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Economic Mineral Deposits: A Review

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A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 22797

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Prof. Dr. Vasilios Melfos

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Department of Mineralogy, Petrology and Economic Geology, Faculty of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
Interests: ore deposits; porphyry-epithermal mineralization; mineralogy; geochemistry; fluid inclusions
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Prof. Dr. Panagiotis Voudouris

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Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens, University Campus-Zografou, 15784 Athens, Greece
Interests: ore minerals; critical metals; magmatic-hydrothermal ore deposits; mineralogy of hydrothermal alterations in porphyry-epithermal systems; mineralogy and genesis of gemstones
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Dr. Grigorios Aarne Sakellaris

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Department of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
Interests: ore deposit modelling, orogenic gold, structural geology, metamorphic petrology, Archean
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Special Issue Information

Dear Colleagues,

Economic mineral deposits occur in all geological environments and are mined in substantial quantities that meet the world demands. Many factors crucial for the formation of mineral deposits control their mineral paragenesis, textures, and mineral chemistry. These features affect the exploration projects and the mining and metallurgical processes of the companies, which invest considerable amounts of capital to extract these deposits.

The Special Issue "Economic Mineral Deposits: A Review" will cover topics related to mineral deposits of broader interest to the geoscience community. It will contain review articles that cover recent advances in our understanding of mineral deposits as demonstrated by studies of geological setting, host rocks, mineralogy, geochemistry, fluid circulation, conceptual model, and formation. These data will contribute significantly to the knowledge about the distribution of economic mineral deposits in specific geotectonic environments through space and time for exploration and exploitation.

Prof. Dr. Vasilios Melfos
Prof. Dr. Panagiotis Voudouris
Dr. Grigorios Aarne Sakellaris
Guest Editors

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

mineral deposits
new economy minerals
industrial minerals
ore forming systems
genetic models
economic viability
mineral exploration

Published Papers (8 papers)

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Research

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25 pages, 11392 KiB

Open AccessArticle

The Geology, Petrography, and Geochemistry of Egyptian Dokhan Volcanics: A Potential Source for Construction Aggregate

by Hatem El-Desoky, Nabil Abd El-Hafez, Ahmed Khalil, Ahmed Arafat, Mahmoud Galal Hasan and Tarik Youssef

Minerals 2023, 13(5), 635; https://doi.org/10.3390/min13050635 - 02 May 2023

Viewed by 1461

Abstract

The present paper focuses on the geology, petrography, and geochemistry of the well-known Dokhan volcanics encountered in the northern part of the Eastern Desert of Egypt. The basalts, andesites, rhyolites, and agglomerates exposed at the Makhar Seal (flood plain) as well as Wadi Abu Zoghot, Wadi El-Ghafiryia, Wadi Al-Radah Luman, Wadi Al-Ushsh, Wadi Umm Sidrah, and Gabal Ghuwayrib are herein examined as sources of coarse aggregate in concrete mixes. A representative total of 28 samples—collected from different Dokhan volcanics—was studied in terms of field geology, petrography, and geochemistry wherein a variety of experiments related to construction material validation apply. The petrographic examination revealed that the studied Dokhan volcanics consist of basic, intermediate, and acidic volcanic igneous rocks. These rocks are represented through basalts, andesites, imperial porphyry, dacites, rhyodacites, rhyolites, and their pyroclastics. Furthermore, the applied geochemical analysis indicated that the studied Dokhan volcanics are alkaline to sub-alkaline, calc-alkaline and classified as basalts, basaltic andesites, andesites, trachyandesites, trachydacites, trachytes, and rhyolites, indicating an initial potential as aggregate for concrete mixes. Finally, the results obtained from incorporating Dokhan volcanics as aggregates in concrete mixes demonstrated a significant improvement in regard to the properties of the comprising concrete mixes. Herein, a higher compressive strength was witnessed after 28 days for Dokhan volcanic concrete, when compared to concrete comprising dolomite aggregate, amounting to an average increase that exceeded 36%. Full article

