A Re–Os isotope study of sedimentary rocks and copper–gold ores from the Ertsberg District, West Papua, Indonesia

Twenty-seven lead-isotope analyses for galena specimens from 14 localities in the Cobalt district represent sulphide-rich interflow sedimentary units in the Archean volcanic sequence, mineralized zones, fracture fillings, and local sulphide concentrations in the Cobalt Group (Proterozoic) sedimentary rocks, and vein-filling and breccia-cementing sulphides from within and near silver–arsenide veins. The analyses define a very homogeneous composition, averaging 206Pb/204Pb = 14.732, 2O7Pb/204Pb = 15.114, and 208Pb/204Pb = 34.301, for lead from these different geological settings. This result is in agreement with textural observations indicating a late paragenetic position for galena in the different settings mentioned. The model age for this lead is in general accord with the U–Pb age obtained in a study by Andrews et al. for a Nipissing diabase sheet at Gowganda.About one third of the galena specimens are interpreted by a two-stage evolution model to have formed or been remobilized during an event in the time range 1650–1945 Ma. The timing and character of this event are not clearly defined. The radiogenic composition of a specimen from the Pan Silver property is comparable to radiogenic values reported by Thorpe and suggests a young galena-forming event in the area.The lead-isotope data are permissive evidence for a genetic link between the Nipissing diabase sheets and mineralization of a variety of types in the Cobalt district. The metal source is not clearly indicated, but one analysis for Archean interflow sulphides suggests than an Archean source is unlikely for the lead in the silver–arsenide veins and other mineralized zones.

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A Review of the Cyanidation Treatment of Copper-Gold Ores and Concentrates

Metals ◽

10.3390/met10070897 ◽

2020 ◽

Vol 10 (7) ◽

pp. 897 ◽

Cited By ~ 2

Author(s):

Diego Medina ◽

Corby G. Anderson

Keyword(s):

Effective Treatment ◽

Review Paper ◽

Mining Industry ◽

Gold Production ◽

Gold Ores ◽

Silver Copper ◽

Copper Gold

Globally, copper, silver, and gold orebody grades have been dropping, and the mineralogy surrounding them has become more diversified and complex. The cyanidation process for gold production has remained dominant for over 130 years because of its selectivity and feasibility in the mining industry. For this reason, the industry has been adjusting its methods for the extraction of gold, by utilizing more efficient processes and technologies. Often, gold may be found in conjunction with copper and silver in ores and concentrates. Hence, the application of cyanide to these types of ores can present some difficulty, as the diversity of minerals found within these ores can cause the application of cyanidation to become more complicated. This paper outlines the practices, processes, and reagents proposed for the effective treatment of these ores. The primary purpose of this review paper is to present the hydrometallurgical processes that currently exist in the mining industry for the treatment of silver, copper, and gold ores, as well as concentrate treatments. In addition, this paper aims to present the most important challenges that the industry currently faces, so that future processes that are both more efficient and feasible may be established.

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Os-isotope study of platinum-group minerals in chromitites in Alpine-type ultramafic intrusions and the associated placers in Borneo

Mineralogical Magazine ◽

10.1180/minmag.1992.056.383.02 ◽

1992 ◽

Vol 56 (383) ◽

pp. 157-164 ◽

Cited By ~ 8

Author(s):

Keiko Hattori ◽

Klaus-Peter Burgath ◽

Stanley R. Hart

Keyword(s):

Igneous Rocks ◽

Chemical Inhomogeneity ◽

Minor Variation ◽

Platinum Group Minerals ◽

Isotope Study ◽

Platinum Group ◽

Individual Grains ◽

A Minor ◽

Os Isotope

Abstract187Os/186Os ratios were determined for in-situ laurite grains in Alpine-type chromitites and platinumgroup minerals (PGM) in the associated alluvial placers in Borneo, Indonesia/Malaysia. The Osisotope ratios of laurite grains in chromite defne an 187Os/186Os ratio for the 100 Ma mantle source of c. 1.04. Thelow 187Os/186Os ratios in all grains confirm the essential derivation of these platinum-group elements (PGE) from the mantle. A minor variation in 187Os/186Os ratios was detected among PGM from placers, but no variation was found within individual grains, including a grain with chemical inhomogeneity. The values are similar to those for PGM in the associated chromitites. The data are consistent with a detrital origin of PGM in placers: the placer PGM originated in the ultramafic section of ophiolities and the release of these grains from igneous rocks and their deposition in placers was almost entirely by mechanical processes.

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Oxygen, carbon and strontium isotope study of the carbonatitic dolomite host of the Bayan Obo Fe-Nb-REE deposit, Inner Mongolia, N China

Mineralogical Magazine ◽

10.1180/minmag.1997.061.407.05 ◽

1997 ◽

Vol 61 (407) ◽

pp. 531-541 ◽

Cited By ~ 61

Author(s):

M. J. Le Bas ◽

B. Spiro ◽

Yang Xueming

Keyword(s):

Sedimentary Rocks ◽

Coarse Grained ◽

Trace Element Geochemistry ◽

Element Geochemistry ◽

Fine Grained ◽

Dolomite Marble ◽

Ore Body ◽

Ore Bodies ◽

Isotope Study ◽

Bayan Obo

AbstractThe large Fe-Nb-REE deposit at Bayan Obo is hosted by a dolomite marble within the thrust complex of marbles, quartzites and slates that belongs to the Bayan Obo Formation of mid-Proterozoic age. The dolomite is either a dolomitized sedimentary limestone subsequently mineralized and tectonically thrust and folded, or a dolomite (or dolomitized) carbonatite intrusion with late-stage recrystallization and mineralization that has been subsequently tectonically deformed.O and C isotope data indicate that the sedimentary limestones and dolomites of the Bayan Obo Formation, which occur in the thrust stack together with quartzites and slates, have values of δO c. +20 per mil (SMOW) and δC c. zero. In contrast, the coarser grained facies of the large (0.5 × 10 km) dolomite marble which hosts the REE ore body has δO per mil values between +8 and +12 and δC values between −5 and −3, whereas the finer-grained recrystallized and REE-mineralized dolomite marble which occurs close to the ore bodies has δO between +12 to +16 and δC between −4 and zero. 87Sr/86Sr data confirm this distinction: >0.710 for the sedimentary rocks and <0.704 for the coarse- and fine-grained dolomite marbles.These data are taken to indicate that the large and coarse-grained dolomite was an igneous carbonatite (as borne out by its fenitic contact rocks and trace element geochemistry), and that the finer grained dolomite recrystallized under the influence of mineralizing solutions which entrained groundwater. The stratiform features in the coarse-grained dolomite that are evident in the field are interpreted as tectonic layering.

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