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Open AccessArticle

Fibrous Platinum-Group Minerals in “Floating Chromitites” from the Loma Larga Ni-Laterite Deposit, Dominican Republic

1
Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), Martí i Franquès s/n, Barcelona 08028, Spain
2
Faculty of Engineering, Universidad Católica Tecnológica del Cibao (UCATECI), Ave. Universitaria, esq. Ave. Pedro Rivera, P.O. Box 401, La Vega, Dominican Republic
*
Author to whom correspondence should be addressed.
Academic Editor: Maria Economou-Eliopoulos
Minerals 2016, 6(4), 126; https://doi.org/10.3390/min6040126
Received: 8 August 2016 / Revised: 10 November 2016 / Accepted: 16 November 2016 / Published: 30 November 2016
(This article belongs to the Special Issue Mineral Deposit Genesis and Exploration)
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. View Full-Text
Keywords: PGE; PGM; fibrous; nanofibers; Ni-laterite; supergene; weathering; neoformation; Falcondo; Dominican Republic PGE; PGM; fibrous; nanofibers; Ni-laterite; supergene; weathering; neoformation; Falcondo; Dominican Republic
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MDPI and ACS Style

Aiglsperger, T.; Proenza, J.A.; Longo, F.; Font-Bardia, M.; Galí, S.; Roqué, J.; Baurier-Aymat, S. Fibrous Platinum-Group Minerals in “Floating Chromitites” from the Loma Larga Ni-Laterite Deposit, Dominican Republic. Minerals 2016, 6, 126. https://doi.org/10.3390/min6040126

AMA Style

Aiglsperger T, Proenza JA, Longo F, Font-Bardia M, Galí S, Roqué J, Baurier-Aymat S. Fibrous Platinum-Group Minerals in “Floating Chromitites” from the Loma Larga Ni-Laterite Deposit, Dominican Republic. Minerals. 2016; 6(4):126. https://doi.org/10.3390/min6040126

Chicago/Turabian Style

Aiglsperger, Thomas; Proenza, Joaquín A.; Longo, Francisco; Font-Bardia, Mercè; Galí, Salvador; Roqué, Josep; Baurier-Aymat, Sandra. 2016. "Fibrous Platinum-Group Minerals in “Floating Chromitites” from the Loma Larga Ni-Laterite Deposit, Dominican Republic" Minerals 6, no. 4: 126. https://doi.org/10.3390/min6040126

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