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Sarah-jane Barnes - One of the best experts on this subject based on the ideXlab platform.
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trace element distribution in primary sulfides and fe ti oxides from the sulfide rich pods of the lac des iles pd deposits western ontario canada constraints on processes controlling the composition of the ore and the use of Pentlandite compositions
Journal of Geochemical Exploration, 2016Co-Authors: Charley J Duran, Sarah-jane Barnes, John T CorkeryAbstract:Abstract There is an on-going debate as to whether the Lac des Iles Pd deposits (Ontario, Canada) are of magmatic or hydrothermal origin. An aspect of the deposits that has not yet been documented is the presence of sulfide-rich pods which occur throughout the host intrusion (the Mine Block Intrusion). The ore mineralogy of the sulfide-rich pods consists of pyrrhotite, Pentlandite, chalcopyrite, ± pyrite, magnetite and ilmenite. We present the trace element concentrations of pyrrhotite, Pentlandite, chalcopyrite, magnetite, and ilmenite from the pods and compare these results with results from other Ni–Cu–platinum-group element (PGE) deposits. The low concentrations of Si and Ca and high concentrations of V, Ni, and Cr in magnetite are consistent with a magmatic origin of the magnetite. Variations in the V and Cr concentrations indicate that magnetite crystallized from a magmatic sulfide liquid during crystal fractionation of the sulfide liquid. The enrichments in Ni, Co, Os, Ir, Ru, and Rh and depletions in Cu, Ag, Cd, and Zn in Pentlandite and pyrrhotite relative to chalcopyrite are also consistent with the formation of the pods by crystallization of a magmatic sulfide liquid. Comparison of pyrrhotite and Pentlandite compositions from Lac des Iles with those from other Ni–Cu–PGE deposits shows that pyrrhotite and Pentlandite derived from evolved magmas have distinct compositions relative to those derived from more primitive magmas. In addition, this comparison shows that Pentlandites from PGE-dominated deposits are richer in Pd and Rh than Pentlandites from Ni–Cu sulfide deposits. A plot of Pd vs Rh appears to be effective at distinguishing Pentlandites of PGE-dominated deposits from those of Ni–Cu sulfide deposits and could possibly be used to adapt exploration strategies.
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Geology, petrography, geochemistry, and genesis of sulfide-rich pods in the Lac des Iles palladium deposits, western Ontario, Canada
Mineralium Deposita, 2016Co-Authors: Charley J Duran, Sarah-jane Barnes, John T CorkeryAbstract:The Lac des Iles Pd deposits are known for their Pd-rich sulfide-poor mineralization. However, previously undocumented sulfide-rich pods also occur within the intrusion that hosts the deposits. Given the complex magmatic and hydrothermal history of the mineralization at Lac des Iles, the sulfide-rich pods could have crystallized from magmatic sulfide liquids or precipitated from hydrothermal fluids. Sulfide-rich pods occur throughout the stratigraphy, in all rock types, and along comagmatic shear zones, and contain net-textured to massive sulfides. They can be divided into four main groups based on the variation in mineral assemblages: (1) pyrrhotite–Pentlandite ± pyrite–chalcopyrite–magnetite–ilmenite; (2) chalcopyrite ± pyrrhotite–Pentlandite–pyrite–magnetite–ilmenite; (3) pyrite ± Pentlandite–chalcopyrite–pyrrhotite–magnetite–ilmenite; and (4) magnetite ± ilmenite–pyrrhotite–Pentlandite–pyrite–chalcopyrite. Whole rock metal contents and S isotopic compositions do not change with the amount of pyrite present, except for slight enrichments in As and Bi. The presence of an essentially magmatic sulfide mineral assemblage (pyrrhotite–Pentlandite ± chalcopyrite) with Pentlandite exsolution flames in pyrrhotite in some pods suggests that the pods crystallized from magmatic sulfide liquids. The very low Cu contents of the pods suggests that they are mainly cumulates of monosulfide solid solution (MSS). We propose a model whereby sulfide liquids were concentrated into dilation zones prior to crystallizing cumulus MSS. Intermediate solid solution crystallized from the fractionated liquids at the edges of some pods leaving residual liquids enriched in Pt, Pd, Au, As, Bi, Sb, and Te. These residual liquids are no longer associated with the pods. During subsequent alteration, pyrite replaced MSS/pyrrhotite, but this did not affect the platinum-group element contents of the pods.
