CHEMICAL AND MINERALOGICAL ANALYSIS OF HIGH-PURITY QUARTZ FROM NEW DEPOSITS IN A GREEK ISLAND, FOR POTENTIAL EXPLORATION

The current study presents an original chemical, elemental and mineralogical characterization of new quartz mineral deposits situated in Ios island, Cyclades, Aegean sea, Greece, via X-Ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) trace-element analysis. Actually, the mineral Quartz (crystalline SiO2) is found in nature in varying quality and is explored and traded for use in different applications of significant importance depending on the quartz purity. The results of the thorough chemical and mineralogical analysis indicate that quartz originating from the location examined in this research is almost free from other microcrystalline phases, and therefore it can be characterized as highly pure α-quartz. Thus, it can be used in the industry of ultra-high purity quartz production for specific applications, as long as the deposits are exploitable. In this framework, a preliminary estimation of the economic benefits from a potential exploration versus the environmental aspects of mining, taking into account sustainability issues in the region, is provided highlighting the local social need

Mineralogical characterization and evaluation of chromite ore in Grevena and Kozani Vourinos massif, Western Macedonia, Greece

Purpose. Chromite samples from Aetoraches mine area in the southern part of the Vourinos complex in Western Macedonia, Greece were examined from mineralogical-geochemical perspective. Methods. Χ-ray Diffraction (XRD) mineral phase analysis, elemental Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS) analysis and Thermogravimetry/Differential Thermogravimetry (TG/DTG) were carried out. Findings. The XRD results showed that all the samples contain mainly magnesium- and aluminum-chromite (“aluminumpicrochromite”) phases, along with forsterite (magnesian olivine), serpentine and chlorite occurrences. Based on the SEMEDS results, the computed average chemical formula indicative of this specific chromite type is: (Fe0.4 Mg0.6) (Cr1.6 Al0.4)O4. The TG-DTG weight losses found to be in the range of 4.4-14.36%, at temperatures between 600 and 750°C, indicated the presence of the hydroxyl-rich silicate minerals, serpentinite and chlorite, in agreement to the Loss of Ignition (LOI) results. The mineral phases detected in the present analyses appear in the dunite/diorite/harzburgite/peridotite main rocks of the ophiolitic complex that hosts the chromite ore. Originality. In the current research, an original characterization, via thorough elemental, phase and thermal analysis, is carried out aiming to enlighten the geochemistry aspects of the Vourinos chromite complex, Region of Western Macedonia, Greece, particularly of easily accessible and exploitable chromite deposits of the Aetoraches mine area. Practical implications. The chromite mineral, and especially the metallurgical type, is of substantial importance in metal industry. In that sense, the findings of the present investigation of chromite purity and mineral structure is a prerequisite for future exploitation of the Aetoraches chromite deposits in particular and broadly for the ongoing exploitation of chromite ore in the Vourinos complex, situated in Region of Western Macedonia, Greece, an area with high unemployment and rather slow economic growth.Мета. Дослідження зразків хромітової руди з рудника “Еторачес” в південній частині масиву Вурінос у Західній Македонії, Греція, з мінералого-геохімічної точки зору для оцінки можливості його промислової розробки. Методика. Були проведені рентгеноструктурний аналіз мінеральної фази (РФА), елементна скануюча електронна мікроскопія у поєднанні з аналізом енергодисперсійної спектроскопії (СЕМ-ЕДС) та термогравіметрія/диференціальна термогравіметрія (TГ/ДТГ). Результати. Результати РФА показали, що всі зразки містять в основному фази хроміту магнію та алюмінію (“пікрохроміт алюмінію”), а також прояви форстериту (магнезіального олівіну), серпентину й хлориту. Отримано середню хімічну формулу на основі результатів СЕМ-ЕДС, яка вказує на конкретний тип хроміта: (Fe0.4 Mg0.6) (Cr1.6 Al0.4)O4. Встановлено, що втрати маси ТГ/ДТГ, виявлені в діапазоні від 4.4 до 14.36%, при температурах від 600 до 750°C, вказують на присутність силікатних мінералів, багатих гідроксилом, серпентиніту і хлориту. Мінеральні фази, виявлені в даному аналізі, присутні в основних породах дуніт/діорит/гарцбургіт/перидотит офіолітового комплексу, що вміщує хромітові руди. Наукова новизна. Надана оцінка геохімічних аспектів хромітового масиву Вурінос, регіон Західної Македонії, Греція, особливо легкодоступних та експлуатованих хромітових родовищ рудником “Еторачес” на основі елементного, фазового та термічного аналізів. Практична значимість. Хромітовий мінерал, особливо металургійний, має велике значення в металургійній промисловості. У цьому сенсі результати даного дослідження чистоти хроміту і мінеральної структури є передумовою для майбутньої експлуатації хромітового родовища рудника Еторачес, зокрема, і в цілому для триваючої розробки хромітової руди в масиві Вурінос. Греція – регіон з високим рівнем безробіття й досить повільним економічним зростанням.Цель. Исследование образцов хромитовой руды из рудника “Эторачес” в южной части массива Вуринос в Западной Македонии, Греция, с минералого-геохимической точки зрения для оценки возможности его промышленной разработки. Методика. Были проведены рентгеноструктурный анализ минеральной фазы (РФА), элементная сканирующая электронная микроскопия в сочетании с анализом энергодисперсионной спектроскопии (СЭМ-ЭДС) и термогравиметрия/дифференциальная термогравиметрия (TГ/ДТГ). Результаты. Результаты РФА показали, что все образцы содержат в основном фазы хромита магния и алюминия (“пикрохромит алюминия”), а также проявления форстерита (магнезиального оливина), серпентина и хлорита. Получена средняя химическая формула на основе результатов СЭМ-ЭДС, указывающая на конкретный тип хромита: (Fe0.4 Mg0.6) (Cr1.6 Al0.4)O4. Установлено, что потери массы ТГ/ДТГ, обнаруженные в диапазоне от 4.4 до 14.36%, при температурах от 600 до 750°C, указывают на присутствие силикатных минералов, богатых гидроксилом, серпентинита и хлорита. Минеральные фазы, обнаруженные в настоящем анализе, присутствуют в основных породах дунит/диорит/гарцбургит/перидотит офиолитового комплекса, вмещающего хромитовые руды. Научная новизна. Дана оценка геохимических аспектов хромитового массива Вуринос, регион Западной Македонии, Греция, особенно легкодоступных и эксплуатируемых хромитовых месторождений рудником “Эторачес” на основе элементного, фазового и термического анализов. Практическая значимость. Хромитовый минерал, особенно металлургический, имеет большое значение в металлургической промышленности. В этом смысле результаты настоящего исследования чистоты хромита и минеральной структуры являются предпосылкой для будущей эксплуатации хромитового месторождения Эторачес, в частности, и в целом для продолжающейся разработки хромитовой руды в массиве Вуринос. Греция – регион с высоким уровнем безработицы и довольно медленным экономическим ростом.The authors would like to thank the Specific-Account Research Committee (ELKE) of University of Western Macedonia, Greece for financing the research work presented here under the research grant “Geochemical characterization and evaluation of chromite ore from mount Vourinos of Grevena and Kozani” (DecisionNo. 8/2019 51.1-51.3). Moreover, the contribution of Agapi Vasiliadou (PhD candidate) and Prof. Andreas Iordanidis of the Department of Mineral Resources Engineering, University of Western Macedonia, Greece for the LOI and thermogravimetry measurements is gratefully acknowledged. Finally, the authors would like to thank Dr. Charalampos Vasilatos of the Department of Geology and Geo-environment, at the National and Kapodistrian University of Athens, Greece for the XRD analyses

