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NWA 1925
NWA 1925, Gabbroic Cumulate
Eucrite
This is one of the rarest Eucrites to ever be found. It is unlike any other known Eucrite, cooled at very slow rate and very deep. This meteorite is essential for any achondrite collection, but there is only a tiny bit available. I have copied the data submitted to the Nomenclature committee as written, it is so complicated. The scientists who worked on this piece were very excited about it, and considered it to be one of the best meteorites that I have ever recovered from Africa! Northwest Africa 1925 A single, 86 g complete
stone was purchased in Tagounite, April 2002. Classification and mineralogy
(T. Bunch and J. Wittke, NAU): gabbroic, cumulate eucrite; tabular crystals
of plagioclase (<4 mm in longest dimension) poikilitically enclosed
by large pyroxenes (up to 8 mm). Plagioclase is An91 with melt inclusions
of a silica polymorph, Mg-augite, and ilmenite. Complex pyroxenes consist
of inverted pigeonite (Fs52.5Wo4.2) with broad (5-8 micron) augite exsolution
lamellae (Fs25Wo41) parallel to (100) of the host opx and blebs of augite
that exsolved prior to or during pigeonite inversion. In addition, relic
patches of pigeonite contain fine augite lamellae parallel to (001).
Chromite, Cr/Cr+Al = 63-73, pyrrhotite, and tiny inclusions in opx of
Ni-poor metal (Ni = 0.48 wt%; Co = 2.28 %) are also present. No ilmenite
or silica was found outside of melt inclusions. Shock level 2/3; weathering
grade, W1. Specimens: 17.2 g, NAU; main mass, Farmer.
Yes, it really does look like granite! |
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