Green pyroxene crystals and flecks of impact glass (gray maskelynite) are much in evidence in this complete slice. Orthopyroxene makes up approximately 70% of the meteorite. This is an equilibrated, unbrecciated, coarse-grained diogenite with an anomalous chemical signature. It is one of only four anomalous diogenites known to exist, which is to say it represents a portion of the asteroid Vesta’s lower crust not previously encountered.
111 x 76 x 3 mm. (4.33 x 3 x 0.1 in.)

76.7 g.

Vesta is the second largest asteroid (525 km in diameter) and the only large asteroid covered with basalt—the same fine-grained volcanic rock that spews from Hawaiian volcanoes, makes up the dark areas of the Moon and the volcanoes on Mars. Overwhelming scientific evidence suggests that three groups of igneous meteorites come from Vesta: howardites, eucrites and diogenites. Eucrites are basalts derived from the surface and upper crust of Vesta; diogenites are from the lower crust (as evidenced by the presence of slowly cooled, large crystals) and howardites are impact mixtures of both groups. Diogenites are rare objects, making up just 0.7% of known meteorites. NWA 10154 is the 10,154th meteorite to be analyzed and catalogued following its recovery in the Northwest African grid of the Sahara Desert. A cataclysmic impact between Vesta and another asteroid ejected this sample into interplanetary space millions of years ago. Apart from the chemical oddities that resulted in this specimen’s anomalous classification, there is no other meteorite that looks like this.

The mass from which this slice was cut will be on display at the Maine Mineral & Gem Museum.

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 catalogue note.