This is anopenaccess article undertheCCBY-NC-SAThis Universidad Nacional Autónoma de México. Peer Reviewing under the responsibility of Manuscript November accepted: 29,2019 Corrected manuscript received: November 22,2019 Manuscript received: May 16,2019 BSGM2020v72n3a201219 72 (3), A201219.http://dx.doi.org/10.18268/ Boletín de la Sociedad Geológica Mexicana, Colombia: Ni-Laterite deposits, Northern (PGE) in Cerro Matoso andPlaneta Rica Platinum-Group Elements Geochemistry of Pablo, J., Ramírez, C.,Pujol-Solà, N., 2020, Aiglsperger, T., Betancur, S., Farré-de- Tobón,M., Weber, Proenza, M., J. A., How tocitethisarticle: [email protected] * Corresponding author:(M.Tobón) Engineering, SE97187Luleå,Sweden. GeosciencesandEnvironmental of Division CivilEngineering andNatural Resources, of 3 Spain. (UB), Martí i Franquès08028 Barcelona, s/n, UniversitatGeologia Aplicada, de Barcelona 2 Colombia. Colombia, Carrera 80 # 65-223, Medellín, Facultad de Minas, Universidad Nacional de 1 Sebastián Mónica Matoso yPlanetaRica,NortedeColombia Geoquímica de los Elementos (EGP)enlosdepósitos del Grupo delPlatino lateríticos de Ni de Cerro Ni-Laterite deposits,NorthernColombia Geochemistry of Platinum-Group Elements (PGE)inCerro Matoso and Planeta Rica license(https://creativecommons.org/licenses/by-nc-sa/4.0/) ue nvriyo Technology,Luleå Universityof Department Departament de Mineralogia, PetrologiaDepartament i Departamento de MaterialesDepartamento y Minerales, Tobón Betancur 1,* , Marion 1 , Júlia Weber Farré-de-Pablo Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín 1 , Joaquín A. Matoso, PlanetaRica,Colombia. minerals (PGM),Cerronumgroup elements(PGE),plati numgroup Keywords: Ni-laterite deposit, plati as by-products duringNi(+Co)production. processescan be applied for their recovery adequate recovery tional PGE deposits, if Rica shouldbe considered as unconven altered pyrite. Cerro Matoso andPlaneta PGMadhered to the porous edges of of textural relations theneoformation suggest Pt nanoparticle, Republic. Inthe case of Dominican alloysfound inlaterites of whichsition, comparableis with PGE-Fe-Ni andchemical compo by their morphology Fe-Ni alloys, is supported thisinterpretation Pt-Ir- arein origin.Inthe caseof secondary platinumgroup minerals(PGM) types of were found withinframboidal pyrite. Both Pt (< 1µm) same zone, nanoparticles of zone inPlaneta Rica. In addition, inthe found inthe limonite–saprolite transition Fe-Ni minerals hosted by Fe-oxyhydroxide PGE-Fe mineral alloyssuch asthe Pt-Ir- of ity between PGE andFe favors the formation by the laterization processes. high affin The PGE are mobilized in different proportions Rh
Geochemistry of PGE in Cerro Matoso and Planeta Rica ABSTRACT Geochemistry of PGE in Cerro Matoso and Planeta Rica INTRODUCTION 1. Introduction 2 2 cal characteristics. most prominent Their use is high-tech metals due totheir physicaland chemi platinum (Pt), and palladium (Pd), are considered iridium (Ir), ruthenium (Ru), rhodium(Rh), Platinum-group elements (PGE), (Os), osmium conditions and microbiotic activity, as well as the 2015, 2016a; Proenza, 2015). Changes in Eh–pH PGE (Aiglsperger enrichmentsecondary of and residual enable rocks ultramafic in processes Australia) (Green andPeck, 2005). Range, Western Australia; Syerston, Southeastern ( rocks ultramafic in profiles lateritic and (e.g. in ophiolites Troodos, Cyprus; Ray Iz, Russia; deposits Shetlands, UK), PGE find we these, allow PGEexploitation onaminorscale. Among the so-called unconventional PGE deposits, which Spanish) inColombia. However, there are also Condoto Complex (CUZAC, by itsacronym in e intrusions, ultramafic Alaskan-type from deposits Noril’sk-Talnakh (Russia);and iii)PGEplacer deposits, sulfide Ni-Cu magmatic High-S ii) Great (South Dyke Africa) and Stillwater (USA); Low-S layered intrusion-hosted, in threeoccur major geological environments:i) these metals main typicalsources2010). The of very rare worldwide ( 2012a). Energía,y (Ministerio deMinas the country of promote the andsocialdevelopmenteconomic a sustainablebe minedin way, thushelpingto made being orderin toidentifyareas fromwhich they can are efforts then, Since Colombia. strategic minerals in included among the list of markets.international For this reason, they were group minerals(PGM) both inthe national and Therefore, therea highdemand for is platinum equipment (Lusty, 2016;EC,2018;USGS, 2018). electronicin applications, jewelry, andlaboratory fromemissions automobiles. They are also used as catalytic converters, which decrease polluting / / . g Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín . Urals (Russia) and Zoned Ultramafic Alto Ultramafic Zoned and (Russia) Urals . Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Recent studies have found that weathering are significance economic with deposits PGE e . g . Holwell and McDonald, http://dx.doi.org/10.18268/BSGM2020v72n3a201219 e . g . Bushveld and e . g . Weld et al e . g ., /72(3)A2012192020 - /72(3)A2012192020 . auso P n do 44 and 29 ppb, respectively, Pt and Pd of values of Greece show mean Fe-Ni1994). The laterites of exhibitsPt values (Augé upto2ppm and Legendre, Caledonia ophiolitic complex (Pirogues zone) to evaluate it. For instance, laterites from the New and several studies have inorder been performed tralia have showninterest their in PGE potential Greece, Cuba, the Republic,Dominican andAus a consequence, countriessuchNew Caledonia, as 2004; Aiglsperger 1994a, 1994b;Wilde (Bowles, profile laterite 1986; Augé and Legendre, 1994;Bowles the of levels upper the PGE in re-precipitation, andconcentration of matter, organic favorpresence of themobility, ANM, 2015). AstudyANM, published byOrtiz Energía,y 2011; MinisteriodeMinas 2012b; potential for Pt exploitation(SGC, the country in days, these areas continue to represent the main originated in Alaskan-Type CUZAC and, nowa were deposits ment (Leal León, 2009).These the Chocó Depart Atrato, andCondotoriversof the San Juan, locateddeposits inthe tributaries of the 20 beginning of Pt(Platina Resources Limited,2019). koz of 105 Australia, has measured mineral resources of over anAlaskan-typeultramafic-maficcomplex in Owendale2015). The lateritic developed deposit, limonite horizon (Aiglsperger 36 ppb, inthe parental rock,to 640 ppbinthe Republic hasatotal PGE content ranging from FalcondoThe Ni-laterite inthe Dominican deposit Pd (Eliopoulos andEconomou-Eliopoulos, 2000). 