dc.creator | González Jiménez, José | |
dc.creator | Deditius, Artur | |
dc.creator | Gervilla, Fernando | |
dc.creator | Reich Morales, Martín | |
dc.creator | Suvorova, Alexandra | |
dc.creator | Roberts, Malcolm | |
dc.creator | Roqué, Josep | |
dc.creator | Proenza, Joaquín A. | |
dc.date.accessioned | 2019-05-31T15:19:14Z | |
dc.date.available | 2019-05-31T15:19:14Z | |
dc.date.created | 2019-05-31T15:19:14Z | |
dc.date.issued | 2018 | |
dc.identifier | American Mineralogist, Volumen 103, Issue 8, 2018, Pages 1208-1220 | |
dc.identifier | 19453027 | |
dc.identifier | 0003004X | |
dc.identifier | 10.2138/am-2018-6424 | |
dc.identifier | https://repositorio.uchile.cl/handle/2250/169363 | |
dc.description.abstract | We report new results of a combined focused ion beam and high-resolution transmission electron
microscopy (FIB/HRTEM) investigation of platinum-group elements (PGE)-rich base-metal sulfides.
The Ni-Fe-Cu base-metal sulfides (BMS) studied are millerite (NiS), pentlandite [(Ni,Fe)9S8], pyrite
(FeS2), and chalcopyrite (CuFeS2). These BMS were found forming composite inclusions (<60 mm
across) within larger unaltered chromite from the Caridad chromite deposit, which is hosted in the
mantle section of the Mayarí-Baracoa Ophiolite in eastern Cuba. Electron probe microanalysis of BMS
revealed PGE values of up to 1.3 wt%, except for pentlandite grains where PGE concentrations can
reach up to 12.8 wt%. Based on the amount of Ru, two types of pentlandite are defined: (1) Ru-rich
pentlandite with up to 8.7 wt% of Ru and <3.5 wt% of Os, and (2) Ru-poor pentlandite with Ru <0.4
wt% and Os <0.2 wt%. Ru-rich pentlandite contains Ir-Pt nanoparticles, whereas the other sulfides
do not host nanometer-sized platinum-group minerals (PGM). The Ir-Pt inclusions are found as: (1)
idiomorphic, needle-shape (acicular) nanoparticles up to 500 nm occurring along the grain boundaries between Ru-rich pentlandite and millerite, and (2) nanospherical inclusions (<250 nm) dispersed
through the matrix of Ru-rich pentlandite. HRTEM observations and analysis of the selected-area
electron diffraction patterns revealed that nanoparticles of Ir-Pt form domains within Ru-rich pentlandite. Fast Fourier transform analyses of the HRTEM images showed epitaxy between Ir-Pt domain
and PGE-poor millerite, which argues for oriented growth of the latter phase. These observations
point to sub-solidus exsolution of the Ir-Pt alloy, although the presence of nanospherical Ir-Pt inclusions in some other grains suggest the possibility that Ir-Pt nanoparticles formed in the silicate melt
before sulfide liquid immiscibility. These Ir-Pt nanocrystals were later collected by the sulfide melt,
preceding the formation of Ru-rich pentlandite. Early crystallization of the Ru-rich pentlandite and
Ir-Pt nanoparticles led to the efficient scavenging of PGE from the melt, leaving a PGE-poor sulfide
residue composed of millerite, pyrite, chalcopyrite, and a second generation of PGE-poor pentlandite. | |
dc.language | en | |
dc.publisher | Walter de Gruyter GmbH | |
dc.rights | http://creativecommons.org/licenses/by-nc-nd/3.0/cl/ | |
dc.rights | Attribution-NonCommercial-NoDerivs 3.0 Chile | |
dc.source | American Mineralogist | |
dc.subject | Applications of Fluid | |
dc.subject | chromite | |
dc.subject | Cuba | |
dc.subject | focused-ion beam (FIB) | |
dc.subject | Melt Inclusions | |
dc.subject | Mineral | |
dc.subject | Nanoparticles | |
dc.subject | platinum-group elements (PGE) | |
dc.subject | transmission electron microscopy (TEM) | |
dc.title | Nanoscale partitioning of Ru, Ir, and Pt in base-metal sulfides from the Caridad chromite deposit, Cuba | |
dc.type | Artículo de revista | |