Papers by Maria Economou-Eliopoulos
Minerals, Jul 19, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Review on the contamination of water resources in European Countries with emphasis to Greece: Risk and opportunities
Elsevier eBooks, 2022
The laterite deposits (Fe-Ni-laterite and bauxites) in the Balkan Peninsula are mainly located in... more The laterite deposits (Fe-Ni-laterite and bauxites) in the Balkan Peninsula are mainly located in the Mirdita-Sub-Pelagonian and Pelagonian geotectonic zones and are of great economic significance. These deposits have been affected by intense tectonism, which has created overthrusting, foliation, folding, and faulting. The investigation of arsenic in laterites is thought to be important for the ferronickel smelting process and the serious affect of the health. Minerals such as iron oxides and pyrite are of particular significance in controlling arsenic mobility, and hence aquifer contamination. Laterite samples from Ni-laterite deposits of Greece (Lokris, Vermio, Edessa, Olympos, Kastoria), Albania (Bitinca and Gouri-Perjuegjiun), Serbia (Rzanovo and Topola), bauxitic laterites and the Parnassos-Ghiona bauxite deposit were analyzed for major and trace elements, including arsenic (As). Arsenic concentrations for all laterite samples from the Balkan Peninsula range from < 2ppm to a few decades ppm. However, arsenic concentrations for the individual laterite occurrences and deposits from Aghios Ioannis vary significantly from <2 ppm to 2600 ppm. Arsenic in the Parnassos-Ghiona deposit ranges from <10 ppm in typical red colored ore to 900 ppm in yellow-grey colored ore. The latter type occurs along and near faults and constitutes a significant (approximately 30 vol. %) portion of the bauxite ores. They are characterized by the presence of abundant pyrite and microorganisms. Elevated arsenic contents are mostly associated with Fe-oxides/hydroxides in Ni-laterites, showing enrichment in REE, Co, Ni, Th and U contents, and with Al-oxides in bauxites. The sulphur isotope compositions of Fe sulphides from the bauxite deposit show a range from +10.2 to-30.2 per mil. Most negative values were obtained from grey-coloured ore samples. The organic matter may be related to the source of arsenic and play a major role in controlling the redox conditions, since they can drive the formation of pyrite or Fe-oxides.
Hydrochemical study of metals in the groundwater of the wider area of Koropi
... "Geochemical characteristics of natural waters contaminated by hexavalent chromium, in E... more ... "Geochemical characteristics of natural waters contaminated by hexavalent chromium, in Eastern Sterea Hellas, Greece", XIX Congress of the Carpathian Balkan Geological Association, Thessaloniki, Greece, vol. 99, p. 347-353
Minerals
This contribution provides an overview of platinum group elements (PGE) distribution and mineralo... more This contribution provides an overview of platinum group elements (PGE) distribution and mineralogy in ophiolitic chromitites, which are unusually enriched in the low melting-point Rh, Pt and Pd (PPGE) compared with most chromite deposits associated with ophiolites, which are dominated by the refractory Os, Ir and Ru (IPGE). The PPGE-rich chromitites examined in this paper have a PPGE/IPGE ratio equal to or higher than 1 and represent about 7% of the ophiolitic chromitite population. These chromitites occur in the mantle unit, in the mantle-transition zone (MTZ), as well as in the supra-Moho cumulate sequence of ophiolite complexes. The age of their host ophiolites varies from Proterozoic to Eocene and, based on their composition, the chromitites can be classified into Cr-rich and Al-rich categories. Mineralogical assemblages observed in this investigation suggest that the PPGE enrichment was achieved in the magmatic stage thanks to the formation of an immiscible sulfide liquid segr...
