are actively being pursued in the manufacturing industry for applications in drug delivery, including cancer therapy, new optical instrumentation, and as superconductors and catalysts. Hough et al. report, for the first time, a natural occurrence of such gold particles that show identical features to their manufactured counterparts. They form where gold deposits in the vast southern part of Western Australia are actively weathering today in the presence of salty groundwaters. The gold crystals are so thin (20 nanometers) that they are transparent to electron beams, and the finest population of nanoparticles are triangular, less than 100 nanometers in size, only 6 nanometers thick, and were previously invisible. These are the first observations of this natural nanoparticulate gold.
Olivine dissolution by acidic fluids in Argyre Planitia, Mars: Evidence for a widespread process?
Joshua L. Bandfield et al., Earth and Space Sciences, Box 351310, University of Washington, Seattle, Washington 98195-1310, USA. Pages 579-582.
Although there is ample evidence for compositions that formed in a water-rich environment at some point in the Martian past, these compositions are limited in areal extent. New results presented by Bandfield et al. combine results from Mars satellite and rover datasets to show that aqueous alteration has been much more extensive than has been presumed by many researchers. Bedrock outcrops show differences in composition with the surfaces and soils derived from these rocks. These differences are the same as would be expected with exposure to small amounts of liquid water. Bandfield et al.'s results indicate that water, in limited amounts, may have a large effect on the formation of the Martian surface, even in regions without obvious water-related features, such as stream valleys or evaporite minerals.
GSA Today Science Article
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