A thermodynamic prediction on the stability of the nukundamite + chalcopyrite and bornite + pyrite assemblages

Kojima, Shoji; Ueno, Takao

doi:10.1180/minmag.1994.058.391.06

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…This result is superior to the work of Kojima and Ueno for the production of Cu 5.5 FeS 6.5 ; they performed more than 70 runs but only 28 were successful. 18 Elemental analyses showed that the mean composition of the samples was (atomic ratio) Cu 53.4, Fe 8.9, S 37.6%. Fig.…”

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confidence: 94%

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Cu5.5FeS6.5 nanotubesâ€”a new kind of ternary sulfide nanotube

et al. 2001

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confidence: 94%

“…However, the use of elemental Cu and Fe does not seem to prevent the formation of Cu 5.5 FeS 6.5 although the yield is not high. As the formation processes of the nanotubes and the Cu 5.5 FeS 6.5 phase in this reaction are complicated, 14,18,20,21 the exact mechanism needs further research.…”

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confidence: 99%

Cu5.5FeS6.5 nanotubesâ€”a new kind of ternary sulfide nanotube

et al. 2001

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“…This mineral assemblage could be named pyrite-bornite zone as mentioned in Gustafson and Hunt 2 . Experimental study by Kojima and Ueno 38 predicted temperature range 350-250ºC by using near-neutral hydrothermal solutions as formation condition of the pyrite + bornite assemblages. At upper levels close to the surface, supergene enrichment gradually is added to the complex.…”

Section: Resultsmentioning

confidence: 99%

Hypogene enrichment in Miduk porphyry copper ore deposit, Iran

Soorani

Bafti

Homam

et al. 2022

Sci Rep

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This study was planned with the aim of identifying the nature and circumstances of the high-graded central core and increasing trend of copper content through depth of 1000 m in Miduk PCD. Mechanisms of high-grading, refer to hypogene enrichment (HE), in PCDs poorly understood. Two main hypotheses for hypogene enrichment formation assumed addition of extra copper to the system, alternatively hypogene leaching and enrichment. In order to obtain alteration-mineralization-geochemical pattern both horizontally and vertically, all macroscopic data extracted from relogging of 6800 m’ drill core along an east–west profile, compiled with microscopic observations from studying of 550 thin-polished sections and copper grades of 3400 samples analyzed by XRF and ICP-OES. Our findings proved hypogene enrichment events at deposit. HE evidences in macroscopic and microscopic scales identified almost as various replacement textures between Fe-Cu sulphides and also vein-reopening by later Cu-mineralization and new generation of disseminated or vein type mineralization. In addition, appearance of dark halo, as consuming intermediate chalcocite phase, around pyrite and chalcopyrite which gradually evolves as bornite, also extruding extra iron as fibrous hematite at the outer edge of bornite product replaced chalcopyrite, partially replacement of bornite and chalcopyrite to hypogene chalcocite and covellite-digenite in deep potassic are other HE evidences in the case study. Here, we draw on microscopic observations and SEM-BSE-EDS results, secondary hypogene genesis for some of bornite and chalcopyrite as a hypogene enrichment evidence. Observations from relogging show that potassic alteration has a relatively good preservation in the center of the deposit from depth to surface, but affected by intense overprinting of subsequent alterations towards margins. Evident function of ore-leaching at margins, also elevated copper grades in central parts of the deposit strongly suggest leaching-fixation mechanism. Where buffer potential of the rock is preserved copper fixation and where it totally eliminated almost complete leaching of copper happened. Consequently, we introduce leaching-fixation as index processes in hypogene enrichment at the case study. We suggest that identifying the nature of hypogene enrichment processes and its characterizations not only improve understanding about PCD’s hydrothermal evolution, but also achieve exploration indicators, furthermore, industrial benefits in the production line.

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“…The consistent association of Cu with both Fe and S in these plots suggests the distribution of Cu-Fe sulfides throughout, although Cu is often incorporated as an impurity within pyrite (Marques et al 2006, Wang et al 2014. Cu sulfides like covellite and mixed-CuFe sulfides like cubanite or the rarer nukundamite (Cu5.5FeS6.5) have been shown in hydrothermal systems (Kojima & Ueno, 1994). In sample 1101_2, the uniform association of Cu with both Fe and S (Figures 10B.…”

Section: Copper (Cu)mentioning

confidence: 84%

Inferences on the influences of age & porosity on oxidative weathering of seafloor massive sulfide deposits at the endeavour segment of the Juan de Fuca Ridge

Herrera

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Hydrothermal activity at mid-ocean ridge spreading centers occurs during the formation of new oceanic crust and is responsible for the accumulation of mineral deposits comprised mainly of inorganic metal sulfides that precipitate from mixtures of seawater and high-temperature, sulfide-rich, oxygen-poor vent fluid. These mineral aggregates are known as seafloor massive sulfide deposits and occupy unique biogeochemical niches that remain largely unexplored. Upon the cessation of hydrothermal activity, massive sulfide deposits undergo alteration via both biotically- and abiotically-mediated geochemical reactions. These processes are collectively described as oxidative weathering. While the observed textures of these deposits suggest significant variation in weathering rates, neither the causes of this variation nor the drivers that govern biogeochemical oxidation of massive sulfides are well-characterized. To begin to describe the mechanisms that dictate these processes, massive sulfide samples were collected from deposits along the Endeavour Segment of the Juan de Fuca Ridge. Coupled synchrotron-based X-ray Absorption Near Edge Spectroscopy (XANES) and X-Ray Fluorescence (XRF) microscopy were utilized to create comprehensive redox maps that allow for characterization of the localized redox environment and identification of weathering products. These techniques are a powerful and so far underutilized tool with which to examine the geochemical landscapes of seafloor massive sulfide deposits. Mineral identifications and spatial distributions were corroborated with optical microscopy and X-Ray Diffraction (XRD). The Juan de Fuca Ridge massive sulfide samples are composed of iron-sulfide phases, primarily pyrite (FeS2), with minor amounts of other metal-bearing sulfides, such as sphalerite ((Zn,Fe)S2) , wurtzite ((Zn,Fe)S2), and cubanite (CuFe2S3). The samples contain rinds comprised of oxides and (primarily iron-bearing) clays that occur along massive sulfide exteriors and within pore channels. Greater amounts of secondary oxides and clays are observed concurrent with increased porosity and internal pore distribution and are inferred to be products of weathering. This study contributes to current understanding of the mineralogy and composition of seafloor massive sulfide deposits and provides new insight into relationships between age, porosity, and oxidative weathering.

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A thermodynamic prediction on the stability of the nukundamite + chalcopyrite and bornite + pyrite assemblages

Cited by 6 publications

References 18 publications

Cu5.5FeS6.5 nanotubesâ€”a new kind of ternary sulfide nanotube

Cu5.5FeS6.5 nanotubesâ€”a new kind of ternary sulfide nanotube

Hypogene enrichment in Miduk porphyry copper ore deposit, Iran

Inferences on the influences of age & porosity on oxidative weathering of seafloor massive sulfide deposits at the endeavour segment of the Juan de Fuca Ridge

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