Distribution of critical metals in evolving pyrite from massive sulfide ores of the Iberian Pyrite Belt

Acknowledgements This research is a contribution to the projects CGL2016-79204-R, PID2019-111715GB-I00 which are supported by the Spanish Government, and 18/IF/6347 granted by Science Foundation Ireland (SFI). The authors thank Cambridge Minerals for access to drill core, sampling assistance and the ongoing collaboration. We are also grateful to Teodosio Donaire for his constructive suggestions in petrogenetic aspects of volcanogenic rocks in the IPB as well as Dany Savard and Audrey Lavoie of LabMaTer, UQAC, for their assistance during the laser ablation analyses. Authors would also like to acknowledge the use of Servicio General de Apoyo a la Investigación-SAI, Universidad de Zaragoza.Supplementary data to this article can be found online at https://doi. org/10.1016/j.oregeorev.2022.105275.With >90 known deposits containing original reserves of >2400 Mt of sulfide ore, the Iberian Pyrite Belt (IPB) is the largest volcanogenic massive sulfide (VMS) province on Earth. In these evolving mineral systems, texturally different pyrite exhibits characteristic mineralogy and trace element fingerprints. Pyrite (Py-1), which is well preserved in the polymetallic ores that crystallized at the earliest stage of VMS deposit formation, consists of kernels of pyrite framboids surrounded by concentric colloform bands and ended by faceted outlines. It is rich in some metals like Pb, Zn, Sb and As (mostly hosted as nano-to-micron-sized particles, including galena, tetrahedrite and arsenopyrite) but depleted in Cu, Co and Bi. In contrast, pyrite from the pyritic and Cu-rich ore overprinted by late fluids exhibits spongy-looking (Py-2) or homogenous (Py-3) cores surrounded by external facets with crystallographic continuity across the whole single grains due to re-crystallization. Py-2 is depleted in most trace elements with the exception of Au and Bi, which occur both in solid solutions and as nano-to-micron-sized inclusions. Py-3 has the highest Cu, Ag, Co and Ni (mainly associated to nano-to-micron-sized particles of tennantite, chalcopyrite and gersdorffite) and the lowest Au contents in the form of native gold. The progressive increase in metal contents from inner to outer parts of Py-1 matches with the onset of the economic metal endowment of VMS deposits in the IPB, whereas Py-2 and Py-3 are associated with metal shoot processes that led to both leached and high-grade ores, very likely when mafic rocks were emplaced into the footwall of the deposits.Projects CGL2016-79204-R, PID2019-111715GB-I00 which are supported by the Spanish Government, and 18/IF/6347 granted by Science Foundation Ireland (SFI

Unveiling High-Tech Metals in Roasted Pyrite Wastes from the Iberian Pyrite Belt, SW Spain

This research was fully funded by the MECRAS Project A-RNM-356-UGR20 “Proyectos de I+D+i en el marco del Programa Operativo FEDER Andalucía 2014–2020” of the Consejería de Economía, Conocimiento, Empresas y Universidad de la Junta de Andalucía (Spain).Supplementary Materials: The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/su151512081/s1The Iberian Pyrite Belt (IPB), in the southwestern Iberian Peninsula, is a large metallogenic province exploited since ancient times. As a result of historical and current mining activity, a vast volume of metallic mineral waste, mainly derived from the processing of pyrite, is still in situ and polluting the environment. A specific mine waste residuum locally known in the area as "morrongos", which was produced during pyrite roasting mainly in the 19th century, is evaluated here in order to unravel untapped resources of high-tech metals commonly used in high-tech devices. Applying a combination of whole-rock geochemical (ICP-AES, ICPMS, FA-AAS) and single-grain mineralogical techniques (EPMA, LA-ICP-MS, FESEM, and FIB-HRTEM) on the "morrongos", we unhide the still-present remarkable concentrations of Au, Ag, Pb, Zn, and Cu in them. The mineralogical expressions for these economic metals include oxides (hematite, magnetite, and hercynite), arsenates, sulfates of the jarosite group, native metals, and, to a lesser extent, relictic sulfides. This first-ever estimation of these economic metals in this type of residue allows their revalorization, highlighting them as suitable sources for the exploitation and recovery of metals necessary for the clean energy transition.Junta de Andalucía, FEDER Andalucía 2014–2020: MECRAS Project A-RNM-356-UGR2

Polymetallic nanoparticles in pyrite from massive and stockwork ores of VMS deposits of the Iberian Pyrite Belt

