Gypsum is a common mineral on Earth that forms in the presence of water, and appears here to be partially covered by darker material along a sloped surface in a trough of Noctis Labyrinthus. Because the gypsum occurs along a slope and it has a patchy occurrence, it probably didn't form as an evaporite but it could be from volcanic vapors or groundwater at this location.

ID: ESP_016120_1730
date: 3 January 2010
altitude: 254 km

https://uahirise.org/hipod/ESP_016120_1730
NASA/JPL-Caltech/University of Arizona
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