Bordj Badji Mokhtar 001        23°11’57.7"N, 1°01’15.0"W

Adrar, Algeria

Find: 2021

Classification: Pallasite (ungrouped)

History: Found in Algeria, 2021. Purchased by Jay Piatek from Habib Naji in March 2021.

Physical characteristics: Single piece with irregular-shaped exterior covered in black fusion crust. Sawcut surface of the deposit sample shows approximately 60% olivine (with opx and other silicate and oxide phases) and 35% metal. Olivine crystals are up to ~1 cm in size with subhedral to rounded shapes with a few fragmental and have predominantly green cores with orange rims.

Petrography: (A. Ross, C. Agee, UNM, D. Dickens NMMS) Electron microprobe analysis reveals the presence olivine, orthopyroxene, kamacite, taenite, troilite, chromite, schreibersite, silica, and merrillite. Orthopyroxene occurs primarily as 100-200 µm grains aggregated around and mantling large olivines and forming boundaries between metal domains and olivine grains. Olivine to orthopyroxene abundance ratio is variable throughout the section ranging from 2:1 to 20:1.

Geochemistry: (A. Ross, UNM) Olivine Fa_14.1±0.2, Fe/Mn=39±1, Fe/Mg=0.16±0.00, n=6; low-Ca pyroxene Fs_12.7±0.1Wo_0.5±0.1, Fe/Mn=24±0, n=6; kamacite Ni=6.3±0.1, Co=0.50±0.06 (wt%), n=2; taenite Ni=21.2±7.8, Co=0.31±0.02 (wt%), n=2. Oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave δ¹⁸O= 3.712, 3.362, 3.779; δ¹⁷O= 1.731, 1.533, 1.768; Δ¹⁷O= -0.229, -0.242, -0.227 (linearized, all per mil, TFL slope=0.528).

Classification: Pallasite ungrouped. This is a pyroxene pallasite with oxygen isotopes that plot below the Main Group, and within the HED and mesosiderite arrays. This pyroxene pallasite has similar oxygen isotopes to the pyroxene pallasite NWA 10019, but with lower Fa values similar to the pallasite main group and lacking feldspar which is present in NWA 10019.

Specimens: 23.9 g including a probe mount on deposit at UNM, Jay Piatek holds the main mass.