The mineralogy of an unusual calc-silicate nodule brought to the surfaoe by the 1902 eruption of La Soufriere volcano on St. Vincent (Lesser Antilles arc) is described. It consists of the crystalloblastic mineral assemblage fassaite pyroxene + grandite garnet + wollastonite + anorthite t calcite. The pyroxene is more aluminous (Al2O3 : 19.66 weight percent) than any previously described from te...

We performed an extensive optical and chemical analysis of a single Keokuk geode using electron microscopy (SEM) with energy dispersive X-ray (EDX) spectroscopy that revealed extraordinary array minerals multiple, complex cycles mineralization. identified at least 15 including 5 that, to our knowledge, have not been reported in previous studies these geodes. Along bitumen we described the occur...

Geochemical models of secondary mineral precipitation on Mars generally assume semiopen systems (open to the atmosphere but closed at the water-sediment interface) and equilibrium conditions. However, in natural multicomponent systems, the reactive surface area of primary minerals controls the dissolution rate and affects the precipitation sequences of secondary phases, and simultaneously, the ...

We present a first paragenetic study of the Wuyier, Wuyisan, Wuyiyi and Shihongtan sandstone-hosted roll-front uranium deposits, northwest China. The mineralization is hosted by Lower–Middle Jurassic coarseto medium-grained sandstones, which are dark-gray to black due to a mixture of ore minerals and carbonaceous debris. The sandstone is alluvial fan-braided river facies. Minerals associated wi...

Mineral precipitation can be observed in natural environments, such as lagoons, rivers, springs, and soils. The primary process has long been believed to abiotic due evaporation, leading phase supersaturation. However, biotic interactions of microbial metabolism, organic compounds, dissolved ions mineral shown laboratory studies using single-organism culture. increase pH inducing calcium carbon...