The geology of non-sulphide zinc deposits

Origin of the Moroccan Touissit-Bou Beker and Jbel Bou Dahar Supergene Non-Sulfide Biomineralization and Its Relevance to Microbiological Activity, Late Miocene Uplift and Climate Changes

Article

Full-text available

Apr 2021

Through integration of Pb-Zn ± Cu non-sulfide mineralogy, texture, and stable isotope (C, O, S) geochemistry, the world-class Touissit- Bou Beker and Jbel Bou Dahar Mississippi Valley-type dis-tricts of the Moroccan Atlasic system have been investigated in order to gain insights into the origin and processes that contributed to the formation of the base metal non-sulfide mineralization. In both districts, direct replacement (“red calamine”) and wallrock replacement (“white calamine”) ores are observed. Based on the mineral assemblages, ore textures, and crosscutting relations, three distinct mineralizing stages are recognized. The earliest, pre-non-sulfide gossanous stage was a prerequisite for the following supergene stages and constituted the driving force that ultimately promoted the leaching of most base metals such as Zn and Cu and alkalis from their rock sources. The following two stages, referred to as the main supergene “red calamine” and late “white calamine” ore stages, generated the bulk of mineable “calamine” ores in the Touissit-Bou Beker and Jbel Bou Dahar dis-tricts. Stable isotope compositions (13CV-PDB, 18OV-SMOW, 34SCDT) support a three-stage model whereby metals were released by supergene acidic fluids and then precipitated by bacteria and archaea-mediated metal-rich meteoric fluids due to a decrease in temperature and/or increase of fO2. Oxygen isotope thermometry indicates decreasing precipitation temperatures with advancing paragenetic sequence from 33° to 18 °C, with wet to semi-arid to arid climatic conditions. The close spatial relationships between coexisting sulfide and non-sulfide mineralization along with stable isotope constraints suggest that the oxidation of sulfides occurred concurrently after the main stage of the Alpine orogeny between 15 Ma and the present. More importantly, the current data show for the first time the involvement of biologically controlled activity as the major driving process that triggered both oxidation and deposition of supergene mineralization at Jbel Bou Dahar and Touissit-Bou Beker districts. Conclusions drawn from this study therefore have implications for supergene Mississippi Valley-type (MVT) -derived non-sulfide deposits worldwide and account for the prominent role of biological processes in the genesis of this category of ore deposits.

A review of major non-sulfide zinc deposits in Iran

Article

Full-text available

Jan 2018

The numerous non-sulfide zinc ore deposits were the historical basis for the development of zinc mining in Iran. They include the Mehdiabad, Irankouh and Angouran world-class deposits, as well as the Zarigan and Haft-har deposits. These deposits were formed by supergene oxidation of primary sulfide minerals during the complex interplay of tectonic uplift, karst development, changes in the level of the water table, and weathering. Zn (Pb) carbonates, Zn-hydrosilicates and associated hydrated phases directly replace the primary ore bodies or fill cavities along fractures related to uplift tectonics. Direct replacement of primary sulfides is accompanied by distal precipitation of zinc non-sulfide minerals in cavities or internal sediments filling. The mineralogy of the non-sulfide mineralization in all six deposits is generally complex and consists of smithsonite, hydrozincite, and hemimorphite as the main economic minerals, accompanied by iron and manganese oxy-hydroxides and residual clays. Commonly, non-sulfide minerals in these deposits consist of two types of ore: red zinc ore (RZO), rich in Zn, Fe, Pb-(As) and white zinc ore (WZO), typically with very high zinc grades but low concentrations of iron and lead. Typical minerals of the RZO are Fe-oxyhydroxides, goethite, hematite, hemimorphite, smithsonite and/or hydrozincite and cerussite. Common minerals of the WZO are smithsonite or hydrozincite and only minor amounts of Fe-oxyhydroxides and hemimorphite.

A Review of Supergene Nonsulphide Zinc (SNSZ) Deposits - the 2014 Update

Chapter

Full-text available

Jan 2015

Gregor Borg

The paper reviews the characteristics of supergene nonsulphide zinc (SNSZ) deposits, the genetic processes that lead to their formation, and the parameters that control their location and preservation. SNSZ deposits form from near-surface or surface oxidation of pre-existing hypogene Zn-rich to at least Zn-bearing hypogene sulphide deposits, which include both volcanic-hosted and sediment-hosted types. They are attractive targets because of their near-surface, open-pittable locations, the lack of sulfur and commonly other deleterious elements (e.g. As, Cd), and their unusually high grades (typically 10-15%, locally >25% Zn). SNSZ deposits form via oxidation by meteoric water, dissolution of primary sulphides, the mobilization and transport of Zn in acidic solution (both vertically and laterally), and re-precipitation as secondary, nonsulphide zinc ore. In detail, however, the process is far more complex due to the high variability of virtually all parameters involved. Crustal uplift, erosion and exhumation of hypogene sulphide ores in a climate with seasonal rainfall are the most important controls on a regional scale. Topographic relief and a position of the exhumed sulphides above the ground water table are prerequisites for intensive oxidation and liberation of base metals. The second most prominent phenomenon of SNSZ deposits is their marked metal fractionation, which typically results in supergene Zn-only ore bodies. This metal fractionation is due to the drastically different solubility of Fe and Mn as opposed to base metals under oxidizing conditions and results commonly in residual Fe-Mn gossans and distal SNSZ deposits. The supergene base metal fractionation between Cu, Pb, and Zn is more subtle but also efficient and largely solubility controlled. The two major host rock types to SNSZ deposits are carbonate and silicate rocks and control the ore mineralogy of the SNSZ deposits, with smithsonite-hydrozincite-hemimorphite associated with the former or by sauconite-hemimorphite-scholzite-tarbuttite associated with the latter. The ore parageneses vary with time, however, according to the pH of the environment, which changes from high pH during an actively sulphide oxidizing, acidic stage to lower pH during the post-oxidation neutral stage. Once formed, the SNSZ are stable and resistant to chemical weathering by oxidized meteoric waters; however, they are vulnerable to mechanical erosion. Preservation of SNSZ ores is best under hyperarid climatic conditions (“mummification”) and even better under a protective cover, preferably of dry, non-reactive sediments. Exploration of SNSZ deposits is most successful where hypogene precursor sulphides have been identified and traces of nonsulphide zinc mineralization outcrop nearby or are detectable by soil geochemistry. Geophysical exploration methods, including magnetic, electrical, and gravity methods, still struggle to detect SNSZ ores, due to minimal contrasts in physical properties between mineralization and host rocks.

Genesis of the Giant Huoshaoyun Non-Sulfide Zinc–Lead Deposit in Karakoram, Xinjiang: Constraints from Mineralogy and Trace Element Geochemistry

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Full-text available

Jun 2023

The Huoshaoyun zinc–lead deposit, a giant non-sulfide deposit in Xinjiang, is one of the most significant discoveries of zinc–lead deposit in China and globally in recent years. The deposit is dominated by zinc–lead non-sulfides, with minor occurrences of sulfides such as sphalerite, galena, and pyrite. The non-sulfide minerals include smithsonite, cerussite, anglesite, and Fe-oxide. This study focuses on the mineralogical characteristics of sulfide and non-sulfide ores, as well as the trace element characteristics of sphalerite, smithsonite, and Fe-oxide. Mineralogical analysis reveals that smithsonite is derived from the oxidation of primary sulfide minerals and can be classified into three types that are generated during different stages of supergene oxidation. The three types of smithsonite are formed through replacing the sphalerite and host limestone, as well as directly precipitating in the fissures and vugs. Trace element analysis of sphalerite indicates that it is rich in Cd, Tl, and Ge, but poor in Fe and Mn. The ore-forming temperature, calculated using the GGIMFis geothermometer, is mostly within the range of 100~150 °C. Moreover, the trace element characteristics, ore-forming temperature, and S and Pb isotope compositions of the sulfide ores of the Huoshaoyun deposit are similar to those of the Jinding and Duocaima MVT lead–zinc deposits, which are also located in the Eastern Tethyan zinc–lead belt. This suggests that the sulfide orebody in the Huoshaoyun Zn-Pb deposit could also be the MVT deposit. Study of the trace element of the non-sulfide minerals shows that the Mn and Cd are relatively enriched in smithsonite, while Ga, Ge, and Pb are enriched in Fe-oxide. This can be attributed to distinct geochemical properties of the trace elements in the non-sulfide minerals of the Huoshaoyun deposit and is consistent with those of the other oxidized MVT deposits, thus indicating the supergene oxidation process of this deposit.

The Phanerozoic Stratabound/Stratiform Ore Deposits of Egypt: Their Mode of Occurrence and Formation in Accordance with the Phanerozoic Geological Evolution

Chapter

May 2023

Mortada Mourad Elaref

The present work provides an integral and comprehensive view on the mode of occurrence and the mode formation of the ores hosted in outcropped Egyptian Phanerozoic rock sequences. The main goal of this work is to discuss the time/space problem of the formation of these deposits and to clarify the regional and local geological factors controlled their formation, in order to be fundamental guides for future exploration and investment plans. Also focusing has been bayed to clarify the sedimentary environments, parageneses, geochemical characteristics, possible source, and economic potentiality of each ore type as well as detailed explanation of the depositional, digenetic, and post-diagenetic (supergenetic) processes involved during the ore formation. The work shed some light on the mining advantages and investment opportunities of some of these ore deposits, as well as the challenges facing the development of their economic return. The ore deposits under consideration are of stratabound/stratiform types, being confined within certain stratigraphic horizons of different ages and paleo-karst-geographic settings which concurrent well with the Phanerozoic geologic history of North Africa and the associated paleo-karst-geographic evolution patterns of the paleo-karst-shorelines and the simultaneous paleo-karst-topographic configurations. The stratiform deposits show conspicuous depositional and diagenetic features of shallow near-shore environments and are hosted within certain marginal stratigraphic units of regional or local magnitudes. The stratabound deposits are genetically related to paleo-karst-erosion surfaces (sequence boundaries) and the related supergenesis as they constitute the main product of deep weathering processes. The concluded basic factors which controlled the formation of these ores at the time(s) and in the place(s) of their formation, can be summed up as follows: (a) the paleo-karst-geography of the paleo-karst-shorelines, (b) the paleo-karst-topographic configurations and distribution of paleo-karst-highs and paleo-karst-lows, (c) the prevailed paleo-karstclimates, (d) the simultaneous availability of the ore components, either from the local medium or from the adjacent hinterlands (d) the availability of a suitable paleo-karst-environments with the related facies hierarchy and possible lateral facies changes, and (e) the prevailed sedimentary dynamics and sedimentation and post-sedimentation processes.KeywordsStratabound depositsDigenetic processespaleo-karst-TethysNeo-TethysSedimentary dynamicsEgypt

Zn-clays in the Kihabe and Nxuu prospects (Aha Hills, Botswana): a XRD and TEM study