(This article belongs to the Special Issue Economic Mineral Deposits: A Review)

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38 pages, 40864 KiB

Open AccessFeature PaperArticle

Polymetallic Uranium Mineralisation in Rohil, Rajasthan, Western India: Insights from Mode of Occurrences, Structural Controls, Alteration Geochemistry and Exploration

by Ajoy Kumar Padhi, Mrinal Kanti Mukherjee, Brajesh Kumar Tripathi, Dheeraj Pande, Balbir Singh Bisht and Bhabesh Chandra Sarkar

Minerals 2023, 13(4), 555; https://doi.org/10.3390/min13040555 - 14 Apr 2023

Cited by 1 | Viewed by 1814

Abstract

Geological and radiometric studies of outcrops aided by extensive subsurface exploration through drill holes in an otherwise soil-covered terrain revealed the existence of low grades, medium tonnage, and metasomatite types of polymetallic uranium deposits at Rohil in India. Microscopic studies, electronprobe micro analyses, and geochemical analyses of samples from lodes indicate the polymetallic nature of mineralisation involving copper and molybdenum, in addition to uranium. Wide variations in the composition of fluid (S-, F-, P-, and O-rich) led to the formation of sulphides, fluorite, U-phosphosilicate, quartz, and magnetite, respectively, and are associated with uraninite. Litho-geochemical analyses from the Rohil deposit indicate multifarious metasomatic alterations associated with polymetallic mineralisation occurring in veins. The major mineralogical and metasomatic controls on rock compositions and the extent of material transfer processes that influenced the host rocks and mineralisati on are quantified by molar element ratio studies and alteration plots. General element ratio (GER) diagrams on chemical analyses of rock samples reveal albitisation and chloritisation as major and microclinisation, sericitisation, carbonatisation, and silicification as minor wall rock alterations associated with ore mineralisation. The alteration box plot between the chlorite–carbonate–pyrite index (CCPI) and the Ishikawa alteration index (AI) indicates the influence of hydrothermal activity and dominance of both albitisation and chloritisation. The ore zone is controlled by meso- and microstructures and the geometry of the soda- and potash-metasomatised zone around hydrothermal veins. This zone contains several anastomosing mineralised veins defined by a prominent joint that is set in quartzite that strikes subparallel to the axial surface of the F₂ isoclinal folds and the pervasive schistosity S₁ in the quartz–feldspar–biotite schist. Aventurisation of albite and microcline, established through electron probe micro analyses, can be considered as a pathfinder for uranium mineralisation. The close association of uranium and metallic sulphide mineralisation with microstructural, mineralogical (albitisation, chloritisation, and microclinisation), and geochemical variations can be applied as suitable exploration guides in a similar geological set-up worldwide. Full article

(This article belongs to the Special Issue Economic Mineral Deposits: A Review)

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15 pages, 12427 KiB

Open AccessArticle

The Impact of Hydrothermal Fluids on Porosity Enhancement and Hydrocarbon Migration in Qamchuqa Formation, Lower Cretaceous, Kirkuk Oil Company

