| Price : 15€/g |
Northwest Africa 14518 (NWA 14518)
(Northwest Africa)
Purchased: 2021
Classification: Mesosiderite (group A3)
History: Purchased from a Moroccan meteorite dealer in 2021.
Physical characteristics: Single object with irregular, dark gray-brown exterior. Saw cut reveals numerous irregular metal domains >1 mm, but also abundant fine-grained metal, distributed uniformly throughout a silicate groundmass.
Petrography: (A. Ross and C. Agee, UNM) Microprobe examination of a polished mount shows pyroxene making up approximately 75% of the silicate portion of this meteorite, ~25% plagioclase, with ~5% minor phases silica, ilmenite, merrillite, chromite, rutile, and troilite. Some pyroxene grains have exsolution lamellae. 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 ?m) grains throughout the silicate domains. Both kamacite and taenite are present. No brecciation observed.
Geochemistry: (A. Ross, UNM) Low-Ca pyroxene Fs31.5±1.3Wo4.3±0.51, Fe/Mn=26±1, n=4; high-Ca pyroxene Fs17.7±0.9Wo37.4±1.6, Fe/Mn=23±1, n=3; plagioclase An88.4±2.0Ab11.0±1.9Or0.6±0.2, n=6; kamacite Fe=93.7±0.2, Ni=6.5±0.2, Co=0.49±0.02 (wt%), n=3; taenite Fe=49.2±2.5, Ni=50.4±2.2, Co=0.07±0.02 (wt%), n=3
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.