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platinum group element concentrations in pyrite from the main sulfide zone of the great dyke of zimbabwe
Mineralium Deposita, 2016Co-Authors: Rubén Piña, Fernando Gervilla, Sarah-jane Barnes, Rosario Lunar, Thomas OberthurAbstract:The Main Sulfide Zone (MSZ) of the Great Dyke of Zimbabwe hosts the world’s second largest resource of platinum-group elements (PGE) after the Bushveld Complex in South Africa. The sulfide assemblage of the MSZ comprises pyrrhotite, Pentlandite, chalcopyrite, and minor pyrite. Recently, several studies have observed in a number of Ni-Cu-PGE ore deposits that pyrite may host significant amounts of PGE, particularly Pt and Rh. In this study, we have determined PGE and other trace element contents in pyrite from the Hartley, Ngezi, Unki, and Mimosa mines of the Great Dyke by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Based on the textures and PGE contents, two types of pyrite can be differentiated. Py1 occurs as individual euhedral or subhedral grains or clusters of crystals mostly within chalcopyrite and Pentlandite, in some cases in the form of symplectitic intergrowths, and is PGE rich (up to 99 ppm Pt and 61 ppm Rh; 1.7 to 47.1 ppm Ru, 0.1 to 7.8 ppm Os, and 1.2 to 20.2 ppm Ir). Py2 occurs as small individual euhedral or subhedral crystals within pyrrhotite, Pentlandite, and less frequently within chalcopyrite and silicates and has low PGE contents (<0.11 ppm Pt, <0.34 ppm Rh, <2.5 ppm Ru, <0.37 ppm Ir, and <0.40 ppm Os). Py1 contains higher Os, Ir, Ru, Rh, and Pt contents than the associated pyrrhotite, Pentlandite, and chalcopyrite, whereas Py2 has similar PGE contents as coexisting pyrrhotite and Pentlandite. Based on the textural relationships, two different origins are attributed for each pyrite type. Py1 intergrowth with Pentlandite and chalcopyrite is inferred to have formed by late, low temperature (<300 °C) decomposition of residual Ni-rich monosulfide solid solution, whereas Py2 is suggested to have formed by replacement of pyrrhotite and Pentlandite caused by late magmatic/hydrothermal fluids.
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Chalcophile and platinum-group element (PGE) concentrations in the sulfide minerals from the McCreedy East deposit, Sudbury, Canada, and the origin of PGE in pyrite
Mineralium Deposita, 2011Co-Authors: Sarah A. S. Dare, Sarah-jane Barnes, Hazel M. Prichard, Peter Charles FisherAbstract:Magmatic sulfide deposits consist of pyrrhotite, Pentlandite, chalcopyrite (± pyrite), and platinum-group minerals (PGM). Understanding the distribution of the chalcophile and platinum-group element (PGE) concentrations among the base metal sulfide phases and PGM is important both for the petrogenetic models of the ores and for the efficient extraction of the PGE. Typically, pyrrhotite and Pentlandite host much of the PGE, except Pt which forms Pt minerals. Chalcopyrite does not host PGE and the role of pyrite has not been closely investigated. The Ni–Cu–PGE ores from the South Range of Sudbury are unusual in that sulfarsenide PGM, rather than pyrrhotite and Pentlandite, are the main carrier of PGE, probably as the result of arsenic contribution to the sulfide liquid by the As-bearing metasedimentary footwall rocks. In comparison, the North Range deposits of Sudbury, such as the McCreedy East deposit, have As-poor granites in the footwall, and the ores commonly contain pyrite. Our results show that in the pyrrhotite-rich ores of the McCreedy East deposit Os, Ir, Ru, Rh (IPGE), and Re are concentrated in pyrrhotite, Pentlandite, and surprisingly in pyrite. This indicates that sulfarsenides, which are not present in the ores, were not important in concentrating PGE in the North Range of Sudbury. Palladium is present in Pentlandite and, together with Pt, form PGM such as (PtPd)(TeBi)_2. Platinum is also found in pyrite. Two generations of pyrite are present. One pyrite is primary and locally exsolved from monosulfide solid solution (MSS) in small amounts (
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chalcophile and platinum group element pge concentrations in the sulfide minerals from the mccreedy east deposit sudbury canada and the origin of pge in pyrite
