Northwest Africa 14498 (NWA 14498)

Morocco

Purchased: 2012

Classification: Ordinary chondrite (LL4-6)

History: Sample was purchased in 2012 from Adam Aaronson at the Tucson mineral show who acquired it from Morocco. Sample is catalogued at ROM as M58214.

Physical characteristics: Single individual, mostly fusion crust covered with well-developed desert polish and minor rusting.

Petrography: Cut surfaces and a petrographic thin section reveal a fragmental breccia, consisting of a green-gray clastic groundmass containing chondrule fragments and angular clasts at all scales ranging up to 2 cm. Clasts are dominantly of petrographic grade 5 and 6 and typically have brown, fine-grained rims of groundmass material. Olivine and pyroxene in chondrule fragments and clasts commonly show undulatory to mosaic extinction. Some clasts in thin section contain shock veins bearing minute sulfide grains. Weathering is limited to Fe-oxide staining near sulfide-rich zones. BSE images show evidence for extensive annealing of all silicate, metal and sulfide grain boundaries in the LL6 clasts. Strings of sub-micron metal inclusions are observed in olivine and Ca-poor pyroxene grains in the LL6 clasts as well as in many smaller monomineralic fragments in the groundmass.

Geochemistry: Olivine is equilibrated throughout meteorite. Ca-poor and Ca-rich pyroxene has varied compositions, but appear equilibrated in the petrographically observed LL6 clasts.EPMA: Olivine Fa_30.89±0.48 (n=30); Ca-poor pyroxene Fs_23.87±2.20 (n=22); Ca-rich pyroxene Wo_33.47±11.36 (n=10); LL6 clasts only: Ca-poor pyroxene Fs_24.87±0.56 (n=7); Ca-rich pyroxene Wo_40.71±1.89 (n=6); BO chondrule fragment: Ca-poor pyroxene Fs_15.55-20.41 (n=2); Ca-rich pyroxene Wo_17.33±3.36 (n=3).

Classification: LL4-6 breccia (S4) W1. Breccia contains abundant highly-shocked clasts and appears to be a mechanical mixture of fragments and groundmass.

Specimens: Type specimen mass as slices, a billet and thin section at ROM. Main mass: D. Gregory.