Article

Feb 2022

Zinc clays are commonly found in oxidized Zn deposits and, even though they rarely represent the main target of the ore exploitation, they can be used as a proxy to restore the genetic conditions during ore-forming processes. This work sheds light on the micro-to nano-mineralogy and on the genesis of Zn-clays in the Kihabe and Nxuu prospects (located in the Aha Hills district, Northern Botswana), through an integrated XRD and TEM study of the mineralized facies occurring in the mineralized system. The Kihabe and Nxuu ores are hosted in a Neoproterozoic metamorphozed quartzwacke unconformably covered by the recent sedimentary rocks, also containing calcretes, of the Kalahari Group. In the analyzed samples, four distinct mineralogical facies have been recognized: i. vanadate calcrete facies, poor of Zn-clays; ii. low Zn-clay facies, characterized mostly by clays showing low Zn concentrations; iii. Zn-clay facies, containing proper Zn clay minerals; iv. sulfide facies, devoid of Zn-clays. In all the facies detrital dioctahedral mica (muscovite and illite) is interstratified with smectite in the form of random (R0) to short-range ordered (R1) I/S, which locally shows significant Zn concentrations. In the sulfide facies kaolinite overgrowing onto mica packets has been detected. The low Zn-clay facies is dominated by Zn-bearing beidellite, with minor kaolinite and fraipontite. The Zn-clay facies consists mostly of a random (R0) interstratified clay between a 7-Å phase corresponding to fraipontite, and a 2:1 swelling clay component identifiable with the dioctahedral smectite, with minor sauconite. The micro-to nanoscale paragenetic study performed by TEM indicates that the above-mentioned clays formed through a multistage process, eventually ending with the genesis of Zn-bearing phyllosilicates assemblages. The main steps were: i. alteration of detrital mica and dissolution of feldspar clasts, which led to the formation of epitaxial kaolinite and replacive beidellite; ii. fertilization of barren clays and formation of replacive to epitaxial fraipontite/smectite and of Zn-bearing mica, through input of Zn2+ deriving from sphalerite or willemite dissolution by mixed meteoric-hydrothermal fluids; iii. formation of low tetrahedral charge sauconite, either in pores or as replacement of K-feldspars under surficial hypersaline conditions, possibly also linked to the establishment of the arid climate in region. These processes provide insights into genesis of Zn-Pb-V ore deposits in northwest Botswana. Furthermore, the identification of a Zn-smectite species having a stevensite-like stoichiometry is valuable for future studies dealing with the systematics of clay minerals.

Critical elements in non-sulfide Zn deposits: a reanalysis of the Kabwe Zn-Pb ores (central Zambia)

Article

Sep 2021

The Kabwe Zn-Pb deposit (central Zambia) consists of a cluster of mixed sulfide and non-sulfide orebodies. The sulfide ores comprise sphalerite, galena, pyrite, chalcopyrite and accessory Ge-sulfides (±Ga and In). The non-sulfide ores comprise: (1) willemite-dominated zones encasing massive sulfide orebodies and (2) oxide-dominated alteration bands, overlying both the sulfide and Zn-silicate orebodies. This study focuses on the Ge, In and Ga distribution in the non-sulfide mineralization, and was carried out on a suite of Kabwe specimens, housed in the Natural History Museum Ore Collection (London). Petrography confirmed that the original sulfides were overprinted by at least two contrasting oxidation stages dominated by the formation of willemite (W1 and W2), and a further event characterized by weathering-related processes. Oxygen isotopic analyses have shown that W1 and W2 are unrelated genetically and furthermore not related to supergene Zn-Pb-carbonates in the oxide-dominated assemblage. The δ 18 O composition of 13.9-15.7‰ V-SMOW strongly supports a hydrothermal origin for W1. The δ 18 O composition of W2 (−3.0‰ to 0‰ V-SMOW) indicates that it precipitated from groundwaters of meteoric origin in either a supergene or a low-T hydrothermal environment. Gallium and Ge show a diversity of distribution among the range of Zn-bearing minerals. Gallium has been detected at the ppm level in W1, sphalerite, goethite and hematite. Germanium occurs at ppm levels in W1 and W2, and in scarcely detectable amounts in hemimorphite, goethite and hematite. Indium has low concentrations in goethite and hematite. These different deportments among the various phases are probably due to the different initial Ga, In and Ge abundances in the mineralization, to the different solubilities of the three elements at different temperatures and pH values, and finally to their variable affinities with the various minerals formed.

Influence of Genetic Processes on Geochemistry of Fe-oxy-Hydroxides in SupergeneZnNon-SulfideDeposits

Article

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Jan 2020

CHARACTERIZATION AND GRAVITY SEPARATION OF NONSULFIDE ZINC DEPOSITS FROM UM GHEIG MINE, RED SEA COAST, EGYPT

Article

Full-text available

Jan 2011

Influence of Genetic Processes on Geochemistry of Fe-oxy-hydroxides in Supergene Zn Non-Sulfide Deposits

Article

Full-text available

Jan 2020

In supergene Zn non-sulfide deposits, the Fe-oxy-hydroxides (FeO/OH) are mainly concentrated in the residual zones (gossan) on top of the oxidized ore bodies, although they can also be found throughout the whole weathering profile coexisting with the primary and secondary ore assemblages. Fe-oxy-hydroxides are rarely pure as they form in systems where a wide range of metals, most of them of economic importance (e.g., Zn, Pb, Co, REE, Sc, Ga, Ge, V, etc.), freely circulate and can be "captured" under specific conditions. Although their occurrence can be widespread, and they have a potential to scavenge and accumulate critical metals, FeO/OH are considered gangue phases during the existing processing routes of Zn non-sulfide ores. Moreover, very little is known about the role of the deposit type on the geochemistry of FeO/OH formed in a specific association. Therefore, this paper provides a comprehensive assessment of the trace element footprint of FeO/OH from a number of Zn non-sulfide deposits, in order to define parameters controlling the metals' enrichment process in the mineral phase. To achieve this, we selected FeO/OH-bearing mineralized samples from four supergene Zn non-sulfide ores in diverse settings, namely Hakkari (Turkey), Jabali (Yemen), Cristal (Peru) and Kabwe (Zambia). The petrography of FeO/OH was investigated by means of scanning electron microscope energy dispersive analysis (SEM-EDS), while the trace element composition was assessed using laser ablation-ICP-MS (LA-ICP-MS). Statistical analyses performed on LA-ICP-MS data defined several interelement associations, which can be ascribed to the different nature of the studied deposits, the dominant ore-formation process and subsequent evolution of the deposits and the environmental conditions under which FeO/OH phases were formed. Based on our results, the main new inferences are: (A) Zinc, Si, Pb, Ga and Ge enrichment in FeO/OH is favored in ores where the direct replacement of sulfides is the dominant process and/or where the pyrite is abundant (e.g., Cristal and Hakkari). (B) When the dissolution of the host-rock is a key process during the supergene ore formation (i.e., Jabali), the buffering toward basic pH of the solutions favors the uptake in FeO/OH of elements leached from the host carbonate rock (i.e., Mn), whilst restricting the uptake of elements derived from the dissolution of sulfides (i.e., Zn, Pb, Ga and Ge), as well as silica. (C) The input of exotic phases can produce significant enrichment in "unconventional" metals in FeO/OH (i.e., Cr and Co at Kabwe; Y at Cristal) depending on whether the optimal pH-Eh conditions are attained. (D) In the Kabwe deposit, FeO/OH records heterogeneous geochemical conditions within the system: where locally basic conditions prevailed during the alteration process, the V and U concentration in FeO/OH is favored; yet conversely, more acidic weathering produced Zn-and Si-bearing FeO/OH.

njma Band 196 Heft 1 p67-88 S and Pb Isotope Geochemistry of the carbonate hosted Au Ag Zn Pb deposits in the Maden Village Ulukisla Nigde Central Taurides South Turkey 91075

Article

Jan 2020

The Maden Village carbonate-hosted Au-Ag-Zn ± Pb deposits in the Bolkar Mountains that are part of the Tau-ride platform, south of Turkey, contain significant none-sulfide ore and relicts of sulfide bodies. The deposits hosted in the Upper Triassic carbonate rocks of the Bolkar Mountains are controlled by E-W trending and 36-45° S-dipping faults, and karst-related structures. The deposits is a formed by supergene oxidation of primary sulfide minerals during complex interaction of tectonic uplift, karst development, changes in the level of the water table and weathering. Zn (Pb) carbonates, Zn-hydrosilicates and associated hydrated phases directly replace the primary ore bodies or fill cavities and pods along fractures within marble are genetically related to the uplift of Tauride block during Oligo-Miocene period. The supergene deposits recharacterized by open space and karst-filling feature. Direct replacement of primary sulphide is accompanied by distal precipitation of non-sulphide minerals in cavities. The mineralogy of non-sulfide minerals consist of cerussite, anglesite, smithsonite, limonite, pyrolusite, psilomelane, manganite, chalcophanite, beudantite, goethite, lepidocrocite, hemimorphite, mimetite, corkite and native gold. In the sulfide ore bodies of Maden Village deposits, the δ 34 S isotope values of galena vary from 3.0 to 5.8 ‰ V-CDT and imply that sulphur originated from a mixture of different sources (me-teoric, magmatic hydrothermal fluids). The lead isotope data for galena showed mean values of 18.991, 15.701, and 39.056 for 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb, respectively. The distribution of the lead isotope ratios shows a cluster in the deposit that is related to the upper crust. The fluid inclusions in sphalerite show that the homogenization temperatures values of up to 290 °C, at a salinity of 6.2 wt.% NaCl equiv. In this study, we propose that ore forming fluids were originally derived magmatic hydrothermal fluids, and that they were mixed with low salinity meteoric water. The re-modified sulfide Pb-Zn mineralization resembles a 'residual and karst fill' sub type of nonsulphide zinc deposits. Au and Ag bearing minerals in the supergene environment consist of native gold hosted in limonite and Ag-bearing cerussite and anglesite.