by Namam M. Salih

Minerals 2023, 13(3), 377; https://doi.org/10.3390/min13030377 - 08 Mar 2023

Cited by 6 | Viewed by 1448

Abstract

The Lower Cretaceous reservoir core samples from the upper part of Qamchuqa Formation, Baba Dome, Kirkuk Oil Company, show evidence for multistage episodes of dolomitization and a complex diagenetic history. Optical microscope reveals muti-phase of diagenesis: an early stage of diagenesis and its alteration, later, by evaporated seawater under near-surface setting conditions, followed by different event of dolomitization. The stylolite microstructures postdate anhydrite and early matrix dolomite crystals (DI) and predated the coarse rhombohedral (DII) and saddle dolomite crystals (SD), which were formed under a deep burial realm. High-resolution data from stable isotopes integrated with intensive optical observation, ImageJ software, and litho-log are utilized to establish a qualified methods for mapping a better image of hydrothermal diagenesis under subsurface conditions. These methods revealed different types of dolomites, mostly focused on fractures and void spaces, and the paragenetic sequence shows the complex history of diagenetic carbonate rocks hosted in the limestone of Qamchuqa Formation. The sequence is started from older to younger as follow: Micritization, early anhydrite mineral formation, early dolomite, stylolization, rhombohedral dolomite, and saddle dolomite crystals. The early dolomite phase is usually corroded by hydrocarbon phase, and, geometrically, the hydrocarbon phase is overgrown by the early dolomite. Therefore, the dolomitizing fluids enhanced the porosity system and had positive impact on the hydrocarbon movement. This phase of dolomite and anhydrite formation were associated with the first groups of δ¹⁸OVPDB and δ¹³CVPDB data, a narrow range of oxygen values, and inverse Js of Lohmann curve fits towards the near-surface and shallow diagenetic settings. Detailed optical microscope and supportive data from oxygen-carbon isotopes of saddle dolomite confirm the presence of hot fluids under subsurface condition. The latter data were supported by light δ¹⁸OVPDB and constant heavy δ¹³CVPDB, which indicates a hot fluid possibly circulated in deep burial conditions, and this is channeled along the fracture and pore spaces, consistent with hydrocarbon migration. These pore spaces influenced by leaching were hydrocarbon migrations associated with hot fluids under deep sitting conditions. However, a remarkable part of pristine microfacies of host limestone was preserved. In summary, this study will add a new understanding and insight into the origin, genesis, and timing of these dolomites and their direct connection to hydrocarbon exploration and development in most reservoir oil rocks, which are exposed to hydrothermal fluids. Additionally, the study adds new data on hydrothermal fluids in subsurface conditions, whereas most of the previous reported work has mostly focused on exposed rock. Full article

(This article belongs to the Special Issue Economic Mineral Deposits: A Review)

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14 pages, 2948 KiB

Open AccessArticle

Elemental Gains and Losses during Hydrothermal Alteration in Awak Mas Gold Deposit, Sulawesi Island, Indonesia: Constraints from Balanced Mineral Reactions

by Ernowo Ernowo, Arifudin Idrus and Franz Michael Meyer

Minerals 2022, 12(12), 1630; https://doi.org/10.3390/min12121630 - 17 Dec 2022

Cited by 1 | Viewed by 1488

Abstract

Hydrothermal gold mineralization is commonly associated with metasomatic processes resulting from interaction of hostrock with infiltrating hot aqueous fluids. Understanding of the alteration mechanism requires quantification of element changes in altered rock, relative to the unaltered or least-altered rock, representing the protolith. Balanced mineral reactions are used to gain quantitative insight into the alteration process associated with gold mineralization at the Awak Mas deposit. Three representative samples were carefully selected from the least-altered pyllite and the two alteration zones bordering the mineralization. Mineral mode, textural features, and mineral compositions were studied by microscopy and electron microprobe analyzer (EMPA). Quantitative modal analysis was performed with a Quanta 650 F QEMSCAN^® system. The hydrothermal alteration sequence around the mineralization starts with the proximal albite–ankerite–pyrite alteration zone via the distal albite–chlorite alteration zone to the least-altered phyllite wall-rock. Balanced mineral reaction calculations were performed to evaluate elemental gains and losses. Most noticeable is the addition of Si, Na and Ca to each alteration zone. This alteration is represented by the almost complete replacement of muscovite by albite. The addition of Fe and S was highest in the albite–ankerite–pyrite alteration zone. Alteration of the least altered phyllite to the albite–chlorite zone involved a mass increase of 14.5% and a neglectable volume increase of 0.6%. The mass and a volume increase from the least altered phyllite to the albite–ankerite–pyrite zone was 40.5% and 0.47%, respectively. The very low volume change during alteration is also corroborated by the textural preservation indicating isovolumetric metasomatic reactions. The replacement of muscovite by albite may have had an important effect on the change of the rock failure mode from ductile to brittle, with consequences for the focusing of fluid flow. Full article

