NWA 1925

EucriteMonomict, gabbroic cumulate
Found 2001
coordinates not recorded

A single fresh stone (W1) weighing 86 g was found in the Sahara desert, and it was later purchased by an American dealer in Tagounite, Morocco. Based on mineral modes, grain size, and chemical composition, NWA 1925 was classified at Northern Arizona University (T. Bunch and J. Wittke) as a gabbroic cumulate eucrite, composed primarily of Ca-rich plagioclase (An91) and clinopyroxene.

Very slow cooling conditions at depth have resulted in unusually large pyroxene crystals (up to 8 mm) which poikilitically enclose lath-shaped plagioclase crystals (<4 mm) – an ophitic texture. Melt inclusions within the plagioclase contain silica, magnesian augite, and ilmenite. The pyroxene consists of inverted pigeonite with exsolved augite, as well as relict pigeonite. Pyrrhotite and chromite are ubiquitous throughout the meteorite, and sparse grains of Ni-poor metal occur. Northwest Africa 1925 has been shocked to stage 2/3.

Northwest Africa 1925 is one among a relatively small cumulate eucrite group represented in part by the monomict breccias Medanitos, Binda, Talampaya, and Dhofar 007, the unbrecciated eucrites Moama, Moore County, Nagaria, and Serra de Magé, and various other eucrites from Antarctica. The photo above shows a 3.4 g partial slice of NWA 1925.

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