Formation of "Martian Blueberries".The exploratory rovers on Mars have identified "Martian Blueberries" in the Meridiani crater. These "blueberries" are composed of spherical hematite hematite (hĕm`ətīt), mineral, an oxide of iron, Fe2O3, containing about 70% metal, occurring in nature in red to reddish-brown earthy masses and in steel-gray to black crystalline forms. ([Fe.sub.2][O.sub.3]) nodules Nodules A small mass of tissue in the form of a protuberance or a knot that is solid and can be detected by touch. Mentioned in: Leprosy and accumulate as a weathering residue on the Martian surface. Hematite formation indicates the possible presence of water in the past. The "blueberries" are similar in appearance to the cemented nodules found in the Jurassic ages Navajo Sandstone Navajo Sandstone is a geologic formation in the Glen Canyon Group that is spread across the U.S. states of northern Arizona, northwest Colorado, Nevada, and Utah (the unit is not part of a group in Nevada). It is located in the Colorado Plateau province of the United States. of Utah (Chan et al., Nature 2004). The Utah nodules have hematite occurring as a ring surrounding a central core of host rock sandstone. The goal of my research is to determine how the hematite tings form and if various mineral grains in the sandstone may induce Eh-pH changes that lead to hematite precipitation. Initial experiments were conducted in a static mode with calcite calcite (kăl`sīt), very widely distributed mineral, commonly white or colorless, but appearing in a great variety of colors owing to impurities. immersed in an aqueous solution of ferrous ammonium sulfate ammonium sulfate, chemical compound, (NH4)2SO4, a colorless-to-gray, rhombohedral crystalline substance that occurs in nature as the mineral mascagnite. It is soluble in water and insoluble in alcohol or liquid ammonia. . Glass tubes packed with inert quartz sand and isolated grains of calcite were also exposed to this solution at a slow flow rate. A pH rise following reaction with calcite was successful in inducing iron precipitation in spherical geometries around the calcite grains. Future tests will examine ways to influence the oxidation state (Eh) of the water solution by adding charcoal to the solution and examining the effect of other mineral phases on hematite precipitation. * Downs, K.C. and D.J. Wronkiewicz. Department Geological Sciences and Engineering, Univ. Missouri-Rolla |
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