This paper reports the first-ever study on nanoscale mineralogy in pyrite from the volcanogenic massive sulfide (VMS) deposits of the Iberian Pyrite Belt, southwestern Iberian Peninsula. It targeted colloform-textured grains formed at low temperature in the distal part of a polymetallic (Pb-Zn) massive sulfide lens hosted in felsic volcanoclastic rocks from the Masa Valverde deposit, and euhedral-textured grains (re)-deposited by higher temperature fluids in the Co-Au rich stockwork hosted in black shales of the Filón Norte orebody of the Tharsis deposit. The results acquired by a combination of techniques for mineral microanalysis and characterization (i.e., reflected light, FE-SEM, EPMA, LA-ICP-MS, HRTEM-STEM and TEM-EDS) show that trace amounts of metals (Au, Ag, As, Pb, Sb, Cu, Co) are incorporated as both lattice-bound and into nanoparticles (NPs). The mode of occurrence is strongly related with the evolutionary history of the mineralization. In the colloform pyrite collected from the massive sulfide lens, a rhythmic banding/oscillatory zonation with up to 3 wt% As, 5,000 ppm Pb, 1,070 ppm Sb and 750 ppm Cu is defined by the coexistence of several nano-sized layers (5 to 100 nm) and NPs (<100 nm) containing all these metals. The NPs include galena [PbS], tetrahedrite [(Cu,Fe)12Sb4S13)] and arsenopyrite [FeAsS] that exhibit euhedral and less frequently anhedral (i.e., droplet-like) morphologies being both randomly and preferentially oriented with respect to As-rich pyrite bands they are usually associated with. These features suggest formation of the NPs via direct deposition from the hydrothermal fluid(s) or low-temperature melts entrained in them as well as exsolution of trace elements originally dissolved in the As-rich pyrite structure. Additionally, some of these NPs are connected to late fractures disrupting the chemical zoning in colloform pyrite documenting a third genetic type of NPs related to late infiltration of fluids post-dating pyrite formation. In contrast, euhedral pyrite from the stockwork form well-developed homogeneous grains with discrete porous areas relatively depleted in Fe (45.20 wt%), and As (8,800 ppm) but enriched in Co (5,900 ppm). At the nanoscale, Co-enriched domains show patchy zoning defined by irregular distribution of Co– and As-rich bands of 200–500 nm in thickness. These nanometer Co– and As-rich bands are often disrupted by micron-to-nano-sized polycrystalline Au-Ag-Hg particles that fill voids in porous areas. Contact morphology anatomy between Co-rich pyrite and inclusions suggests that the Au-Ag-Hg particles are negative crystals occupying spaces originated in pyrite by coupled dissolution-reprecipitation reaction. Likewise, HRTEM observations along such pyrite-inclusion contacts show the existence of polycrystalline matrices in both pyrite and Au-Ag-Hg inclusions, the former consisting of nano-sized domains of arsenian pyrite and/or arsenopyrite in As-free pyrite and the Au-Ag-Hg inclusions made up of multiple crystal domains including nano-crystallites of Au0/Ag0 or electrum. Recognition of crystalline nanodomains and NPs in these polycrystalline matrices raises the possibility that Au NPs or nanomelts already present in the hydrothermal fluid catalyzed the formation of these heterogeneous crystals

Coupling Mineralogy, Textures, Stable and Radiogenic Isotopes in Identifying Ore-Forming Processes in Irish-Type Carbonate-Hosted Zn–Pb Deposits

Irish-type deposits comprise carbonate-hosted sphalerite- and galena-rich lenses concentrated near normal faults. We present new data from the Tara Deep resource and overlying mineralization, at Navan, and the Island Pod deposit and associated Main zone orebodies, at Lisheen. Tara Deep mineralization predominantly replaces Tournasian micrites and subordinate Visean sedimentary breccias. The mineralization is mainly composed of sphalerite, galena, marcasite and pyrite. A range of Cu- and Sb-bearing minerals occur as minor phases. At Tara Deep, paragenetically early sulfides exhibit negative &delta;34S values, with later phases displaying positive &delta;34S values, indicating both bacterial sulfate reduction (BSR) and hydrothermal sulfur sources, respectively. However, maximum &delta;34S values are heavier (25&permil;) than in the Main Navan orebody (17&permil;). These mineralogical and isotopic features suggest that Tara Deep represents near-feeder mineralization relative to the Navan Main orebody. The subeconomic mineralization hosted in the overlying Thin Bedded Unit (TBU) comprises sphalerite replacing framboidal pyrite, both exhibiting negative &delta;34S values (&minus;37.4 to &minus;8.3&permil;). These features indicate a BSR source of sulfur for TBU mineralization, which may represent seafloor exhalation of mineralizing fluids that formed the Tara Deep orebody. The Island Pod orebody, at Lisheen, shows a mineralogical paragenetic sequence and &delta;34S values broadly similar to other Lisheen orebodies. However, the lack of minor Cu, Ni, and Sb minerals suggests a setting more distal to hydrothermal metal feeder zones than the other Lisheen orebodies. Pb isotope data indicate a very homogeneous Lower Palaeozoic Pb source for all Navan orebodies. Lower Palaeozoic metal sources are also inferred for Lisheen, but with variations both within and between orebodies. Carbon and oxygen isotopic variations at Navan and Lisheen appear to result from fluid-carbonate rock buffering. The emerging spectrum of mineralogical and isotopic variations define proximal to distal characteristics of Irish-type systems and will assist in developing geochemical vectoring tools for exploration

