Confidence Hills Mineralogy and Chemin Results from Base of Mt

Introduction: The Mars Science Laboratory (MSL) rover Curiosity recently completed its fourth drill sampling of sediments on Mars. The Confidence Hills (CH) sample was drilled from a rock located in the Pahrump Hills region at the base of Mt. Sharp in Gale Crater. The CheMin X-ray diffractometer completed five nights of analysis on the sample, more than previously executed for a drill sample, and the data have been analyzed using Rietveld refinement and fullpattern fitting to determine quantitative mineralogy. Confidence Hills mineralogy has several important characteristics: 1) abundant hematite and lesser magnetite; 2) a 10 Å phyllosilicate; 3) multiple feldspars including plagioclase and alkali feldspar; 4) mafic silicates including forsterite, orthopyroxene, and two types of clinopyroxene (Ca-rich and Ca-poor), consistent with a basaltic source; and 5) minor contributions from sulfur-bearing species including jarosite. CheMin X-ray Diffraction: The CH XRD data were processed to generate a conventional 1-D XRD pattern for analysis. Prior to conversion, instrumental artifacts (bright spots on the CCD) were removed from the image. The 1-D XRD pattern were used for phase identification, quantitative phase analysis, and background modeling . Rietveld refinement using Topas [1] (Fig. 1) was used to determine the abundances presented in Table 1 and to refine unit-cell parameters of major and minor phases.