(This article belongs to the Special Issue Economic Mineral Deposits: A Review)

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20 pages, 9781 KiB

Open AccessArticle

Petrographic and Geochemical Analysis of Indus Sediments: Implications for Placer Gold Deposits, Peshawar Basin, NW Himalaya, Pakistan

by Abdul Mateen, Ali Wahid, Hammad Tariq Janjuhah, Muhammad Saleem Mughal, Syed Haroon Ali, Numair Ahmed Siddiqui, Munib Ahmed Shafique, Olga Koumoutsakou and George Kontakiotis

Minerals 2022, 12(8), 1059; https://doi.org/10.3390/min12081059 - 22 Aug 2022

Cited by 6 | Viewed by 3403

Abstract

Alluvial placer gold deposits that accumulate in streams across the globe are essentially allochthonous sedimentary deposits that are transported from their source to their location of deposition. The purpose of this study was to find placer gold deposits in alluvial sediments along the Indus River in the NW Himalaya of Pakistan. The investigated region was divided into five clusters based on river morphology. The research focused on mineralogical distribution, sediment source, gold transport distance, elemental composition, and gold concentration in river sediments. Throughout, during the deposition at point and channel bars, the mixed source of alluvial sediments was revealed by its mineralogical composition. However, the SEM analysis demonstrated that the gold grains had a high flatness index, indicating that they had been transported a significant distance. The elemental composition of several samples revealed a significant concentration of silicon dioxide, iron oxide, and alumina oxide transported from the Himalaya. The study of the trace elements indicated gold and related base metals with granitic provenance were transported from an acidic/granitic source. Based on gold concentration, it is demonstrated that the left riverbank (clusters C1, C2, and C3) has a higher concentration of gold deposits and higher potential for economic gold exploration than the right bank (clusters C4 and C5) due to the lower velocity of running water in the study area. The findings revealed that the studied area has good potential for commercial exploration of gold resources, and the workflow can be adopted in any region with a similar geological setting and morphology. Full article

(This article belongs to the Special Issue Economic Mineral Deposits: A Review)

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21 pages, 2155 KiB

Open AccessReview

Methods of Extracting TiO₂ and Other Related Compounds from Ilmenite

by A. H. Janaka Sampath, Nadeera Dilshan Wickramasinghe, K. M. Nalin de Silva and Rohini M. de Silva

Minerals 2023, 13(5), 662; https://doi.org/10.3390/min13050662 - 11 May 2023

Viewed by 5285

Abstract

Although ilmenite and rutile are extensively used to extract TiO₂ at the industrial level, through the sulphate and chloride processes, they can also be recognized to possess the potential to be employed as the raw material to synthesize other titanium compounds as well. The Pulmoddai mineral sand deposit in Sri Lanka is considered as a valuable resource containing pure ilmenite and can be used as a very good source of both titanium and iron. Because of the lower TiO₂ content compared to rutile, processes, such as the Becher process, Laporte process and Kataoka process, have been developed to upgrade ilmenite into higher grade synthetic rutile. Additionally, research studies have been carried out to develop methods, such as the hydrochloride process, H₃PO₄/NH₃ process, alkaline roasting process, aluminothermic reduction method, alkaline decomposition method, molten salt electroreduction method and magnesiothermic reduction method, to synthesize TiO₂ and other related titanium compounds, such as titanium and iron oxides, composites and alloys, from naturally occurring ilmenite where these methods possess both rewards as well as drawbacks over the others. Full article

(This article belongs to the Special Issue Economic Mineral Deposits: A Review)