88 ppb Pt and 186 ppb and maximum values of to 39ppmAg inElRoble. 3ppmAu andup burgitic Unit; andanaverage of ppb Pd, and 54ppbAu inthe Medellín Metaharz Cerro Matoso; up to 874ppbPt, 810 of canga and 3.6ppmAgwere detected in the magnetic ~6.4ppmAu these units anddeposits. Values of in potential unexplored identifies deposit, sulfide gitic Unit, Cerro Matoso, andElRoble massive the MedellínMetaharzburColombia, including (2004) about precious metals (Au, AgandPGE) in In Colombia,Pt has been extracted since the et al th century from century the alluvial et al ., 2015,2016a,2016b).As ., 2003;Proenza et al ., 2015; Proenza, et al et al et al ., ., - - - - - . Unit. Modified after Geotec Ltda.Unit. Modified (2003);Guzmán after Geotec Figure 1 rseto Ni-laterite afterCerro Matoso. prospect of whichthe most important is second economic Planeta Rica, of UPME, 2009),andthe deposit exploited (Castro,deposit in the country 1987; being the most important and theNi-lateriteonly Matoso S.A. mine(operated by South32 Ltd.) recognizednickel deposits in Colombia: the Cerro (limonite profile the six arehorizon). studieddeposits two The of weathering the of levels most PGE in the upper enrichmentand secondary of residual favor rocks ultramafic on processes ering two Ni-laterite deposits, investigating how weath andPlaneta units.ultramafic Rica our We researchfocused on Matoso Cerro the specifically bia, in laterites formed over ultramafic rocks in Colom PGE time,first the occurrence and distribution of thispaper is to analyze, for the of purpose The Locationand geological mapof thestudyareascorresponding and tothe PlanetaRicaPeridotites theCerro Matoso Ultramafic Boletín de la Sociedad Geológica Mexicana Mexicana Mexicana Geológica Geológica Sociedad Sociedad la la de de Boletín Boletín http://dx.doi.org/10.18268/BSGM2020v72n3a201219 et al . (2004);Gómez - - - et al . (2015);and Mora company hasnotyet made available a public a its mineral resources.in order to determine The in thelast5years, conducteddrilling campaigns alsobelongs to Cerrodeposit Matoso S.A., which, Planeta Rica day inthe area. mining title of The exploratoryonly work outtothis been carried has Ni-laterite after Cerro Matoso, important source of Planeta consideredRica is most asthesecond of resource (South32, 2019). Althoughthe deposit 32Mtand312inmineral total ore reserve of to continue for 10years more, given that it has a has been exploited since 1982andit is expected mine 41.1kTinFY19(South32, 2019). The of ferronickel alloy,producers of withaproduction the world’smajor Cerroone of Matoso is deposit able report far is fromso the United Nations, pub the resources found, andthe only avail report of /72(3)A2012192020 / 72(3)A2012192020 et al . (2017). 3 3 - -
Geochemistry of PGE in Cerro Matoso and Planeta Rica INTRODUCTION INTRODUCTION / GEOLOGICAL Geochemistry of PGE in Cerro Matoso and Planeta Rica SETTING 2. Geologicalsetting 4 4 PGE occurrence inNi-laterites. in Colombiaandwillalsoserve as anexample of Pt newunconventional exploration targets of of researchfavoridentificationour will the of results mining project wasnot economically feasible. The basis, a dry 5.2Mton andconcludedthat a of report calculatedlished in1975.This Ni reserves (LMV) in northern Colombia(Figure 1). (LMV) innorthern the Lower Magdalena ValleySan Jorge Basin of unit called the San Jacinto Fold Belt (SJFB) and the locatedsuture this in zone, between the structural Cerromafic Matoso rocks and of Planeta Rica are 1984; Nivia,1996;Kerr and the Caribbean Plateau ( Nivia Bartok oceanic MOR( in environmentselements formed of different with associated be may rocks Mora al (Cediel rocks ultramafic dispersed of presence the defined by is and east, the to units continental oceanic unitsto the west and cates the collision of Romeral Fault RFSdemar System (RFS). The is limited by asuture, known regionally as the Andes theNorthern margin of thewestern tion of configura tectonic plains.recentThe alluvial and inter-mountain valleys(Cauca and Magdalena), tains ranges(Western, Central, and Eastern), three moun ismainlymade up of bian territory al Cediel (Toussaint, 1996; Ramos andAleman, 2000; transcurrent fault during the Cenozoicsystems along subsequently fragmented and dispersed and margin continental the of segments different along diachronously accreted affinity, were which oceanic allochthonous of terranes with aseries of the South American continental margin tion of Andes is characterized byNorthern the interac the Meso-CenozoicThe tectonic evolution of / / ., 2003;Villagómez, 2010; Spikings ., 2012;Spikings Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín The geographic configuration of the Colom of configuration geographic The et al et al et al et al ., 2017). The origin of these ultramafic these of origin The 2017). ., ., 1996;Spadea 1996), and Espinosa, ., 1985), intra-oceanic islandarcs ( ., 2003;Villagómez, 2010; Bayona et al ., 2015;Mora et al ., 1997). The ultra ., 1997).The e . g http://dx.doi.org/10.18268/BSGM2020v72n3a201219 . Millward et al et al ., 2017). ., 2015; et al e e . . g g et et ., /72(3)A2012192020 ------/72(3)A2012192020 . . 2.1. CERRO MATOSO ULTRAMAFIC UNIT Jacinto Formations. Based onU/Pb geochronol the Middle to Upper Eocene Chengue andSan to Lower Eocene San Cayetano Formation, and ceous CansonaFormation, the Upper Paleocene mez, 2010; Mora Colombia duringthe Eocene (Villagó margin of a fore-arc in environment andlater accreted to the northern deposited were which influence comprise marine sediments with terrigenous Geotec Ltda, 2003; Guzmán Caro, 1980;González andLondoño, 2001; San Jerónimo, San Jacinto, andLuruaco(Duque- three anticlinorium structures: It ismade upof Basin andto the west by the Sinu Lineament. SJFB islimited to the east byThe the San Jorge 1986). 