The rock may not look like anything special, but it is in fact a rare find. Laboratory analysis reveals that a specimen purchased from a Moroccan meteorite dealer in 2011 is the first sample that originates from Mars that is similar to the water-rich rocks that NASA's rovers have examined.
The meteorite is called Northwest Africa (NWA) 7034, and contains a concentration of water by weight that is about ten times higher than in any of the other 100 or so known rare rocks that get ejected from Mars' surface into space when an asteroid hits the planet and eventually make their way to Earth.
NWA 7034 is the only known Martian sample on Earth that comes from a specific critical period about 2 billion years ago when it is believed that Mars became colder and drier than it was originally.
The elemental composition of the meteorite closely resembles that of rocks which were examined in 2005 by NASA's Spirit rover at Gusev Crater. The rocks found there showed evidence of chemical alteration by interactions with liquid water. NWA 7034's composition also matches that of rocks studied by NASA's newest Mars rover, Curiosity.
NWA 7034 is the second-oldest Martian meteorite, dating back from 2.1 billion years ago. According to the lead researcher in the study, Carl Agee, it provides a "missing link" in the planet's geological record. The oldest Martian meteorite is 4.5 billion ears old, and all other Martian meteorites are 1.3 billion years old.
Evidence indicates that portions of Mars were once warmer and wetter, and could have thus been a haven for carbon-based life about 4 billion years ago. NWA 7034's relatively high water content, which could be as much as 0.6% by weight, suggests that "crustal or surface processes involving water may have lasted" well beyond the 4 billion year mark, said Agee.
The meteorite is composed of volcanic rock, and the presence of water in it suggests that crustal rocks on Mars interacted with surface water that was delivered by volcanic activity, near-surface reservoirs or by impacting comets.