Northwest Africa 8338 (NWA 8338)

(Northwest Africa)

Purchased: 2013

Classification: HED achondrite (Eucrite, melt breccia)

History: Purchased by Ali and Mohammed Hmani in Erfoud, Morocco, 2013.

Physical characteristics: Single stone, light brown-green, weathered, irregular surface, with some vesicles visible, one prominent vesicle ~2 cm in diameter. Saw cut reveals scattered plagioclase and pyroxene fragments up to 3 mm set in a very fine grained matrix, numerous vesicles throughout, many <1 mm, though larger >1 mm also present.

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows many fragmental plagioclase and pyroxene grains 50-2000 μm surrounded by vesicular melt veins and pools, some melt zones transitioning to a groundmass of very fine-grained acicular plagioclase and equant pyroxene. Fragmental plagioclase and pyroxene show irregular resorption or reaction rims, most pyroxene possess exsolution lamellae. Accessory iron metal, troilite, chromite, and silica.

Geochemistry: (C. Agee and H. Miley, UNM) Low-Ca pyroxene Fs_56.9±5.0Wo_8.2±4.3, Fe/Mn=32±1, n=17; augite Fs_29.9±1.8Wo_41.3±2.0, Fe/Mn=32±2, n=12; plagioclase An_88.8±4.0, n=9.

Classification: Achondrite (Eucrite, melt breccia) fragmental, equilibrated basaltic eucrite grains set in a vesicular eucritic melt rock.

Specimens: 24.3 g including a probe mount on deposit at UNM, Ali and Mohammed Hmani hold the main mass.