146 m (López-Rendón, a maximum height of m (Mejía 48 of and Durango, 1982; López-Rendón, 1986) and thickness profile laterite age Hoyos andVelázquez, 1996),reaching anaver and Duque-Caro, 1981;López-Rendón, 1986; moment, the laterization process (Dueñas began dean orogeny (Middle Eocene) and,from that its emplacement took placeduringthe pre-An al (Hoyosdeposits andVelázquez, 1996;Gómez FormationPliocene Cerrito andrecent alluvial the that underlies discordantly the sediments of 1982; López-Rendón, 1986; Gleeson a partially harzburgiteserpentinized (Mejía andDurango, to corresponds unit ultramafic The 1996; GonzálezandLondoño, 2001)(Figure 2). (López-Rendón, 1986;Hoyos andVelázquez, 252m.a.s.l. before miningbegan mum height of ~425 haandit hadamaxi It covers anarea of it outcrops asanoval-shaped hilltrending NW. Montelíbano, Colombia,and the southwest of at located is Unit Ultramafic Matoso Cerro The arcs, respectively. Cretaceous oceanic andcontinental magmatic Chengue/ San Jacinto sequences represent Late al and Hf-isotopes on detrital zircons,ogy Mora . (2017) suggested that. (2017) suggested the San Cayetano and ., 2015).According to some geological models, et al ., 2017): the Upper Creta et al ., 2004). They et al ., 2004) et et ------Figure 2 Londoño and González,1997; Gleeson andMatoso mine,with thelocationofstudied samples and pits dumpslocation of theapproximate (Modified theextraction after associated with tachylite and fault zones, domi 4) Fe-oxides andgoethite; dominated by quartz and smaller amounts of 3) smectite; also containssmallamountsof veryfabric; itis rich inFe-oxides andgoethite, and the original rock anyfeature of horizon devoid of 2) gibbsite; with amajorproportion of non-magnetic, goethite; and b)anodularcanga, of and dominated by maghemite and minoramounts red horizon, extremely hard, strongly magnetic, 1) from toptobottom,are: by seven horizons (Gleeson characterized is Matoso Cerro of profile lateritic Gleeson (Brand silicate-type hydrous as sified Cerro Matoso Ni-laterite hasbeen clas deposit the main Ni ores, the of Based on the mineralogy Left: Local geologyofCerro Matosomodified after Gómez Red laterite Canga, which can be divided into two types Black saprolite Yellow laterite et al ., 2003;Freyssinet : a red-brown, very soft, fine-grained : a silt- to clay-grained horizon: a silt- to clay-grained : adark to blackgreen interval Boletín de la Sociedad Geológica Mexicana Mexicana Mexicana Geológica Geológica Sociedad Sociedad la la de de Boletín Boletín et al et al http://dx.doi.org/10.18268/BSGM2020v72n3a201219 ., 2004;and Gómez et al ., 2004), which, ., 2005). The ., 2005). The et al : a) a dark ., 1998; et al - - ,. 2015). et al . (2015).Right:Satelliteimage(Google Earth) showing theCerro pletely understood, originally misnamed as pletely understood, Matoso.horizon atypical is This andnotcom enstatite, andchromite. rock) 7) serpentine, with minorsiderite-magnesite; by sepiolite, pimelite, quartz, Fe-oxides, Ni-rich dominated is mineralogy its soft; and fine-grained sepiolite, serpentine, andquartz; content of the protolith andwith a high some rare remnants of containing silt, to sand fine from ranging size grain nated by Fe-oxides, sepiolite, smectite, andquartz; major exploitationareas: mining Pit 1 andPit 2. to faultzones withinthedeposit. phasesandFe-oxides amorphous associated up of made texture, and glassy with fined-grained, very “tachylyte”. It is a dark-brown to black horizon, An additional horizon canbe found at Cerro The CerroThe Matosodivided intotwo mineis 6) 5) aeu fforsteritic olivine, serpentine, : made up of Green saprolite Brown saprolite Brown Saprolitized peridotite and peridotite (unweathered /72(3)A2012192020 / 72(3)A2012192020 : the mainNi-ore horizon, green, : anorange-brown horizon, with 5 5 -
Geochemistry of PGE in Cerro Matoso and Planeta Rica GEOLOGICAL SETTING Geochemistry of PGE in Cerro Matoso and Planeta Rica GEOLOGICAL SETTING Figure 3 6 6 and peridotites. laterite, brown saprolite, saprolitized peridotites, acterized from toptobasebyred laterite, yellow Fe-oxyhydroxides, clays,char andquartz, anditis mineral assemblagetion. The is dominated by and peridotite. tachylite, saprolite, green saprolitized peridotite, red laterite, blacksaprolite, sequence composedof a is characterized by zone ata canga the top of pimelite, sepiolite, nimite, andNi-smectites. It concentrated in four majorNi-bearing phases: profiles asdescribedbelow (Gleeson twoThese pitsexhibit characteristic weathered / / Geologicalmapof thePlanetaRicaareawithlocationof the PR-1136 drillhole. Modified after Ramírez Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín b) The Pit 2 profile has a lower Ni concentra Ni lower a has profile 2 Pit The b) Ni-grade, highest the has profile 1 Pit The a) http://dx.doi.org/10.18268/BSGM2020v72n3a201219 et al ., 2004): /72(3)A2012192020 - - /72(3)A2012192020 2.2. PLANETA RICAPERIDOTITES (Naciones Unidas, 1975), located near the Pla isolated hills; Queresa, Porvenir, andSabana Cerro Matoso (Figure 1), andcomprise three of Planeta Rica PeridotitesThe crop out to the north dotite (unweathered rock). - saprolitized peridotite – peridotite; and 4)peri - saprolitized peridotite – peridotite; 3) red laterite rolitized saprolite peridotite – peridotite; 2) green of: 1)redconsists laterite saprolite - green - sap sequences common 10m,andthemost average of has considerably decreased to its thicknessan At present, the Cerro Matoso Ni-laterite deposit et al . (2019). - - - sured for the Ni-laterites found inthe Queresa and ever, sub-economicmineral resources were mea studied thantheCerroless Matoso How deposit. the studied area (Ramírez of Nuevo Paraíso Basalts, which outcrop to the south lavasThese are genetically associated with the Unidas,and Duque-Caro, 1975;Dueñas 1981). with basaltic lavasstones alternated (Naciones chert, mudstone,siliceous and lime sandstones Formation. marinelayers These are by composed byLate Cretaceous marinelayersfrom the Casona Planeta Rica Peridotites2019). The are overlaid Late Jurassicage (Ramírez (SSZ) ophiolite of Both unitscorrespond toasupra-subductionzone gabbros, gabbros, hornblende andpyroxenites.of intruded by the Porvenir Gabbro