Gypsum, a common mineral composed of calcium sulfate, lies scattered in this newly-released image of the Olympia Undae region of Mars. ... Made on October 1, 2006, the image covers about 12 square kilometers (7.5 sq. mi.) Gypsum, used commonly on Earth as the substance in wallboard, is a sulfate-rich mineral that forms by evaporation and requires large amounts of water for its formation. In this image, brighter areas contain more gypsum and darker areas less so. ...