Discovery of Ni-smectite-rich saprolite at Loma Ortega, Falcondo mining district (Dominican Republic): geochemistry and mineralogy of an unusual case of “hybrid hydrous Mg silicate – clay silicate” type Ni-laterite

Esperança Tauler, John F. Lewis, Cristina Villanova-de-Benavent, Thomas Aiglsperger, Joaquín A. Proenza, Cristina Domènech, Tamara Gallardo, Francisco Longo, Salvador Galí

Research output: Contribution to journalArticle

Abstract

Hydrous Mg silicate-type Ni-laterite deposits, like those in the Falcondo district, Dominican Republic, are dominated by Ni-enriched serpentine and garnierite. Recently, abundant Ni-smectite in the saprolite zone have been discovered in Loma Ortega, one of the nine Ni-laterite deposits in Falcondo. A first detailed study on these Ni-smectites has been performed (μXRD, SEM, EPMA), in addition to a geochemical and mineralogical characterisation of the Loma Ortega profile (XRF, ICP-MS, XRD). Unlike other smectite occurrences in laterite profiles worldwide, the Loma Ortega smectites are trioctahedral and exhibit high Ni contents never reported before. These Ni-smectites may be formed from weathering of pyroxene and olivine, and their composition can be explained by the mineralogy and the composition of the Al-depleted, olivine-rich parent ultramafic rock. Our study shows that Ni-laterites are mineralogically complex, and that a hydrous Mg silicate ore and a clay silicate ore can be confined to the same horizon in the weathering profile, which has significant implications from a recovery perspective. In accordance, the classification of “hybrid hydrous Mg silicate – clay silicate” type Ni-laterite deposit for Loma Ortega would be more appropriate.

Original languageEnglish
Pages (from-to)1011-1030
Number of pages20
JournalMineralium Deposita
Volume52
Issue number7
DOIs
Publication statusPublished - 1 Oct 2017

Keywords

  • Clay silicate deposit
  • Dominican Republic
  • Hydrous Mg silicate deposit
  • Ni-laterite
  • Ni-smectite

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