unit, composed Caro, 1981).OnPorvenir hillthe peridotites are (Naciones Unidas, 1975; Dueñasand Duque- and sheared peridotites and highlyserpentinized serpentinites assemblagemade upof mainly is the N–Sdirection. rockin 10km The extent of unit hasanelongated shape, withamaximum Colombia. The neta Rica townin northwestern (Naciones Unidas, 1975;Dueñas an earlyTertiary age for the laterization process the Oligocene-Miocene de Orocontinental Ciénaga Formation, suggesting by overlaid are profile minerals.accessory pentine and enstatite, withspinelandmagnetite as ser harzburgitehighly serpentinized made up of ing somepyroxene relicts from theoriginalrock; slightly more clayey thanthe laterite and preserv originalrock fabric; ervation of horizon withearthyand withoutpresconsistency droxides andmagnetite; Fe-oxyhy variable of consisting dimensions of zones, in four from toptobottom: divided profile laterite of meters 8to 10 Unidas (1975) reportedof a thickness Porvenir hills (Naciones Unidas, 1975). Naciones The Planeta Rica Ni-lateritebeen has The deposit The Planeta Rica PeridotitesThe and its lateritic 4) Saprolitized peridotite, corresponding to 3) Saprolite, dark brown incolor, –greenish 2) Ferrolitic laterite, adark brown orreddish presented1) Canga as non-continuousblocks Boletín de la Sociedad Geológica Mexicana Mexicana Mexicana Geológica Geológica Sociedad Sociedad la la de de Boletín Boletín et al http://dx.doi.org/10.18268/BSGM2020v72n3a201219 ., 2019)(Figure 3). et al. , 1981). et al ., ------3. Samplingstrategy 4. Analyticalmethods peridotite. from the red laterite and one from the saprolitized samples four comprehend: profile CMM-03 the from the saprolitized peridotite. samplesfrom The red laterite, one from saprolite, the green andone the from sample one by: composed are profile 01 collected (Figurefrom samples 4).The the CMM- ~3 kg each, with their respective duplicates, were eight samples of weathered thickness. Atotal of of m 2.8 has profile CMM-03 the and weatheredthickness of m 2 has profile CMM-01 The 2). were sampledat the Cerro Matoso mine(Figure CMM-03) and (CMM-01 profiles exposed Two Au (Table 2). Pd, Rh,Ru,1 ppb, IrandOswas and2ppb for Chan andFinch detection limit for (2001). The Pt, tion Fire Assay, following the method described by PGE and Au contents using Nickel Sulfide Collec the Spectrometry (ICP-MS) was usedto determine spectrometry. Inductively Coupled Plasma -Mass Perth (Australia) (XRF) using X-Ray Fluorescence and trace elements at Intertek Genalysis Ltd., Seventeen samples were analyzed for major, minor, Table 1. the bothweathering areas profiles are shown of in idotite (Figure general characteristics 5).The of saprolite,the green andone sample from the per laterite andsaprolite horizons, two samples from one sample from the transition zone between threethe canga, samples from the red laterite, onwards.depth One sample wascollected from andsheared peridotite fromserpentinized, this intensely saprolitized, and profile weathering of the drillhole was30m,with approximately 14m out duplicates) were total length of collected. The inches andweigh between 0.5kgand2.7(with 2 ½ eight samples with a core diameter of total of the Porvenir hill(Figure 3).A part of the northern taken from one drillhole (PR-1136), located in In the Planeta Ricaperidotite, were samples /72(3)A2012192020 / 72(3)A2012192020 7 7 - - -
GEOLOGICAL SETTING / SAMPLING Geochemistry of PGE in Cerro Matoso and Planeta Rica STRATEGY / ANALYTICAL METHODS Geochemistry of PGE in Cerro Matoso and Planeta Rica ANALYTICAL METHODS Figure 4 8 8 / / Schematic weatheringsampling Schematic profilesatstations CMM-01and CMM-03 inCerro Matoso. Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín http://dx.doi.org/10.18268/BSGM2020v72n3a201219 /72(3)A2012192020 /72(3)A2012192020 4.1. CONCENTRATION OF HEAVY MINERALS Figure 5 described inAiglsperger hslab-barcelona.com/) following the methodology Barcelona (http://www. the University of of tory hydroseparation techniques inthe HS-11 labora In thisstudy, PGMs were concentrated using et al from them,even withvery sizessmall (Aiglsperger lateritic obtain PGMs samples andsuccessfully impulses. Bythese means it is possible to process wave diverse with pressure constant at flow water laminar beachby placer deposits a combination of heavyminerals. technique This simulates natural technique for non-chemical concentration of effective very a be to proved has hydroseparation et al tion, andseparation by(Aiglspergerdense liquids ods such ascrushing, screening, magnetic separa meth traditional difficult by extremely is µm <40 sizes ppbsandgrain PGE content in the order of PGMsinsampleswithtotal Concentration of Schematic weathering profile at sampling PR-1136 drill hole and photos of the boxes containing the drill cores in Planeta Rica. in Planeta cores drill the containing boxes the of photosandhole drill PR-1136 sampling at profile weathering Schematic ., 2011,2015;Navarro-Ciurana ., 2011, 2015). However, inthe last decade et al Boletín de la Sociedad Geológica Mexicana Mexicana Mexicana Geológica Geológica Sociedad Sociedad la la de de Boletín Boletín . (2011). http://dx.doi.org/10.18268/BSGM2020v72n3a201219 et al ., 2012). - - - 5.1. CERRO MATOSO 5. Wholerockgeochemistry 4.2. MINERALOGICAL CHARACTERIZATION cmoe fred laterite) in the CMM-01 and (composed of thelimonitehorizon maincomponent of The in backscattered electron (BSE)mode. weretions 20keVaccelerating voltage and 5nA de Barcelona operating (CCiTUB). The condi Cienti Centres trometer 250 microanalysis system(EDS) at the equipped with anINCAenergy-dispersive spec electronscanning emission microscope (FE-SEM) FEI XTE 325/D8395 and a JEOL JSM-7100 field tronmicroscopy (SEM) using bothaQuanta 200 Afterwards, they were examined by scanningelec subsequently studied by reflected light microscopy. mounted aspolishedmono-layer resin blocksand resultingThe heavymineral concentrates were /72(3)A2012192020 / 72(3)A2012192020 fics i Tecnòlogics de la Universitat la de i Tecnòlogics fics 9 9 - - -
