Conception Junction        40°16’N, 94°41’W (both ±5')

Missouri, USA

Found: 2006

Classification: Pallasite (Main group, anomalous)

History: A single mass was discovered protruding from a hillside near Conception Junction, Missouri.

Physical characteristics: The exterior of the meteorite is weathered. Much of the interior shows only minor oxidation.

Petrography: Meteorite has a typical main-group pallasite (PMG) structure with roughly equal portions of metal and silicate. The olivine masses are slightly rounded, though a few surfaces show sharply defined angles. Olivines show millimeter-scale fractures. Schreibersite is rare, perhaps 0.5% of the exposed (25 cm² surface). Minor FeS.

Geochemistry: Compositional data: Co 6.0 mg/g; Ni 79 mg/g; Ga 24 μg/g; Ge ~80 μg/g; As 29 μg/g; Ir 0.50 μg/g; Au 2.39 μg/g. Data are the mean of duplicate determinations. The composition of the metal differs in detail from other pallasites. For example, the Ir concentration is 0.50 ug/g, with the nearest relative Seymchan at 0.67 μg/g and Barcis at 0.32 μg/g.

Classification: On element-Au diagrams, Conception Junction plots distinctly lower than most PMG on Ni and Cu and above most PMG on Co, Ga, As, and Ir diagrams; it is therefore classified as PMG-anomalous (PMG-an). Its Ni and Cu contents are the lowest known for PMG. Its nearest PMG-an neighbor on most diagrams is Krasnojarsk. The low Ni and high Co could reflect unrepresentative sampling of kamacite and taenite but these are the means of two replicates.

Specimens: 113.58 g type specimen, UCLA.  Main mass, Karl Aston, Dave Gheesling and RWard

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