Palladseite and its oxidation: evidence from Au-Pd vein-type mineralization (jacutinga), Cauê iron-ore mine, Quadrilátero Ferrífero, Minas Gerais, Brazil

Cabral, Alexandre Raphael; Lehmann, Bernd; Kwitko, R.; Galbiatti, Henry Francisco; Pereira, M. C.

doi:10.1180/0026461026620033

Cited by 27 publications

(14 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It occurs as virtually sulphide-free, hematitic veins ranging in width from a few millimetres to usually no more than half a metre, which truncate the S 1 foliation of the host itabirite (Touzeau, 1892;Cabral et al, 2002a;Lüders et al, 2005). The cross-cutting relationships were overlooked by Olivo et al (1995), who erroneously ascertained that the Itabira 'jacutinga' was synchronously emplaced with ductile shearing (Galbiatti, 1999;Cabral et al, 2002b). Gold grains found in 'jacutinga' are typically palladiferous.…”

Section: Study Areas and Geological Settingmentioning

confidence: 99%

Evidence for metre-scale variations in hematite composition within the Palaeoproterozoic Itabira Iron Formation, Minas Gerais, Brazil

Cabral¹,

Lehmann²,

Galbiatti³

et al. 2006

Mineral. mag.

Self Cite

View full text Add to dashboard Cite

Hematite is a mineral the chemical composition of which rarely differs significantly from stoichiometric Fe2O3. As such, little attention has been paid to the mineral chemistry of hematite in Precambrian iron formations, where hematite forms monomineralic high-grade orebodies. Electron microprobe analysis of hematite from two iron-ore deposits, Cauê (Itabira district) and Gongo Soco, in the Palaeoproterozoic Itabira Iron Formation, Quadrilátero Ferrífero of Minas Gerais, Brazil, has revealed distinct variations in chemical composition with respect to Ti and Cr. Hematite containing Ti and/or Cr is of very local occurrence in the itabirite unit and shows a spatial relationship to hematitic, palladiferous gold-bearing veins (known as ‘jacutinga’), occurring either within the veins (adjacent to, or included in, palladiferous gold grains) or in their vicinity. Where present, titaniferous hematite (to ∼1.3 wt.% TiO2) is lepidoblastic and defines a pervasive tectonic foliation (S1). In contrast, Ti-free, chromiferous hematite (to ∼6.4 wt.% Cr2O3) characteristically occurs as inclusions in palladiferous gold within S1-truncating ‘jacutinga’. Replacement of granoblastic, Ti-free, chromiferous martite with relicts of magnetite by lepidoblastic, Cr-depleted, titaniferous hematite proves that Cr and Ti were mobile during metamorphism. Chromium was ultimately fractionated into the hematite found in auriferous aggregates within cross-cutting ‘jacutinga’. A positive correlation between Cr and Pt in bulk-rock samples from the Itabira district suggests that Cr is a potential prospective guide for Au-Pd-Pt-bearing hematitic veins (‘jacutinga’).

show abstract

Section: Study Areas and Geological Settingmentioning

confidence: 99%

Evidence for metre-scale variations in hematite composition within the Palaeoproterozoic Itabira Iron Formation, Minas Gerais, Brazil

Cabral¹,

Lehmann²,

Galbiatti³

et al. 2006

Mineral. mag.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The mineralization also contains platinum and palladium selenides such as palladseite (Davis et al, 1977) and sudovikovite. The latter occurs as inclusions both in hongshiite (PtCu) (Kwitko et al, 2002) and specularite (Cabral et al, 2002). Fluid inclusion homogenization temperatures in specularite from Gongo Soco cluster at about 160°C and have around 10 wt percent NaCl equiv (V. Lüders, unpublished data).…”

Section: Discussionmentioning

confidence: 99%

The Serra Pelada Au-Pd-Pt Deposit, CarajasMineral Province, Northern Brazil: Reconnaissance Mineralogy and Chemistryof Very High Grade Palladian Gold Mineralization