Geochemistry of PGE in Cerro Matoso and Planeta Rica ANALYTICAL METHODS / WHOLE ROCK GEOCHEMISTRY Geochemistry of PGE in Cerro Matoso and Planeta Rica WHOLE ROCK GEOCHEMISTRY Table 1. Characteristics of thematerialsfoundTable 1.Characteristics intheCerro Matosoand PlanetaRicaweathering profiles. 10 10 03 profile (Figure 6and Table 2). the CMM- the limonite horizon of the bottom of at and profile CMM-01 the in saprolite green the zone at between the boundary the red laterite and changes in chemistry mark the Mg discontinuity (6 wt.%and0.6wt.%,respectively). Thus, these profile the of top the towards decrease contents litized peridotite. Conversely, the SiO the highest values corresponding tothe sapro wt.% SiO main components, withvalues between 41 and 46 litized peridotite horizons SiO show~13 wt.%Fe rolite and saprolitized peridotite horizons, which values strongly decrease towards sap the green Fe is profiles CMM-03 / / Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín 2 andbetween 25 to 32 wt.% MgO, with
2 O Saprolite zone Limonite zone Unweathered (ferricrete or 3 Clasification Canga zone . In the. In saprolite and sapro duricrust) 2 O rock 3 (66-71.6 wt.%). These (66-71.6 wt.%). These
2 andMgO are the
http://dx.doi.org/10.18268/BSGM2020v72n3a201219
sheared and fractured. Sporadic irregular carbonateveins. In general, the rock is notably serpentinized, contains magnetiteand bastiteafter pyroxene. structure.Granularof texture mottledappearance,strongly Light grayto dark color. Very hard rock, compact, massive grains of disseminated millimetric chromite. harder the of saproliteThe top usually is siltycrumbly and andbase is the original structure of the rock and has serpentinized peridotite relicts. Variablecolorfromstronggreenish yellow, brown to preserves the manganese oxides. It has millimeter and e shows roundedholes with iron oxide crusts and black patchesof porous, fine to medium subangular blocky structure. Occasionally it Variable colour from red to dark reddish brown, clayey silt texture, goethite,as hematite and magnetite. very hard and very compact. It consists mainly of iron oxides such Dark reddishbrown veryto brown dark colour, strongly magnetic, 2 andMgO and more compact. It bastitepresents after pyroxene and /72(3)A2012192020 - - - /72(3)A2012192020
Characteristics <0.6 wt.%, respectively. highest contents of The ~0.14 wt.%, ~0.06-0.19 wt.%, and to values of towardsthe saprolite and saprolitized peridotite 3.69 wt.%Cr 1.44 wt.%MnO, 0.6-1.02 wt.% Co reach a maximum at the the top profile,of contents with values 0.7- Their 6). (Figure profile ering similar distribution throughout pattern the weath wt.% NiO). MnO, Co 2.8 to (up Ni in rich unusually is profile CMM-03 peridotite. However, the the parental rock of values These decrease down profile. to <0.06 wt.%inthe saprolitized CMM-01 from horizon theyeven reach saprolite 2.4wt.%inthe green and profiles, both from horizon laterite red the in Contents in NiOrange between 1.2 and1.9wt.%
longated roots. 2 O
3 , andtheydecrease progressively 3 O 4
, andCr 2 O 3 O 3 have a very 4 , andupto - (Esmeralda hill)and2). B)CMM-03profile (pit Figure 6 Weathering profilesinCerro Matososhowing the distribution patternofrelevant majorand minor elements.A) CMM-01profile Boletín de la Sociedad Geológica Mexicana Mexicana Mexicana Geológica Geológica Sociedad Sociedad la la de de Boletín Boletín http://dx.doi.org/10.18268/BSGM2020v72n3a201219 /72(3)A2012192020 / 72(3)A2012192020 11 11
Geochemistry of PGE in Cerro Matoso and Planeta Rica WHOLE ROCK GEOCHEMISTRY Geochemistry of PGE in Cerro Matoso and Planeta Rica WHOLE ROCK GEOCHEMISTRY of Cerro Matosoand PlanetaRica. Table 2.Majorand minor elementscontents(inwt.%)and PGEand Auconcentration (inppb) of thethreestudied weathering profiles 12 12 /
Profile CMM-01 / Profile CMM-03 (Cerro Matoso) Profile PR-1136 (Planeta Rica) Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín
(Cerro Matoso) Mexicana Geológica Sociedad la de Boletín CMM- CMM- CMM- CMM-03- CMM-03- CMM-03- CMM-03- CMM- 1-PR-1136- 2-PR-1136- PR-1136- PR-1136- PR-1136- PR-1136- 1-PR- 2-PR- PR-1136- Samples 01-LA 01-SV 01-PS LA-N4 LA-N3 LA-N2 LA-N1 03-PS C-LR C-LR LR LA LA-SC SC 1136-SV 1136-SV P RL with Material type RL GS SP RL RL RL SP C C + RL RL RL RL TZ GS GS P silica frag. Depth From (m) 0 0.8 2 0 0.8 1 2 2.1 0 0.1 0.8 2.9 5.4 5.8 6.6 7.25 26.5 To (m) 0.8 2 3.5 0.8 1 2 2.1 2.8 0.1 0.8 2.9 5.4 5.8 6.6 7.25 14.1 26.75 (wt.%) dl SiO2 0.01 8.96 45.83 41.87 6.23 22.96 9.18 11.29 40.84 6.72 6.5 3.27 2.85 2.6 2.7 22.8 38.61 38.63 Al2O3 0.01 7.56 1.74 0.41 3.14 2.67 5.82 6.43 1.21 8.8 11.34 9.45 10.31 9.29 7.81 6.43 2.32 1.01 Fe2O3 0.01 66.18 13.02 12.34 71.64 58.28 64.32 61.41 13.96 72.03 66.45 73.01 72.4 72.04 71.83 53.11 19.48 8.19 MnO 0.01 0.73 0.12 0.15 1.06 0.8 1.44 0.79 0.14 1.23 0.63 0.4 0.44 0.67 1.29 0.91 0.27 0.11 MgO 0.01 1.08 25.43 32.44 0.62 0.58 2.59 3.33 29.44 0.62 1.41 1.24 1.31 1.29 1.47 3.34 23.85 38.05 CaO 0.01 0.02 0.48 0.04
TiO2 0.01 0.1 0.01
- 0.8 wt.%Co limonite to saprolite zone (>1.2 wt.% MnO and behaviors (Barnes behaviors (Barnes groups according to their physical andchemical 2 and MgO show the opposite behavior, /72(3)A2012192020 / 72(3)A2012192020 3 O 4 et al ). NiO is concentrated). NiOis the in ., 1985): the iridium group 2 and0.6wt.%MgO. 13 13
WHOLE ROCK GEOCHEMISTRY / Geochemistry of PGE in Cerro Matoso and Planeta Rica PGE DISTRIBUTION PGE DISTRIBUTION IN WEATHERING Geochemistry of PGE in Cerro Matoso and Planeta Rica PROFILES / PGM MINERALOGY 6.1. CERRO MATOSO 14 14 the CMM-01 and CMM-03 weathering profiles. weathering CMM-03 and CMM-01 the PGEandAu in Figure 8 showsthe distribution of Rh, Pd,Pt),where thelatter group includesAu. (IPGE- Os, Ir, Ru) andthepalladium group (PPGE- and saprolitized peridotite (Table 2). ppb inthetransitionzone between the red laterite 21 low (~6 ppbonaverage) with amajorvalue of between 4 ppband13ppb. Au contentsare very in the saprolitized peridotite, withconcentrations 61 ppbPt, and 58ppbPd.AllPGEare depleted laterite, inwhich the horizon contains63ppbRu, red the of intervals third and first the in observed highest PGE valuesand Ir (24-33 ppb). The are correspond to Rh (9-12 ppb), Os (11-32 ppb), and 39to 58 ppbPd, whereas the lower ones ranging