POSSIBLE DETECTION OF A JAHNSITE-WHITEITE GROUP PHOSPHATE MINERAL BY MSL CHEMIN IN GLEN TORRIDON, GALE CRATER, MARS

Introduction: The CheMin instrument on the Mars Science Laboratory (MSL) Curiosity rover is an X-ray diffractometer, and can detect minerals more abundant than ~1%, determine unit-cell parameters of minerals and corresponding constraints on their compositions, determine the abundances of minerals, and constrain the abundance(s) of X-ray amorphous material(s) [1-3]. In several recently analyzed samples, CheMin has detected a sharp diffraction peak corresponding to a mineral lattice spacing (i.e., d-spacing) of ~9.22Å, which is distinct from any spacing in common rock-forming minerals. This peak could represent a mixed-layer serpentine-talc phase [4,5], or a hydrous manganesebearing phosphate mineral of the jahnsite-whiteite group [4-6]. In this abstract, we explore the likelihood and implications of the latter. Diffraction Data: The CheMin instrument is a transmission powder X-ray diffractometer [1]. It generates an X-ray beam, which is collimated and passes through a sample of vibrating, moving powder. Diffracted X-rays are collected on an energy-dispersive CCD plane, and the results processed to yield typical 1dimensional XRD patterns (Fig. 1). The 1-D patterns are processed with the software programs JADE© and FULLPAT [7] to give diffraction d-spacings, mineral identifications, compositional constraints, and proportions of crystalline and X-ray amorphous materials.