The rocks were oddly rusty and salty and smelled like rotten eggs, its discoverers said.
Initially, a team at the University of New Mexico (UNM) caused a stir when its analysis hinted that the pair may hail from Venus or the moon.
But other teams then hurried to get pieces of the space rocks for analyses of their own—and for the most part, they disagree.
GRA 06128 looks like rocks retrieved from the lunar highlands by the Apollo 16 astronauts in 1972, but it contains much more sodium, research has shown.
The rock is also much older than the Venusian surface, according to the newer analysis, thereby eliminating that possibility.
The identity of the meteorites' source remains exciting and mysterious, said Allan Treiman, a scientist with the Lunar and Planetary Institute in Houston who led one of the recent investigations of the rocks.
"From what has been reported so far, it's pretty clear that the meteorite is not from the Earth, or the moon, or Venus, or any of the common sources of meteorites," he said. "It's much harder to know where it is from."
Both teams—along with three others—are presenting findings about the meteorites at the 39th Lunar and Planetary Science Conference in Houston this week.
Not of This World?
GRA 06128 and its mate are slab-shaped, gray rocks containing bits of black glass.