Ni-sepiolite-falcondoite in garnierite mineralization from Falcondo Ni-laterite deposit, Dominican Republic
Abstract
New chemical and structural data on sepiolite-falcondoite in garnierite veins from the Falcondo Ni-laterite deposits, central Dominican Republic, are reported. Samples of Ni-sepiolite-falcondoite vary in colour from whitish green to green depending on the NiO content (wt.%) and the amount of silica present. The texture is normally schistose and friable but samples with considerable quartz and/or amorphous silica are compact and hard. Back-scattered electron images indicate that the samples are composed of at least three generations of Ni-sepiolite-falcondoite. The extreme refined cell parameters for Ni-sepiolite-falcondoite vary from 13.400(2), 27.006(4), 5.273(1) Å to 13.340(3), 27.001(6), 5.267(1) Å (space group Pncn). As the Ni content increases there is a small reduction in the a parameter. Chemical compositions determined by electron probe microanalysis cover a large interval of the Ni-sepiolite-falcondoite solid solution (Fal3 and Fal77). Individual samples show a considerable range in composition with the widest range determined in one sample from 4.63 to 22.40 wt.% NiO.
Keywords: Crystal chemistry; Dominican Republic; Falcondo; Falcondoite; Garnierite; Ni-laterites; Ni-sepiolite.
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To Cite this article: Tauler, E., Proenza, J.A., Galí, S., Lewis, J.F., Labrador, M., García-Romero, E., Suarez, M., Longo, F., Bloise, G. (2009): Ni-sepiolite-falcondoite in garnierite mineralization from Falcondo Ni-laterite deposit, Dominican Republic. Clay Minerals, 44, 435-454.
