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Mineralogical characterization of gold ore from the Barberton greenstone belt, South Africa
Thesis (PhD (Geology))--University of Pretoria, 2014.
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| Format: | Thesis |
| Language: | English |
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2026
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| _version_ | 1867613583842476032 |
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| access_status_str | Open Access |
| author2 | Merkle, R.K.W. (Roland Karl Willi), 1954- |
| author_browse | Merkle, R.K.W. (Roland Karl Willi), 1954- |
| author_facet | Merkle, R.K.W. (Roland Karl Willi), 1954- |
| collection | Thesis |
| description | Thesis (PhD (Geology))--University of Pretoria, 2014. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/110010 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:38:27.571Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/110010 Mineralogical characterization of gold ore from the Barberton greenstone belt, South Africa Merkle, R.K.W. (Roland Karl Willi), 1954- m.alnagashi@gmail.com Altigani, Mohammed Alnagashi Hassan Thesis (PhD (Geology))--University of Pretoria, 2014. Archaean greenstone belt, which the Barberton Greenstone Belt (BGB) forms part of, represents essential contributors in world gold production. In this belt, the geological setting of the original source of mineralization (mafic rocks) coupled with the high sensitivity of these rocks to metamorphism and hydrothermal alterations complicate the determination of the genesis and characteristics of gold deposits associated with these greenstone belts. Understanding of the influences of mineral associations, metamorphism, deformation, and alterations on these intensively re-worked and stressed rocks, which are definitely have been subjected to multiple phases of gold and sulphides mineralisation, is very important in order to characterize and distinguish the criteria of gold and associated sulphides within these deposits, and to shed a light on the gold trace elements fingerprinting technique. In the forensic geosciences, the identification of the gold source, mineralogical and chemical criteria, associations, and genesis is very useful to fight and stop gold thefts and illicit market crimes. In South Africa, the stolen gold value is equal to more than 1.6% of the global gold production annually; only 2% of this stolen gold was discovered. In this study, gold mineralizations and their associations in the Sheba, Fairview, and New Consort Mines at the BGB, have been studied. Various microscopic and analytical methods were applied to identify and determine the optical, mineralogical, chemical characterizations of gold deposits, and their associations. These techniques are transmitted, ore, and Scanning Electron microscopy, X-Ray Diffraction, X-Ray Fluorescence, Electron Microprobe Analysis, Laser Ablation-inductively Coupled Plasma-Mass Spectrometry, and Laser Ablation-inductively Coupled Plasma Mass Spectrometry-Elemental Mapping. LA-ICP-MS data of the three studied mines were reported in count per seconds (cps), while EMPA results were counted as wt. %. In the research, an attempted to standardize the LA-ICP-MS data base on the EMPA results from the same analysed spots; however no kind of relationships were found between the two techniques. Many procedures were used to quantify the LA-ICP-MS result (based on sulphur and iron as internal standards), or by using the sum of the raw counts. Nevertheless, none of these attempts are vi workable. The reasons are thought to be differences in ablation rates, fractionation between certain elements (i.e. Fe - Ni), instrumental factors, differences in spot depths and sizes, and differences in accuracy and limit of detections for both techniques. A similarity in the gold genesis and ore associations was determined between the Sheba and Fairview Mines. Both of these mines are dominated by pyrite, arsenopyrite, and pyrrhotite as an assemblage for gold mineralizations. However, in the New Consort Mine, gold is associated with Ni-rich arsenides and sulfosalts, which beside chalcopyrite and pyrrhotite represent the principal ore phases in this mine. The gold mineralization chemical, mineralogical, association, and structural criteria in these three mines indicate that this type of deposit is mesothermal (orogenic). The silicates and sulphides assemblage of the Sheba and Fairview Mines suggest a green schist facies formation conditions for gold. However, in the New Consort Mine gold formed at higher temperatures up to higher amphibolite metamorphic facies. In these, three studied mines; it found that most of sulphides contain sub-microscopic gold either as minute native films and sheets, or in atomic form trapped inside the cell-structure of these sulphides and sulfosalts due to sulphide-surface absorption or elemental-exchange. Both of these gold types are refractory and cause lot of difficulties during extraction processes. At least two generations of gold were identified at these mines: the first generation occurs inside or surrounded by sulphides (mainly pyrite). The second generation is commonly found within the silicates (mostly quartz). These two gold generations accompany different silicates and sulphides associations. The first generation was deposited pre- or syn-genetically with the sulphides, as invisible phases (very minute grains or ionic stages in the sulphides structure). The second gold generation was remobilized into the free-lodes within the silicates. The fineness of the native gold in these mines is very high, containing up to 97 wt. % gold, 4.5 wt. % silver, and traces of copper, nickel, and iron. During LA-ICP-MS studies, gold and sulphide grains with high Cl, Br, Na, and I were observed. These elements contents and relationships characterize the chemistry and precipitation processes from different possible sources of vii fluids. It implies two types of mineralizations in the study area, which part of them formed due to boiling process. Pyrite of the Sheba and Fairview mines present in two major generations; the early one is deformed and contains considerable amounts of arsenic and gold, more than the younger one that grew in idiomorphic shapes close to the later quart-carbonate veins or surrounded the older pyrite phase. New Consort Mine sulphides are rich in Ni, Co, and As, which represent the main gold bearing-domains. LA-ICP-MS mapping technique applied on three pyrite grains from the Sheba mine, revealed an existence of very tiny minerals in Nano scale within the pyrite type 2. It also shows an elemental zoning within these pyrite grains. The distribution and relationships of the trace elements in these pyrite grains indicate three genetic behaviours: 1) Al, Mn, Hg, Se, Ti, V, Cr, and Sn distributed normally within pyrite, reflecting a synchronous formation of these domains with pyrite. 2) As, Ni, Co, Zn, and Sb distributed log normally in the pyrite, indicating post-interference due to late solutions. Moreover; 3) Au and Ag show normal and up normal distribution within pyrite. Geology PhD (Geology) 2026-05-15T17:26:04Z 2026-05-15T17:26:04Z 14/05/08 2014 Thesis http://hdl.handle.net/2263/110010 en application/pdf |
| spellingShingle | Mineralogical characterization of gold ore from the Barberton greenstone belt, South Africa |
| title | Mineralogical characterization of gold ore from the Barberton greenstone belt, South Africa |
| title_full | Mineralogical characterization of gold ore from the Barberton greenstone belt, South Africa |
| title_fullStr | Mineralogical characterization of gold ore from the Barberton greenstone belt, South Africa |
| title_full_unstemmed | Mineralogical characterization of gold ore from the Barberton greenstone belt, South Africa |
| title_short | Mineralogical characterization of gold ore from the Barberton greenstone belt, South Africa |
| title_sort | mineralogical characterization of gold ore from the barberton greenstone belt south africa |
| url | http://hdl.handle.net/2263/110010 |