This close-up image taken by the Mars Exploration Rover Spirit's microscopic imager shows a section of the hole drilled into the rock dubbed "Mazatzal" after the hole was ground for a second time. The first drilling by the rover's rock abrasion tool left an incomplete hole, so a second one was performed. The blue arrow points to leftover portions of the dark rind that coats Mazatzal and the scrape marks left by the rock abrasion tool. The yellow arrow highlights the bright edges surrounding the leftover rind. The crack in the rock may have once contained fluids out of which minerals precipitated along its walls (red arrows). Mazatzal is a highly coated rock, containing at least four "cake layers": a top coat of dust, a pinking coating, a dark rind and its true interior. The observed area is 3 centimeters (1.2 inches) across. This image was taken on sol 85.
Image credit: NASA/JPL/USGS/Cornell