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Minerals
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Geology and Mineralogy of Zn-Pb Nonsulfide Deposits
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Geology and Mineralogy of Zn-Pb Nonsulfide Deposits

A special issue of Minerals (ISSN 2075-163X).

Deadline for manuscript submissions: closed (30 September 2017) | Viewed by 23909

Special Issue Editor

Prof. Dr. Maria Boni

E-Mail Website
Guest Editor
Department of Earth Sciences, Environment and Resources, University of Naples Federico II, 80138 Napoli NA, Italy
Interests: Zn-Pb deposits; bauxites; nonsulphide Zn deposits; critical metals; laterites
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

“Nonsulfides” is a term, which has been used to define a special deposit type, considered as derived from the weathering of Zn(Pb) sulfide concentrations. Nonsulfide zinc deposits can be distinguished between supergene and hypogene, according to their mineralogy, geological characteristics and genetic setting. The supergene ores formed by weathering and oxidation, whereas the hypogene ores are considered hydrothermal, or associated with metamorphic processes on primary sulfide ores. The mineralogy of supergene deposits and their location relative to the precursor sulfide bodies reflect the composition of the primary assemblage and host rock, as well as the hydrologic regimes and climate.

The zinc minerals in supergene deposits are the carbonates smithsonite and hydrozincite, and the silicates hemimorphite and sauconite. Zinc can also be hosted in clay minerals other than smectite, as in chlorite-like clays. High amounts of Zn also occurin Mn-(hydr)oxides, as well as in Fe-(hydr)oxides and phosphates. The Zn-silicate willemite occurs only in few supergene deposits, on which there is always a hint of being partly hypogene.

The economic value of Zn-Pb nonsulfides is highly variable, and it resides on the mineralogy of the contained metals. Some technical problems encountered during processing can be thus mitigated by a better identification of the mineralogical assemblage. This should be a fundamental step in the exploration, because most extraction processes are highly sensitive to mineralogy.

If you are interested in contributing to this special issue, we encourage you to send the tentative title(s) and abstract(s) of your submission(s) to the Editorial Office () by 30 April 2017.

Prof. Dr. Maria Boni
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Zn(Pb) nonsulfides
  • Supergene
  • Hypogene
  • Mineralogy
  • Exploration

Published Papers (4 papers)