Mineralium Deposita, 2011Co-Authors: Sarah A. S. Dare, Sarah-jane Barnes, Hazel Margaret Prichard, Peter Charles FisherAbstract:Magmatic sulfide deposits consist of pyrrhotite, Pentlandite, chalcopyrite (± pyrite), and platinum-group minerals (PGM). Understanding the distribution of the chalcophile and platinum-group element (PGE) concentrations among the base metal sulfide phases and PGM is important both for the petrogenetic models of the ores and for the efficient extraction of the PGE. Typically, pyrrhotite and Pentlandite host much of the PGE, except Pt which forms Pt minerals. Chalcopyrite does not host PGE and the role of pyrite has not been closely investigated. The Ni–Cu–PGE ores from the South Range of Sudbury are unusual in that sulfarsenide PGM, rather than pyrrhotite and Pentlandite, are the main carrier of PGE, probably as the result of arsenic contribution to the sulfide liquid by the As-bearing metasedimentary footwall rocks. In comparison, the North Range deposits of Sudbury, such as the McCreedy East deposit, have As-poor granites in the footwall, and the ores commonly contain pyrite. Our results show that in the pyrrhotite-rich ores of the McCreedy East deposit Os, Ir, Ru, Rh (IPGE), and Re are concentrated in pyrrhotite, Pentlandite, and surprisingly in pyrite. This indicates that sulfarsenides, which are not present in the ores, were not important in concentrating PGE in the North Range of Sudbury. Palladium is present in Pentlandite and, together with Pt, form PGM such as (PtPd)(TeBi)2. Platinum is also found in pyrite. Two generations of pyrite are present. One pyrite is primary and locally exsolved from monosulfide solid solution (MSS) in small amounts (<2 wt.%) together with pyrrhotite and Pentlandite. This pyrite is unexpectedly enriched in IPGE, As (± Pt) and the concentrations of these elements are oscillatory zoned. The other pyrite is secondary and formed by alteration of the MSS cumulates by late magmatic/hydrothermal fluids. This pyrite is unzoned and has inherited the low concentrations of IPGE and Re from the pyrrhotite and Pentlandite that it has replaced.
John T Corkery - One of the best experts on this subject based on the ideXlab platform.
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trace element distribution in primary sulfides and fe ti oxides from the sulfide rich pods of the lac des iles pd deposits western ontario canada constraints on processes controlling the composition of the ore and the use of Pentlandite compositions
Journal of Geochemical Exploration, 2016Co-Authors: Charley J Duran, Sarah-jane Barnes, John T CorkeryAbstract:Abstract There is an on-going debate as to whether the Lac des Iles Pd deposits (Ontario, Canada) are of magmatic or hydrothermal origin. An aspect of the deposits that has not yet been documented is the presence of sulfide-rich pods which occur throughout the host intrusion (the Mine Block Intrusion). The ore mineralogy of the sulfide-rich pods consists of pyrrhotite, Pentlandite, chalcopyrite, ± pyrite, magnetite and ilmenite. We present the trace element concentrations of pyrrhotite, Pentlandite, chalcopyrite, magnetite, and ilmenite from the pods and compare these results with results from other Ni–Cu–platinum-group element (PGE) deposits. The low concentrations of Si and Ca and high concentrations of V, Ni, and Cr in magnetite are consistent with a magmatic origin of the magnetite. Variations in the V and Cr concentrations indicate that magnetite crystallized from a magmatic sulfide liquid during crystal fractionation of the sulfide liquid. The enrichments in Ni, Co, Os, Ir, Ru, and Rh and depletions in Cu, Ag, Cd, and Zn in Pentlandite and pyrrhotite relative to chalcopyrite are also consistent with the formation of the pods by crystallization of a magmatic sulfide liquid. Comparison of pyrrhotite and Pentlandite compositions from Lac des Iles with those from other Ni–Cu–PGE deposits shows that pyrrhotite and Pentlandite derived from evolved magmas have distinct compositions relative to those derived from more primitive magmas. In addition, this comparison shows that Pentlandites from PGE-dominated deposits are richer in Pd and Rh than Pentlandites from Ni–Cu sulfide deposits. A plot of Pd vs Rh appears to be effective at distinguishing Pentlandites of PGE-dominated deposits from those of Ni–Cu sulfide deposits and could possibly be used to adapt exploration strategies.
