@article{fdi:010064629,
  title = {{G}oethite aging explains {N}i depletion in upper units of ultramafic lateritic ores from {N}ew {C}aledonia},
  author = {{D}ublet, {G}. and {J}uillot, {F}arid and {M}orin, {G}. and {F}ritsch, {E}mmanuel and {F}andeur, {D}. and {B}rown, {G}. {E}.},
  editor = {},
  language = {{ENG}},
  abstract = {{A}n upward loss of {N}i is commonly reported in the oxide-rich unit of {N}i-laterite deposits developed over ultramafic rocks in tropical regions, especially in freely drained and deeply weathered regoliths. {B}ecause goethite is the major mineral constituent of such oxide-rich units, this {N}i loss has been linked to compositional changes in goethite. {I}n the present study, we have investigated possible correlations between {N}i contents in the bulk laterite, and the evolution of goethite in terms of composition and crystallinity, in two {N}i-rich and one {N}i-poor lateritic profiles from {N}ew {C}aledonia. {N}i {K}-edge {E}xtended {X}-ray {A}bsorption {F}ine {S}tructure ({EXAFS}) spectroscopy indicates that goethite hosts the main fraction of {N}i in the three profiles investigated. {A}sbolane/lithiophorite identified as accessory minerals by {X}-ray diffraction ({XRD}) have little effect on the vertical variations in bulk {N}i content in spite of the fact that the {N}i contents of these {M}n-oxides can be significant at certain depths. {T}he gradual decrease in {N}i content from the bottom to the top of the three {N}i lateritic profiles correlates with a decrease in the {N}i content of goethite as determined by electron probe micro-analysis. {I}n addition, {XRD} data show that these compositional trends are linked to an increase of the mean coherent domain size of goethite. {T}hese observations support the hypothesis that {N}i is expelled from goethite as it ages through successive dissolution and recrystallization cycles during the lateritization process. {C}omparison of laterites having different degrees of weathering suggests that this aging process could also play a significant role in the regional variability of {N}i content in {N}i-laterite deposits.},
  keywords = {{NOUVELLE} {CALEDONIE}},
  booktitle = {},
  journal = {{G}eochimica et {C}osmochimica {A}cta},
  volume = {160},
  numero = {},
  pages = {1--15},
  ISSN = {0016-7037},
  year = {2015},
  DOI = {10.1016/j.gca.2015.03.015},
  URL = {https://www.documentation.ird.fr/hor/fdi:010064629},
}