Northwest Africa 16900 (NWA 16900) Tiris Zemmour, Mauritania Purchased: 2024 Classification: Primitive achondrite (Brachinite) History: A single uncrusted 23.2 kg stone was found by Hameti and Omar Harras in the Tiris Zemmour region of Mauritania in 2024. Salek Mrabih (Dominions meteors) purchased the sample from the finders in in 2024. Physical characteristics: The sample is ovoid shaped, lacks a fusion crust and is partially colored with a yellowish-orange calcite patina. Cut face shows a granoblastic texture and dark colored-opaque grains. Petrography: Description and classification (A. Love, App): Sample shows a granoblastic texture composed of (vol%): olivine (86); twinned diopside (5) and twinned plagioclase (2) that meet at 120° grain boundaries and have an average grainsize of 483 µm (n=47). Additional minerals are marcasite, phosphates, troilite, chromite, and FeNi droplets occur within some silicates. Geochemistry: (A. Love, App) Olivine (Fa29.4±0.3, Fe/Mn=56.3_2.2, n=18); Ca pyroxene (Fs9.3±0.1Wo43.6±0.1, Fe/Mn=26.8±2.2, N=10); plagioclase (An27.9±2.3Ab70.6±2.3Or1.5±0.5, n=8); Chromite (Cr#=84.3±0.2, Mg#=23.6±0.7, TiO2 Wt%=1.3±0.0, n=6). Classification: primitive achondrite (Brachinite U-S2 moderate weathering) Ultramafic assemblage with equilibrated texture dominated by relatively iron-rich olivine and subordinate clinopyroxene and plagioclase are consistent with brachinites. Specimens: Salek Mrabih (Dominions meteors) holds the main mass. One endcut and a slice weighing 65.2 g and a polished mount and thin section are on deposit at App. Data from: MB113 Table 0 Line 0: State/Prov/County: Tiris Zemmour Date: P 2024 Mass (g): 23200 Pieces: 1 Class: Brachinite Shock stage: U-S2 Weathering grade: moderate Fayalite (mol%): 29.4±0.3 Ferrosilite (mol%): 9.3±0.1 Wollastonite (mol%): 43.6±0.1 Classifier: A. Love, App Type spec mass (g): 65.2 Type spec location: App Main mass: Salek Mrabih (Dominions meteors) Finder: Hameti and Omar Harras Comments: Submitted by Anthony Love