Cabral

Lehmann

Kwitko³

et al. 2002

Economic Geology

Self Cite

View full text Add to dashboard Cite

A historic drill core from the Serra Pelada open pit was only recently assayed and has spectacular gold, palladium, and platinum grades over a 43-m-depth interval (4,709 g/t Au, 1,174 g/t Pd, 204 g/t Pt). The Au-Pd-Pt mineralization in a bonanza-grade interval (54.5-55.0 m @ 132,000 g/t Au, 11,400 g/t Pd, 359 g/t Pt) consists of coarse-grained, up to several centimeter-large, dendritic palladian gold aggregates (Au 7 Pd) with abundant inclusions of guanglinite (Pd 3 As), "stibio-guanglinite" (Pd 3 [As,Sb]), sudovikovite (PtSe 2), palladseite (Pd 17 Se 15), and an unnamed Pd-Pt-Se alloy. The palladian gold aggregates are often coated by goethite and are embedded in a powdery, ferruginous, clay-rich matrix with fragments of vein quartz. Iron and manganese oxides occur as vug fillings in palladian gold and are associated with native palladium and Pd-oxygenated compounds. The near-surface bonanza palladian gold mineralization is part of a larger, deeply weathered, hydrothermal system which, in deepest drill holes (>300 m), has a relict sulfide assemblage with a variable degree of overprint by iron oxides, sericite, and kaolinite. The deep system still has gold, palladium, and platinum grades in the g/t range and displays erratically high contents in light rare earth elements, bismuth, and selenium. Drill core samples from intermediate depth (157-275 m) are high in gold, palladium, and platinum and show a very pronounced bismuth enrichment, as well as enrichment in iridium, mercury, rare earth elements, uranium, copper, and lead. The shallow drill core is extremely enriched in gold, palladium, platinum, mercury, and manganese. The occurrence of gold dominantly as an Au-Pd alloy, the abundant selenide and arsenide inclusions in palladian gold, and the characteristic mercury signature point to an origin of the near-surface bonanza ore from a sulfur-deficient hydrothermal system, with apparently only minor supergene precious metal enrichment.

show abstract

“…The association of selenides at Minais Gerais and Serra Pelada in Brazil (Davis et al 1977, Olivo & Gauthier 1995, Cabral et al 2002, Cabral & Lehmann 2007 consists of the following minerals: palladseite, sudovikovite, chrisstanleyite, and jacutingaite. Palladium selenides also were observed in carbonaceous Precambrian black shale in the Voronezh crystalline massif in Russia (Rudashevskiy et al 1995).…”

Section: Minerals In the Systemmentioning

confidence: 99%

THE SYSTEM Hg-Pd-Se AT 400 C: PHASE RELATIONS INVOLVING TISCHENDORFITE AND OTHER TERNARY PHASES

Drábek¹,

Vymazalová²,

Laufek³

2014

The Canadian Mineralogist

View full text Add to dashboard Cite

Phase relations in the Hg-Pd-Se system were studied by the evacuated silica glass tube technique. For kinetic reasons, experiments were performed in the range 350-400 ºC. We present here the 400 ºC condensed isothermal section for the Hg-Pd-Se system, based on literature data and on our experiments. Two ternary phases were known previously: Pd 8 Hg 3 Se 9 , which corresponds to tischendorfite, and Pd 2 HgSe 3 . We report here on a third phase, Pd 5 HgSe. Tischendorfite forms stable assemblages with palladseite (Pd 17 Se 15 ), tiemannite (HgSe), potarite (PdHg), and with the phase Pd 2 HgSe 3 . In turn, Pd 2 HgSe 3 forms stable assemblages with PdSe 2 (orthorhombic), palladseite (Pd 17 Se 15 ), tischendorfite (Pd 8 Hg 3 Se 9 ), and tiemannite (HgSe). The phase Pd 5 HgSe, stable near the Pd-rich corner of the system, forms stable assemblages with metallic Pd, PdHg (potarite), palladseite (Pd 17 Se 15 ), and other Pd-rich binary palladium selenides. Palladseite forms limited solidsolution and dissolves up to 4.15 at.% Hg at 350 ºC. This solid solution forms stable assemblages with Pd 8 Hg 3 Se 9 , PdSe 2 , and HgPd (potarite). There are no joins involving HgSe (tiemannite) and binary Pd selenides.

show abstract

Palladseite and its oxidation: evidence from Au-Pd vein-type mineralization (jacutinga), Cauê iron-ore mine, Quadrilátero Ferrífero, Minas Gerais, Brazil

Cited by 27 publications

References 19 publications

Evidence for metre-scale variations in hematite composition within the Palaeoproterozoic Itabira Iron Formation, Minas Gerais, Brazil

Evidence for metre-scale variations in hematite composition within the Palaeoproterozoic Itabira Iron Formation, Minas Gerais, Brazil

The Serra Pelada Au-Pd-Pt Deposit, CarajasMineral Province, Northern Brazil: Reconnaissance Mineralogy and Chemistryof Very High Grade Palladian Gold Mineralization

THE SYSTEM Hg-Pd-Se AT 400 C: PHASE RELATIONS INVOLVING TISCHENDORFITE AND OTHER TERNARY PHASES

Contact Info

Product

Resources

About