{"id":3737,"date":"2020-01-20T14:32:44","date_gmt":"2020-01-20T14:32:44","guid":{"rendered":"http:\/\/caribbeanlithos.ub.edu\/?p=3737"},"modified":"2026-03-04T15:24:18","modified_gmt":"2026-03-04T15:24:18","slug":"2019-nanoscale-partitioning-of-ru-ir-and-pt-in-base-metal-sulfides-from-the-caridad-chromite-deposit-cuba","status":"publish","type":"post","link":"https:\/\/caribbeanlithos.ub.edu\/?p=3737","title":{"rendered":"2019: Nanoscale partitioning of Ru, Ir, and Pt in base-metal sulfides from the Caridad chromite deposit, Cuba"},"content":{"rendered":"\n

Nanoscale partitioning of Ru, Ir, and Pt in base-metal sulfides from the Caridad chromite deposit, Cuba <\/strong><\/p>\n\n\n\n

Abstract<\/p>\n\n\n\n

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 \u03bcm across) within larger unaltered chromite from the Caridad chromite deposit, which is hosted in the mantle section of the Mayar\u00ed-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. <\/p>\n\n\n\n

Keywords:<\/strong> Nanoparticles; platinum-group elements (PGE); focused-ion beam (FIB); transmission electron microscopy (TEM); chromite; Cuba; Applications of Fluid, Mineral, and Melt Inclusions<\/p>\n\n\n\n

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To Cite this article:<\/strong> Gonz\u00e1lez-Jim\u00e9nez, J.M.; Deditius, A.; Gervilla, F.; Reich, M.; Suvorova, A.; Roberts, M.P.; Roqu\u00e9-Rosell, J.; & Proenza, J. A. (2018). Nanoscale partitioning of Ru, Ir, and Pt in base-metal sulfides from the Caridad chromite deposit, Cuba. American Mineralogist<\/em>, 103<\/em>(8), 1208-1220. <\/p>\n\n\n\n

DOI<\/strong>:  10.2138\/am-2018-6424
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<\/p>","protected":false},"excerpt":{"rendered":"Nanoscale partitioning of Ru, Ir, and Pt in base-metal sulfides from the Caridad chromite deposit, Cuba 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 Continue Reading<\/a>","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[129,40,44],"tags":[],"class_list":["post-3737","post","type-post","status-publish","format-standard","hentry","category-publications2019","category-cuba","category-publications","cat-129-id","cat-40-id","cat-44-id"],"_links":{"self":[{"href":"https:\/\/caribbeanlithos.ub.edu\/index.php?rest_route=\/wp\/v2\/posts\/3737","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/caribbeanlithos.ub.edu\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/caribbeanlithos.ub.edu\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/caribbeanlithos.ub.edu\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/caribbeanlithos.ub.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3737"}],"version-history":[{"count":3,"href":"https:\/\/caribbeanlithos.ub.edu\/index.php?rest_route=\/wp\/v2\/posts\/3737\/revisions"}],"predecessor-version":[{"id":3750,"href":"https:\/\/caribbeanlithos.ub.edu\/index.php?rest_route=\/wp\/v2\/posts\/3737\/revisions\/3750"}],"wp:attachment":[{"href":"https:\/\/caribbeanlithos.ub.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3737"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/caribbeanlithos.ub.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3737"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/caribbeanlithos.ub.edu\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3737"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}