It was originally classified as a eucrite, a group of meteorites thought to be from the asteroid Vesta.

BBC: Mercury meteorite puzzle

The Dawn probe was launched in 2007 and has already sent back dramatic pictures from the giant asteroid Vesta.

CNN: While you were working: An asteroid just flew by

Unlike any other asteroid known today, Vesta has an iron core surrounded by layers of mantle rock and crust, similar to Earth and Mars, preliminary gravity and density measurements suggest.

WSJ: Asteroid Vesta Gets a Close Study

It will linger at Vesta, the second most massive object in the asteroid belt, until next summer, when it is scheduled to depart for a larger asteroid called Ceres.

WSJ: Asteroid Vesta Gets a Close Study

Vesta and Ceres are the two most massive objects in the main asteroid belt.

CNN: While you were working: An asteroid just flew by

The probe entered a special low-altitude orbit for about five months to allow the GRAND instrument to analyze emissions from Vesta's surface that result from collisions between cosmic ray particles and elements in the asteroid's dirt.

MSN: Surprisingly, giant asteroid Vesta covered in hydrogen