NWA 2999 was one of the first available angrite meteorites on the collector market. At the time, emerging research pointed to the possibility that Angrites may have originated from the planet Mercury. It may have certain characteristics that suggest it is a planetary meteorite, but perhaps not from Mercury. It may represent another undiscovered large asteroid. There are less than two dozen known angrite achondrites, and this one has a low-TKW, so there is not much to go around.
Northwest Africa 2999
Morocco or Algeria
Find: 2004
Achondrite (angrite)
History: Twelve individual dark brown stones totaling 392 g, each with a thin fusion crust, were purchased from a Moroccan dealer in Tagounite by G. Hupé in August 2004.
Physical Characteristics: Grain size is predominantly from 0.1 to 0.5 mm, but all stones have irregularly distributed, larger yellowish plagioclase grains (up to 6 mm across) exhibiting an iridescent luster.
Petrography: (A. Irving and S. Kuehner, UWS; T. Bunch and J. Wittke, NAU) Based upon examination of thin sections of all separate stones, this meteorite is texturally heterogeneous. Terrestrial weathering has resulted in partial replacement of metal and minor grain boundary staining by iron hydroxides. The overall texture is protogranular, but there are large porphyroclasts of anorthite, spinel, and polygranular olivine. Anorthite also occurs as narrow (10–20 µm wide) coronas around spinel grains adjacent to clinopyroxene and both spinel and diopside are compositionally zoned away from the coronas. Texturally, this meteorite is very different from most angrites.
Classification: Achondrite (angrite).
