Northwest Africa 14987 (NWA 14987)

(Northwest Africa)

Purchased: 2021

Classification: Mesosiderite (group A3)

History: Purchased by Ziyao Wang in June 2021 from Bala Adi in Tindouf, Algeria.

Physical characteristics: Three identical appearing pieces. Weathered orange-brown exterior with some metal exposed. Saw cut reveals numerous irregular polycrystalline metal domains >1 mm distributed uniformly throughout a silicate groundmass.

Petrography: (A. Ross and C. Agee, UNM) Reflected light microscopy of a polished mount shows pyroxene making up approximately 70% of the silicate portion of this meteorite, plagioclase (~25% of the silicate fraction), and minor silica, merrillite, chromite, schreibersite, troilite, and pentlandite. Plagioclase is often poikilitically enclosed in larger pyroxene grains; no was olivine detected. Metal makes up approximately 35% of this meteorite and is primarily segregated into irregular ameboid domains >1 mm, although there are scattered smaller (~10 μm) grains throughout the silicate domains. Both kamacite and taenite are present. No brecciation observed.

Geochemistry: (A. Ross, UNM) Low-Ca pyroxene Fs_29.9±1.0Wo_3.4±2.3, Fe/Mn=21±1, n=6; plagioclase Ab_7.0±1.7An_92.8±1.7, n=6.

Classification: Mesosiderite-A3. Relatively high abundance of plagioclase and silica consistent with group A. Segregated metal, presence of some texturally and chemically equilibrated silicates, and absence of significant brecciation consistent with type 3.

Specimens: 41 g including a probe mount on deposit at UNM, WangZ holds the main mass.