Northwest Africa 1644

Morocco

Purchased 2001 spring

Achondrite (eucrite, polymict)

A mass of 214 g was purchased by Bessey from a dealer in Morocco. Mineralogy and classification (S. Singletary, MIT): brecciated texture with several large lithic and mineral clasts in a fragmental matrix. The clasts resemble diogenites, cumulate and basaltic eucrites in mineral composition and texture. Medium-grained cumulate eucrite clasts of ophitic texture consist of plagioclase (An91–94) and pigeonite (Wo5–10, En37–52), minor orthopyroxene (Wo3, En53) and Ti-rich chromite. Basaltic eucrite clasts with a sub-ophitic texture contain extremely iron-rich augite (possibly pyroxferroite; Wo16–31, En3–8), plagioclase (An82–87), a silica phase and Ti­rich chromite. Sparse (<5 vol%) diogenitic clasts consist of orthopyroxene (Wo2–5). Pyroxene Fe/Mn ranges from 27–33. The possible pyroxferroite grains have Fe/Mn 27–45. Matrix is pyroxene (pigeonite, augite, and orthopyroxene), minor olivine, Fe-rich sulfides, Ti-rich chromite and rare spherules of glass; one zircon grain was observed; one symplectitic grain composed of silica, augite and fayalite is interpreted to be the result of pyroxferroite breakdown. Specimens, type specimen, 20 g, TCU; main mass, Bessey.