HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Journal articles

Nickel dispersion and enrichment at the bottom of the regolith: formation of pimelite target-like ores in rock block joints (Koniambo Ni deposit, New Caledonia)

Michel Cathelineau 1 Benoît Quesnel 2 Pierre Gautier 2 Philippe Boulvais 2 Clément Couteau 3 Maxime Drouillet 3
1 GeoRessources
2 GR - Géosciences Rennes
3 Koniambo Nickel SAS
Abstract : In New Caledonian Ni deposits, the richest Ni silicate ores occur in fractures within the bedrock and saprolite, generally several tens of meters to hundred meters below the present-day surface. Fracture-related Ni silicate ore accounts for high Ni grades, at least a few weight percent above the average exploited grade (2.5 %). These Ni-rich veins are affected by active dissolution-precipitation processes at the level of the water table. Ni in solution is precipitated as silicates in thin layer cementing joints. This mineralization is characterized by chemical and mineralogical concentric zoning with an outer green rim around an inner white zone composed, from the edge to the centre of the block, (i) a highly oxidized and altered zone, (ii) a green pure Ni-rich pimelite zone, (iii) a zone (limited to a few centimetres) with a mixture of Ni-poor kerolite and Ni-rich pimelite and intermediate colours and (iv) a large white Mg-kerolite mineralization zone. This study proposes that the concentric zonation results from evapo-precipitation process related to alternate periods of hydration and drying, induced by water table movements. This extensive dispersion of Ni in concentrically zoned ores can partly explain the rather monotonous Ni grade of the bulk exploitation at the base of the regolith with values between 2 and 3 wt%.
Keywords : Dissolution-precipitation Ni-laterite Garnierite Kerolite-pimelite New Caledonia
Document type :
Journal articles
Complete list of metadata
https://hal-insu.archives-ouvertes.fr/insu-01184853
Contributor : Isabelle Dubigeon Connect in order to contact the contributor
Submitted on : Tuesday, August 18, 2015 - 9:28:25 AM
Last modification on : Wednesday, May 11, 2022 - 4:34:06 AM

Identifiers

Collections

INSU | CNRS | UNIV-RENNES1 | GR | OSUR | GEORESSOURCES-UL | UNIV-LORRAINE | OTELO-UL | GR-3T | UNIV-RENNES | RESSOURCES21 | ANR | UR1-ENV | UR2-HB | UNIV-RENNES2 | INRAE

Citation

Michel Cathelineau, Benoît Quesnel, Pierre Gautier, Philippe Boulvais, Clément Couteau, et al.. Nickel dispersion and enrichment at the bottom of the regolith: formation of pimelite target-like ores in rock block joints (Koniambo Ni deposit, New Caledonia). Mineralium Deposita, Spinger, 2016, 51 (2), pp.271-282. ⟨10.1007/s00126-015-0607-y⟩. ⟨insu-01184853⟩

Export

BibTeX TEI DC DCterms EndNote Datacite

Share

Metrics

Record views

137