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Geology, petrography, geochemistry, and genesis of sulfide-rich pods in the Lac des Iles palladium deposits, western Ontario, Canada
Mineralium Deposita, 2016Co-Authors: Charley J Duran, Sarah-jane Barnes, John T CorkeryAbstract:The Lac des Iles Pd deposits are known for their Pd-rich sulfide-poor mineralization. However, previously undocumented sulfide-rich pods also occur within the intrusion that hosts the deposits. Given the complex magmatic and hydrothermal history of the mineralization at Lac des Iles, the sulfide-rich pods could have crystallized from magmatic sulfide liquids or precipitated from hydrothermal fluids. Sulfide-rich pods occur throughout the stratigraphy, in all rock types, and along comagmatic shear zones, and contain net-textured to massive sulfides. They can be divided into four main groups based on the variation in mineral assemblages: (1) pyrrhotite–Pentlandite ± pyrite–chalcopyrite–magnetite–ilmenite; (2) chalcopyrite ± pyrrhotite–Pentlandite–pyrite–magnetite–ilmenite; (3) pyrite ± Pentlandite–chalcopyrite–pyrrhotite–magnetite–ilmenite; and (4) magnetite ± ilmenite–pyrrhotite–Pentlandite–pyrite–chalcopyrite. Whole rock metal contents and S isotopic compositions do not change with the amount of pyrite present, except for slight enrichments in As and Bi. The presence of an essentially magmatic sulfide mineral assemblage (pyrrhotite–Pentlandite ± chalcopyrite) with Pentlandite exsolution flames in pyrrhotite in some pods suggests that the pods crystallized from magmatic sulfide liquids. The very low Cu contents of the pods suggests that they are mainly cumulates of monosulfide solid solution (MSS). We propose a model whereby sulfide liquids were concentrated into dilation zones prior to crystallizing cumulus MSS. Intermediate solid solution crystallized from the fractionated liquids at the edges of some pods leaving residual liquids enriched in Pt, Pd, Au, As, Bi, Sb, and Te. These residual liquids are no longer associated with the pods. During subsequent alteration, pyrite replaced MSS/pyrrhotite, but this did not affect the platinum-group element contents of the pods.
Charley J Duran - One of the best experts on this subject based on the ideXlab platform.
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trace element distribution in primary sulfides and fe ti oxides from the sulfide rich pods of the lac des iles pd deposits western ontario canada constraints on processes controlling the composition of the ore and the use of Pentlandite compositions
Journal of Geochemical Exploration, 2016Co-Authors: Charley J Duran, Sarah-jane Barnes, John T CorkeryAbstract:Abstract There is an on-going debate as to whether the Lac des Iles Pd deposits (Ontario, Canada) are of magmatic or hydrothermal origin. An aspect of the deposits that has not yet been documented is the presence of sulfide-rich pods which occur throughout the host intrusion (the Mine Block Intrusion). The ore mineralogy of the sulfide-rich pods consists of pyrrhotite, Pentlandite, chalcopyrite, ± pyrite, magnetite and ilmenite. We present the trace element concentrations of pyrrhotite, Pentlandite, chalcopyrite, magnetite, and ilmenite from the pods and compare these results with results from other Ni–Cu–platinum-group element (PGE) deposits. The low concentrations of Si and Ca and high concentrations of V, Ni, and Cr in magnetite are consistent with a magmatic origin of the magnetite. Variations in the V and Cr concentrations indicate that magnetite crystallized from a magmatic sulfide liquid during crystal fractionation of the sulfide liquid. The enrichments in Ni, Co, Os, Ir, Ru, and Rh and depletions in Cu, Ag, Cd, and Zn in Pentlandite and pyrrhotite relative to chalcopyrite are also consistent with the formation of the pods by crystallization of a magmatic sulfide liquid. Comparison of pyrrhotite and Pentlandite compositions from Lac des Iles with those from other Ni–Cu–PGE deposits shows that pyrrhotite and Pentlandite derived from evolved magmas have distinct compositions relative to those derived from more primitive magmas. In addition, this comparison shows that Pentlandites from PGE-dominated deposits are richer in Pd and Rh than Pentlandites from Ni–Cu sulfide deposits. A plot of Pd vs Rh appears to be effective at distinguishing Pentlandites of PGE-dominated deposits from those of Ni–Cu sulfide deposits and could possibly be used to adapt exploration strategies.
