Eine Sulfidparagenese mit kupferhaltigem Zonarpyrit von Nukundamu/Fiji

Frenzel, Gerhard; Ottemann, J.

doi:10.1007/bf00205203

Cited by 12 publications

(6 citation statements)

References 4 publications

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“…As such, it is not easy to determine the mode of occurrence of Cu in pyrite. Previous studies have reported that the pyrite structure can accommodate Cu (Frenzel and Ottemann, 1967;Einaudi, 1968;Clark, 1970;Radcliffe and McSween, 1970;Pacevski et al, 2008), even reaching levels of several thousand ppm (Reich et al, 2013;Yuan et al, 2018). However, no notable negative correlations are found between Cu and Fe contents to support the Cu 2+ ↔ Fe 2+ substitutional mechanism in our results and other mid-ocean hydrothermal fields (Fig.…”

Section: Pyritementioning

confidence: 97%

Mineralogy and Chemistry of Sulfides from the Longqi and Duanqiao Hydrothermal Fields in the Southwest Indian Ridge

Zhang

Hou

et al. 2018

Acta Geologica Sinica (Eng)

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Recent investigations found that hydrothermal activity and sulfide mineralization occurs along the Southwest Indian Ridge (SWIR). The Longqi and Duanqiao hydrothermal fields between 49° E and 53° E of the SWIR are two prospective mineralization areas discovered by Chinese scientists. With the aim to determine the mineralogical and chemical characteristics of sulfide minerals, we have conducted detailed studies for samples from the two areas using an optical microscope, X‐ray diffractometer, scanning electron microscope, and electron microprobe. The mineralization processes in the Longqi area are divided into three main stages: (1) the low‐medium‐temperature stage: colloform pyrite (Py I) + marcasite → euhedral pyrite (Py II), (2) the high‐temperature stage: isocubanite (±exsolved chalcopyrite) + pyrrhotite → coarse‐grained chalcopyrite (Ccp I), and (3) the medium–low‐temperature stage: sphalerite + fine‐grained chalcopyrite inclusions (Ccp II) → aggregates of anhedral pyrite (Py III) ± marcasite → Fe‐oxide (‐hydroxide) + amorphous silica. The mineralization processes in the Duanqiao area are divided into two main stages: (1) the medium–high‐temperature stage: subhedral and euhedral pyrite (Py I′) → coarse‐grained chalcopyrite (Ccp I′) and (2) the medium–low‐temperature stage: sphalerite → fine‐grained chalcopyrite (Ccp II′) + chalcopyrite inclusions (Ccp II′) → silica‐cemented pyrite (Py II′) + marcasite → Fe‐oxide + amorphous silica. We suggest that the fine‐grained chalcopyrite inclusions in sphalerite from Longqi and Duanqiao were formed by co‐precipitation and replacement mechanisms, respectively. Primary sphalerites from both fields are enriched in Fe (avg. 5.84 wt% for the Longqi field vs. avg. 3.69 wt% for the Duanqiao field), Co (avg. 185.56 ppm for the Longqi field vs. 160.53 ppm for the Duanqiao field), and Cd (avg. 1950 ppm for the Longqi field vs. avg. 525.26 ppm for the Duanqiao field). Cu contents in pyrite from the Duanqiao field (Py I′: avg. 849.23 ppm and Py II′: avg. 1191.11 ppm) tend to be higher than those from the Longqi field (Py I: avg. 26.67 ppm, Py II: avg. 445 ppm, and Py III: avg. 179.29 ppm). Chalcopyrite from both fields is enriched in Zn (Ccp I: avg. 3226.67 ppm, Ccp II: avg. 9280 ppm, Ccp I′: avg. 848 ppm, Ccp II′ (inclusions): avg. 1098 ppm, and Ccp II′ (fine‐grained): avg. 1795 ppm). The varying contents of Zn in the different pyrite and chalcopyrite generations may result from the zone refining process. An integrated study of the mineralogy and mineralogical chemistry suggests that the hydrothermal fluids of the Longqi area are likely conditioned with higher temperatures and relatively lower fO2 and fS2 than those of the Duanqiao area, but in contrast to the former, the latter is much affected by the compositions of the surrounding rocks.