Gold Behavior in Supergene Profiles Under Changing Redox Conditions: The Example of the Las Cruces Deposit, Iberian Pyrite Belt.

The Las Cruces deposit is in the eastern end of the Iberian Pyrite Belt (SW Spain). It is currently being mined by Cobre Las Cruces S.A. The main operation is focused on the supergene Cu-enriched zone (initial reserves of 17.6 Mt @ 6.2% Cu). An Au-Ag-Pb-rich gossan resource (3.6 Mt @ 3.3% Pb, 2.5 g/t Au, and 56.3 g/t Ag) occurs in the upper part of the deposit. The Au grade ranges from 0.01 ppm to >100 ppm, and occurs as three different Au ore types: (1) Au mineralization in the upper part of the gossan linked to Fe-oxides lithofacies, (2) Au concentration in the lower part of the gossan associated with leached black shales, and (3) Au ore in the cementation zone related to subvertical fractures. A hydroseparation device has been used to obtain heavy mineral concentrates from selected samples of different ore types. Reflected-light microscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and electron probe microanalysis (EPMA) were used to study the separated Au particles. Significant differences between the defined ore types include the Au-bearing lithologies, mineral associations, textural features, particle sizes, morphologies, and fineness. Au-rich minerals include native Au, Au-Ag electrum, and Au-Ag-Hg amalgams. Gold-bearing mineral associations include Pb-oxihalides, Fe-oxides, galena, pyrite, cinnabar, and Ag-sulfosalts. The Au enrichment mechanism in the supergene profile involves (1) dissolution of Au from the primary sulfides as chloride-rich ionic complexes during the weathering of the deposit under subaerial exposure; dissolved Au is transported downward through the supergene profile under acidic and oxidized conditions; (2) destabilization of the Au complexes by Fe-controlled redox reactions; as a consequence, coarse-grained, high-fineness Au particles precipitated in association with Fe-oxyhydroxides. This resulted in secondary concentration in the upper gossan; and (3) after deposition of cover sediments took place a progressive change in the system conditions resulting in a later Au remobilization as hydroxidehalide, hydroxide, thiosulfate, and bisulfide complexes in the lowermost gossan and cementation zone. The main pathways for migration of enriched fluids to the cementation zone are secondary permeability zones linked to Alpine reactivated faults. Deposition of Au seems to be related to fluid interaction with reductant lithologies, including black shales and the primary sulfides

Mineralogía preliminar del depósito estratoligado de Cu Cabezo de la Mina, Cordilleras Béticas

Esta contribución científica es un producto del proyecto PROYEXCEL_00705 "Metallogeny of Cobalt in the Betic Cordillera (Ref.P21-00705), financiado por la Junta de Andalucía-Consejería de Economía y Conocimiento y "FEDER una manera de hacer Europa"

Genetic Links between Irish-type Zn-Pb Deposits and Related Geochemical Halos

A broad geochemical dispersion halo has been identified with a direct link to the underlying Tara Deep deposit at Navan, Ireland. In situ laser S isotope analyses have been performed on petrographically well characterized samples from the halo. Four mineral assemblages have been identified. 1) In black shales, laminated pyrite comprising thin layers of framboidal low-delta S-34 pyrite with minor interstitial sphalerite. 2) Pyritized calcarenites are widely distributed and occur chiefly as biodebris replaced by low-delta S-34 pyrite. 3) A replacive assemblage occurs as late remobilizations exhibiting both crosscutting and bedding-parallel styles, overprinting the early laminated pyrite. It comprises mostly marcasite, with minor pyrite, sphalerite, chalcopyrite, galena, stibnite, arsenopyrite and pentlandite, with high delta S-34 values. 4) Hydrothermal cherts comprise thick microcrystalline quartz bands rimmed by dolomite, associated with marcasite, pyrite, sphalerite, chalcopyrite, galena, Ni-sulfosalts and stibnite with high delta S-34 values. These results indicate overlapping diagenetic and multi-phase hydrothermal sulfide mineralization. First, laminated pyrite and pyritized calcarenites suggests a bacterial origin within sediments during early diagenesis. Later, hydrothermal chert and replacive sulfides suggest hydrothermal exhalation during early-mid diagenesis. Similarities in mineralogy and S isotope compositions suggest genetic links between the halo and the underlying Tara Deep deposit

