)

Morocco

Purchased: 2017

Classification: Lunar meteorite

Physical characteristics: Physical Characteristics: The ROM specimen is one of many pieces found by a meteorite hunter in Morocco. The largest fragments are over 2 kg, with many smaller pieces adding to a total of approximately 10 kg. All specimens observed lacked fusion crust and most were covered in a very thin surface coating of white caliche. However two specimens, which were apparently exposed to the desert winds, showed no caliche, exposing a dark-gray interior with obvious lithic clasts.

Petrography: (ROM; K. Hewson, V. Di Cecco, I Nicklin, ROM) In hand sample and thin section the specimen shows lithic and mineral clasts set in a dark-gray, glassy matrix. No vesicles were observed. The largest lithic clast in the ROM specimen is light gray in color and measures 1 × 0.5 cm. Two other relatively large clasts are of a more mixed mineralogy.

Geochemistry: (K. Hewson, V. Di Cecco) Feldspar grains have highly anorthitic composition (An_90.9-98.6Ab_0.0-7.4Or_0.1-2.1, n = 94), which is consistent both in the clasts and the matrix. Olivine grains, although rare, are forseritic (Fa_28.0-44.5, FeO/MnO = 84.8-119.2, n=15). Pyroxene grains are more common than olivine and are variable in composition. They include augite (En_30.2-48.4Fs_23.7-26.6Wo _2.5-26.6, FeO/MnO = 52.4-61.1, n=5), pigeonite (En_40.4-68.0Fs_23.3-49.0Wo_6.0-19.1, FeO/MnO = 51.8-63.6, n=14) and enstatite (En_64.0-65.5Fs_31.6-32.1Wo _2.5-3.9, FeO/MnO = 57.6-62.9 n=3).

Classification: Lunar (feldspathic impact-melt breccia). The largest lithic clast noted has an anorthitic composition, as given by the geochemistry. The two other relatively large clasts have noritic and olivine-noritic compositions based on geochemistry and mineral modality. Mineral fragments are anorthite, clino and orthopyroxenes and rare olivine. Both the lithic and mineral clasts show extensive shock features including mosaicism, planar fracturing and, in the lithic clasts, granularization of the component minerals. Despite the generally uniform caliche coating on most of the specimens the weathering is minimal being confined largely to the exterior but with some very few, very fine fractures containing material similar to the caliche coating which is predominantly barite.

Specimens: The ROM holds the main mass of this sample, which originally weighed 28 g. It is now composed of 2 pieces weighing 17.52 and 4.83 g, a thin section, a thin section billet, and 0.20 g of cutting dust.