NORTHWEST AFRICA 033


CL4
(C3 in MetBull 85)
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Found 1999
30° 54' N., 3° 58' W.

A stone weighing 192 g was found in the Moroccan Sahara and was designated NWA 033, also known as Taouz 003. Classification was completed at the Institut für Planetologie, Münster, Germany (main mass is with JNMC). This carbonaceous chondrite is unusual with regards to its low matrix abundance and nearly equilibrated olivines within the chondrules. It has an O-isotope composition nearly identical to that of Allende and Axtell, with an oxygen three-isotope plot within the CV–CK field (see diagram below). However, it contains less trapped noble gases, having only a cosmogenic component of neon. The meteorite has a CRE age of ~20 m.y.

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Diagram credit: Metzler et al., GCA, vol. 304, (2021)
'The Loongana (CL) group of carbonaceous chondrites'
(https://doi.org/10.1016/j.gca.2021.04.007)

After further in-depth analyses of NWA 033 as well as Coolidge (C4), Loongana 001 (C4), Los Vientos 051 (C3.9), and NWA 13400 (C3.9), Metzler et al. (2021) assigned these five meteorites to a new CL group which derives its name from Loongana 001. See the Coolidge page for further information about this group.

The percentage mean deviation (PMD) of olivine fayalite values was used by Metzler et al. (2021) as an indicator of the degree of equilibration. Northwest Africa 033 has a PMD value below 5% and is therefore designated petrologic type 4. The meteorite is shocked to stage S2 and is highly weathered to a grade of W3/4.

The specimen of NWA 033 shown above is a 5.3 g partial slice with some remnant fusion crust. The top photo below shows the reverse side, while the bottom photos show petrographic thin section micrographs of NWA 033, courtesy of Jürgen Nauber of JNMC-Zurich Meteorites (top) and Peter Marmet (bottom).

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Photo courtesy of JNMC-Zurich Meteorites

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click on image for a magnified view

Photo courtesy of Peter Marmet