S and Pb Isotope Geochemistry of the carbonate-hosted Au-Ag-Zn ± Pb deposits in the Maden Village (Ulukıla-Nide), Central Taurides, South Turkey

Article

Jun 2019
NEUES JB MINER ABH

The Maden Village carbonate-hosted Au-Ag-Zn ± Pb deposits in the Bolkar Mountains that are part of the Tauride platform, south of Turkey, contain significant none- sulfide ore and relicts of sulfide bodies. The deposits hosted in the Upper Triassic carbonate rocks of the Bolkar Mountains are controlled by E-W trending and 36-45° S-dipping faults, and karst- related structures. The deposits is a formed by supergene oxidation of primary sulfide minerals during complex interaction of tectonic uplift, karst development, changes in the level of the water table and weathering. Zn (Pb) carbonates, Zn-hydrosilicates and associated hydrated phases directly replace the primary ore bodies or fill cavities and pods along fractures within marble are genetically related to the uplift of Tauride block during Oligo-Miocene period. The supergene deposits recharacterized by open space and karst-filling feature. Direct replacement of primary sulphide is accompanied by distal precipitation of non-sulphide minerals in cavities. The mineralogy of non-sulfide minerals consist of cerussite, anglesite, smithsonite, limonite, pyrolusite, psilomelane, manganite, chalcophanite, beudantite, goethite, lepidocrocite, hemimorphite, mimetite, corkite and native gold. In the sulfide ore bodies of Maden Village deposits, the δ34S isotope values of galena vary from 3.0 to 5.8 ‰ V-CDT and imply that sulphur originated from a mixture of different sources (meteoric, magmatic hydrothermal fluids). The lead isotope data for galena showed mean values of 18.991, 15.701, and 39.056 for 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb, respectively. The distribution of the lead isotope ratios shows a cluster in the deposit that is related to the upper crust. The fluid inclusions in sphalerite show that the homogenization temperatures values of up to 290 °C, at a salinity of 6.2 wt.% NaCl equiv. In this study, we propose that ore forming fluids were originally derived magmatic hydrothermal fluids, and that they were mixed with low salinity meteoric water. The re-modified sulfide Pb-Zn mineralization resembles a ‘residual and karst fill’ sub type of nonsulphide zinc deposits. Au and Ag bearing minerals in the supergene environment consist of native gold hosted in limonite and Ag-bearing cerussite and anglesite.

PREPUBLICATION: Critical elements in nonsulphide Zn deposits: A reanalysis of the Kabwe Zn-Pb ores

Article

Full-text available

Jan 2017

The Kabwe Zn-Pb deposit (central Zambia) consists of a cluster of mixed sulfide and non-sulfide orebodies. The sulfide ores comprise sphalerite, galena, pyrite, chalcopyrite and accessory Ge-sulfides (±Ga and In). The non-sulfide ores comprise: (1) willemite-dominated zones encasing massive sulfide orebodies and (2) oxide-dominated alteration bands, overlying both the sulfide and Zn-silicate orebodies. This study focuses on the Ge, In and Ga distribution in the non-sulfide mineralization, and was carried out on a suite of Kabwe specimens, housed in the Natural History Museum Ore Collection (London). Petrography confirmed that the original sulfides were overprinted by at least two contrasting oxidation stages dominated by the formation of willemite (W1 and W2), and a further event characterized by weathering-related processes. Oxygen isotopic analyses have shown that W1 and W2 are unrelated genetically and furthermore not related to supergene Zn-Pb-carbonates in the oxide-dominated assemblage. The δ ¹⁸ O composition of 13.9–15.7‰ V-SMOW strongly supports a hydrothermal origin for W1. The δ ¹⁸ O composition of W2 (−3.5‰ to 0‰ V-SMOW) indicates that it precipitated from groundwaters of meteoric origin in either a supergene or a low- T hydrothermal environment. Gallium and Ge show a diversity of distribution among the range of Zn-bearing minerals. Gallium has been detected at the ppm level in W1, sphalerite, goethite and hematite. Germanium occurs at ppm levels in W1 and W2, and in scarcely detectable amounts in hemimorphite, goethite and hematite. Indium has low concentrations in goethite and hematite. These different deportments among the various phases are probably due to the different initial Ga, In and Ge abundances in the mineralization, to the different solubilities of the three elements at different temperatures and pH values, and finally to their variable affinities with the various minerals formed.

Mineralogical and Radiological Micro-Analysis of Raw Sands and Their Processed By-Products for Land Reclamation Applications

Article

Full-text available

Jun 2017

Abstract: In this study, forty samples of different types of raw sands, magnetite, green silicate and processed mixture of ilmenite, magnetite and green silicates have been mineralogical and radiometrically investigated after preparation. Determination of the mineral contents, radioactivity levels and their corresponding environmental impacts was also carried out. The radioactivity: 238U, 232Th, 226Ra and 40K, of these samples are of naturally occurring origin. The EDX analysis was applied for identification of trace elements in the samples. The microscopic investigations of the samples indicate that the black sand samples are economically rich in heavy minerals such as ilmenite, magnetite, zircon, rutile and monazite; in addition to leucoxene. While the processed and unprocessed green silicate contain ilmenite, zircon, sphene, monazite and calamine with quartz and other silicate minerals. The highest values of activity concentrations of 238U, 232Th, 226Ra and 40K were observed in black sand, processed and unprocessed green silicates amples. These high radioactivities are attributed to the presence of zircon, monazite and sphene. The radiological hazard parameters; the absorbed dose rate (D), annual effective dose equivalent AEDE, radium equivalent activity Raeq, external hazard index Hex, internal hazard index Hin and gamma activity concentration index Iγ of the studied samples were estimated. The results obtained were tabulated, evaluated, interpreted and discussed.

GEOLOGY AND MINERALOGY OF CARBONATE-HOSTED AU-AG�PB-ZN DEPOSITS IN THE MADEN VILLAGE (ULUKISLA), NIGDE, SE TURKEY

Conference Paper

Full-text available

Jun 2014

Asuman Kahya

M.Z. Farag , N.A. Abdel-Khalek M.S. Hassan, M.M. El Aref and A.W. El Manawi (2012):Upgrading of Egyptian Nonsulfide Zinc Ore by Gravity Separation Techniques. Journal of Metalurigical Engineering (ME), ME Volume 1, Issue 1 April 2012, p. 6 – 13.

Article

Full-text available

Apr 2012

Alteration of High Alkaline and Alkaline Basaltic Rocks: Parent Rocks in the Lava Durian Orchard, Sisaket Province, NE Thailand

Article

Full-text available

Dec 2021

Lava Durian Sisaket is the first geographically identified (GI) fruit related to the volcano in Thailand and distributed in three districts of Sisaket Province, the southernmost edge of the Khorat Plateau. The parent rocks of orchards are important for the description of soil and rock relation with respect to mineralogical and geochemical characteristics. This work aims to study lithology, mineralogy, and geochemistry of basaltic rocks, parent rocks of in situ soil in these orchards, and delineate the existing basaltic soil models. The several orchards are covered by reddish-brown to brown in situ soils, weathered from mafic volcanic rocks: porphyritic olivine basalt, vesicular olivine basalt, and nephelinite. The microscopic image analysis, XRD, and MiniSEM-EDS are used to classify mineralogy, while XRF and analysis of large and rare elements in ICP-MS/ICP-OES were used to determine parental rocks geochemistry and alteration. The olivine basalts comprise forsterite microphenocrysts associated with bytownite, diopside, augite, pigeonite, and ilmenite groundmass, while nephelinite is composed of nepheline groundmass and bytownite-labradorite, diopside, augite, pigeonite, and ilmenite crystals. In addition, these basalts display high alteration rates, especially olivine highly altered to iddingsite. According to the geochemical data, Sisaket’s basalts were identified as alkali basalt and nepheline basanite with high LILEs and LREEs (La, Nd, Pr, Gd, Eu). The kaolinite, smectite, and illite are altered from felsic minerals, while the chlorite and iddingsite are from mafic minerals. The mineralogical analyses classified secondary phyllosilicates related to low-moderate temperature hydrothermal fluid, very high cation exchange capacity (H+ , K+ , Ca2+ , Mg2+ ), and tropical weathering. The alkaline and high alkaline basalts, presenting as parent rocks, are one of the parameters that produced good nitisal soil of Sisaket’s agricultural areas.

C-O Stable Isotope Geochemistry of Carbonate Minerals in the Nonsulfide Zinc Deposits of the Middle East: A Review

Article

Full-text available

Nov 2017

Zinc nonsulfides are well represented in the Middle East, with occurrences in Turkey, Iran, and Yemen. Their genesis can be constrained by using carbon and oxygen isotope systematics applied to carbonate minerals. The δ 13 C ratios of smithsonite and hydrozincite in Iran and Turkey are comprised in the typical interval of supergene Zn carbonates (−0.4 and −7.1 V-PDB). The oxygen isotope geochemistry is more complex. Oxygen isotope compositions of smithsonite of the Hakkari deposit (Turkey) (δ 18 O from 24.2 to 25.6 V-SMOW) point to precipitation temperatures between~4 and~18 • C, corresponding to a normal weathering environment at these latitudes, whereas δ 18 O of smithsonite from other Middle East deposits (Angouran in Iran, Jabali in Yemen) point to the precipitation from low-to medium-temperature hydrothermal fluids. The CO isotopic compositions of hydrozincite from the Mehdi Abad, Irankuh, and Chah-Talkh deposits can be only partially compared with those of smithsonite, because the oxygen isotopes fractionation equation for hydrozincite-water is not known. A comparison between the geochemical characteristics of all Zn-nonsulfide ores in the Middle East indicates that, even though several mineral deposits are derived from supergene weathering processes, other ones have been deposited from fluids associated with magmatic activity (Angouran, Iran) or with hydrothermal systems (Jabali, Yemen). This suggests that it is not possible to apply a common interpretative model to the genesis of all nonsulfide deposits in the Middle East.

Trace element geochemistry of iron-(oxy)-hydroxides in Ni(Co)-laterites: Review, new data and implications for ore forming processes

Article

Sep 2021
ORE GEOL REV

Iron-(oxy)-hydroxide (FeO/OH) phases are abundant in all supergene ore deposits. The most common FeO/OH phase in supergene environments is goethite, although hematite, lepidocrocite, ferrihydrite, and maghemite can also occur. Natural FeO/OHs are rarely chemically pure, as a range of metal cations can be readily incorporated into their mineral structure. Although an extensive body of literature exists on the scavenging action of synthetic FeO/OHs, there is a general lack of studies of natural systems and, more specifically, of studies dealing with the geochemistry of trace elements in FeO/OHs associated with supergene ores. Furthermore, although it is known that FeO/OHs in supergene ore systems typically contain elevated levels of useful metals like REE, Sc, V, Co, Mn, Cr, and Ni, in most cases, these phases are considered as gangue and hence, the metals are not recovered. Only in the case of Ni(Co)-laterite deposits the FeO/OHs are often exploited for Ni and Co, and sometimes for Sc. Most previous works on Ni(Co)-laterite deposits have focused on the lateritization process of the parent rocks and the mineralogy of the resulting Ni(Co)-bearing minerals. Only rarely have published studies focused on REE, V, Sc, and PGE deportment within FeO/OHs. In this study, we describe new mineralogical and chemical data (XRPD, SEM-EDS, EPMA, ICP-AES, LA-ICP-MS, and TEM-HRTEM) obtained from a range of natural FeO/OH samples collected from four important Ni(Co)-laterite deposits, namely Wingellina (Western Australia), Piauí (Brazil), Karaçam and Çaldağ (Turkey). In the course of this study, we investigated the geochemistry of goethite and hematite within the oxidation zone of the respective laterite profiles, evaluating the deportment of minor metals such as Ti, Sc, Cr, Ni, Co, V, Zn, and Mn. Although derived from different parent rocks located in different geographic areas, the FeO/OH samples collected share a number of common features. In particular, there are commonalities in ore textures, mineralogy, and metal deportment. Based on multivariate statistical analysis, the chemistry of the studied FeO/OHs define three major elemental associations: i) Mn–Al–Ti–Sc–V as evident in goethite samples from Wingellina; ii) Mg–Ni–Si–Zn as exemplified by samples from Karaçam and Piauí, and iii) Cr–V as illustrated by the Çaldağ samples. These contrasting geochemical footprints can be explained in terms of first- and second-order controls with the chemical composition of the parent rock representing the first-order, and favorable pH conditions for the fixation of trace elements within FeO/OHs representing the second-order control. Seasonality and maturation may be additional factors influencing FeO/OHs mineralogy, as periods of arid climate may have favored the dehydration of some FeO/OHs to form more stable species (such as goethite to hematite) over time. In summary, our observations have helped to better understand the ore deposition model relating to surficial weathering systems and have also established the parameters that control the distribution of economically relevant by-product metals in FeO/OHs in diverse conditions during the formation of Ni(Co)-laterites.

