Northwest Africa 15296 (NWA 15296)

(Northwest Africa)

Purchased: 2022

Classification: Ordinary chondrite (L, melt rock)

History: The meteorite was reportedly found 2021 in Mali and subsequently purchased from a meteorite dealer in Algeria.

Physical characteristics: Many dark brownish fragments without fusion crust.

Petrography: The igneous rock displays a granular texture of predominantly 30-200 µm sized partly euhedral olivine and pyroxene grains together with interstitial Si,Al-rich mesostasis. Olivine shows weak and pyroxene strong compositonal zoning. Pyroxene are often overgrown by thin augite margins. Opaque phases are chromite, sulfides, and rare FeNi metal typically occurring as blebs in the mesostasis. Neither feldspar nor relict chondrules detected. The meteorite contains shock melt veins and pockets.

Geochemistry: olivine: Fa_25.3±1.2 (Fa_23.8-28.3, FeO/MnO=47±3, n=10); pyroxene: Fs_16.3±2.2Wo_15.0±13.1 (Fs_12.7-18.8Wo_2.2-34.8, FeO/MnO=24±3, n=15); mesostasis (wt%): SiO₂: 68.5±1.4, Al₂O₃: 19.5±0.5, Na₂O: 3.77±0.32, K₂O: 0.65±0.04, CaO: 2.22±0.12, MgO: 0.54±0.10, FeO: 1.32±0.29, TiO₂: 0.09±0.03, N=7

Classification: L-melt rock. The silicate composition do not exactly fit the range for equilibrated L chondrites, but this is often the case with chondritic melt rocks, and L is the closest match.