A Unique Piece of Mars

Following the pioneering Mars Exploration Rovers, NASA's Curiosity rover is actively exploring the crustal rocks of Mars. Despite the exciting results returned by the rovers, there is no substitute for a hand sample of crustal rock. Because such samples will not be returned to Earth anytime soon, geochemists who want a piece of Mars in their labs must satisfy themselves with martian meteorites (1). These comprise a group of igneous rocks with telltale signs of martian alteration products (2) and have provided ground truth for the information returned by the rovers. Oddly, however, the hundred or so known martian meteorites are chemically unrepresentative of the martian crust determined by missions (3). On page 780 of this issue, Agee et al. (4) put an end to this conundrum with the finding of a new martian meteorite, Northwest Africa (NWA) 7034, a basaltic breccia unique among known martian meteorites with respect to age, oxygen isotopes, and petrology.