Eucrite, polymict, anomalous
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Purchased October 2015
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Four pieces of a polymict eucrite having a combined weight of 1,193 g were purchased by M. Jost from a Moroccan dealer. A type sample was sent to the University of Washington in Seattle (A. Irving and S. Kuehner) for analysis and classification, and NWA 10674 was determined to be an anomalous polymict eucrite breccia.

Northwest Africa 10674 is a complex breccia composed predominantly of eucritic clasts (orthopyroxene with exsolved pigeonite and calcic plagioclase) having variable textures, mixed with disaggregated eucrite-related clastic material. Minor phases in the eucrite breccia include silica polymorph, chromite, ilmenite, troilite and fayalite, as well as sparse diogentic clasts (~2 vol%). The meteorite is unusual in that it contains abundant metal-bearing vitric breccia clasts (20 vol%) composed of magnesian silicates (orthopyroxene and olivine) interspersed with grains of FeNi-metal (kamacite) within glass.

Notably, Warren et al. (2017) identified several cm-scale, metal-rich (12–17 vol%), ovoid silicate nodules in the polymict eucrite Camel Donga. These nodules are enriched in Ni and trace siderophile elements and lack other evidence for in situ reduction. They concluded that the metal nodules reflect the addition of an impactor component to the material that was precursory to Camel Donga. They speculate that this was a complex two-stage process involving metasomatic alteration by a reducing fluid that originated as a metal- and volatile-rich carbonaceous-chondritic (e.g., CM-type) contaminant. See the Camel Donga page for a photo and further details about this alteration process.

The specimen of NWA 10674 shown above is a 7.08 g partial slice acquired from the Space Jewels Switzerland Collection of Marc Jost. Click on the photos below to see magnified images.

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click on photos for a magnified view