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Geology, petrography, geochemistry, and genesis of sulfide-rich pods in the Lac des Iles palladium deposits, western Ontario, Canada
Mineralium Deposita, 2016Co-Authors: Charley J Duran, Sarah-jane Barnes, John T CorkeryAbstract:The Lac des Iles Pd deposits are known for their Pd-rich sulfide-poor mineralization. However, previously undocumented sulfide-rich pods also occur within the intrusion that hosts the deposits. Given the complex magmatic and hydrothermal history of the mineralization at Lac des Iles, the sulfide-rich pods could have crystallized from magmatic sulfide liquids or precipitated from hydrothermal fluids. Sulfide-rich pods occur throughout the stratigraphy, in all rock types, and along comagmatic shear zones, and contain net-textured to massive sulfides. They can be divided into four main groups based on the variation in mineral assemblages: (1) pyrrhotite–Pentlandite ± pyrite–chalcopyrite–magnetite–ilmenite; (2) chalcopyrite ± pyrrhotite–Pentlandite–pyrite–magnetite–ilmenite; (3) pyrite ± Pentlandite–chalcopyrite–pyrrhotite–magnetite–ilmenite; and (4) magnetite ± ilmenite–pyrrhotite–Pentlandite–pyrite–chalcopyrite. Whole rock metal contents and S isotopic compositions do not change with the amount of pyrite present, except for slight enrichments in As and Bi. The presence of an essentially magmatic sulfide mineral assemblage (pyrrhotite–Pentlandite ± chalcopyrite) with Pentlandite exsolution flames in pyrrhotite in some pods suggests that the pods crystallized from magmatic sulfide liquids. The very low Cu contents of the pods suggests that they are mainly cumulates of monosulfide solid solution (MSS). We propose a model whereby sulfide liquids were concentrated into dilation zones prior to crystallizing cumulus MSS. Intermediate solid solution crystallized from the fractionated liquids at the edges of some pods leaving residual liquids enriched in Pt, Pd, Au, As, Bi, Sb, and Te. These residual liquids are no longer associated with the pods. During subsequent alteration, pyrite replaced MSS/pyrrhotite, but this did not affect the platinum-group element contents of the pods.
Zhitao Yuan - One of the best experts on this subject based on the ideXlab platform.
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the role of sodium oleate naol in the magnetic separation of Pentlandite from serpentine using magnetic coating
Powder Technology, 2019Co-Authors: Zhitao Yuan, Xuan Zhao, Zhongyun TongAbstract:Abstract The efficient separation of Pentlandite from serpentine remains a challenging issue in the processing of nickel sulfide ores. In this study, selective magnetic coating-magnetic separation was employed to separate the Pentlandite from serpentine with adding NaOL as a coagulant, which is different from the conventional flotation. The results indicate that it was very effective for their separation. Furthermore, the role of NaOL in the separation was evaluated in detail by means of adsorption tests, zeta potential measurements, Fourier transform infrared (FTIR) spectra analyses, solution chemistry calculations X-ray photoelectron (XPS) spectra analyses, and scanning electron microscopy-energy dispersive spectra (SEM-EDS) analyses. It turns out that NaOL can adsorb selectively onto the surfaces of Pentlandite and magnetite through the Ni and Fe sites (serpentine was pre-depressed by sodium hexametaphosphate (NaHMP)) and form the hydrophobic surfaces between the two minerals. As a result, the Pentlandite surface was selectively coated by the magnetite fines and then was separated from serpentine using magnetic separation. Therefore, our results provide an alternative technology for their separation and exhibit great potential for further study and applications.
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the role of sodium oleate naol in the magnetic separation of Pentlandite from serpentine using magnetic coating
Powder Technology, 2019Co-Authors: Jiwei Lu, Zhitao Yuan, Zhongyun Tong, Mingming Li, Xuan Zhao, Lixia Li, Shengliang QiAbstract:Abstract The efficient separation of Pentlandite from serpentine remains a challenging issue in the processing of nickel sulfide ores. In this study, selective magnetic coating-magnetic separation was employed to separate the Pentlandite from serpentine with adding NaOL as a coagulant, which is different from the conventional flotation. The results indicate that it was very effective for their separation. Furthermore, the role of NaOL in the separation was evaluated in detail by means of adsorption tests, zeta potential measurements, Fourier transform infrared (FTIR) spectra analyses, solution chemistry calculations X-ray photoelectron (XPS) spectra analyses, and scanning electron microscopy-energy dispersive spectra (SEM-EDS) analyses. It turns out that NaOL can adsorb selectively onto the surfaces of Pentlandite and magnetite through the Ni and Fe sites (serpentine was pre-depressed by sodium hexametaphosphate (NaHMP)) and form the hydrophobic surfaces between the two minerals. As a result, the Pentlandite surface was selectively coated by the magnetite fines and then was separated from serpentine using magnetic separation. Therefore, our results provide an alternative technology for their separation and exhibit great potential for further study and applications.
