Northwest Africa 4536
Western Sahara
Find: December 2006
Achondrite (eucrite)

History: Purchased in Erfoud (Morocco) in December 2006.

Physical characteristics: One piece with nearly complete (90%) shiny dark, cracked fusion crust and deep, well-formed regmaglypts. Interior is light greenish-yellow in color. Sawn section displays two lithologies: one fine-grained with millimeter length laths, dark needles (plagioclase and pyroxene) and white spots, the other is gray and brecciated with dominant pyroxene. Total weight, 283.1 g.

Petrography: (A. Jambon, O. Boudouma and D. Badia, UPVI) Fine-grained lithology dominated by equant grains of plagioclase and pigeonite. Accessories phases are ilmenite, augite, silica, and troilite. Plagioclase and pigeonite form equant sub-hexagonal crystals of about 5–20 μm. Mode (vol%): Plagioclase 44, pigeonite 27, augite 16, silica 10, ilmenite and troilite 1, fractures and voids 3. The coarse-grained lithology is dominated by shocked basaltic eucrite with grains of 0.2 to 1 mm. Laths of plagioclase interstitial to pyroxene.

Mineralogy: (EMPA and SEM). Plagioclase An89; pigeonite En35Fs63Wo2, FeO/MnO = 33, Mg# = 0.36; augite En30Fs30Wo40, FeO/MnO = 34, Mg# = 0.50.

Classification: Basaltic, dimict eucrite; fresh sample, no weathering is observed.