The Mars Hand Lens Imager (MAHLI) on NASA's Mars rover Curiosity acquired closeup views of sands in the "Rocknest" wind drift to document the nature of the material that the rover scooped, sieved, and delivered to the Chemistry and Mineralogy Experiment and the Sample Analysis at Mars in October and November.
This photo shows some of the variety of coarse sand grains observed on a portion of the Rocknest wind drift. The sample shows translucent grains, gray and white sand, in addition to two blue-gray glassy spheres and a glassy ellipsoid. The spherical and ellipsoidal grains were likely formed from molten droplets that cooled above the Martian surface to form glass, either during an explosive volcanic eruption or an impact cratering event. Similar grains are found in association with impacts on Earth and explosive volcanoes on the moon. The larger glassy sphere is 0.026 inches in diameter.