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Research

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25 pages, 8057 KiB  
Article
C–O Stable Isotopes Geochemistry of Tunisian Nonsulfide Zinc Deposits: A First Look
by Hechmi Garnit, Maria Boni, Giuliana Buongiovanni, Giuseppe Arfè, Nicola Mondillo, Michael Joachimski, Salah Bouhlel and Giuseppina Balassone
Minerals 2018, 8(1), 13; https://doi.org/10.3390/min8010013 - 09 Jan 2018
Cited by 11 | Viewed by 5835
Abstract
A preliminary C–O stable isotopes geochemical characterization of several nonsulfide Zn-Pb Tunisian deposits has been carried out, in order to evidence the possible differences in their genesis. Nonsulfide ores were sampled from the following deposits: Ain Allegua, Jebel Ben Amara, Jebel Hallouf (Nappe [...] Read more.
A preliminary C–O stable isotopes geochemical characterization of several nonsulfide Zn-Pb Tunisian deposits has been carried out, in order to evidence the possible differences in their genesis. Nonsulfide ores were sampled from the following deposits: Ain Allegua, Jebel Ben Amara, Jebel Hallouf (Nappe Zone), Djebba, Bou Grine, Bou Jaber, Fedj el Adoum, Slata Fer (Diapir Zone), Jebel Ressas, Jebel Azreg, Mecella (North South Axis Zone), Jebel Trozza, Sekarna (Graben Zone). After mineralogical investigation of selected specimens, the C–O stable isotopic study was carried out on smithsonite, hydrozincite, cerussite and calcite. The data have shown that all the carbonate generations in the oxidized zones of Ain Allegua and Jebel Ben Amara (Nappe Zone), Bou Jaber, Bou Grine and Fedj el Adoum (Diapir Zone), Mecella and Jebel Azreg (North South Zone) have a supergene origin, whereas the carbonates sampled at Sekarna (Graben Zone) (and in limited part also at Bou Jaber) precipitated from thermal waters at moderately high temperature. Most weathering processes that controlled the supergene alteration of the Zn-Pb sulfide deposits in Tunisia had probably started in the middle to late Miocene interval and at the beginning of the Pliocene, both periods corresponding to two distinct tectonic pulses that produced the exhumation of sulfide ores, but the alteration and formation of oxidized minerals could have also continued through the Quaternary. The isotopic characteristics associated with the weathering processes in the sampled localities were controlled by the different locations of the sulfide protores within the tectonic and climatic zones of Tunisia during the late Tertiary and Quaternary. Full article
(This article belongs to the Special Issue Geology and Mineralogy of Zn-Pb Nonsulfide Deposits)
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9420 KiB  
Article
Identification of Zn-Bearing Micas and Clays from the Cristal and Mina Grande Zinc Deposits (Bongará Province, Amazonas Region, Northern Peru)
by Giuseppe Arfè, Nicola Mondillo, Giuseppina Balassone, Maria Boni, Piergiulio Cappelletti and Tommaso Di Palma
Minerals 2017, 7(11), 214; https://doi.org/10.3390/min7110214 - 07 Nov 2017
Cited by 11 | Viewed by 4982
Abstract
Zn-bearing phyllosilicates are common minerals in nonsulfide Zn deposits, but they seldom represent the prevailing economic species. However, even though the presence of Zn-bearing clays is considered as a disadvantage in mineral processing, their characteristics can give crucial information on the genesis of [...] Read more.
Zn-bearing phyllosilicates are common minerals in nonsulfide Zn deposits, but they seldom represent the prevailing economic species. However, even though the presence of Zn-bearing clays is considered as a disadvantage in mineral processing, their characteristics can give crucial information on the genesis of the oxidized mineralization. This research has been carried out on the Mina Grande and Cristal Zn-sulfide/nonsulfide deposits, which occur in the Bongará district (Northern Peru). In both of the deposits, Zn-bearing micas and clays occur as an accessory to the ore minerals. The XRD analyses and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) investigations revealed that the Zn-bearing micas that are occurring in both deposits mostly consist of I/S mixed layers of detrital origin, which have been partly altered or overprinted by sauconite during the supergene alteration of sulfides. Sporadic hendricksite was also identified in the Cristal nonsulfide mineral assemblage, whereas at Mina Grande, the fraipontite-zaccagnaite (3R-polytype) association was detected. The identified zaccagnaite polytype suggests that both fraipontite and zaccagnaite are genetically related to weathering processes. The hendricksite detected at Cristal is a product of hydrothermal alteration, which is formed during the emplacement of sulfides. The complex nature of the identified phyllosilicates may be considered as evidence of the multiple processes (hydrothermal and supergene) that occurred in the Bongará district. Full article
(This article belongs to the Special Issue Geology and Mineralogy of Zn-Pb Nonsulfide Deposits)
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Review

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17 pages, 3871 KiB  
Review
The Proterozoic Vazante Hypogene Zinc Silicate District, Minas Gerais, Brazil: A Review of the Ore System Applied to Mineral Exploration
by Gema R. Olivo, Lena V. S. Monteiro, Fernando Baia, Paul Slezak, Igor Carvalho, Neil A. Fernandes, Gustavo D. Oliveira, Basilio Botura Neto, Alexandra McGladrey, Adalene M. Silva, Márcia A. Moura and Daniel Layton-Matthews
Minerals 2018, 8(1), 22; https://doi.org/10.3390/min8010022 - 15 Jan 2018
Cited by 11 | Viewed by 6694
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Geology and Mineralogy of Zn-Pb Nonsulfide Deposits)
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3452 KiB  
Review
C–O Stable Isotope Geochemistry of Carbonate Minerals in the Nonsulfide Zinc Deposits of the Middle East: A Review
by Nicola Mondillo, Maria Boni, Michael Joachimski and Licia Santoro
Minerals 2017, 7(11), 217; https://doi.org/10.3390/min7110217 - 10 Nov 2017
Cited by 4 | Viewed by 5245
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Geology and Mineralogy of Zn-Pb Nonsulfide Deposits)
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