The operating energy range encompasses a significant number of important K and L absorption edges for low- and medium-Z elements, and relatively thick (~10 – 20 μm) samples will be able to be studied with both absorption and phase contrast techniques, with lateral resolutions down to ~20 nm depending on the imaging mode.
Mineral grains were collected in the shallow soils of the Greater Sudbury area, Ontario, Canada, where large fluctuations in the soil pH have occurred during emissions of vast amounts of sulfuric acid and particulate matter (a result of decades of smelter activity in the Sudbury mining district) and subsequent reclamation efforts using lime and phosphates. Observations with HRTEM indicate that limited diffusion of elements in silicified Fe-hydroxide coatings has been the key to the preservation of a rarely observed mineralogy and chemistry.
Earth was a completely different planet more than 2.5 billion years ago. Little is known about this critical time when cratonic continental seeds formed; life emerged; and precious mineral resources concentrated.
Transmission electron microscopy (TEM) in combination with the focused ion beam (FIB) technique and other analytical methods (SEM, XRD, XRF and ICP-OES) are used to characterize the chemical and mineralogical composition of phases within confined pore spaces of the clay minerals montmorillonite and kaolinite and in the surrounding tailings material.
Sb isotopic analysis is presented as a novel technique to examine the raw material used to opacify the earliest glass. It is demonstrated that Egyptian and Mesopotamian glass factories likely used an identical source of Sb, possibly originating from the Caucasus.
In 24 dated stratigraphic sections in 10 countries of the Northern Hemisphere, the YDB layer contains a clearly defined abundance peak in nanodiamonds (NDs), a major cosmic-impact proxy. Observed ND polytypes include cubic diamonds, lonsdaleite-like crystals, and diamond-like carbon nanoparticles, called n-diamond and i-carbon.
The authors report full-vector paleointensity measurements of Archean to Hadean zircons bearing magnetic inclusions from the Jack Hills conglomerate (Western Australia) to reconstruct the early geodynamo history. Data from zircons between 3.3 billion and 4.2 billion years old record magnetic fields varying between 1.0 and 0.12 times recent equatorial field strengths.
Earth's composition differs from its meteoritic precursors. An evaluation of the evidence suggests that some material could have been lost to space during collisions, which may explain Earth's unusual plate tectonic regime and habitable climate.
Geochemical Perspectives Letters is a new journal of the European Association of Geochemistry.
Ath Godelitsas's insight:
A putative light element in Earth’s core is sulphur; however, estimates of core S abundance vary significantly and, due to its volatile nature, no unequivocal S isotopic signature for core fractionation has thus far been detected. Here the authors present new high precision isotopic data for Cu, a chalcophile (sulphur-loving) element, which shows that Earth’s mantle is isotopically fractionated relative to bulk Earth. Results from high pressure equilibration experiments suggest that the sense of Cu isotopic fractionation between BSE and bulk Earth requires that a sulphide-rich liquid segregated from Earth’s mantle during differentiation, which likely entered the core.
For As(V), AFM results showed that it interacts strongly with the calcite surface, and XAS results showed that As(V) was mostly incorporated in the calcite structure. For As(III), AFM results showed much less impact on calcite growth and dissolution and less incorporation was observed. This was confirmed by XAS results that indicate that As(III) was partly oxidized into As(V) before being incorporated into calcite and the resulting calcite contained 36% As(III) and 64% As(V).
The August issue of Elements demonstrates the application of geochemistry to a variety of societally and economically important areas, including: mineral exploration; environmental mineralogy; environmental problems in cities, using London (England) as a case study; food industry authenticity; law enforcement; and medical advancements. A significant driver for the research described in all of these articles is analytical achievement and translating this to a societal application (http://www.geochemsoc.org/news/2015/08/11/elements-social-and-economic-impacts-geochemistry).
Washington, DC—New research from a team led by Carnegie’s Robert Hazen predicts that Earth has more than 1,500 undiscovered minerals and that the exact mineral diversity of our planet is unique and could not be duplicated anywhere in the cosmos. Minerals form from novel combinations of elements. These combinations can be facilitated by both geological activity, including volcanoes, plate tectonics, and water-rock interactions, and biological activity, such as chemical reactions with oxygen and organic material.
by: Ross R. Large, Daniel D. Gregory, Jeffrey A. Steadman, Andrew G. Tomkins, Elena Lounejeva, Leonid V. Danyushevsky, Jacqueline A. Halpin, Valeriy Maslennikov, Patrick J. Sack, Indrani Mukherjee, Ron Berry, Arthur Hickman
Ath Godelitsas's insight:
LA-ICPMS analysis of over 4000 sedimentary pyrite grains in 308 samples from 33 locations around the world, grouped over 123 determined ages, has enabled the uathors to track, in a first order sense, the Au content of the ocean over the last 3.5 billion years.
The high amounts of organic carbon (4.1–27.5%) result in the formation of Fe sulphides, predominantly pyrite, already at the surface sediment layers. Pyrite morphologies include monocrystals, polyframboids, and complex FeS–FeS2 aggregates. According to synchrotron-generated micro X-ray fluorescence and X-ray absorption near-edge structure spectra, authigenically formed, Mn-containing, Fe(III) oxyhydroxides (goethite type) co-exist with pyrite in the sediments studied.
Andrew joined Curtin in 2015 as Director of The Institute for Geoscience Research (TIGeR). Between 1981 and 1995 he was a Lecturer in Earth Sciences in the University of Cambridge, and from 1995 until 2014 was Professor of Mineralogy at the University of Münster, Germany.
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