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2016-11-30

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cc-by (c) Aiglsperger, Thomas Hans et al., 2016
Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/151708

Fibrous platinum-group minerals in 'floating chromitites' from the Loma Larga Ni-laterite deposit, Dominican Republic

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https://doi.org/10.3390/min6040126

Abstract

This contribution reports on the observation of enigmatic fibrous platinum-group minerals (PGM) found within a chromitite body included in limonite ("floating chromitite") from Ni-laterites in the Dominican Republic. Fibrous PGM have a Ru-Os-Ir-Fe dominated composition and are characterized by fibrous textures explained by grain-forming fibers which are significantly longer (1-5 µm) than they are wide (~100 nm). Back-scattered electron (BSE) images suggest that these nanofibers are platinum-group elements (PGE)-bearing and form <5 µm thick layers of bundles which are oriented orthogonal to grains' surfaces. Trace amounts of Si are most likely associated with PGE-bearing nanofibers. One characteristic fibrous PGM was studied in detail: XRD analyses point to ruthenian hexaferrum. However, the unpolished fibrous PGM shows numerous complex textures on its surface which are suggestive for neoformation processes: (i) features suggesting growth of PGE-bearing nanofibers; (ii) occurrence of PGM nanoparticles within film material (biofilm?) associated with PGE-bearing nanofibers; (iii) a Si-rich and crater-like texture hosting PGM nanoparticles and an Ir-rich accumulation of irregular shape; (iv) complex PGM nanoparticles with ragged morphologies, resembling sponge spicules and (v) oval forms (<1 µm in diameter) with included PGM nanoparticles, similar to those observed in experiments with PGE-reducing bacteria. Fibrous PGM found in the limonite may have formed due to supergene (bio-)weathering of fibrous Mg-silicates which were incorporated into desulphurized laurite during stages of serpentinization.

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Fibres tèxtils, República Dominicana, Meteorització química

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Textile fibers, Dominican Republic, Chemical weathering

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Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)

Citation

AIGLSPERGER, Thomas Hans, et al. Fibrous platinum-group minerals in 'floating chromitites' from the Loma Larga Ni-laterite deposit, Dominican Republic. Minerals. 2016. Vol. 6, num. 4, pags. 126. ISSN 2075-163X. [consulted: 11 of August of 2026]. Available at: https://hdl.handle.net/2445/151708

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