Othrisオフィオライト複合岩体,ギリシアからの超苦鉄質溶岩と高Mg玄武岩質岩脈【Powered by NICT】
Lithos, 2017
Ore Geology Reviews, 2008
Podiform chromitites are frequently distributed as lensoidal pods in the central and southern par... more Podiform chromitites are frequently distributed as lensoidal pods in the central and southern parts of the Eastern Desert, Egypt. They are, in most cases, hosted by fully serpentinized peridotite which is a part of dismembered ophiolite complexes of the Pan-African belt of Late Precambrian age. Serpentinites are the predominant components in the ophiolitic mélange, either as a matrix or as variably sized blocks, and are derived from harzburgite and subordinate dunite. The central Eastern Desert (CED) chromitites have a wide compositional range from high-Cr to high-Al varieties, whilst those of the southern Eastern Desert (SED) have a very restricted compositional range. The Cr# ratio of spinel ranges from 0.5 up to 0.8 in the former, while it is around 0.8 in the latter. Platinum-group element (PGE) mineralization has been recently reported in podiform chromitites from the late Proterozoic Pan-African ophiolite of the Eastern Desert of Egypt. The populations of platinum-group minerals (PGM) in the studied CED and SED chromitites are quite distinguishable; they are mainly sulfides (Os-rich laurite) in the former, and Os-Ir alloy in the latter. Sulfarsenides and arsenides are also found in subordinate amounts from both chromitites. The most abundant base metal sulfides (BMS) in the Eastern Desert chromitites of Egypt are millerite, heazlewoodite, pentlandite, chalcopyrite and pyrite. The sulfur fugacity and temperature conditions are the main controlling factors of PGE mineralogy in the host chromitite at the initial stage within the upper mantle. Os-rich laurite is stable at high sulfur fugacity and low temperature conditions, whereas Os-Ir alloy is stable at lower sulfur fugacity and higher temperature
Minerals
The research interest for many authors has been focused on the origin, recovery, and exploration ... more The research interest for many authors has been focused on the origin, recovery, and exploration of critical metals, including platinum-group elements (PGEs), with the aim of finding new potential sources. Many giant porphyry Cu deposits are well known around the Pacific Rim, in the Balkan–Carpathian system, Himalayas, China, and Malaysia. However, only certain porphyry Cu-Au deposits are characterized by the presence of significant Pd and Pt contents (up to 20 ppm). This contribution provides new analytical data on porphyry-Cu-Au±Pd±Pt deposits from the Chalkidiki Peninsula and an overview of the existing geochemical characteristics of selected porphyry-Cu deposits worldwide in order to define significant differences between PGE-fertile and PGE-poor porphyry-Cu intrusions. The larger Mg, Cr, Ni, Co, and Re contents and smaller LILE elements (Ba and Sr) in fertile porphyry-Cu-Au-(PGE) reflect the larger contribution from the mantle to the parent magmas. In contrast, the smaller Mg, ...
Minerals
In this study, we have compiled new and existing mineralogical and geochemical data on Fe-Mn mine... more In this study, we have compiled new and existing mineralogical and geochemical data on Fe-Mn mineralization from the Aegean region [Attica (Grammatiko, Legrena, and Varnavas), Evia and Milos islands], aiming to provide new insights on the genesis of Fe-Mn mineralization in that region and its potential environmental implications. A common feature of those deposits is the relatively low Cr, Co, V, Ni, Mo, and Cd content, whereas Ba, As, W, Cu, Pb, and Zn show remarkably variable values. The Mn-Fe deposits from Milos exhibit the highest tungsten content, while a positive trend between MnO and W, combined with a negative trend between MnO and Fe2O3 suggests the preference of W to Mn-minerals. The occurrence of bacterio-morphic Fe-Mn-oxides/hydroxides within Mn-Fe mineralizations in the studied region, indicates the important role of micro-organisms into redox reactions. Moreover, the presence of micro-organisms in the Fe-Mn-deposits, reflecting the presence of organic matter confirms a...
Minerals
This Special Issue “Bio-Geochemistry of Heavy Metals/Metalloids” contains a series of papers that... more This Special Issue “Bio-Geochemistry of Heavy Metals/Metalloids” contains a series of papers that cover a range of topics highlighting the role of microorganisms in ore-forming biochemical processes and potential environmental risk (the first to fourth papers), in the assessment of potentially toxic element contamination using plants and living benthic Foraminifera (the fifth and sixth papers), and in the phytoremediation of contaminated land (the seventh paper) [...]
Geologica Balcanica
Fe-Ni ore samples from the Sfikia (Veria), Alonakia, Stournari, Kria Vrissi and Mavrolivado (Verm... more Fe-Ni ore samples from the Sfikia (Veria), Alonakia, Stournari, Kria Vrissi and Mavrolivado (Vermio) and Edessa deposits, plus underlying hornstone and talc-schist, were analyzed for major, minor and trace elements, including REE, Pt, Pd and Au. Also, chromite grain-fragments in Ni-Iaterites, from northern Greece, Bitincka (Albania), Ržanovo (FYROM) and Šumadija (Yugoslavia) were analyzed by electron microprobe. In general, there is a wide variation in the major, minor and trace element content since they cover a variety of Ni-laterite deposits. The Au, Pt and Pd contents are low, although higher than in bauxite ores from Greece, ranging between <5 and 20 ppb, <10 and 99 ppb, <1 and 22 ppb, respectively. The rare earth element (REE) content ranges from less than 10 ppm to 260 ppm. In the majority of the analyzed samples there is a preference of Ce over La. Thorium and U contents range from <0.5 to 36 ppm, and <0.5 to 12.5 ppm respectively. On the basis of factor analy...