The nature of Zn-phyllosilicates in the nonsulfide Mina Grande and Cristal zinc deposits (Bongará District, Northern Peru): The TEM-HRTEM and AEM perspective

Article

Aug 2020

Zn-phyllosilicates are common minerals in nonsulfide Zn deposits and can give crucial information about the genesis of these oxidized mineralizations. They seldom represent the prevailing economic species but might have a significant impact on mineral processing. This study has been carried out on the Mina Grande and Cristal Zn-sulfide/nonsulfide deposits, which occur in the Bongará district (Amazonas region, northern Peru). The Cristal and Mina Grande orebodies are hosted by the sedimentary (prevailingly carbonate) successions of the Pucará Group (Condorsinga formation, Lower Jurassic), in an area affected by Neogene tectonics and characterized by Late Miocene and Pliocene-Early Pleistocene uplift phases (Andean and Quechua tectonic pulses). The Cristal deposit consists of both sulfide (sphalerite with minor pyrite and galena) and nonsulfide concentrations. The nonsulfides consists of smithsonite, hemimorphite, hydrozincite, chalcophanite, goethite, and greenockite, locally associated with Zn-bearing phyllosilicates. The Mina Grande deposit consists almost exclusively of Zn-oxidized minerals in limestone host rocks. The nonsulfides association consists of hydrozincite, hemimorphite, smithsonite, fraipontite, and Fe-(hydr)oxides, also containing a clayey fraction. The study deals with TEM-HRTEM and AEM investigations on clayey materials, to determine their crystal-chemical features and the origin of the complex Zn-clays-bearing parageneses. In both deposits, Zn-bearing illites (1Md and 2M polytypes) and I/S clay minerals (I3) are the main detected phases, with few compositions close to (Zn-bearing) muscovite. In the clayey fraction at Mina Grande, fraipontite, a Zn-bearing mica called K-deficient hendricksite, and (Zn-bearing) kaolinite also occur. Zn-illites and smectites (always containing Zn in variable amounts) characterize the mineral association at Cristal. The investigated compositional gap between di- and tri-octahedral Zn-phyllosilicates gives indications on the genetic relationships between them and advances on the knowledge of these species. The present work gives an insight into the Zn-bearing phyllosilicates systems by determining the amount/mode of metal incorporation in their lattices and understanding the relationships of natural occurring clay-rich complex associations, which can act as models for possible synthetic counterparts.

Supergene nonsulfide Zn–Pb mineralization in the Mehdiabad world‑class sub‑seafloor replacement SEDEX‑type deposit, Iran

Article

Aug 2020
INT J EARTH SCI

The world-class Mehdiabad nonsulfide deposit consists of several accumulations of Zn-Pb-Fe nonsulfide minerals, derived from supergene of a vent-proximal sub-seafloor replacement SEDEX-type deposit hosted in lower Cretaceous clastic-carbonate rocks of the Taft and Abkuh Formations. The main sulfides are galena, sphalerite, pyrite and minor amounts of chalcopyrite, which have been partially or completely transformed into nonsulfide minerals by supergene processes. Currently, the Zn mineralization in the Abkuh Formation (ore horizon II) is almost fully oxidized: the Mehdiabad deposit can be assigned to both direct replacement and wall-rock replacement types. The time of the formation of the nonsulfide deposit has not been determined, but it is probable that the main supergene happened during Tertiary, possibly between post-Cretaceous to present. The mineralogy of the nonsulfide mineralization is generally complex and consists of smithsonite, hydrozincite, and hemimorphite as the main economic minerals, accompanied by cerussite, anglesite, iron-manganese oxy-hydroxides, sauconite and Zn-rich clays. Commonly, nonsulfide minerals in this deposit consist of two types of ore: red zinc ore (RZO), rich in Zn, Fe, Pb-(As) and white zinc ore (WZO), typically with very high zinc grades but low concentrations of iron and lead. The proposed three-step scenario for the deposition of nonsulfide mineralization in the Mehdiabad deposit comprises: 1) the deposition of primary sulfides contemporaneous with lower Cretaceous clastic-carbonate host rocks to form SEDEX-type mineralization; 2) during the Late Cretaceous to present, regional uplift lead to deformation, folding and thrusting of sulfide-bearing lower Cretaceous sequence; and 3) as a result, Zn–PbFe sulfides, hosted in carbonates experienced oxidation under an arid-warm climate to form the supergene nonsulfide ore mineralizations.

Geological, Geochemical and Microthermometric Characteristics of the Hakkari Region Zn-Pb Deposits, SE Turkey

Article

Jul 2020
ORE GEOL REV

The Hakkari region in SE Turkey contains large Zn-Pb deposits, primarily of non-sulfide ore in Upper Triassic passive margin carbonates. In the Karakaya, Meskantepe and Üzümcü Zn-Pb deposit, the 3 main and more than 15 ore layers alternate with a thick-bedded limestone. The feeder in the region veins are well defined, containing both non-sulfide and sulfide ore. Primary sulfide ore contains between 1-37 % Zn, has transformed to “non-sulfide” ore containing Zn>10%. Both non-sulfide and sulfide ore is associated with As, Se, Hg, Tl, Mn and Sb, which is similar to other SEDEX deposits. The average δ³⁴S of the stratiform and feeder zone sulfides are 2.1 ‰ and 1.67 ‰, respectively. Sulfur isotope data of sphalerite, galena and pyrite (from -3.4 to 8.8 ‰) indicates that sulfur came from a homogeneous large source. Sulfate was reduced by the process of thermochemical sulfate reduction (TSR) rather than bacterial sulfate reduction (BSR). Lead isotope values (²⁰⁶Pb/²⁰⁴Pb ≈ 18.49, ²⁰⁷Pb/²⁰⁴Pb ≈ 15.66 and ²⁰⁸Pb/²⁰⁴Pb ≈ 38.69) reflect an evolved upper crustal source. The homogenisation temperature (Th) and salinity of fluid inclusions is from 165 to 289 °C, and from 1 to 22 % equiv. NaCl salinity. Such a wide range of Th and salinity, and Cl/Br ratio (409 from sphalerite and galena; 662 from barite) of fluid inclusions may indicate mixing of basinal brines and seawater. Successive ore levels, laminated with shale-carbonate rich in organic matter, formed on the seafloor as banded and replacement ore. Trace element associations, fluid inclusion and isotope data indicate that the Zn-Pb deposits were formed as synsedimentary processes associated with feeder systems during the initiation of the Triassic rifting as a vent-proximal SEDEX-type. The metals (Pb, Zn, Fe) were leached from Palaeozoic and older clastic rocks in the Arabian platform by seawater sourced fluids, and ascended through deep fractures. The metalliferous fluids should have formed vein type mineralization in feeder zone, sub-seafloor replacement type ore under the ocean floor, and stratiform ore on the seafloor.

Mineralogy and Zn Chemical Speciation in a Soil-Plant System from a Metal-Extreme Environment: A Study on Helichrysum microphyllum subsp. tyrrhenicum (Campo Pisano Mine, SW Sardinia, Italy)

Article

Full-text available

Mar 2020

Environmental contamination due to human activities is a worldwide problem that has led to the development of different remediation techniques, including biotechnological approaches such as phytoextraction and phytostabilization. These techniques take advantage of pioneer plants that naturally develop tolerance mechanisms to survive in extreme environments. A multi-technique and multi-disciplinary approach was applied for the investigation of Helichrysum microphyllum subsp. tyrrhenicum samples, bulk soil, and rhizospheres collected from a metal-extreme environment (Zn-Pb mine of Campo Pisano, SW Sardinia, Italy). Zinc, Pb, and Cd are the most abundant metals, with Zn attaining 3 w/w% in the rhizosphere solid materials, inducing oxidative stress in the roots as revealed by infrared microspectroscopy (IR). X-ray diffraction (XRD), scanning electron microscopy (SEM), and chemical analysis coupled with synchrotron radiation-based (SR) techniques demonstrate that quartz, dolomite, and weddellite biominerals precipitate in roots, stems, and leaves, likely as a response to environmental stress. In the rhizosphere, Zn chemical speciation is mainly related to the Zn ore minerals (smithsonite and hydrozincite) whereas, in plant tissues, Zn is primarily bound to organic compounds such as malate, cysteine, and histidine molecules that act as metal binders and, eventually, detoxification agents for the Zn excess. These findings suggest that H. microphyllum subsp. tyrrhenicum has developed its own adaptation strategy to survive in polluted substrates, making it a potential candidate for phytostabilization aimed at mitigating the dispersion of metals in the surrounding areas.

Smithsonite flotation with lauryl phosphate

Article

Mar 2020
MINER ENG

Smithsonite, the most abundant nonsulfide zinc mineral, has attracted growing attention due to the demand for zinc and the exhaustion of traditional sulfide zinc resources. Traditional flotation techniques are not efficient and do not easily separate smithsonite from other carbonate minerals, such as calcite. In this regard, lauryl phosphate was evaluated as a flotation collector with respect to physicochemical aspects, which include surface charge, wettability, and flotation performance by the examination of contact angle, zeta potential, sum frequency generation spectroscopy (SFG), and flotation experimental results, as well as interaction energy calculations. The contact angle, zeta potential, and SFG results indicate that lauryl phosphate prefers to adsorb at the smithsonite surface when compared to calcite. The microflotation and interaction energy results further confirmed that an obvious flotation difference was observed between smithsonite and calcite, using lauryl phosphate between pH 5 and pH 9. However, the use of the typical collector, dodecylamine, results in no significant difference between smithsonite and calcite flotation recovery as a function of pH. These findings provide a comprehensive evaluation of the potential of lauryl phosphate as an effective collector in recovering smithsonite from oxide zinc ores.