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16 pages, 7539 KiB

Open AccessReview

Case Histories of Orogenic Gold Deposits

by Franz Michael Meyer

Minerals 2023, 13(3), 369; https://doi.org/10.3390/min13030369 - 06 Mar 2023

Cited by 1 | Viewed by 2651

Abstract

This review compares genetic parameters of 12 orogenic gold deposits. The set of examples is considered to represent largely the variability of orogenic gold deposit (OGD) characteristics. The data are presented in tables and include following definitive parameters: regional geologic settings, nature of hosts rocks and mineralization, ore controlling structures, ages of host rocks and mineralization and timing of mineralization relative to metamorphism, hydrothermal alteration mineralogy and ore mineral assemblages, isotopic signatures, physical conditions of ore formation and proposed origin of ore fluids aa well as gold reserves, production, and grades. This allows comparison of deposits from different geologic terrains having different ages and formed under different P-T conditions. The data are further discussed before the background of the orogenic gold system and the crustal metamorphic models that provide different scenarios to explain the source of ore fluids. The orogenic gold system model advocates a metal and fluid source external to the terrain in which mineralization occurred, but the model applies only for 3 of the 12 deposits studied. All other deposits formed most likely from a crustal source, which would favor the crustal metamorphic model. However, the formation of hypozonal OGDs cannot be accounted for by the crustal metamorphic model or by the metamorphic devolatilization model. The data identify a set of coherent signatures in OGDs, but there seem to be no unified model for all possible environmental conditions and facets of ore formation and fluid sources, tectonic and lithologic setting, and scale of gold endowment. Full article

(This article belongs to the Special Issue Economic Mineral Deposits: A Review)

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28 pages, 8001 KiB

Open AccessFeature PaperReview

Sources of Hydrothermal Fluids Inferred from Oxygen and Carbon Isotope Composition of Calcite, Keweenaw Peninsula Native Copper District, Michigan, USA

by Thomas J. Bodden, Theodore J. Bornhorst, Florence Bégué and Chad Deering

Minerals 2022, 12(4), 474; https://doi.org/10.3390/min12040474 - 13 Apr 2022

Cited by 1 | Viewed by 3013

Abstract

The Mesoproterozoic North American Midcontinent Rift hosts the world’s largest accumulation of native copper in Michigan’s Keweenaw Peninsula. During a regional metamorphogenic-hydrothermal event, native copper was deposited along with spatially zoned main-stage minerals in a thermal high. This was followed by deposition of late-stage minerals including minor copper sulfide. Inferences from the oxygen and carbon isotopic composition of main-stage hydrothermal fluids, as calculated from 296 new and compiled isotopic measurements on calcite, are consistent with existing models that low-sulfur saline native copper ore-forming fluids were dominantly derived by burial metamorphic processes from the very low sulfur basalt-dominated rift fill at depth below the native copper deposits. Co-variation of oxygen and carbon isotopic compositions are consistent with mixing of metamorphic-derived fluids with two additional isotopically different fluids. One of these is proposed to be evolved seawater that provided an outside source of salinity. This fluid mixed at depth and participated in the formation of a well-mixed hybrid metamorphic-dominated ore-forming fluid. Secondary Ion Mass Spectrometry in-situ isotopic analyses of calcite demonstrate a high degree of variability within samples that is attributed to variable degrees of shallow mixing of the hybrid ore-forming fluid with sulfur-poor, reduced evolved meteoric water in the zone of precipitation. The oxygen and carbon isotopic compositions of 100 new and compiled measurements on late-stage calcite are mostly isotopically different than the main-stage hydrothermal fluids. The late-stage hydrothermal fluids are interpreted as various proportions of mixing of evolved meteoric water, main-stage hybrid ore-forming fluid, and shallow, evolved seawater in the relatively shallow zone of precipitation. Full article

(This article belongs to the Special Issue Economic Mineral Deposits: A Review)

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