The meteorite is relatively rich in water - about 6,000 parts per million - compared with typical Martian meteorites that contain about 200- to 300 parts per million. It is similar to basaltic rocks on Earth that form in volcanic eruptions.
"The fact that this meteorite formed in the presence of water suggests that maybe this water hung around for a while, maybe a bit longer than previously thought. It at least opens our minds to the idea that maybe Mars climate change was more transitional, rather than an abrupt loss of atmosphere and water," Agee said.
Like other Mars meteorites, NWA 7034, nicknamed "Black Beauty," also contains tiny bits of carbon, formed from geologic, not biological activity, said Andrew Steele, who studies Mars meteorites at the Carnegie Institution of Washington DC.
Steele, who also is a member of the Curiosity science team, would like to do more analysis on the meteorite with instruments that are similar to those on the rover.
Scientists don't know why more meteorites like Black Beauty haven't been found on Earth. The period of time from which they originated may be relatively short, or most may not survive the trip through Earth's atmosphere.
"(Mars meteorites) are tough, but by the time they get here they're quite friable and brittle," Steele told Discovery News.
"This one does look completely different," he added. "It's jet black. The others are slightly greenish cast."
After an initial battery of tests revealed the rock's unique nature, meteorite hunters returned to the area where it was found to search for other similar stones, Agee said.
"It took several months to get an idea of what it was," Agee said. "We eventually realized there was no other conclusion but that it was Martian and that it was different from all the other ones."
"If it were similar, we would have known within one day," he added.
Four more pieces, all smaller than the original, have now been found.
The research appears in this week's journal Science.