Calcium Sulfates at Gale Crater and Limitations on Gypsum Stability

• Published in: NASA Center for AeroSpace Information (CASI). Conference Proceedings
• Main Authors: Vantiman, D T, Martinez, G M, Morris, R V, Crisp, J A, Rampe, E B, Bristow, T F, Blake, D F, Yen, A H, Ming, D W, Rapin, W, Meslin, P -Y, Morookian, J M
• Format: Conference Proceeding
• Language: English
• Published: Hampton NASA/Langley Research Center 20.03.2017
• Subjects: Calcium sulfate; Crystal structure; Curiosity (Mars rover); Dehydration; Gypsum; Mars craters; Mars rovers; Mineralogy; Organic chemistry; Sedimentary rocks; Stratigraphy

The Mars Science Laboratory rover has been exploring sedimentary rocks of the Bradbury group and overlying Murray formation, as well as the unconformably overlying Stimson formation. Early in exploration, and continuing to present, there have been observations of many Ca-sulfate veins that cut all three stratigraphic units. The CheMin XRD instrument on Curiosity provides complete mineralogy for drilled or scooped samples, with explicit identification of gypsum, bassanite, and anhydrite (crystal structure of so-called "soluble anhydrite," or gamma-CaSO4, is so similar to bassanite that it can't be distinguished at CheMin 2-theta resolution; here we refer to these similar dehydrated forms simply as bassanite).