The rocks were found on a hill overlooking a site called “Marathon Valley,” named as such because Opportunity will have traveled 26.2 miles on Mars by the time it gets there.
"We drove to the edge of a plateau to look down in the valley, and we found these big, dark-gray blocks along the ridgeline," Opportunity Project Scientist Matt Golombek, of NASA's Jet Propulsion Laboratory, said in a statement. "We checked one and found its composition is different from any ever measured before on Mars. So, whoa! Let's study these more before moving on.”
Upon inspection of the martian rocks, researchers found them to be rich in silicon and aluminum, which make them different than anything else that has been found by Opportunity, or its twin rover Spirit, NASA officials said.
Both Spirit and Opportunity were sent to Mars in January 2004 to search for water activity on Earth’s red neighbor.