UDEI STATION

A 103 kg mass was seen and heard to fall in the daytime near the Benue River in Nigeria. The Geological Survey of Nigeria learned of the event in 1935 when the mass was recovered from a shallow hole six miles west of the railway station at Udei and 23 miles north of Makurdi. Some reports state that a second mass exists.

The IAB iron-meteorite complex, recently proposed by Wasson and Kallemeyn (2002), comprises iron meteorites from the former IAB-IIICD group, as well as numerous related irons. Many of the members contain silicate inclusions with chondritic compositions. Udei Station is a low-Au member of the IAB complex that is closely related to the main group. On a Ni-Au diagram, a grouplet of six members has been resolved in an area close to the sLL subgroup, but with lower Ni contents. These meteorites were named the Udei Station grouplet. Although theories of formation of these irons commonly attribute their origin to impact melt pools, correlations between Ni abundance and several chemical and physical properties alternatively suggest an interaction with a crystallizing metallic core. The absolute I–Xe retention age, relative to the Shallowater standard, was calculated to be at least 4.537 b.y., while the metamorphic resetting of the K–Ar chronometer occurred ~4.31 b.y. ago (Bogard et al, 2005).

Udei Station is a medium octahedrite that contains a high proportion of silicates and troilite. Silicates range in size from single grains to as large as 8 cm and are composed of enstatite, olivine, oligoclase, and diopside. Udei Station plots as an anomalous member of group I in several regards. It contains a clast best described as a peridotite, composed of the most Fe-rich mafic minerals found among IAB irons. The above specimen is a 26.3 g partial slice displaying a high content of silicates.

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