Mesosiderite — B4 Timbuktu, Mali (16°47’23”N, 3°0’15” W)

Meteorites are named after the places to which they have been “delivered”. Originating in the asteroid belt between Jupiter and Mars, the meteorite from which this complete slice is derived landed in Timbuktu and was discovered in 2015 when an unusual rock was found by a local resident. A Moroccan meteorite dealer happened to be visiting Timbuktu, recognized the rock as a meteorite and bought it from the finder. Mesosiderites are a class of stony-iron meteorites that consist of roughly equal parts of metallic nickel-iron and silicate. There are only four mesosiderites with the B4 designation, which indicates the abundances of different minerals and the degree of recrystallization. Unlike pallasites, which formed at the boundary of the stony mantle and molten core of an asteroid that was later disrupted by a collision, the formation of mesosiderites is less well understood. One leading model is that this material formed when the semi-molten core of one asteroid collided with the basaltic surface of a larger asteroid.

Christie's would like to thank Dr. Alan E. Rubin at the Institute of Geophysics and Planetary Physics, University of California, Los Angeles for his assistance in preparing this catalog note.