Gemstone of the Year
This image shows layers of rock stacked like a staircase, their edges extending diagonally from top left to bottom right and stepping downward from the lower left to the top right. At the far left of the image is an eroded, round crater filled with a row of nearly parallel sand dunes. To the right of the crater, a pinkish-colored layer of light-toned rock within the staircase contains opal.
Image Credit: NASA/JPL-Caltech/Univ. of Arizona