Northwest Africa 13964 (NWA 13964)

(Northwest Africa)

Purchased: 2021 Mar

Classification: Lunar meteorite (feldspathic breccia)

History: Purchased by Craig Zlimen and Mark Lyon in March 2021 from an Algerian dealer. The main mass plus an additional piece were subsequently acquired by Alan Ginsberg.

Physical characteristics: Two similar-appearing pieces (4630 g, 1900 g) lacking fusion crust, which are naturally broken portions of a single meteorite stone. The material is composed of relatively large beige and light gray, angular clasts in a medium gray matrix.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Anorthositic breccia composed of >95 vol.% anorthitic plagioclase as both polymineralic lithic clasts (anorthosite, plagioclase-rich basalt) and mineral grains within a fine grained matrix. The most common mafic phase is olivine, but orthopyroxene, augite and pigeonite are also present, along with accessory Ti-chromite, troilite, rare armalcolite and minor secondary barite.

Geochemistry: Olivine (Fa_23.2-33.3, FeO/MnO = 88-102, N = 4), low-Ca pyroxene (Fs_28.6-35.8Wo_2.0-3.5, FeO/MnO = 51-59, N = 3), pigeonite (Fs_24.4-29.4Wo_9.2-9.5, FeO/MnO = 44-48, N =2), augite (Fs_11.9-20.1Wo_38.9-43.8, FeO/MnO = 45-56, N = 2), anorthite (An_95.9-96.8Or_0.1±0.0, N = 3), armalcolite (Mg_0.4Fe_0.46Cr_0.06Al_0.07Ti_1.97O₅).

Classification: Lunar (anorthositic breccia).

Specimens: 26.1 g including one polished thin section at UWB; 4630 g stone plus a 441 g piece from the 1900 g stone with Mr. A. Ginsberg; remainder held jointly by Mr. C. Zlimen and Mr. M. Lyon.