New insights into the genesis of willemite (Zn2SiO4) from zinc nonsulfide deposits, through trace elements and oxygen isotope geochemistry

Article

Mar 2020
ORE GEOL REV

Download the full-text here: https://authors.elsevier.com/a/1abgmcTGy28A4

Effect of Slime and Impurity Removal as a Pre-Treatment Stage Using a Low-Grade Zinc-Oxide Sample

Article

Full-text available

Sep 2019

A low-grade zinc-oxide sample (6–8% Zn) from Mehdiabad mine in Iran, with a high amount of slime and iron (17–19% Fe) and manganese (5–7% Mn) impurities was studied. Pre-treatment processes, such as desliming and wet high-intensity magnetic separation were applied for impurity removal. Petrographic studies showed that the zinc minerals were hemimorphite, hetaerolite, smithsonite, sphalerite and a low amount of zincite; lead was present in galena and manganese was in hetaerolite and pyrolusite. The gangue minerals were dolomite, calcite, hematite, goethite, pyrite and quartz. From a processing perspective, the sample can be characterized as a low-grade zinc-oxide sample. Experimental data and scanning electron microscopy/energy-dispersive X-ray spectroscopy analysis showed that desliming prior to magnetic separation is required, and the optimum concentration ratio and recovery in the absorbed part can be determined by applying one stage of wet high-intensity magnetic separation with grinding and a magnetic field intensity for 16 min and 14 000 G. By considering the abovementioned conditions, the concentration ratio and recovery of iron and manganese in the absorbed part have been obtained as 1.42 and 1.54 and 73.28% and 79.79%, respectively, and the non-absorbed part of the pre-treatment stage with 10.56% Fe, 3.29% Mn and 6.83% Zn can be considered as flotation feed.

Stable isotopes of Nonsulphide Zn-Pb ores in Britain and Ireland: fluid characteristics and paleoclimatic variability

Article

Jul 2019

Stable isotope (C–O) analysis was applied to smithsonites and cerussites from Zn(Pb) nonsulphide ores from Britain and Ireland, to determine the nature of the fluids responsible for the precipitation of secondary carbonates, and any relationship with palaeoclimatic conditions. The carbon isotope compositions of the Irish smithsonites show a major contribution of organic carbon whereas those of both Zn- and Pb-carbonates in the UK deposits indicate contribution of organic carbon and host-rock carbonates. δ ¹⁸ O VSMOW values for cerussite from both areas are about 13‰ lower than those of smithsonites, UK smithsonite δ ¹⁸ O VSMOW values are more variable than those for cerussites and the Irish smithsonites have unusually high values. Isoscape maps indicate that δ ¹⁸ O values for both carbonates are higher in the west and decrease toward the east. This trend correlates with a general decrease in the oxygen isotope compositions of rainwater moving eastward, and suggests that oxidation of sulphides occurred at temperatures of about 15–20°C, under climatic conditions warmer than today. Supplementary material: A comprehensive overview of the investigated sites, detailed data for the samples and SEM images are available at https://doi.org/10.6084/m9.figshare.c.4579535

Density Functional Theory Study on the Surface Properties and Floatability of Hemimorphite and Smithsonite

Article

Full-text available

Nov 2018

Hemimorphite and smithsonite are all-important zinc oxide minerals. The beneficiation and separation of them using flotation method is usually considered difficultly. Minerals surface wettability and its regulation are the core issues in the flotation process, which closely correlate with the surface properties of the minerals. Therefore, an in-depth understanding of the surface properties of the two minerals is of great significance for the study of the flotation technology of them. In this study, the surface properties of the hemimorphite (110) surface and the simthsointe (101) surface, and their relationships to the mineral floatability have been investigated by first-principle calculation method based on density functional theory. The calculation results demonstrated that the hemimorphite (110) surface exhibited more obviously surface reconstruction. For the orbital energy level of the surface atoms of two minerals, the O 2p orbital is closer to the Fermi level than the Zn 3d. Chemical bond Mulliken population value indicated that the ionicity of the unsaturated linkage on the smithsonite (101) surface was stronger than that on the hemimorphite (110) surface. The absolute values of the ratios of negative charges to positive charges on the surfaces of hemimorphite and smithsonite were 1.529 and 1.256 respectively. These results implied that the O atoms on hemimorphite (110) surface are more impede collector molecule, such as hydroximic acid, bond with Zn atom, hemimorphite (110) surface is more readily wetted by water. This study provides comprehension at an atomic level to the relationship between surface properties and the floatability of hemimorphite and smithsonite.

The Zn-Pb sulfide and Pb-Zn-Ag non-sulfide Kuh-e-Surmeh ore deposit, Zagros Belt, Iran: Geologic, mineralogical, geochemical, and S isotopic constraints

Article

Aug 2018
J GEOCHEM EXPLOR

The carbonate-hosted Kuh-e-Surmeh deposit is located in the Zagros Simply Folded Belt, southwestern Iran. The semi-conformable tabular–like ore body lies within the northern flank of the NW– trending Kuh-e-Surmeh anticline. It is comprised of sulfide and non-sulfide base-metal ore types. The sulfide ore has a simple mineralogy and consists almost entirely of sphalerite, galena, and pyrite. Sphalerite is the main sulfide mineral having both crystalline and colloform texture. The Fe content of the sphalerite ranges between 0.04 and 8.9 wt% with the dark sphalerite zones containing higher (3.37–8.9 wt%) Fe values. Crystalline sphalerite is the main source of Ag in the sulfide ore. Galena formed simultaneously with and after sphalerite mineralization. The precipitation of pyrite occurred during the pre- to late sulfide ore mineralization phases. Anglesite is the most abundant non-sulfide mineral. Gray-colored, massive anglesite contains >100 ppm Ag, representing the main host of Ag mobilized during supergene events. On the basis geochemical data, in non-sulfide portion, there is an increase in Ag values with increasing Pb contents, independent of depth. The sulfur isotope enrichment factor (εSO4–primary sulfide minerals= 7.8 ‰) reflects the SO4-2 of the late stage gypsum formed by sulfate generated from the dissolution of primary sulfate minerals that mixed with sulfate originating from the oxidation and dissolution of sulfide minerals. Topographic relief, tectonic fracture systems, reactivation of the Surmeh Fault, and uplift related to the Zagros Orogeny all favored the establishment of arid climate conditions, providing an ideal environment for converting Zn-Pb sulfide ore to Pb-Zn-Ag non-sulfide ore.

Formation of secondary nonsulfide zinc ore in Cho Dien Pb-Zn deposits

Article

Full-text available

Jun 2018

In Viet Nam, non-sulfide zinc ore in the Cho Dien deposit has been exploited for a long time. Up to the present, zinc ore remains the major exploited ore in Cho Dien. There are numerous studies of Pb-Zn ore in Cho Dien. However, most of the studies have dedicated only to description of mineralogical and chemical composition of Pb-Zn ore. There has been no publication on this non-sulfide zinc ore. Based on the mineralogical studies, the content of Pb and Zn in groundwater determined by reflective microscope, SEM, EPMA and ICP-MS methods, the study explained the formation of secondary non-sulfide zinc ore in the Cho Dien deposit. Strong weathering process makes the upper part of ore bodies completely oxidized. Difference in geochemical behavior of lead (Pb) and zinc (Zn) in the oxidation process of Pb-Zn ore is the reason to form non-sulfide zinc ore in the Cho Dien deposit. Oxidation of primary Pb-Zn ore is mainly sphalerite, pyrite, galena minerals which creates a low pH environment and transforms of zinc from immobile (sphalerite - ZnS) to mobile (Zn2+) and retained in solution under acid pH conditions whereas lead has the tendency to form soluble minerals (anglesite, cerussite). The acid neutralization actions of the surrounding rocks make zinc precipitate, to form secondary non-sulfide zinc minerals.ReferencesAndreas Nuspl, 2009. Genesis of nonsulfide zinc deposits and their future utilization (www.geo.tu freiberg.de/oberseminar/OS_09/Andreas_Nuspl.pdf.Boland M.B., et al., 2003. The Shaimerden supergene zinc deposit, Kazakhstan: Economic Geology, 98(4), 787-795.Heyl A.V., Bozion C.N., 1962. Oxidized zinc deposits of the United States, Part 1. General Geology: U.S. Geological Survey Bulletin 1135-A.Jurjovec J., et al., 2002. Acid neutralization mechanisms and metal release in mine tailings: A laboratory column experiment: Geochimica et Cosmochimica Acta, 66, 1511-1523.Large D., 2001. The geology of non-sulphide zinc Deposits - an Overview: Erzmetall, 54(5), 264-276.Maria Boni, 2003. Nonsulfide Zinc Deposits: a new - (old) type of economic mineralization. Society for geology applied to mineral deposits (SGA) News, Number 15. https://www.e sga.org/fileadmin/sga/newsletter/news15/art01.html.McPhail D.C., et al., 2003, The geochemistry and mobility of zinc in the regolith: in Roach, I.C., ed., Advances in Regolith, 287-291.Murray W. Hitzman, et al., 2003. Classification, genesis, and exploration guides for non-sulfide zinc deposits: Economic Geology, 98(4), 685-714.Nguyen Van Pho, 2006. Studying dispersive degree of Pb and assess the current status of Pb pollution in Pb-Zn Cho Dien, Bac Kan. Final report.NguyenVan Pho, 2013. Wet tropical wethering in Viet Nam. Natural Science and Technology Publisher.Nicola Mondillo, 2013. Supergene Nonsulfide Zinc-Lead Deposits: The Examples of Jabali (Yemen) and Yanque (Peru). Doctoral thesis.Nordstrom D.K., Alpers C.N., 1999. Geochemistry of acid mine waste. Review in Economic Geology, the environmental geochemistry of ore deposits/Eds. G.S.Plumlee, M.J. Logsdon. Part A: Processes, techniques, and health issues, 6A, 133-160.Reynolds N.A., et al., 2003. The Padaeng Supergene Nonsulfide Zinc Deposit, Mae Sod, Thailand. Economic Geology, 98(4), 773-785.Sangameshwar S.R., Barnes H.L., 1983. Supergene Processes in Zinc-Lead-Silver Sulfide Ores in Carbonates: Economic Geology, 78, 1379-1397.Stumm W., Morgan J.J., 1996. Aquatic Chemistry, Third Edition. John Wiley & Sons, New York, NY.Takahashi T., 1960. Supergene alteration of zinc and lead deposits in limestone: Economic Geology, 55, 1083-1115.Thornber M.R. and Taylor G.F., 1992. The mechanisms of sulphide oxidation and gossan formation, in: Butt, C.R.M., and Zeegers H., (Eds.)., Regolith exploration geochemistry in tropical and subtropical terrains, in Govett G.J.S., ed., Handbook of exploration geochemistry: Amsterdam, Elsevier, 4, 119-138.Tran Tuan Anh, 2010. Studying accompanying component in the types of potential deposits of basic metals and precious - rare metals of north Viet Nam to improve the efficiency of mining and environmental protection. Final report. KC.08.24/06-10.Vito Coppola, et al., 2007. Non-sulfide zinc deposits in Upper Silesia, Southern Poland. Proceeding of the Ninth Biennial SGA Meeting, Dublin, 1401-1404.Vito Coppola et al., 2009. Nonsulfide zinc deposits in the Silesia - Cracow district, Southern Poland. Springer Link, 44, 559-580.Williams P.A., 1990. Oxide zone geochemistry: Ellis Horwood Ltd., Chichester, UK, 286p.

