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2016-05-01

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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/160531

Ni-phyllosilicates (garnierites) from the Falcondo Ni-laterite deposit (Dominican Republic): Mineralogy, nanotextures, and formation mechanisms by HRTEM and AEM

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https://doi.org/10.2138/am-2016-5518

Abstract

Ni-bearing magnesium phyllosilicates (garnierites) are significant Ni ores in Ni-laterites worldwide. The present paper reports a detailed TEM investigation of garnierites from the Falcondo Ni-laterite deposit (Dominican Republic). Different types of garnierites have been recognized, usually consisting of mixtures between serpentine and talc-like phases that display a wide range of textures at the nano meter scale. In particular, chrysotile tubes, polygonal serpentine, and lizardite lamellae are intergrown with less crystalline, talc-like lamellae. Samples consisting uniquely of talc-like and of sepiolite-falcondoite were also observed, occurring as distinctive thin lamellae and long ribbon-shaped fibers, respectively. HRTEM imaging indicates that serpentine is replaced by the talc-like phase, whereas TEM-AEM data show preferential concentration of Ni in the talc-like phase. We suggest, therefore, that the crystallization of Ni-bearing phyllosilicates is associated with an increase in the silica activity of the system, promoting the replacement of the Ni-poor serpentine by the Ni-enriched talc-like phase. These results have interesting implications in material science, as garnierites are natural analogs of Ni-bearing phyllosilicate-supported synthetic catalysts. Finally, SAED and HRTEM suggest that the Ni-bearing talc-like phase corresponds to a variety of talc with extra water, showing larger d(001) than talc (i.e., 9.2-9.7 angstrom), described as 'kerolite'-'pimelite' in clay mineral literature.

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Níquel, Mineralogia, República Dominicana

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Nickel, Mineralogy, Dominican Republic

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

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VILLANOVA DE BENAVENT, Cristina, et al. Ni-phyllosilicates (garnierites) from the Falcondo Ni-laterite deposit (Dominican Republic): Mineralogy, nanotextures, and formation mechanisms by HRTEM and AEM. American Mineralogist. 2016. Vol. 101, num. 6, pags. 1460-1473. ISSN 0003-004X. [consulted: 10 of August of 2026]. Available at: https://hdl.handle.net/2445/160531

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