from 49to63ppbRu, 44to61ppbPt, tents correspond to Ru, Pt, and Pd, with values between 4ppband8inthewhole profile. between 2 ppband12ppb. Au contentsrange saprolitegreen and the saprolitized peridotite are all these elements in boththe concentrations of content belowis the detection limit (Table 2). The the limonitehorizon,up to8ppb,Os andtheRh other PGE, Ir concentrates only upto 22 ppbin up to 41, 40and30ppb, respectively. Amongthe reaches profile CMM-01 in horizon laterite red <50 ppb(Table 2). contents in the saprolite and unweathered rock are PGE total the profiles weathering both laterite.In red interval of corresponding to the uppermost between 181ppband259PGE,thelatter the same horizon inthe CMM-03 profile contains the CMM-01profilezon isof 141 ppb. In contrast, Os, Ir, andRh. ite. Inall cases, Pt and Pdare more abundant than the saprolitic horizon andthe saprolitized peridot the limonite horizon andshow astrong decrease in In both profiles the highest PGE contents occur at / / Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín In the CMM-03 profile the highest PGE con PGE highest the profile CMM-03 the In Pt, Pd and Ru inthe concentrationThe of PGEconcentrationThe inthe red laterite hori http://dx.doi.org/10.18268/BSGM2020v72n3a201219 /72(3)A2012192020 - - - /72(3)A2012192020 6.2. PLANETA RICA 7. PGMMineralogy RICA 6.3. IPGEVSPPGEINCERRO MATOSO ANDPLANETA (30-35 ppb), Rh (11-13 ppb), and Os (10-19 ppb) 57 and74ppb, andPd between 47and74ppb. Ir tent ranges between 58and83ppb, Ru between Ir, Rh,andOs. Pt, Ru, andPd are generally more abundant than (total PGE range between 30 ppband149ppb). saprolitegreen and inthe unweathered peridotite ppb). Conversely, PGEare stronglythe in depleted (272ppb)andthe transition zonein canga (259 centrate towardsthe limonite horizon, but mainly con to tend PGE where profile, PR-1136 the in PGE and Au Figure 9 shows the distribution of horizons form Planeta selected Rica, was for horizonsform sition zone between the limonite and saprolite Sample PR-1136-SC, corresponding to the tran and 131ppb. PPGE content inthishorizon ranges between 81 Rica isabove 119 ppb, whereas in Cerro Matoso Planeta PPGE content in the limonite horizon of the Interestingly, 10). (Figure profile weathering elements veryis similar throughout the groupsof (Table 2). However, both the general behavior of 1.6 reaches ratio IPGE/PPGE the where profile, the CMM-01 saprolitized peridotite zone of that indicates which PPGE>IPGE. An exception is observed in the <1 (~0.88), are profiles IPGE/PPGE ratiosThe for the three analyzed (Table 2). 24 ppb in the the lateritetransition zoneprofile of generally very low (~8 ppb),although they reach 1ppband8ppb. Au contents are to values of varies between 3ppband39decrease are less abundant. Inthe saprolite horizon, PGE In the limonite andtransition zone the Pt con - - - 03 profile (Pit 2). 03 profile(Pit Figure 8 WeatheringMatoso showing profiles inCerro thedistribution ofPGEand Au.A)CMM-01profileand (Esmeralda Hill) B)CMM- Boletín de la Sociedad Geológica Mexicana Mexicana Mexicana Geológica Geológica Sociedad Sociedad la la de de Boletín Boletín http://dx.doi.org/10.18268/BSGM2020v72n3a201219 /72(3)A2012192020 / 72(3)A2012192020 15 15
Geochemistry of PGE in Cerro Matoso and Planeta Rica PGE MINERALOGY Geochemistry of PGE in Cerro Matoso and Planeta Rica PGE MINERALOGY / DISCUSSION Figure 9 16 16 al tration (Ndjigui andBilong, 2010;Aiglsperger PGE concen wt.%), which are good indicators of contains highMnO(1.29wt.%)andCo samplealso higher PGEcontents(259ppb).The PGM concentration by hydroseparation doto its spectrum usingSEM-EDS. not possibleit was toobtainanaccurate X-ray probably PGM;however, due to their small size framboidal texture are (Figure grains 12). These porousand highly gregated pyrite with crystals inter-ag µm to 1µm, adhered of to interstices size rangingfromanhedral grains, withgrain 0.1 irregular edges, andarough surface; and ii) tiny, 11) showing elongated anhedral morphology, Fe-Ni alloysincluded inFe-oxyhydroxide (Figure / / ., 2016a,2016b). Weathering profileofthePR-1136drill hole (PlanetaRica) showing thedistribution of PGEand Au. Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Two types of PGM grains were PGM grains found: i)Pt-Ir- Two typesof http://dx.doi.org/10.18268/BSGM2020v72n3a201219 3 O 4 (0.2 et /72(3)A2012192020 - - /72(3)A2012192020 AND PLANETA RICAPROFILES 8.1. ELEMENTSMOBILITYINTHECERRO MATOSO 8. Discussion h eceia itiuino Fe geochemicalThe distribution of 2015; Farré-de-Pablo González-Jiménez abrasion (Bowles, 1986;Ndjigui and Bilong, 2010; with polygonalevidenceslacking sections of igneousorigin is euhedral of crystals primary the since typical shapeof formation, secondary suggest these grains shape and occurrence of The er aooadteP-16poieo Planeta Cerro Matoso and the PR-1136 profile of Co 3 O 4 , andCr 2 O 3 et al in the CMM-01 profile of profile CMM-01 the in et al ., 2014;Aiglsperger ., 2017). 2 O 3 , MnO, et al ., Figure 10 hwtepeeeta ocnrto fNi minerals show the preferential concentration of in the rock, asreported in several studies which microfracturesfilling garnierite to probablydue is profile CMM-03 NiO enrichment 2.8wt.%. This reaches values of the of peridotite saprolitized profiles in fromboth areas. However, wt.%) the NiOcontentin 3.19 to (up horizon saprolitic towards the parent rock.NiO concentrates in the concentrations from the Mg discontinuity zone their increasing sharply profile, the along trends rock.Conversely, SiO saprolite) and towards the unweathered parent (transition zone between red laterite and green strongly decrease inthe Mg discontinuity zone limonite horizon. However, their concentrations these elements are in the highest concentration of Rica (Figures 6A,7andTable 2) show that the IPGE (Os+Ir+Ru) vs. PPGE (Pt+Pd+Rh) content in the Ni-laterite profiles of PPGE(Pt+Pd+Rh) IPGE CerroMatoso and content intheNi-laterite (Os+Ir+Ru) vs. PlanetaRica. 2 andMgOshowinverse Boletín de la Sociedad Geológica Mexicana Mexicana Mexicana Geológica Geológica Sociedad Sociedad la la de de Boletín Boletín http://dx.doi.org/10.18268/BSGM2020v72n3a201219 hntercnet ntelmnt oio fthan their contents inthe limonite horizon of up to 3.7 wt.%,which are almost 1%higher NiO contents up to 1.8 wt.%andCr laterite veryrich iniron (Fe Matoso, located inPit 2 (Figure 2),showsa red sperger al 1966;Brand (Cornwall, the hydrous Mgsilicate-type deposits teristic of from Cerro Matoso andPlaneta characRica is major oxides in the Ni-lateritebehavior profiles of Villanova-de-Benavent (Freyssinet in veins and fractures andasthin coatings injoints 2). According tothe mineralogical studyas well CMM-01 andPR-1136 (Figure 6BandTable ., 2005;Villanova-de-Benavent utemr, h CM0 poie f Cerro of profile CMM-03 the Furthermore, et al et al ., 2016a). /72(3)A2012192020 / 72(3)A2012192020 ., 2005;Cluzel and Vigier, 2008; et al et al ., 2014). This chemical., 2014). This 2 ., 1998;Freyssinet O 3 >60wt.%),with et al ., 2014;Aigl 2 O 3 contents 17 17 et - -