Geochemical constrains on the origin, geotectonic setting and exploration for chromite deposits in ophiolite complexes
Mineral Deposits at the Beginning of the 21st Century
Ultramafic lavas and pyroxene-spinifex high-Mg basaltic dykes from the Othris ophiolite complex, Greece
The compositional variation of the chromite within the saprolite zone and the Fe-Ni ore, includin... more The compositional variation of the chromite within the saprolite zone and the Fe-Ni ore, including high-Cr and –Al type, indicate that the Kastoria and Palaiochori deposits have been transported and redeposited even over a short distance, although they lie on a saprolite zone. Despite their relatively high Mn, Zn and Co contents in the whole Ni-laterite ore, only chromite dispersed within the Kastoria deposit exhibits a significant Mn, Zn or Co-enrichment in the ferroan chromite zone, in contrast to the Palaiochori deposit. Assuming that the Mn 2+ Zn 2+ Co 2+ -enrichment has taken place after re-deposition of the weathering material, during diagenesis-metadiagenesis, this difference in the trace element content of chromite may indicate that the Eh pH conditions are major controlling factor of their composition. The presence of plant fossils within the Palaiochori Fe-Ni laterite deposit suggests that the environment of the sediment was a reducing one. In addition, the abundance of Fe...
Journal of the Virtual Explorer
The platinum-group elements (Os, Ir, Ru, Rh, Pd and Pt) or PGEs, which are the most valuable elem... more The platinum-group elements (Os, Ir, Ru, Rh, Pd and Pt) or PGEs, which are the most valuable elements, are of strategic importance due to their growing use in advanced technologies and automobile catalyst converters. They traditionally are associated with mafic-ultramafic complexes, and have been described in a wide range of geotectonic settings. The majority of the world supply of PGE is produced from magmatic ores derived from basaltic magmas and is associated with primary magmatic. Major Pt and Pd economic mineralization is hosted in well-defined stratiform reefs of large layered intrusions, as is exemplified by the Bushveld Complex (South Africa), the Great Dyke (Zimbabwe) and the Stillwater Complex (USA). The types of mafic-ultramafic complexes dominant in Greece, which belong to the Balkan-Carpathian system, are ophiolites associated with orogenetic zones. Although chromite is major collector of the PGs, their content in chromite deposits, such as the large deposits of Othrys and Vourinos, and chromite occurrences hosted in ophiolites of Pindos, Rhodope and Serbo-Macedonian massifs, Edessa-Veria-Vermio, Euboea and Skyros islands, is generally low (few hundreds of ppb). However, PGE-enrichment: (a) in all PGE, (b) only in Os, Ir and Ru or (c) in Pt and/or Pd, are a common feature of disseminated chromite and/or relatively small chromite occurrences, of both high-Cr and high-Al type, in the uppermost parts of the mantle and/or in the lowest crust sequence. Examples of PGE-enrichment include the ophiolites of Pindos, Skyros Island and Veria (Greece). The platinum group minerals (PGM) may be precipitated directly from silicate melt (S-poor), immiscible sulfide liquids, and the magmatic volatile phases. PGM can be classified into two subgroups: the more Os-, Ir-and Ru-rich or IPGE (Ir-goup) and Pt, Pd-rich or PPGE (Pt-group) assemblages. The more Pt-and Pd-rich assemblages (Pd–Pt, Pd–Pt-alloys, Pt-arsenides, most likely sperrylite) occur interstitial to chromite grains. On the basis of field and experimental data small grains of PGM (average 25 μm) of the IPGE-goup, commonly laurite, as inclusion in unaltered chromite have been interpreted as an early magmatic phase formed by direct crystallization of a basaltic magma. The presence of members of the irarsite-hollingworthite solid-solution series and other Os-, Ir, Ru-and Rh-bearing PGM in PGE-enriched altered chromitites from some ophiolite complexes may indicate either in situ alteration or/and remobilization and re-deposition of PGE. A salient feature of the latter case is the presence of extremely large (over 1.3 mm) PGM grains and extremely abundant PGM small grains/fragment (over 100) dispersed along a highly fragment chromitite zone, in a distance over 3 mm. They occur within small chro-mite occurrences located along a shear zone of strongly brecciated chromite ore of Veria having high PGE (up to 25 ppm) content. Such fluid-driven multistage platinum-min-eralization and subsolidus reactions are considered to be widespread, but the system is considered to be a closed one with respect to PGE. The relatively high IPGE-enrichment in chromitites seems to be related to post magmatic processes covering a long period of deformation episodes, starting from the asthenosheric mantle flow (plastic deformation). Thus, most targeting locations general in ophiolite complexes may be are (a) for the chro-mitite-IPGM associations exclusively small chromite occurrences along shearing zones of ophiolite complexes, postdating their initial/magmatic PGE deposition, and (b) for the PPGE the uppermost parts of the mantle and the lowest crust sequence. Platinum and Pd contents in sea-floor massive sulfides are very limited. However, el
Abstract: The chemistry of the groundwater in Eastern Sterea Hellas (central Euboea and Asopos va... more Abstract: The chemistry of the groundwater in Eastern Sterea Hellas (central Euboea and Asopos valley), central Greece, has revealed high concentrations of hexavalent chromium in groundwater systems exceeding, sometimes, the Greek and the EU drinking water ...