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Section: Pyritementioning

confidence: 97%

Mineralogy and Chemistry of Sulfides from the Longqi and Duanqiao Hydrothermal Fields in the Southwest Indian Ridge

Zhang

Hou

et al. 2018

Acta Geologica Sinica (Eng)

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“…Frenzel & Otteman (1967) and Clark (1970) observed a hypogene sulphide with optical properties similar to those of idaite, but exhibiting a chemical composition corresponding to Cu 5 FeS 6 . This mineral was the natural analogue of the compounds previously synthesised by Merwin & Lombard (1937) and later by Yund (1963).…”

Section: Introductionmentioning

confidence: 94%

Occurrence of sulphides on the bornite-idaite join from Vielsalm, Stavelot Massif, Belgium

Hatert

2004

ejm

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Sulphides with chemical compositions between idaite and bornite have been identified from several quartz veins crosscutting Ordovician schists in Vielsalm, Belgium. Idaite is an oxidation product of bornite, and occurs in the more oxidised parts of the quartz veins. The alteration sequence bornite ® "anomalous bornite" ® idaite is observed, associated with the growth of chalcopyrite lamellae parallel to the {100} and {111} directions of precursor bornite. Electron microprobe analyses indicate a chemical composition significantly enriched in Cu, when compared with the ideal composition of idaite, Cu 3 FeS 4 , as well as a progressive compositional evolution from bornite to idaite. The X-ray powder pattern is indexed in the space group I42m, similar to that of stannite, and gives the unit-cell parameters a = 5.279(4) and c = 10.47(2) Å.

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“…Both types of kuroko deposits exhibit identical zoning of siliceous ore, yellow ore and black ore in ascending order, and typical black ores consist mainly of sphalerite, galena, pyrite, chalcopyrite and small amounts of covellite, marcasite, enargite and luzonite (e.g. Frenzel and Ottemann, 1967;Matsukuma and Horikoshi, t970;Shimazaki, 1974;Colley and Rice, 1975;Eldridge et al, 1983). In addition to these minerals, black ores from the Japanese kuroko deposits frequently include tetrahedritetennantite and bornite in association with pyrite, and an appreciable amount of nukundamite is observed in the black ores from the Fijian deposit.…”

Section: Conditions For Formation Of Nukundamite-bearing Assemblagesmentioning

confidence: 99%

“…As principal sulphide minerals in yellow and siliceous ores, chalcopyrite and pyrite with small mounts of sphalerite, galena and bornite occur commonly in both types ofkuroko deposits. In the Frenzel and Ottemann (1967), Matsukuma and Horikoshi (1970), Shimazaki (1974), CoUey and Rice (1975), Eldridge et aL (1983).…”

Section: Conditions For Formation Of Nukundamite-bearing Assemblagesmentioning

confidence: 99%

“…However, in another quaternary system Cu-Fe-Bi-S, the nukundamite + chalcopyrite assemblage was obtained under hydrothermal conditions (Sugaki et al, 1981(Sugaki et al, , 1984. Thus, it is still uncertain which Frenzel and Ottemann (1967) 56.3 9.8 -33.7 99.8 (Nukundamu) 41.9 8.3 -49.7 Colley and Rice (1975) 56.9 9.6 0.1 0.04 33.5 99.8 (Nukundamu) 42.2 8.2 0.04 0.03 49.6 Clark (1970) 56.7 9.5 -33.9 100.1 (Aucanquilcha) 42.1 8.0 -49.9 Sugaki et al (1975) 56.9 9.0 33.8 99.7 (synthetic) 42.4 7.6 49.9 Sugaki et al (1981) 55.9 10.0 33.8 99.8 (synthetic) 41.6 8.5 49.9 Sugaki et al (1982) 55.7 10.4 34.2 100.2 (synthetic) 41.2 8.7 50.1 55.5…”

Section: Introductionmentioning

confidence: 99%

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

Kojima

Ueno

1994

Mineral. mag.

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A thermodynamic prediction of the Gibbs free energy of formation (AG~) of nukundamite (empirical composition CUs.sFeS6.5) was made in order to specify whether the nukundamite + chalcopyrite or the bornite + pyrite assemblage is stable in the Cu-Fe-S system. The results of calculations using previously reported data of AG~ values of some Cu-Fe-sulphide minerals in equilibrium with nukundamite indicate that the total free energy of the nukundamite + chalcopyrite assemblage is appreciably higher than that of the bornite + pyrite assemblage in the temperature range 250-400~ This means that nukundamite + chalcopyrite is a metastable assemblage under common ore-forming conditions.The occurrence of nukundamite is not uncommon in the Fijian kuroko deposits in contrast to the Japanese kuroko deposits. A thermochemical treatment for this phenomenon leads to the interpretation that the black ore containing nukundamite in the Fijian deposit was formed under relatively highsulphidation and low-pH conditions. This suggestion is in good agreement with the present experimental result that the bornite + pyrite assemblage was produced in the temperature range 350-250~ by using near-neutral hydrothermal solutions.

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Eine Sulfidparagenese mit kupferhaltigem Zonarpyrit von Nukundamu/Fiji

Cited by 12 publications

References 4 publications

Mineralogy and Chemistry of Sulfides from the Longqi and Duanqiao Hydrothermal Fields in the Southwest Indian Ridge

Mineralogy and Chemistry of Sulfides from the Longqi and Duanqiao Hydrothermal Fields in the Southwest Indian Ridge

Occurrence of sulphides on the bornite-idaite join from Vielsalm, Stavelot Massif, Belgium

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

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