The rock "Ithaca" shown here, with a rougher lower texture and smoother texture on top, appears to be a piece of the local sedimentary bedrock protruding from the surrounding soil in Gale Crater. NASA's Curiosity Mars rover used its Mast Camera (Mastcam) to take this image during the 439th Martian day, or sol, of Curiosity's work on Mars (Oct. 30, 2013). The black-outline rectangle indicates the area where the rover's Chemistry and Camera instrument (ChemCam) used its laser and remote micro-imager to inspect Ithaca. That inspection included the 100,000th laser shot fired by ChemCam on Mars. The 0.1 meter scale bar at lower left is about 4 inches.
Figure A is an unannotated version of this Mastcam image.