Geochemistry of PGE in Cerro Matoso and Planeta Rica DISCUSSION Geochemistry of PGE in Cerro Matoso and Planeta Rica DISCUSSION Figure 11 PLANETA RICALATERITES 8.2. ENRICHMENTOFPGE INCERRO MATOSO AND 18 18 the three analyzed laterite profiles occur towards occur profiles laterite analyzed three the In Planeta Rica, the highest PGE contents from this conclusion. further geochemical studies are needed to confirm anoxide-type Mineralogical and deposit. of istics silicate-type, but locallyalsoexhibits the character Cerrodominantly ahydrous Matoso is deposit Mg (1987) and Gleeson et al. (2004), we consider that Republic). Therefore, with Castroagreement in from (Falcondo LomaOrtega mine, Dominican Mg silicate-claysilicate” inNi-laterite deposit al profiles, and oxide-type and Tauler silicate-type thatNi-laterite most contain hydrous deposits Mg al (Brand the upper saprolite and the lower limonite horizon where between the Ni is mainly hosted, that forms dominated byFe-oxyhydroxides ( and Al-rich andSiO environments andare characterized by a Fe-, Cr-, can bepresent Oxide-type deposits in allclimatic Matoso couldrepresent an oxide-type deposit. the above results, the CMM-03 profile from Cerro 65% Fe-oxyhydroxides, mainlygoethite. Based on the lateritic material from Pit 2 hasmore than outbycarried analyses SUMICOL S.A. (2002), thermogravimetric and thermodifferential the as / / 21)rpre neapeo “hybrid hydrous . (2017)reported an example of ., 2005;Proenza, 2015). Brand Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Backscattered electron(BSE)imagesofPGM(Pt-Ir-Fe-Ni) grainsincluded withinaFe-oxyhydroxide (Fe-O/-OH). et al ., 1998;Gleeson 2 andMgOpoorhorizon, et al ., 2003;Freyssinet http://dx.doi.org/10.18268/BSGM2020v72n3a201219 et al e . (1998) noted . g ., goethite) et et /72(3)A2012192020 - /72(3)A2012192020 the limonite zone andtransition zone, andshow a Bowles rockprior to weathering (Fuchsand Rose, 1974; PGE in the parent occurrence of the mode of the Cl concentration from water in the soil, and redistribution may be affected by the Eh-pH ratio, Aiglsperger and Lazarenkov, 2001;NdjiguiandBilong, 2010; oulos and Economou-Eliopoulos, 2000; Talovina limonite zone (Plimer and Williams, 1987;Eliop these metalstowardsthe favor of the migration PGE can be related to laterization processesthat and Aiglsperger Salpéteur and Rose (1974), Plimer and Williams (1987), Similar results were previouslyobserved by Fuchs Ru, and Pd are more mobile than Ir, Os, andRh. different in proportions throughout mobilize the weathering profile. Pt, PGE that indicate them, rock, as well as the positive correlations between with respect to the initial concentrations inthe the weathering profile,towards the upper levels of peridotite(parent rock).ing serpentinized strong decrease towards the saprolite and underly although high Pt mobilityalso requires acidic con Pt and Pd, low temperature favor the mobility of temperature. Furthermore, Cl-rich solutions at can bemobilized asinorganic complexes at low that Pt and Pd are redox sensitive elements and oesuisso httemblt fthe Some studiesshow that the mobility of PGE preferentialThe concentration of Authorssuch Colombo as et al et al ., 1994a, 1994b; Salpéteur et al . (1995), Ndjigui andBilong (2010), et al ., 2015). This mobilization., 2015). This and . (2015). et al . (2008)showed et al ., 1995). - - - Figure 12 product obtained by Falcondo after processing the ppb.However,640 and 250 final between the ues Falcondo display PGE val Ni-laterite of deposit Republic.Dominican in horizonsthe in These Falcondo, horizonsfrom Ni-laterite of deposit (2015, 2016a,2016b)inthe equivalent weathering total PGE contentsreported byAiglsperger less than 300 ppb, thisvalue is comparable to the nitic zoneCerro in Matoso andPlaneta Rica is Ndjigui andBilong, 2010). (Bowles metals coexisting withiron oxides andmanganese alloysrich these in 1994b); orco-precipitation of (Plimer and Williams, 1987; Bowles profiles oxidized in accumulation and migration, PGE-bearing minerals, subsequent differentiation, of lead todissolution can conditions 1996). These Williams, 1987;Salpéteur ditions (pH<6) (Fuchsand Rose, 1974;Plimer and Although total PGE concentration inthe limo BSEimageof porouspyritegrains(Py)hosting submicrometric crystals,possibly PGM. et al ., 1994a, 1994b; Salpéteur Boletín de la Sociedad Geológica Mexicana Mexicana Mexicana Geológica Geológica Sociedad Sociedad la la de de Boletín Boletín et al ., 1995;Gammons, http://dx.doi.org/10.18268/BSGM2020v72n3a201219 et al et al ., 1994a, ., 1995; et al - - . RICA 8.3. PGMINTHELATERITE PROFILE OFPLANETA droxidethe transitionzone in between thelimo alloy wasfoundwithin a Fe-oxyhy as an inclusion profile,this domain. In ides acomplex Pt-Ir-Fe-Ni horizon, which ischaracterized by a Fe-oxyhydrox limonite the in found are profile weathering Rica the Planeta PGEin highestconcentrationsThe of Cuba). dressing of plants(mainnickeldeposits ore Moa and Nikaro the of concentrates) sulfide 2–6ppmin nickel products (with PGE contents of are lost in tailings, sulfide concentrates, and in end- Lazarenkov potential nonconventional PGE source. Similarly, considered authors the Ni-laterite asa deposit the total PGEcontents. Therefore, these ppm of tallurgical extraction) shows anincrease up to 2 mined material ( /72(3)A2012192020 et al / 72(3)A2012192020 . (2005) demonstrated that PGMs i . e . ferronickel-cone after pyrome 19 19 - - - -
