This partial slice originates from the single 20 kg mass of NWA 7831 found in March 2013. NWA 7831 is composed almost entirely of yellow-green crystals of orthopyroxene (a magnesium- and iron-rich silicate). As determined by spectroscopic analysis, diogenites originate from within the upper mantle of Vesta but NWA 7831 originated from greater depths — the telltale large crystals being the giveaway. Two massive asteroid impacts on Vesta billions of years ago ejected tremendous amounts of material into interplanetary space, a small amount of which fell to Earth, including this most unusual meteorite. The specimen is composed almost entirely of translucent, yellow-green orthopyroxene with sparse amounts of metal, troilite, chromite, anorthite and clinopyroxene. The matrix is homogenous apart from a webbing of dense fine-grained, opaque material which animates the cut and polished surface. From the asteroid Vesta, orbiting the Sun between Mars and Jupiter, and the only asteroid we can see with the naked eye, this is a fine representation of a bizarre meteorite. (For more on Vesta see lot 68.)

Christie's would like to thank Dr. Alan E. Rubin at the Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles for his assistance in preparing this catalogue.

99 x 117 x 1mm (4 x 4.66 x 0.1 in.) and 35.62 grams