The Proterozoic Vazante Hypogene Zinc Silicate District, Minas Gerais, Brazil: A Review of the Ore System Applied to Mineral Exploration

Article

Full-text available

Jan 2018

The Proterozoic Vazante zinc silicate district in Minas Gerais, Brazil, hosts world-class hypogene willemite deposits in dolomitic rocks interbedded with siliciclastic rocks deposited in subtidal to supratidal environments. Willemite ore bodies are structurally controlled along regional NE-trending structures which are interpreted as being active during the Neoproterozoic Brasiliano orogeny. The hydrothermal alteration is characterized by an early stage of Fe-dolomite, which replaced the host dolomitic rocks, followed by precipitation of minor sphalerite and then hematite and willemite. Elements commonly enriched in the zinc ore include As, Ba, Be, Bi, Cd, Co, Fe, Ge, In, Mo, Ni, Sb, Se, U, V and W. Mineralogical, fluid inclusion and isotopic data indicates that mixing of S-poor metalliferous saline fluids with meteoric water favored the formation of willemite ore. Carbonaceous phyllites from the underlying thick siliciclastic sequence show evidence of early enrichment in zinc (and ore-related metals) and remobilization, respectively, prior to and during the Brasiliano orogenic event. This unit is interpreted as a possible source of ore-related elements. It is proposed that during the Brasiliano orogeny, hot (T > 170 °C) saline fluids (>15 wt % eq. NaCl) leached metals from siliciclastic source rocks and precipitated willemite ore in the overlying dolomitic sequence along structures that favored mixing with oxidizing meteoric water.

Germanium enrichment in supergene settings: evidence from the Cristal nonsulfide Zn prospect, Bongará district, northern Peru

Article

Full-text available

Feb 2018
MINER DEPOSITA

Supergene nonsulfide ores form from the weathering of sulfide mineralization. Given the geochemical affinity of Ge to Si4+ and Fe3+, weathering of Ge-bearing sulfides could potentially lead to Ge enrichments in silicate and Fe-oxy-hydroxide minerals, although bulk rock Ge concentrations in supergene nonsulfide deposits are rarely reported. Here, we present the results of an investigation into Ge concentrations and deportment in the Cristal supergene Zn nonsulfide prospect (Bongará, northern Peru), which formed from the weathering of a preexisting Mississippi Valley-type (MVT) sulfide deposit. Material examined in this study originates from drillcore recovered from oxidized Zn-rich bodies ~ 15–20 m thick, containing ~ 5–45 wt% Zn and Ge concentrations ~ 100 ppm. Microanalysis and laser ablation-ICP-MS show that precursor sphalerite is rich in both Fe (mean Fe = 8.19 wt%) and Ge (mean Ge = 142 ppm). Using the mineral geothermometer GGIMFis—geothermometer for Ga, Ge, In, Mn, and Fe in sphalerite—proposed by Frenzel et al. (Ore Geol Rev 76:52–78, 2016), sphalerite trace element data from the Cristal prospect suggest a possible formation temperature (TGGIMFis) of 225 ± 50 °C, anomalously high for a MVT deposit. Germanium concentrations measured in both goethite (mean values 100 to 229 ppm, max 511 ppm) and hemimorphite (mean values 39 to 137 ppm, max 258 ppm) are similar to concentrations measured in hypogene sphalerite. Additionally, the Ge concentrations recorded in bulk rock analyses of sphalerite-bearing and oxidized samples are also similar. A persistent warm-humid climate is interpreted for the region, resulting in the development of an oxidation zone favoring the formation of abundant Zn hydrosilicates and Fe hydroxides, both able to incorporate Ge in their crystal structure. In this scenario, Ge has been prevented from dispersion during the weathering of the Ge-bearing sulfide bodies and remains in the resultant nonsulfide ore.

C–O Stable Isotope Geochemistry of Carbonate Minerals in the Nonsulfide Zinc Deposits of the Middle East: A Review

Article

Full-text available

Nov 2017

Zinc nonsulfides are well represented in the Middle East, with occurrences in Turkey, Iran, and Yemen. Their genesis can be constrained by using carbon and oxygen isotope systematics applied to carbonate minerals. The δ13C ratios of smithsonite and hydrozincite in Iran and Turkey are comprised in the typical interval of supergene Zn carbonates (−0.4 and −7.1‰ V-PDB). The oxygen isotope geochemistry is more complex. Oxygen isotope compositions of smithsonite of the Hakkari deposit (Turkey) (δ18O from 24.2 to 25.6‰ V-SMOW) point to precipitation temperatures between ~4 and ~18 °C, corresponding to a normal weathering environment at these latitudes, whereas δ18O of smithsonite from other Middle East deposits (Angouran in Iran, Jabali in Yemen) point to the precipitation from low- to medium-temperature hydrothermal fluids. The C–O isotopic compositions of hydrozincite from the Mehdi Abad, Irankuh, and Chah-Talkh deposits can be only partially compared with those of smithsonite, because the oxygen isotopes fractionation equation for hydrozincite-water is not known. A comparison between the geochemical characteristics of all Zn-nonsulfide ores in the Middle East indicates that, even though several mineral deposits are derived from supergene weathering processes, other ones have been deposited from fluids associated with magmatic activity (Angouran, Iran) or with hydrothermal systems (Jabali, Yemen). This suggests that it is not possible to apply a common interpretative model to the genesis of all nonsulfide deposits in the Middle East.

Mineralogical and geochemical characterization of supergene Cu–Pb–Zn–V ores in the Oriental High Atlas, Morocco

Article

Full-text available

Oct 2017
MINER DEPOSITA

In the Moroccan High Atlas, two sulfide deposits hosted by Jurassic dolostones underwent significant weathering. In the Cu deposit of Jbel Klakh, several stages of supergene mineralization are distinguished: (1) the replacement of hypogene sulfides in the protolith (chalcopyrite) by secondary sulfides in the cementation zone (bornite, digenite, chalcocite, covellite), (2) the formation of oxidized minerals in the saprolite (malachite, azurite, brochantite) where the environment becomes more oxidizing and neutral, and (3) the precipitation of late carbonates (calcite) and iron (hydr-)oxides in the laterite. The precipitation of carbonates is related to the dissolution of dolomitic host rocks, which buffers the fluid acidity due to the oxidation of sulfides. In the Jbel Haouanit Pb–Zn deposit, the mineral assemblage is dominated by typical calamine minerals, Cu minerals (chalcocite, covellite, malachite), and a Cu–Pb–Zn vanadate (mottramite). Galena is successively weathered in anglesite and cerussite. Sphalerite is weathered in smithsonite, which is rapidly replaced by hydrozincite. Late iron (hydr-)oxides are mainly found at the top of both deposits (laterite). Both deposits are thus characterized by specific mineral zoning, from laterite to protolith, related to variations in the mineralogy and ore grades and probably caused by varying Eh-pH conditions.

The Influence of Fault Structures on the Genesis of Supergene Zinc Deposits

Chapter

Full-text available

Jan 2009

Gregor Borg

Downward-percolating oxidizing meteoric waters are the single most important factor in the processes that transform primary, hypogene, sulfide protore to secondary, supergene, nonsulfide ore. Faults provide the secondarily enhanced permeability pathways for these fluids and thereby exert a fundamental control over the formation of many—if not most—supergene deposits. Under the relatively low confining lithostatic pressures at or near the earth’s surface, fault structures are commonly highly permeable and allow selective weathering and related supergene processes to occur more quickly and reach more deeply than local exhumation and erosion, the greatest threats to any supergene ore deposit subsequent to its formation. On encountering sulfides, meteoric waters charged with atmospheric oxygen initiate a metal fractionation process involving the liberation and acidic mobilization of soluble base metals, the residual enrichment of insoluble materials in situ, and the progressive reprecipitation of metals at some distance from their source. This fractionation process is fundamentally controlled by the differential solubility of the metals involved and by the hydrodynamic behavior of the supergene meteoric fluids. In turn, the migration of these fluids depends on the permeability of the rocks, which is predominantly fault- and fracture-controlled. Finally, precipitation and fixation of the supergene ore minerals depend on the type and reactivity of available host rocks and the surface area available for reaction. The contribution of fault and fracture zones is arguably more important to the genesis of supergene zinc deposits than for other supergene base metal deposits, such as Cu-enrichment blankets, because of zinc’s particularly high solubility and mobility in the supergene environment. Several common examples of fault control can be seen in supergene zinc deposits, including the following: 1. Faults that simply provide access for oxidizing meteoric fluids to hypogene sulfide ores and convert them into supergene ore in situ or near the fault zones. 2. Faults that juxtapose sulfide protore source rocks and highly reactive trap rocks (e.g., carbonate rocks) in such a way that oxidation, remobilization, and reprecipitation occur in close proximity, although not in situ. 3. Fault blocks of impermeable lithotypes can act as hydrologic barriers to supergene ore fluids transporting dissolved base metals away from their sulfide sources and cause “ponding” or diversion of these fluids away from potential reactive hosts. The first increases residence time and consequently, fluid-wall rock interaction, whereas the second can create dispersion halos or even force metal-bearing groundwaters to surface, where they can form springs. Both processes can create metal halos detectable by exploration programs. 4. Fault systems (especially transpressive wrench systems) that fracture large volumes of rock on all scales can increase both permeability of the fractured rock and increase reactive surface area to an exceptional degree. Locally, such pervasive fracture patterns can provide the ground preparation necessary to turn relatively unreactive host rocks such as impermeable metasiliciclastic or volcaniclastic rocks into trap rocks. In some cases (e.g., Skorpion) this can make these shattered rocks more favorable than more reactive adjacent carbonates to which the fluids have more limited access. 5. Only faults and fault breccias have the extent to allow ultradeep meteoric oxidation and supergene mineralization to penetrate more than 1,000 m below surface, in situations where this is generally considered to be well below the groundwater table.