Geochemistry of PGE in Cerro Matoso and Planeta Rica DISCUSSION DISCUSSION / CONCLUSIONS / Geochemistry of PGE in Cerro Matoso and Planeta Rica ACKNOWLEDGEMENTS 9. Conclusions 20 20 Fe-oxyhydroxides orsmectites. PGMfound The in could behostedbyZn, minerals like secondary as well as transitionmetals such asNi,Co, Cu,and Pt, Pd, andRu, cated thatconcentrations high of (2005) and Ndjigui and Bilong (2010), which indi with observationsmade by Oberthür and Melcher nite and saprolite horizons.in accordanceis This from Cerro Matoso and PR-1136 profile from Planeta Rica show highFe profile PR-1136 and Matoso Cerro from the CMM-01 profile The geochemical of patterns theporous pyrite. of Pt to the interstices could explain the transport of Fe-richin Eh (>0.4) high conditions soils, which transported in solution under acidic (pH<6) and Lazarenkov, 2001). In addition, those elements are (Talovina concentration and Cl the by influenced weathering crusts are strongly in natural waters of showedsoils that Pt and Pdsolubilitymobility lateritic in contents Cl different at water in bility more,calculations onPGE solu thermodynamic thepyrite. Further adhered totheporousedges of taking place PGMneoformation evidence of to PGE-bearing particles that would constitute altered pyrite correspond aggregates of interstices infer that the <1 µmbright particles within the (Plimer and Williams, 1987). Considering this, we studies, Pt and Pd mobilize during pyrite oxidation therein) and, according to some experimental and González-Jiménez, 2016, andreferences 2016b). PGM (Aiglsperger secondary neoformed processes. PGE alloys The would form and/or laterizationduring the serpentinization the magmatic stage and subsequently dissolved during PGM formed could correspond to primary in the Dominican Republic case, the PGE alloys Republic (Aiglsperger identified in Loma Peguera deposit, in Dominican FePt-Ir-Fe-Ni oxides nanoparticles within pores of the present studysimilar tothe densely packed is / / Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín PGE are highly siderophile elements (O’Driscoll et al 2 O ., 2015,2016b).Like 3 andAl http://dx.doi.org/10.18268/BSGM2020v72n3a201219 2 O 3 contents in situ et al as ., /72(3)A2012192020 - - - /72(3)A2012192020 Acknowledgements Pt, Pd, and Ru more mobilethanOs, Ir, andRh. being proportions, different in mobilize correlation between them indicate that PGE ered peridotite. distribution The andthe positive saprolite thegreen to theunweath upper level of zone, andtheir concentration decreases from the Planeta Rica are concentrated in the limonite CMM-03 profile. fromistics oxide-type deposits, asindicated by the alsocontainssomeareasdeposit withcharacter silicate-type deposits. However, Cerro Matoso hydrousMg horizons, which characteristic is of and low SiO dad Nacional de Colombia, as well as by amaster theUniversi la República, the 35671project of de la Investigación yla Tecnología del Banco de the Fundación para la Promoción 4002 project of Promociónde Jóvenes Investigadores ARES, the Convocatoria ACGGP-Aportes Fondo y Corrigan Geofísicos del Petróleo (ACGGP) through the XV supported financially by been the Colombiana Asociación de Geólogos y has research This future projects. the refinery operation and increase the viability of for flow cash positivecreate a could consideration considered as unconventional PGE deposits. This by-products. Therefore, these two canbe deposits recovered as be could they and products final the refinery adequate methods couldincrease the PGE concentration in applying However, ppb. of the order Planeta Rica limonite horizonsare of conditions. transported in solutionunder acidic andhigh-Eh pyrite aggregates. In these cases, Pt may have been altered of the interstices occurred encrustedin irregular nanoparticle sized PGM of formation Fe-oxyhydroxide. Similarly, it isinferred that neo alloys, such asthe Pt-Ir-Fe-Ni PGM hosted in a PGE-Fe secondary mineral of the formation The high affinity between PGE and Fe favors Fe and PGE between affinity high The highestPGEvalues inCerroThe Matoso and PGE concentrationCerro in Matoso and 2 and MgO contents in their andMgOcontentsin limonite - - - - References zalo Castillo, Cristian Conde, Yuli, Yuris Daza, Wilson engineers: Escobar, Esteban Gómez, Gon mine (operated by South32 Ltd), specially to the Matoso Cerro of staff the thank to want Wealso ment withthe Universidad NacionaldeColombia. Gutiérrez Cáceres through acooperation agree sponsored by grant degree FundaciónJuan Pablo Aiglsperger, T., Proenza, J.A., Lewis, J. F., Aiglsperger, T., Proenza, J.A., Zaccarini,F., Lewis, Aiglsperger, T., Proenza, J.A., Zaccarini,F., Agencia Nacional de Minería (ANM), 2015, greatly improved ourmanuscript. the anonymous reviewers for their criticism that and Alejandro Argumedo, andwe want to thank phases sample processing, especiallyEstebanArrieta of some and fieldwork the supported who the SEMERU researchthe students of group, campaign in2016-2017. Finally, we want to thank holes on the Porvenir hill during the exploration drill the to access and sites mine different the at Urangofor allowingthe sampling and Guillermo oregeorev.2015.10.010 73, 127–147. https://doi.org/10.1016/j. Dominican Republic: Reviews, Ore Geology Ni LateritesSc, PGE)in fromCuba andthe Durisova, J., 2016a,Critical metals (REE, Labrador, M.,Svojtka, M.,Rojas-Purón, A., doi.org/10.1007/s00126-014-0520-9 50,105–123.https:// Mineralium Deposita, Caribe peridotite Republic):(Dominican the Falcondo Ni-laterite Loma deposit, 2015, Platinum group minerals (PGM) in J.F., Garuti, G., Labrador, M., Longo, F., de Mineralogía,15,23–24. techniques: Revista de La Sociedad Española PGM inlaterites by usinghydroseparation Looking for needles in a haystack: how to find Labrador, M.,Navarro-Ciurana, D., 2011, platino.pdf.>, visited onOctober 30th, 2016. co/sites/default/files/DocumentosAnm/ Nacional de Minería, available in
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