After shooting it with lasers and X-rays, NASA's Curiosity rover has determined that a rock nicknamed "Jake Matijevic" is of a variety that no other rover has ever spotted on Mars.

More Curiosity Coverage Curiosity Close-Ups: The Rover's Detailed Photoshoot of Itself Curiosity Rover’s Self-Portraits Transport You to MarsThe rock, a highly fractionated alkalic rock type, is relatively well known to geologists because it is common in rift zones on Earth and island chains such as the Hawaiian Islands.

"This is a rock type which had not been seen before" by previous Mars rovers including Spirit and Opportunity, said Roger Weins, principle investigator for Curiosity's ChemCam instrument, during a NASA press conference Oct. 11. It forms under relatively high pressure and often in the presence of water. While Curiosity is mostly focused on sedimentary rocks that could indicate the presence of past conditions for life, Matijevic is an igneous rock that likely formed about 5 miles under the Martian surface.

The rover had been investigating Matijevic mostly as an early test of the instruments on its arm, such as the Alpha Particle X-Ray Spectrometer (APXS), which bombards a sample with X-rays to determine its chemical composition. Curiosity also used its ChemCam instrument to shoot the rock with more than 400 laser blasts, vaporizing microscopic amounts and then analyzing the resulting dust and plasma. This investigation showed that the rock contained a lot of elements such as silicon, aluminium, sodium, and potassium.

"This was surprising because it differed from the composition from what we know of rocks on Mars," said Edward Stolper, Curiosity science team co-investigator, during the conference.

Scientists think this rock formed in the interior of Mars when magma moved up through cooler rock. As the magma cooled, elements including nickel, iron, and magnesium crystallized out of it first, leaving behind a material rich in silicon, aluminum, sodium, and potassium, as well as a higher fraction of dissolved water. Though the rock was unusual, the Curiosity team was careful to point out that it was just one isolated sample and not to extrapolate too much about early Martian geology based on it.

Engineers also discussed the case of the mysterious plastic object that Curiosity had spotted several days ago while scooping bits of Martian soil. They concluded that it is likely a bit of bonding material that fell off the rover or a piece of tubing that came off the descent stage and was recently blown off the probe. In either case, "it's completely inconsequential to the rover’s function" and no further pieces have been seen, said engineer Chris Roumeliotis, the lead turret rover planner. Curiosity is continuing to go through its Martian dust rinse and repeat cycle to clean out its sample delivery instrument of any left-over contaminants from Earth.