Platinum group element and gold concentrations in Greek bauxites
Geologica Balcanica, Apr 30, 1991
Applied Geochemistry, 1995
Basalt in the Furutobe District of the Kuroko mine area in Japan is characterized by abundant chl... more Basalt in the Furutobe District of the Kuroko mine area in Japan is characterized by abundant chlorite and epidote. Fluid inclusion studies indicate that chlorite is formed at lower temperatures (230-25O'C) than epidote (250-280"(I). The seawater/basalt mass ratio for the early chlorite-rich alteration was high (max. 40), but that for the later alteration was low (0.1-I .8). The CaO, Na20 and Si02 of the bulk rock correlate negatively with MgO, while Fe0 and X Fe correlate positively with MgO. These changes in the characteristic features of hydrothermal alteration from early to late are generally similar to those for a midocean ridge geothermal system accompanying basalt alteration. The MgOiFeO ratios ofchlorite and actinolite and the Fe,O, concentration of enidote from the basalt are greater t&n' those of mid-ocean ridge basalt probably owing to the differences in ihe FezO3/FeO and MgO/ Fe0 ratios of the parent rocks. The lower CaO concentration and the higher Na.0 concentration of the bulk rock compared with altered mid-ocean ridge basalt can be interpreted in terms of the difference in original bulk rock compositions. The Furutobe basalt, as well as other submarine back arc basalts, contains more vesicles filled with hydrothermal minerals (epidote, calcite, quartz, chlorite, pyrite) than do the mid-ocean ridge basalts. The abundance of vesicles plays an important role in controlling the secondary mineralogy and geochemistry of hydrothermally altered submarine back arc basin basalts.
Minerals
In this contribution we review the mineralogical characteristics of five new and rare minerals di... more In this contribution we review the mineralogical characteristics of five new and rare minerals discovered in the Othrys and Vermion ophiolites located in Greece, with the aim to better understand their origin. Three new minerals, namely tsikourasite Mo3Ni2P(1+x) (x < 0.25), grammatikopoulosite NiVP and eliopoulosite V7S8, were found in the chromitite from the Agios Stefanos deposit, whereas arsenotučekite Ni18Sb3AsS16 was discovered in the Eretria (Tsangli) chromium mine, located in the Othrys ophiolite complex. The formation of the new phosphides tsikourasite and grammatikopoulosite and the sulfide eliopoulosite from Agios Stefanos took place after the precipitation of the host chromitite. Very likely, they formed at lower pressure in an extremely low fO2 and reducing environment during the serpentinization that affected the host ophiolite. The origin of arsenotučekite in chromitites coexisting with Fe–Ni–Cu-sulfide mineralization and magnetite at the Eretria (Tsangli) mine, is ...
Minerals
The present study is an integrated approach to the Pt, Pd, and Rh cycling derived from catalytic ... more The present study is an integrated approach to the Pt, Pd, and Rh cycling derived from catalytic converters along highway roadsides of the Athens Basin, including their contents, the dispersed Pt- and Pd-bearing nano- and microparticles in dust and bioaccumulation in plants, aiming to assess the auto-catalyst-derived environmental impact to the large city of Athens and the potential human health risk. The determined mean values of 314 Pt, 510 Pd, and 23 Rh (all in μg/kg) in dust samples are much lower than the 2070 μg/kg Pt and 1985 μg/kg Pd contents in gully pots in the Katechaki peripheral highway and higher than the mean values of 230 Pt, 300 Pd, and 13 Rh (all in μg/kg) in the soil samples. With the exception of two samples from gully pots, from 51% to 70% of the samples (for the Pd and Pt, respectively) fall in the range from 100 to 400 μg/kg. The calculated accumulation factors showed means of 3.88 μg/kg Pd and 2.95 μg/kg Pt for plants and tree leaves, but any significant diff...
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Papers by Maria Economou-Eliopoulos