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Magnetic separation of Pentlandite from serpentine by selective magnetic coating
International Journal of Minerals Metallurgy and Materials, 2019Co-Authors: Zhitao Yuan, Xiao-fei Guo, Zhongyun TongAbstract:In this study, Pentlandite was selectively separated from serpentine using magnetic coating technology by adjusting and optimizing pH, stirring speeds, magnetic field intensities, and dosages of sodium hexametaphosphate (SHMP) and sodium oleate (SO). A magnetic concentrate with Ni grade of 20.8% and Ni recovery of 80.5% was attained under the optimized operating conditions. Considering the above, the adsorption behaviors of SHMP and SO and the surface properties of minerals after the magnetic coating were studied by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results show that magnetite was preferentially coated on the Pentlandite surfaces and sparingly coated on the serpentine surfaces in the presence of SHMP and SO. Furthermore, calculations by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory indicate that the preferential adsorption of magnetite on the Pentlandite surfaces is due to the presence of a hydrophobic interaction between the magnetite and Pentlandite, which is much stronger than the interaction between magnetite and serpentine.
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Surface Modification of Pentlandite and Serpentine with Reagents and Magnetite for Magnetic Separation
JOM, 2018Co-Authors: Zhitao Yuan, Zhongyun TongAbstract:In this study, selective magnetic coating was employed to separate Pentlandite and serpentine. The surface properties of minerals with and without reagents and magnetite were characterized by zeta potential measurements, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). Zeta potentials showed that the surfaces of serpentine and magnetite were both negatively charged with the addition of sodium hexametaphosphate. Thus, serpentine was hardly coated by magnetite due to the electrostatic repulsion between them. The results of SEM and FTIR demonstrated that a magnetic coating of magnetite was observed on the Pentlandite rather than on the serpentine. The VSM measurements confirmed that the magnetism of Pentlandite was increased significantly due to the selective adsorption of magnetite on its surfaces; therefore, Pentlandite was successfully separated from serpentine by magnetic separation. The study shows that selective magnetic coating technology has the alternative potential to separate Pentlandite from serpentine.
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Enhancement of Pentlandite surface magnetism and implications for its separation from serpentine via magnetic separation
Transactions of Nonferrous Metals Society of China, 2017Co-Authors: Zhitao Yuan, Jiongtian Liu, Shuang-yu WangAbstract:Abstract The magnetism of Pentlandite surface was enhanced through the selective precipitation of micro-fine magnetite fractions on Pentlandite surfaces. This was achieved through adjustment of slurry pH and addition of surfactants. The results showed that at pH 8.8 with the addition of 100 g/t sodium hexametaphosphate, 4.5 L/t oleic acid, and 4.5 L/t kerosene, significant amount of fine magnetite particles adhered to the Pentlandite surface, while trace amount of coating was found on serpentine surfaces. Thus, the magnetism of Pentlandite was enhanced and Pentlandite was well separated from serpentine by magnetic separation under the magnetic field intensity of 200 kA/m. Scanning electron microscopy (SEM) and zeta potential measurement were performed to characterize changes of mineral surface properties. Calculations of the extended Derjaguin–Landau–Verwey–Ocerbeek (EDLVO) theory indicated that, in the presence of surfactants the total interaction energy between magnetite and Pentlandite became stronger than that between magnetite and serpentine. This enabled the selective adhesion of magnetite particles to Pentlandite surfaces, thereby enhancing its magnetism.
Sarah A. S. Dare - One of the best experts on this subject based on the ideXlab platform.
