Dunite 1 2

NWA 15717 pairing

Northwest Africa 15717 (NWA 15717)

Place of discovery: Northwest Africa

Purchased: 2022

Classification: Ungrouped achondrite, lherzolitic breccia.

History: The meteorite was purchased from a meteorite dealer in Morocco.

Physical characteristics: Several light grayish to cream-coloured fragments with patches of black fusion crust.

Petrography: The meteorite is an achondritic breccia composed up to 2 cm sized lithic and up to 8 mm sized euhedral to subhedral mineral fragments in a fine-grained cataclastic and related matrix. Most abundant in all lithologies are Mg-rich, mostly compositionally homogeneous olivine (about 75 vol%) and low-Ca pyroxene (about 20 vol%). Zoned olivine and exsolved pyroxenes are rare. Accessories (about 5 vol%) include silica, chromite, FeS, kamacite, and taenite. Contains augite-chromite and orthopyroxene-chromite symplectites. No feldspar found.

Geochemistry: compositions of individual olivine grains: Fa9.8±0.1, FeO/MnO=37±3, n=7; Fa16.7±0.1, FeO/MnO=37±1, n=7; Fa18.6±0.1, FeO/MnO=38±2, n=10; Fa20.1±0.1, FeO/MnO=41±2, n=7; Fa24.9±0.1, FeO/MnO=40±1, n=7; fayalite: Fa82.7±0.2, FeO/MnO=39±1, n=5; zoned olivine: Fa25.3±3.1 (Fa21.6-29.1, FeO/MnO=43±3, n=7); low-Ca pyroxene: Fs34.5±0.3Wo3.6±0.2, FeO/MnO=28-31, n=7); low-Ca pyroxene host to exsolution lamellae: Fs65.4±0.4Wo7.4±0.1 (Fs64.7-65.7Wo7.2-7.6, FeO/MnO=24-27, n=7); Ca-pyroxene exsolution lamellae: Fs38.5±1.8Wo38.1±2.2 (Fs37.3-41.6Wo34.3-40.0, FeO/MnO=29-34, n=7); chromite: Mg#41.5±0.8, Cr#70.2±0.2, n=7

Mass (g): 1000

Pieces: several

Class: Achondrite-ung

Shock stage: low

Weathering grade: low

Magnetic suscept.: 3.29

Classifier: A. Greshake, MNB

Main mass: Polandmet - Marcin Cimala


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