Howardite
TKW 428 grams. Fall not observed.
Fabrice writes:
History: Purchased by Adam Bates from a meteorite dealer in Morocco, August, 2012.
Physical characteristics: Single stone, dark brown, lightly weathered, and fusion crusted. Saw cut reveals fresh, brecciated texture, numerous white and dark clasts up to 3mm, set in a medium-gray groundmass.
Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows a brecciated texture with a wide range of silicate grain sizes, 1-500 µm, with three distinct pyroxene populations: 40% diogenitic, 36% main group eucritic, and 24% cumulate eucritic; n=50. Some pyroxenes show zoning in backscatter electron images, while others display exsolution lamellae. Phase proportions: pyroxene ~70%, plagioclase ~20%, with accessory silica, ilmenite, troilite, and low-Ni iron metal.
Geochemistry: (C. Agee and M. Spilde, UNM) Diogenite low Ca-pyroxene Fs26.0±2.5Wo2.7±1.2, Fe/Mn=31±2, n=20; cumulate eucrite low-Ca pyroxene Fs43.4±4.0Wo4.3±2.9, Fe/Mn=33±3, n=11; cumulate eucrite augite Fs21.6Wo41.6, Fe/Mn=29; main group pyroxene Fs53.2±6.6Wo11.4±8.9, Fe/Mn=33±4, n=18; plagioclase Or0.4±0.1Ab9.2±2.4An90.3±2.5 n=4.
Specimens: 21.09 g including a probe mount on deposit at UNM, Adam Bates holds the main mass.
Click to view larger photos #1 #2
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