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The Occurrence and Origin of Pentlandite-Chalcopyrite-Pyrrhotite Loop Textures in Magmatic Ni-Cu Sulfide Ores
Economic Geology, 2020Co-Authors: Stephen Barnes, Valentina Taranovic, Louise Schoneveld, Eduardo T. Mansur, Margaux Le Vaillant, Sarah A. S. Dare, Sebastian Staude, Noreen J. Evans, Daryl E. BlanksAbstract:Abstract Pentlandite is the dominant Ni-hosting ore mineral in most magmatic sulfide deposits and has conventionally been interpreted as being entirely generated by solid-state exsolution from the high-temperature monosulfide solid solution (MSS) (Fe,Ni)1–xS. This process gives rise to the development of loops of Pentlandite surrounding pyrrhotite grains. Recently it has been recognized that not all Pentlandite forms by exsolution. Some may form as the result of peritectic reaction between early formed MSS and residual Ni-Cu–rich sulfide liquid during differentiation of the sulfide melt, such that at least some loop textures may be genuinely magmatic in origin. Testing this hypothesis involved microbeam X-ray fluorescence mapping to image Pentlandite-pyrrhotite-chalcopyrite intergrowths from a range of different deposits. These deposits exemplify slowly cooled magmatic environments (Nova, Western Australia; Sudbury, Canada), globular ores from shallow-level intrusions (Norilsk, Siberia), extrusive komatiite-hosted ores from low and high metamorphic-grade terranes, and a number of other deposits. Our approach was complemented by laser ablation-inductively coupled plasma-mass spectrometry analysis of palladium in varying textural types of Pentlandite within these deposits. Pentlandite forming coarse granular aggregates, together with loop-textured Pentlandite where chalcopyrite also forms part of the loop framework, consistently has the highest Pd content compared with Pentlandite clearly exsolved as lamellae from MSS or pyrrhotite. This is consistent with much of granular and loop Pentlandite being formed by peritectic reaction between Pd-rich residual sulfide liquid and early crystallized MSS, rather than forming entirely by subsolidus grain boundary exsolution from MSS, as has hitherto been assumed. The wide range of Pd contents in Pentlandite in individual samples reflects a continuum of processes between peritectic reaction and grain boundary exsolution. Textures in metamorphically recrystallized ores are distinctly different from loop-textured ores, implying that loop textures cannot be regenerated (except in special circumstances) by metamorphic recrystallization of original magmatic-textured ores. The presence of loop textures can therefore be taken as evidence of a lack of penetrative deformation and remobilization at submagmatic temperatures, a conclusion of particular significance to the interpretation of the Nova deposit as having formed synchronously with the peak of regional deformation at temperatures within the sulfide melting range.
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Chalcophile and platinum-group element (PGE) concentrations in the sulfide minerals from the McCreedy East deposit, Sudbury, Canada, and the origin of PGE in pyrite
Mineralium Deposita, 2011Co-Authors: Sarah A. S. Dare, Sarah-jane Barnes, Hazel M. Prichard, Peter Charles FisherAbstract:Magmatic sulfide deposits consist of pyrrhotite, Pentlandite, chalcopyrite (± pyrite), and platinum-group minerals (PGM). Understanding the distribution of the chalcophile and platinum-group element (PGE) concentrations among the base metal sulfide phases and PGM is important both for the petrogenetic models of the ores and for the efficient extraction of the PGE. Typically, pyrrhotite and Pentlandite host much of the PGE, except Pt which forms Pt minerals. Chalcopyrite does not host PGE and the role of pyrite has not been closely investigated. The Ni–Cu–PGE ores from the South Range of Sudbury are unusual in that sulfarsenide PGM, rather than pyrrhotite and Pentlandite, are the main carrier of PGE, probably as the result of arsenic contribution to the sulfide liquid by the As-bearing metasedimentary footwall rocks. In comparison, the North Range deposits of Sudbury, such as the McCreedy East deposit, have As-poor granites in the footwall, and the ores commonly contain pyrite. Our results show that in the pyrrhotite-rich ores of the McCreedy East deposit Os, Ir, Ru, Rh (IPGE), and Re are concentrated in pyrrhotite, Pentlandite, and surprisingly in pyrite. This indicates that sulfarsenides, which are not present in the ores, were not important in concentrating PGE in the North Range of Sudbury. Palladium is present in Pentlandite and, together with Pt, form PGM such as (PtPd)(TeBi)_2. Platinum is also found in pyrite. Two generations of pyrite are present. One pyrite is primary and locally exsolved from monosulfide solid solution (MSS) in small amounts (
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chalcophile and platinum group element pge concentrations in the sulfide minerals from the mccreedy east deposit sudbury canada and the origin of pge in pyrite
Mineralium Deposita, 2011Co-Authors: Sarah A. S. Dare, Sarah-jane Barnes, Hazel Margaret Prichard, Peter Charles FisherAbstract:Magmatic sulfide deposits consist of pyrrhotite, Pentlandite, chalcopyrite (± pyrite), and platinum-group minerals (PGM). Understanding the distribution of the chalcophile and platinum-group element (PGE) concentrations among the base metal sulfide phases and PGM is important both for the petrogenetic models of the ores and for the efficient extraction of the PGE. Typically, pyrrhotite and Pentlandite host much of the PGE, except Pt which forms Pt minerals. Chalcopyrite does not host PGE and the role of pyrite has not been closely investigated. The Ni–Cu–PGE ores from the South Range of Sudbury are unusual in that sulfarsenide PGM, rather than pyrrhotite and Pentlandite, are the main carrier of PGE, probably as the result of arsenic contribution to the sulfide liquid by the As-bearing metasedimentary footwall rocks. In comparison, the North Range deposits of Sudbury, such as the McCreedy East deposit, have As-poor granites in the footwall, and the ores commonly contain pyrite. Our results show that in the pyrrhotite-rich ores of the McCreedy East deposit Os, Ir, Ru, Rh (IPGE), and Re are concentrated in pyrrhotite, Pentlandite, and surprisingly in pyrite. This indicates that sulfarsenides, which are not present in the ores, were not important in concentrating PGE in the North Range of Sudbury. Palladium is present in Pentlandite and, together with Pt, form PGM such as (PtPd)(TeBi)2. Platinum is also found in pyrite. Two generations of pyrite are present. One pyrite is primary and locally exsolved from monosulfide solid solution (MSS) in small amounts (<2 wt.%) together with pyrrhotite and Pentlandite. This pyrite is unexpectedly enriched in IPGE, As (± Pt) and the concentrations of these elements are oscillatory zoned. The other pyrite is secondary and formed by alteration of the MSS cumulates by late magmatic/hydrothermal fluids. This pyrite is unzoned and has inherited the low concentrations of IPGE and Re from the pyrrhotite and Pentlandite that it has replaced.
