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A nano-block fine structure of native crystals of isoferroplatinum and Os-Ir-Ru solid solution alloys has been discovered in layered intrusions of the Russian Far East and in chromitites of the Southern Urals. Evidence of the self aggregation of nano-sized noble metal phases has also been observed in gaseous sublimate phases of the active volcanic fumaroles at the Kudryavy volcano. This study combines techniques of atomic force microscopy (AFM), Auger- and X-ray-photoelectron spectroscopy (XPS) as well as modern methods of image analysis. A new approach is essential for development of a theoretical basis for the origin of noble metal ores which were formed under magmatic to hydrothermal conditions. The nano-block parquet-type fine structure was first observed using AFM on the facet surface of coarse (2-3 mm) crystals of isoferroplatinum. The different scales and repetitive character of the nano-block integration were estimated using conventional Fourier- and wavelet transforms. This specific type of scalable structure, comprising a regular combination of nano blocks (or parquets) of different sizes, can be considered as a quasi-crystalline structure. The smallest elements of the structure were estimated to be a few tens of nanometres. The surface of the Os-Ir-Ru alloy crystals is also characterised by a structure that is based on the regular combination of rhomb-shaped blocks of different scale. The same process of the nano-phase aggregation was also observed in the sublimates of gaseous fluids in the fumarolic fields of the Kudryavy volcano. A PtCl2[P(C4H9)3]2 compound, associated with Pt(OH)2 and native platinum in also include various rare- and noble-metal mineral phases identified with using XPS method. The platinum spectrum disappeared after etching to a depth of 40-60 nm, suggesting that Pt-bearing phases are of nano-size.
The given data suggest the existence of such aperiodic structures as quasicrystals in nature. The aperiodicity of their structure is indicated by the absence of a translation mechanism, although such structures are characterised by rotational symmetry and fractal ordering. The latest is one of the main characteristics of nanosystems under disequlibrium conditions given sufficient energy and mass flow. The formation of similar fractal structures in nature appears to relate to specific conditions involving steep gradients: firstly a steep temperature gradient, which causes numerous structural phases to form within a finite time interval, and secondly steep chemical potential gradients. Such processes can result from heterogeneous gas-transport reactions of gas - solid and gas - liquid - solid under disequilibrium conditions. These reactions are evident during mineral sublimation from volcanic gas, but a similar mechanism can control the deposition of mineral phases accompanying platinum metal mineralization, at least under the conditions that relate to the formation of the crystals that have been studied in this project.
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