Genetic Links between Irish-type Zn-Pb Deposits and Related Geochemical Halos

A broad geochemical dispersion halo has been identified with a direct link to the underlying Tara Deep deposit at Navan, Ireland. In situ laser S isotope analyses have been performed on petrographically well characterized samples from the halo. Four mineral assemblages have been identified. 1) In black shales, laminated pyrite comprising thin layers of framboidal low-delta S-34 pyrite with minor interstitial sphalerite. 2) Pyritized calcarenites are widely distributed and occur chiefly as biodebris replaced by low-delta S-34 pyrite. 3) A replacive assemblage occurs as late remobilizations exhibiting both crosscutting and bedding-parallel styles, overprinting the early laminated pyrite. It comprises mostly marcasite, with minor pyrite, sphalerite, chalcopyrite, galena, stibnite, arsenopyrite and pentlandite, with high delta S-34 values. 4) Hydrothermal cherts comprise thick microcrystalline quartz bands rimmed by dolomite, associated with marcasite, pyrite, sphalerite, chalcopyrite, galena, Ni-sulfosalts and stibnite with high delta S-34 values. These results indicate overlapping diagenetic and multi-phase hydrothermal sulfide mineralization. First, laminated pyrite and pyritized calcarenites suggests a bacterial origin within sediments during early diagenesis. Later, hydrothermal chert and replacive sulfides suggest hydrothermal exhalation during early-mid diagenesis. Similarities in mineralogy and S isotope compositions suggest genetic links between the halo and the underlying Tara Deep deposit

Zonaciones de Co, Cu y Ni en minerales hidrotermales del grupo de la pirita

Este estudio y el contrato predoctoral de AMRFG es apoyado por el proyecto PROYEXCEL_00705 "Metallogeny of Cobalt in the Betic Cordillera (Ref.P21-00705)”, financiado por la Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades y "FEDER una manera de hacer Europa"

Pyritic mineralization halo above the Tara Deep Zn-Pb deposit, Navan, Ireland: Evidence for sub-seafloor exhalative hydrothermal processes?

The Tara Deep Zn-Pb deposit, at Navan, Ireland, includes sub-economic pyrite-rich mineralization extending laterally for about 2 × 2 km within the overlying Lower Viséan calc-turbidites, known as the ‘New-Thin Bedded Unit’. Here, we investigate the genesis of this pyritic mineralization and its links to the limestone-hosted Zn-Pb deposit lying 100 m below it. Four mineral assemblages have been identified: 1) in black shales, laminated pyrite comprises thin framboid-rich layers with minor interstitial sphalerite, both showing variable but low δ34S values ranging from −37.4 to 3.3‰; 2) in calcarenite and calcsiltite layers, pyritized fossils are widely distributed and occur chiefly as biodebris replaced by low δ34S pyrite (mean values of −13.2‰); 3) a replacive assemblage occurs as late remobilizations exhibiting both crosscutting and bedding-parallel styles, overprinting the early laminated pyrite. It comprises mostly of marcasite, with minor pyrite, sphalerite, chalcopyrite, galena, stibnite and Co-pentlandite, with high δ34S values up to 24.5‰; and 4) in black shales, bedded sulfide-rich cherts comprising microcrystalline quartz lenses exhibit δ18O mean values of 25.3‰. Cherts are rimmed by dolomite, associated with marcasite, pyrite, sphalerite, chalcopyrite, galena, siegenite and stibnite also with high δ34S values up to 44.2‰. In general terms, pyrite shows a relatively high Co/Ni ratio &gt; 1 and sphalerite Zn/Cd ratios vary from 268 to 364. Textural analysis indicates overlapping of early-diagenetic and multi-phase hydrothermal sulfide mineralization. Development of laminated pyrite and pyritized calcarenites suggests that this mineralization was generated during early diagenesis, close to the seawater-sediment interface in oxygen-poor conditions under the influence of low-temperature hydrothermal fluid circulation. Later hydrothermal cherts and replacive sulfides suggest discharge of relatively warm hydrothermal fluids during early to mid-diagenesis, presumed to be linked to movements of nearby normal faults. Similarities in mineralogy and S isotope compositions suggest genetic links between the sub-economic pyritic mineralization and the underlying Tara Deep deposit, and consequently, that the former represents a geochemical halo with direct applicability in exploration for Zn-Pb deposits