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the distribution of platinum group elements pge and other chalcophile elements among sulfides from the creighton ni cu pge sulfide deposit sudbury canada and the origin of palladium in Pentlandite
Mineralium Deposita, 2010Co-Authors: Sarah A. S. Dare, Sarah-jane Barnes, Hazel Margaret PrichardAbstract:Concentrations of platinum group elements (PGE), Ag, As, Au, Bi, Cd, Co, Mo, Pb, Re, Sb, Se, Sn, Te, and Zn, have been determined in base metal sulfide (BMS) minerals from the western branch (402 Trough orebodies) of the Creighton Ni–Cu–PGE sulfide deposit, Sudbury, Canada. The sulfide assemblage is dominated by pyrrhotite, with minor Pentlandite, chalcopyrite, and pyrite, and they represent monosulfide solid solution (MSS) cumulates. The aim of this study was to establish the distribution of the PGE among the BMS and platinum group minerals (PGM) in order to understand better the petrogenesis of the deposit. Mass balance calculations show that the BMS host all of the Co and Se, a significant proportion (40–90%) of Os, Pd, Ru, Cd, Sn, and Zn, but very little (<35%) of the Ag, Au, Bi, Ir, Mo, Pb, Pt, Rh, Re, Sb, and Te. Osmium and Ru are concentrated in equal proportions in pyrrhotite, Pentlandite, and pyrite. Cobalt and Pd (∼1 ppm) are concentrated in Pentlandite. Silver, Cd, Sn, Zn, and in rare cases Au and Te, are concentrated in chalcopyrite. Selenium is present in equal proportions in all three BMS. Iridium, Rh, and Pt are present in euhedrally zoned PGE sulfarsenides, which comprise irarsite (IrAsS), hollingworthite (RhAsS), PGE-Ni-rich cobaltite (CoAsS), and subordinate sperrylite (PtAs2), all of which are hosted predominantly in pyrrhotite and Pentlandite. Silver, Au, Bi, Mo, Pb, Re, Sb, and Te are found predominantly in discrete accessory minerals such as electrum (Au–Ag alloy), hessite (Ag2Te), michenerite (PdBiTe), and rhenium sulfides. The enrichment of Os, Ru, Ni, and Co in pyrrhotite, Pentlandite, and pyrite and Ag, Au, Cd, Sn, Te, and Zn in chalcopyrite can be explained by fractional crystallization of MSS from a sulfide liquid followed by exsolution of the sulfides. The early crystallization of the PGE sulfarsenides from the sulfide melt depleted the MSS in Ir and Rh. The bulk of Pd in Pentlandite cannot be explained by sulfide fractionation alone because Pd should have partitioned into the residual Cu-rich liquid and be in chalcopyrite or in PGM around chalcopyrite. The variation of Pd among different Pentlandite textures provides evidence that Pd diffuses into Pentlandite during its exsolution from MSS. The source of Pd was from the small quantity of Pd that partitioned originally into the MSS and a larger quantity of Pd in the nearby Cu-rich portion (intermediate solid solution and/or Pd-bearing PGM). The source of Pd became depleted during the diffusion process, thus later-forming Pentlandite (rims of coarse-granular, veinlets, and exsolution flames) contains less Pd than early-forming Pentlandite (cores of coarse-granular).