NWA 8659 (Brecciated Monomict Eucrite - Stannern Trend) SOLD OUT

NWA8659(MM)A 45.8g desert varnished stone was found by a nomad searching the deserts of Northwest Africa in 2013. I subsequently purchased the stone from a dealer within the United States in December of the same year.  A sample was sent to Dr. Paul Warren who initially determined the stone to be a Momomict Eucrite and continued further study on the stone. It appeared to be very evolved eucrite which warranted further and more detailed study. After the submission of a second sample to UCLA, Dr. Warren conducted extensive studies including gathering REE data on the two samples and concluded the eucrite to have Stennern Trend affinities, with TiO2 levels far exceeding that of Stannern itself (only one eucrite is known to have higher TiO2).  The stone continues to be studied as it is providing valuable clues to the origination and aqueous alteration of olivine rich veins within eucrites. Dr. Warren has submitted an abstract detailing his work on this stone for the 2015 Meteoritical Society meeting in Berkeley, with a future paper to follow. A copy of the abstract (prior to its release) can be seen here.   See the Meteoritical Bulletin entry here. Slices of the stone were prepared by the  Montana Meteorite Laboratory and will come in a labeled meteorite display box.

Petrography as follows:

Slices through the stone indicate that most of the material is thoroughly brecciated, yet a single large clast comprising about 40% of the stone is essentially unbrecciated. The unbrecciated material shows a subopthitic texture with grain size typically 2 mm. Minor Fe-metal. The pyroxenes are to an unusual extent pervaded by secondary olivine-dominated veins. Pyroxene is mostly equilibrated to a tie-line between low-Ca pyroxene En32.0±0.7Wo3.4±0.4, FeO/MnO wt ratio 33.6±1.5, n=11, and high-Ca pyroxene En26.6±0.1Wo42.3±0.2, n=6, but in the cores of a few large grains a low-Ca zoning trend survives with composition as magnesian as En58Wo7; primary-igneous plagioclase An81.3±2.4, n=40; secondary veins within pyroxenes have An98 plagioclase, along with olivine Fa83.5±0.5, n=11. Oxygen isotopes:  δ17O 2.083, δ18O 4.376, Δ17O -0.227 (all normalized). Bulk composition: (fused-bead EPMA, in wt%, derived from a 0.28 g powder) SiO2 49.5, TiO2 1.28, Al2O3 11.5, Cr2O3 0.24, MgO 5.5, FeO 18.2, MnO 0.51; mg# 0.349; trace elements (µg/g) Sc 29.9, V 43, Ni 11, Co 7.5, La 7.1, Sm 4.1, Eu 0.90, Lu 0.49, Hf 2.6

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