Observation of >5 wt % zinc at the Kimberley outcrop, Gale crater, Mars

Article

Feb 2016

Zinc-enriched targets have been detected at the Kimberley formation, Gale crater, Mars, using the Chemistry Camera (ChemCam) instrument. The Zn content is analyzed with a univariate calibration based on the 481.2 nm emission line. The limit of quantification for ZnO is 3 wt.% (at 95% confidence level) and 1 wt.% (at 68% confidence level). The limit of detection is shown to be around 0.5 wt.%. As of sol 950, 12 targets on Mars present high ZnO content ranging from 1.0 wt.% to 8.4 wt.% (Yarrada, sol 628). Those Zn-enriched targets are almost entirely located at the Dillinger member of the Kimberley formation, where high Mn and alkali contents were also detected, probably in different phases. Zn enrichment does not depend on the textures of the rocks (coarse-grained sandstones, pebbly conglomerates, resistant fins). The lack of sulfur enhancement suggests that Zn is not present in the sphalerite phase. Zn appears somewhat correlated with Na2O and the ChemCam hydration index, suggesting that it could be in an amorphous clay phase (such as sauconite). On Earth, such an enrichment would be consistent with a supergene alteration of a sphalerite gossan cap in a primary siliciclastic bedrock or a possible hypogene non-sulfide zinc deposition where Zn, Fe, Mn, would have been transported in a reduced sulfur-poor fluid and precipitated rapidly in the form of oxides.

Geochemistry, mineralogy, and development constraints of the Changarzeh non-sulfide ore, southern Natanz: Implications on tracing of carbonate rock-hosted supergene Pb-Zn deposits

Article

Jan 2024

Ebrahim Tale Fazel

Integrated Geology, Mineralogy, Element and C–O–S–Pb Isotopes Characteristics Elucidate Ore Genesis of the World-Class Huoshaoyun Zn–Pb Deposit in Karakoram Area, Xinjiang, Northwest China

Article

Jul 2023
ORE GEOL REV

Zinc Extraction; In Brief Review from Past to Present

Chapter

Jan 2023

Haldun Kurama

This chapter is a brief review of the past and future of the Zn extraction process. Firstly, the history of Zn extraction is given. Then pyro- and hydrometallurgical Zn production methods are covered. Fe removal processes are briefly explained. Finally, the current Zn extraction situation is highlighted.KeywordsZincPyrometallurgyHydrometallurgyRLEFe removal processes

Ancient Ore Deposits

Chapter

Nov 2020

Andreas Hauptmann

Mineral deposits have supplied useful and valuable material for human consumption long before they became objects of scientific curiosity or commercial exploitation (Misra 2000). In fact, the earliest human interest in rocks and beautifully coloured minerals was probably because of the easy accessibility at the surface, e.g. of the earthy red hematite, malachite, gold and gemstones in placers. As an example might be the almost industrial use of red pigments for thousands and thousands of rock paintings in the National Park of Serra da Capivara in eastern Brazil some 35,000 years ago (Guidon and Delibrias 1986). The red pigment hematite used in masses for the paintings must have been exploited from the huge Itabirite Banded Iron Formation.

‫Mineralogy and Geochemistry of Pb-Zn mineralization in the Nesar area, West of Khomein, Central Iran

Conference Paper

Full-text available

Nov 2020

Mohammad Yazdi

Abstract Nesar Pb-Zn deposit is located in the south of Lakan village. This vaillage is located in the Markazi province, central Iran. The exploration area of Nesar is situated in NW of Lakan village. The area is located in the middle part of the Sanandaj-Sirjan geotectonic Zone. The main faults of the area are in the main trend of this zone (NW - SE). The local faults of the area are in the trend of W-E. The major rock units of the area include phyllite and schist (Triassic age), metamorphosed sandstone, phyllite and schist (Jurassic age), yellow sandy-dolomite, massive gray limestone, interlayers of calcareous shale (Cretaceous) and Quaternary alluvium. The northern part of the area is mainly composed of gray massive limestone, calcareous marl, yellow sandy-dolomite (Lower Cretaceous) and Jurassic sandstones. The major ore minerals in the host rocks are galena, sphalerite, hematite and goethite. Minor ore minerals are cerusite, chalcopyrite, pyrite and malachite. The mineralization is mainly vein type and is associated with different facies of limestones. The main alteration is silicification and rarely dolomitization. The mineralization is mainly associated with silicification. The geochemical analyses of the 116 samples show that the Zn, Pb and Ag are the most anomalous elements. The average concentration is for Zn (4%), Pb (1.3%) and Ag (10ppm). The data show that the Zn has enough cat of grad for mining. The structural and textural evidences such as vein and veinlet mineralization, and solid solution,… show that the mineralization is epigenetic type. Geological, petrographic, mineralogical, geochemical and host rocks data show that the mineralization in the Nesar area is Irish type. Keywords: Pb-Zn mineralization, Irish type, Nesar, Khomein, Central Iran

New insights into the crystal chemistry of sauconite (Zn-smectite) from the Skorpion zinc deposit (Namibia) via a multi-methodological approach

Article

Full-text available

Jul 2020

A multi-methodical characterization of a sauconite (Zn-bearing trioctahedral smectite) specimen from the Skorpion ore deposit (Namibia) was obtained by combining X-ray powder diffraction (XRPD), Cation Exchange Capacity (CEC) analysis, Differential Thermal Analysis (DTA), Thermogravimetry (TG), Fourier Transform Infrared spectroscopy (FTIR) and Transmission Electron Microscopy (TEM-HRTEM-AEM). The X-ray diffraction powder pattern exhibits the typical features of turbostratic stacking disorder with symmetrical basal 00l reflections and long-tailed hk-bands, confirmed also by TEM observations. Besides sauconite, the sample also contains minor amounts of kaolinite, dioctahedral smectite and quartz. CEC analysis provides a total of Ca (∼69%), Mg (∼26%), Na (∼4%) and K (0.7%) exchangeable cations. Therefore, Zn is located exclusively within the octahedral site of sauconite. TG analysis provides a total mass loss of about 17% in the studied sample. Three endothermic peaks can be observed in the DTA curve, associated to dehydration and dehydroxylation of the material. An exothermic peak at 820°C is also present as a consequence of dissociation and recrystallization phenomena. The infrared spectrum shows the typical Zn3OH stretching signature at 3648 cm-1 , whereas, in the OH/H2O stretching region two bands at 3585 and 3440 cm-1 can be associated to stretching vibrations of the inner hydration sphere of the interlayer cations and to absorbed H2O stretching vibration, respectively. Diagnostic bands of kaolinite impurity at ~3698 and 3620 cm-1 are also found, whereas 2:1 dioctahedral layer silicates may contribute to the 3585 and 3620 cm-1 bands. Finally, using the one layer supercell approach implemented in the BGMN software, a satisfactory XRPD profile fitting model for the Skorpion sauconite was obtained. The findings have implications not only for economic geology/recovery of critical metals but, more generally, in the field of the environmental sciences.

Análise dos Domínios geo-mineralógicos das minas de Zn-(Pb-Ag) de Vazante e Extremo Norte, MG: implicações para geometalurgia

Thesis

Full-text available

Apr 2019

Fernando Fagundes Fontana

The Vazante Group hosts the major hypogene, nonsulfide Zn deposit known worldwide (e.g., Vazante; >60 Mton @ 20% Zn), which also contains Pb and Ag concentrations. The Vazante Mine (VZT) and its continuity, the North Extension Mine (EN), are subdivided into five geo-mineralogical domains, since three belonging to VZT: Lumiadeira 1 (LUM1); Lumiadeira 2 (LUM2); Sucuri (SUC), and two to EN: North Extension 1 (EN1); North Extension 2 (EN2). Field studies, systematic sampling, petrography, scanning electronic microscopy, automated mineralogy via Mineral Liberation Analyzer, and lithochemical analyses were carried out aiming to characterize each domain in detail, connect their geological and mineralogical aspects, and point to possible features responsible for changes on ore quality during ore beneficiation. The nonsulfide Zn orebodies at VZT and EN are anastomosed, composed of willemite (Zn2SiO4), and hosted by dolomite breccias and subordinately by metapelite, metabasic rocks, and hematite breccias. Minor sulfide-rich orebodies occur mainly imbricated within willemite orebodies or as veins and veinlets. The willemite crystals show infilling textures, such as colloform and fibrous-radiated (type I), reequilibrium texture, such as granoblastic (type II), or fine-grained textures, when controlled by late fissures (type III). Thus, willemite registers a complex sequence of processes and conditions responsible for the nonsulfide Zn ore generation. Zinc, Fe, C, Ca, SiO2, and Mg are the main chemical compounds of the ore. At EN, the Fe (<26.7%) and hematite contents in the ore are, on average, higher than those of VZT. Lead and Ag, co-products of Zn exploitation, are chiefly found at VZT, in the LUM1 and SUC domains, concentrated in sulfide-rich bodies. Terrigenous elements, such as Al, K, Rb, Sc, Co, Th, and La, are positively anomalous in the LUM2 domain indicating the influence of metapelite host in the south sector of VZT. In this case, willemite ore may contain up to 15% Zn-talc, related to lower Zn recoveries. If the willemite ore is hosted by metabasic rocks, franklinite, a deleterious phase into processing, might be the main Zn-bearing phase (<25%). If hosted by hematite breccias, characteristic of the EN2 domain, willemite is commonly comminuted and the Fe and hematite contents might be a limiting for beneficiation. The results herein presented show that each geo-mineralogical domain exhibits their own characteristics. Ore thickness, format, and depth of bodies, the nature of host rocks, and mineral replacements affect the mineralogy and quality of Zn ore directly. Those factors express geological processes and characteristics of the deposit environment that may be restricted or more frequent at a certain domain, thus creating specific signatures for the analyzed ore, which might be spatialized and monitored integrating a geometallurgical model.

Geology and Geochemistry of the Giant Huoshaoyun Zinc-Lead Deposit, Karakorum Range, Northwestern Tibet

Article

Full-text available

Feb 2019
ORE GEOL REV

The recently discovered giant Huoshaoyun zinc-lead deposit in the Karakorum Range, northwestern Tibet, China, consists of a major zinc-lead carbonate and a minor lead-dominant sulfide mineralization with metal reserves of zinc and lead of over 16 million tons. The zinc-lead carbonate mineralization is composed of smithsonite and cerussite, with laminated, massive, veined, and botryoidal textures, showing sedimentary and metasomatic structures. The lead-dominant sulfide mineralization is composed mainly of galena and minor sphalerite and pyrite, with laminated, brecciated, and veined textures. The laminated sulfide mineralized zones occur at the top of the deposit, whereas the zinc-lead carbonate mineralized bodies are located below the sulfide zones. Lead-dominant sulfide veins cut the zinc-lead carbonate ores and the host limestone. The sequence of formation of the lead-zinc ores with various mineral colors in thin sections is as follows: (1) light-colored to yellowish, fine- to coarse- and subhedral to euhedral smithsonite; (2) yellowish to reddish, fine- to coarse- and subhedral to euhedral smithsonite; (3) light-colored veined smithsonite; (4) white coarse-grained, xenomorphic cerussite; (5) colorless euhedral to sub-angular quartz crystals; (6) euhedral to anhedral lead-zinc sulfides and gypsum. The metallogenetic mineralization events of the Huoshaoyun deposit are: (1) early hydrothermal syn-sedimentary smithsonite mineralization; (2) hydrothermal replacive smithsonite mineralization; (3) vein-type smithsonite mineralization; (4) open space filling and replacive cerussite mineralization; (5) lead-zinc sulfide mineralization. The fluid inclusions of cerussite indicate that the hydrothermal fluids of the cerussite ore-forming stage are characterized by a temperature range of at least 186 oC to 206 oC and low salinities (0.7 to 1.2 wt. % NaCl eq.). The source of oxygen and carbon for the zinc-lead carboante mineralization is possibly consistent with the involvement of marine water and a magmatic fluid, and is probably dominated by the magmatic fluid. The source of sulfur for the lead-dominant sulfide mineralization is possibly related to a magma reservoir. The zinc-lead-carbonate portion of the deposit represents a primary hypogene non-sulfide mineralization.

