NWA 7809, enstatite achondrite

This meteorite was initially classified as an aubrite, but Udry et al. took a closer look at this stone and a few other NWA “aubrites” and showed that they were different: Reclassification of four aubrites as enstatite chondrite impact melts (2019).

After reviewing the data and samples in person: NWA 4799 and NWA 7809 are paired, and NWA 11071 is likely paired with those two finds. Fusion-crusted specimens from this find tend to be less weathered than smaller fragments, and the slight differences in %vol fresh metal versus weathering products reflect that.  There is also a fair amount of textural variation within the find; I purchased this 77 gram stone from the same seller as NWA 7809, and at the same time.  It is likely paired.

While these meteorites do appear to have affinities to EH chondrites, calling a coarse-grained plutonic rock an “impact melt” is…pretty strange, and without precedent.  They’re not impact melts.

In accordance with prior classification schemes, these four meteorites should be classified as ungrouped enstatite achondrites with EH affinities, until enough unpaired members are found, to warrant designating a new group.

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