The accumulation of Ni in serpentines and garnierites from the Falcondo Ni-laterite deposit (Dominican Republic) elucidated by means of μXAS

Josep Roqué-Rosell, Cristina Villanova-de-Benavent, Joaquín A. Proenza

Research output: Contribution to journalArticle

Abstract

Ni-bearing serpentines and garnierites (Ni-bearing Mg-phyllosilicates) are the main Ni ores in the Falcondo Ni-laterite deposit (Dominican Republic). In the present paper a set of garnierite samples and the associated Ni-bearing serpentines with characteristic mineral compositions and textures, from the saprolite horizon, were studied by EMPA, μXRF and μXAS. The ultimate goal is to elucidate, for the first time, the Fe speciation and the Ni local environment of saprolite ores from Ni-laterites of the Dominican Republic. The chemical composition of the minerals has been obtained by means of EMPA and the Ni, Fe and Cr elemental maps obtained by μXRF allowed distinguishing the saprolite fragments containing Ni-bearing serpentines and Fe oxyhydroxides from the garnierite veins. The Fe K-edge μXANES demonstrated that Fe in the Ni-poor primary serpentine is mostly in the Fe2+ form, whereas in the Ni-bearing serpentine constituting the bulk of the saprolite and in the Fe-bearing garnierite Type I Fe was in the form of Fe3+. In parallel, the local environment of Ni determined by means of Ni K-edge μEXAFS confirmed that in Ni-poor primary serpentines Ni formed a homogeneous Ni–Mg solid solution, in garnierites formed Ni–Ni clusters, and in Ni-bearing secondary serpentines Ni was found in Ni–Mg and Ni–Ni mixed sites. This paper explains the accumulation of Ni, the speciation of Fe in garnierites with various mineral compositions and in Ni-bearing serpentines from the saprolite horizon in Ni-laterite deposits.

Original languageEnglish
Pages (from-to)48-69
Number of pages22
JournalGeochimica et Cosmochimica Acta
Volume198
DOIs
Publication statusPublished - 11 Nov 2016

Fingerprint

Bearings (structural)
laterite
Deposits
saprolite
Minerals
X-ray fluorescence
Ores
mineral
Chemical analysis
phyllosilicate
solid solution
Solid solutions
Textures
texture
chemical composition

Keywords

  • EMPA
  • Falcondo
  • Garnierites
  • Iron
  • Nickel
  • Serpentines
  • μXAS
  • μXRF

Cite this

Roqué-Rosell, Josep ; Villanova-de-Benavent, Cristina ; Proenza, Joaquín A. / The accumulation of Ni in serpentines and garnierites from the Falcondo Ni-laterite deposit (Dominican Republic) elucidated by means of μXAS. In: Geochimica et Cosmochimica Acta. 2016 ; Vol. 198. pp. 48-69.
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The accumulation of Ni in serpentines and garnierites from the Falcondo Ni-laterite deposit (Dominican Republic) elucidated by means of μXAS. / Roqué-Rosell, Josep; Villanova-de-Benavent, Cristina; Proenza, Joaquín A.

In: Geochimica et Cosmochimica Acta, Vol. 198, 11.11.2016, p. 48-69.

Research output: Contribution to journalArticle

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T1 - The accumulation of Ni in serpentines and garnierites from the Falcondo Ni-laterite deposit (Dominican Republic) elucidated by means of μXAS

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KW - Nickel

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KW - μXAS

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