Application of mineralogy and trace/rare earth elements geochemistry to determine of strategic element-bearing phases in the Angouran Zn-Pb mine, SW Zanjan

Article

Full-text available

Apr 2018

The Angouran Zn-Pb mine, SW Zanjan, is located within the Sanandaj-Sirjan Zone. It is hosted by metamorphic complex of Takab with Proterozoic age. The mineralization of Zn-Pb is located at the contact between footwall micaschists (Kahar Formation) and hanging wall marbles (Jangutaran Formation). The ore mineralization is divided into sulfide and carbonate orebodies. Sulfide ore dominated by sphalerite, galena and pyrite. The texture of sulfide ore is massive, brecciated and disseminated. The carbonate ore is brecciated, colloform, open space filling and dominated by smithsonite, hemimorphite, cerussite and mimetite. Smithsonite is the abundant mineral in carbonate ore and consists of three types with different colors. Ore geochemistry shows low total REE contents of all samples. Mineralized schists has relatively high REE contents and display high LREE/HREE. The chemical analyses of separated sphalerite and smithsonite using ICP-MS+ICP-OES+INAA methods show an enrichments of Ag, Ga, Ge, In, Cd, Co, Ni, As and Se in sphalerites and Cd, Ni, Co and As in smithsonites. These suggest smithsonite in the carbonate ore and sphalerites in sulfide ore are the main host minerals of trace elements.

Fluid Evolution in the Southern Part of the Proterozoic Vazante Group, Brazil: Implications for Exploration of Sedimentary-Hosted Base Metal Deposits

Article

Sep 2017
ORE GEOL REV

The Proterozoic Vazante Group carbonate rocks were submitted to multiple stages of fluid circulation from diagenesis to orogenesis as documented by detailed mineralogical, fluid inclusion and isotopic studies of the Upper Morro do Pinheiro and Lower Pamplona members from the Serra do Poço Verde Formation in the southern part of the paleo-basin. These units are the main hosts for the hypogene, structurally-controlled zinc silicate deposits in the Vazante Zinc District, including the Vazante mine, which is considered to be the largest willemitic (Zn2SiO4) deposit in the world, with estimated total resources of 40–60 Mt at 20% Zn. Five hydrothermal alteration types were identified in the Southern Extension of the Vazante Group. (I) Early stage alteration comprises dolomite substitution bands and nodules, associated with moderate salinity H2O-NaCl-CaCl2 fluids, with temperatures around 90 °C, interpreted as late-diagenetic. The calculated C and O isotopic compositions of the fluids suggest meteoric and/or connate origin and interaction with organic carbon. (II) Pre-ore stage alteration is evidenced by dog-tooth dolomite and quartz with minor Fe-oxi/hydroxides which fills dissolution voids formed by H2O-NaCl-CaCl2 ± MgCl2 fluids at temperatures around 100° to 150 °C. The C isotopic data also indicate interaction with organic carbon. The two first stages are poor in ore-related elements. (III) Ore stage encompasses four phases of mineral precipitation. The first is distal and characterized by red stained dolostones due to disseminated hematite and red dolomite. The second is the main phase of the ore stage, composed of massive red dolomite, massive hematite and willemite with enrichment mainly in Fe2O3, SiO2, Ag, As, Cd, Cu, Ni, Pb, Se and Zn. The third phase comprises white dolomite, hematite and traces of willemite with enrichment in MnO, Cd, Ni and Pb. The calculated C and O isotopic compositions of the fluids (at 180 °C) associated with pervasive alteration yielded values heavier than the diagenetic stage and lower than the host rock. The fourth phase corresponds to Zn-chlorite and quartz which are associated with H2O-NaCl fluids of variable salinities and distinct temperatures (90–140 °C and 170–190 °C). (IV) Pyrite-bearing vein characterized by pyrite, sphalerite, white dolomite, fine hematite and late quartz, with C and O isotopic and fluid inclusion compositions that are similar to the three phases of dolomite of the ore stage. These data suggest a co-genetic relationship of these two alteration styles. (V) The late sulfide stage characterized by rare galena-bearing stringers with sphalerite, chalcocite, greenockite, covellite and white dolomite that cross-cut the main ore stage phases. The ore-related fluid compositions associated with the silicate zinc mineralization in the southern part of the Vazante Group are also similar to the fluids reported in previous work for the sulfide zinc-lead deposits in the northern part, indicating favorable conditions for metal transport during the Brasiliano Orogeny. Sulfide ore would have precipitated in zones where sulfur was available and silicate zinc in structures where mineralizing fluids interacted with evolved meteoric water. This finding implies that carbonate sequences in other districts with sulfide lead-zinc deposits may also host hypogene silicate zinc deposits.

Genetic Relationship of Minerals and Carbonate Units of Stratigraphy Sequence in the Ahmadabad Deposit (NE of Bafq) Using Data Related to Rare Earth Elements

Article

Full-text available

Jan 2017

Stability of biological and inorganic hemimorphite: Implications for hemimorphite precipitation in non-sulfide Zn deposits

Article

Jul 2017
ORE GEOL REV

Hemimorphite, Zn4Si2O7(OH)2•H2O, one of the most common minerals in non-sulfide Zn deposits, together with smithsonite and hydrozincite, is one of the most abundant minerals in the “calamine” deposits in SW Sardinia. In spite of their importance for the development of ore genesis models, the stability properties of hemimorphite are poorly known. This paper presents solubility experiments on two different types of hemimorphite: a “geological” hemimorphite from a supergene non-sulfide Zn deposit, of supposed abiotic origin, and a hemimorphite precipitated by bacterial activity. Both specimens were characterized, before and after the experiment, by Synchrotron Radiation X-ray powder diffraction, Scanning Electron Microscopy, and X-ray Absorption Spectroscopy. The calculated solubility product constants (logKs) are similar for both “geological” and biogenic hemimorphite (30.3±0.4 and 30.5±0.1, respectively). During the solubility experiment, biological hemimorphite undergoes an amorphous to crystalline phase transition, and the distinctive features (mineralized bacterial sheaths and organic filaments), that allowed us to demonstrate its biological origin, are no longer recognizable by Scanning Electron Microscopy.

Economic Geology Principles and Practice: Metals, Minerals, Coal and Hydrocarbons - Introduction to Formation and Sustainable Exploitation of Mineral Deposits (1st ed.)

Book

May 2011

Walter Leopold Pohl

Wisely used, mineral resources create wealth, employment, a vital social and natural environment, and peace. If the reverse of these conditions occurs only too often, illustrating the so-called “resource curse”, this should be attributed to the true perpetrators, namely irresponsible, weak or selfish leaders. This book, however, does not intend to provide rules for good governance. I wrote it as a broad overview on geoscientific aspects of mineral deposits, including their origin, geological characteristics, the principles of the search for ores and minerals, and the investigation of newly found deposits. In addition, practical and environmental aspects are adressed that arise during the life cycle of a mine and after its closure. I am convinced that in our time, economic geology cannot be tought, studied, or practiced without an understanding of environmental issues. The scientific core of the book is the attempt to present the extraordinary genetic variability of mineral deposits in the frame of fundamental geological process systems. The comprehensive approach of this book – covering materials from metal ores to minerals and hydrocarbons – is both an advantage and a loss. The second concerns the sacrifice of much detail, but I promote the first for its benefit of a panoramic view over the whole field of economic geology. Being aware that the specialist level of subjects presented in this book fills whole libraries, I do hope that even experienced practitioners, academic teachers and advanced students of particular subjects will find the synopsis useful. Over more than 50 years, several editions of this book were published in German language. Since the first edition (Wilhelm & Walther E. Petrascheck 1950), the book was intended to provide a concise introduction to the geological setting of mineral deposits, including its application to exploration and mining. The target audience has changed, however. Originally, it was written for students of mining engineering. Today, it is mainly directed to aspiring and practicing geologists. Each of the seven chapters of the book was developed with my own students as a university course, and should be useful to fellow academic teachers. After initially working in industry I never lost contact with the applications of economic geology which is my motive for the constant interweaving of practical aspects in the text and for dedicating one of the chapters to the practice of economic geology. For professional reference purposes, practitioners in geology and mining should appreciate this melange of science and application. Frequent explanations and references to environmental and health aspects of extraction and processing of ores and minerals should assist users involved in environmental work. To those with no background in geology, I recommend they acquire an introductory geoscience text for looking up terms that are employed but not explained in the book. Compared with the last German-language edition (Pohl 2005), this book has been rewritten for an international public. Although it retains a moderate European penchant by referring to examples from this region, important deposits worldwide are preferentially used to explain genetic types and practical aspects. I trust that this will be useful to both scholars and practitioners, wherever they work. Generally, it was my ambition to represent the state of the art in economic geology, by referring to and citing recent publications as well as earlier fundamental concepts. This should assist and motivate students to pursue topics to greater depth. Many people have supported me in my life-long pursuit of theory and practice of economic geology, and helped with this book, especially by donating photographs. I cannot name them all but in captions, donors are acknowledged. Here, just let me say thank you.

Sedimentary associations and regolith

Chapter

Jul 2010

Peter Laznicka

Sediments and sedimentary rocks as hosts to giant metallic deposits have already been invoked in several earlier chapters like oceanic sediments (Chapter 5); sediments in island arcs and Andeantype continental margins (Chapters 5 and 6, respectively), sedimentary rocks in the volcanosedimentary orogens (Chapter 9) and in early Precambrian greenstone belts (Chapter 10), in Proterozoic-style intracratonic settings (Chapter 11) and in rift settings (Chapter 12). In all these chapters the sediments or sedimentary rocks, and processes that formed them, have been treated as second-order divisions, subordinated to the firstorder categories like volcanism, magmatism and hydrothermal activity based on geotectonic and lithotectonic premises.

The geology of non-sulphide zinc deposits - An overview

Abstract

No full-text available

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