This focus-merge image from the Mars Hand Lens Imager (MAHLI) on the arm of NASA's Mars rover Curiosity shows a rock called "Burwash." The rock has a coating of dust on it. The coarser, visible grains are windblown sand.
The focus merge combines portions of eight images taken with the camera held in one position while the MAHLI focus mechanism moved for each of the eight exposures to capture features at different distances in focus. The images were taken during the mission's 82nd sol, or Martian day (Oct. 29, 2012).
MAHLI viewed the rock from a distance of about 4.5 inches (11.5 centimeters). The image covers an area about 3 inches by 2.2 inches (7.6 centimeters by 5.7 centimeters). Burwash is located near the rover's left-front wheel where the rover has been stationed while scooping soil at the site called "Rocknest."