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OUADANGOU (7.88 gram)


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[ Meteoritical Bulletin Database ]


Classification: Ordinary chondrite (L5)
Time/Place: Fell: November 2003 in Gnagna, Burkina Faso
Mass: 4.44 kg

History: In November of 2003, Michael Farmer traveled to Burkina Faso to purchase meteorites. During his visit he heard of a recent fall near the town of Bilanga. Mr. Farmer bought ~1.6 kg of the new fall in Bilanga, then traveled to the fall site ~40 km NNW to the villages of Batiawo and Lampiaiyre  (several km SE of Oudangou). Here he purchased the remaining 2.84 kg of stones. According to the villagers of Batiawo and Lampyaire, the stones fell within the villages and surrounding bushland, during the afternoon in early November 2003, though the exact date could not be agreed upon. Several of the stones from Batiawo had been broken into pieces by villagers. The largest stone (broken into three pieces) is 2031 g.

Physical characteristics: All stones are well-rounded showing broad, poorly developed regmaglypts, and covered by a velvety fusion crust up to 0.5 mm thick. The few reddish patches on the exterior are from the local soil. Interior is primarily white, with heterogeneous distribution of gray clasts. Clasts to 5 cm, rounded, some with scalloped margins. A few large metal-troilite nodules, to 1.5 cm. Sparse shock veining. None of the stones show signs of rusting.

Petrography: (L. Garvie, ASU) Matrix largely recrystallized with disseminated plagioclase grains <50 μm, rarely to 200 μm. Scattering of distinct chondrules, some to 1 mm, including RP, PO, and BO. Localized melting forming silicate-metal-sulfide pods. Two 1 cm2 sections show ~10 Cu grains each. Cu grains (<50 μm across) occur at metal/sulfide boundaries, and associated as a complex taenite-troilite-copper assemblage. Troilite grains show a range of pressure effects from undistorted and monocrystalline, to those with undulose extinction and a few exhibiting spindle-like twin lamellae. Chromite grains extensively fractured. Range of achondritic clast types, from dark and fine-grained to light colored with a sugary texture. Two of the light-colored clasts contain white veins. Clasts largely metal-troilite free, medium-grained, some vuggy with euhedral crystals.

Geochemistry: Olivine Fa24.6±0.3, range 24.1 to 25.3, FeO/MnO=48.3±3.3, n=13. Two grains P-rich, with P2O5 to 0.11 wt%. Low Ca pyroxene Fs20.2±0.2, range 20.2 to 20.6, Wo1.4±0.1, range 1.2 to 1.6, n=7.