A preliminary provenance study of marble artifacts from Aiani, ancient upper Macedonia, Greece

Preliminary results on the provenance study of ancient marbles from Aiani, ancient Upper Macedonia, Northern Greece are presented in this work. Several samples (both archaeological and modern) were collected and analysed using thermoluminesence (TL) and Environmental Scanning Electron Microscopy coupled with Energy Dispersive System (ESEM/EDS). Chemical, morphological and mineralogical features revealed by ESEM/EDS, combined with TL spectra of natural and irradiated samples, allowed us to make some preliminary suggestions on the origin of ancient marble artefacts. According to ESEM/EDX results, Tranovalto marbles situated just Southwards of Aiani, where some modern white marble quarries occur, could be the most probable origin. TL spectra do not reveal any clear differences, except that of higher intensity of the fresh marbles comparing to the intensity of the ancient ones. Thus, a more detailed analytical work, employing more samples and analytical techniques is proposed in order to achieve satisfactory results.Peer Reviewe

Planning Sustainable Deep Sea Mining

The increase in world population and the expected global development of the world economy after the COVID-19 pandemic will continue to impose unprecedented pressure on securing the supply of minerals. The World Bank report “Minerals for Climate Action: The Mineral Intensity of the Clean Energy Transition” finds that the production of minerals such as graphite, lithium and cobalt could increase by nearly 500% by 2050, to meet the growing demand for clean energy technologies. Many of these critical minerals are found in the deep seabed, the only place on earth where mineral resources have not been exploited yet. There is a strong need to ensure that these critical minerals will be extracted in a sustainable way, verifying the protection of the marine environment and biodiversity. The regulatory, financial and engineering challenges for deep sea mining are considerable, but in fact are not considered prohibitive, taking into account the remarkable achievements in recent years. On the other hand, it is evident that the existing modern ecosystem-based management approaches cannot be applied to deep sea areas without detailed knowledge of the individual species and ecosystems; most of the species living on the deep-sea floor remain unknown up until now. There is a need for the development of a new environmental management approach for each specific area. The successful procedures of Natura 2000 can be followed, and the necessary information on the existing environmental conditions has to be collected separately at every site for a minimum period of 10–15 years. Natura 2000, the world’s largest ecological network united under a single, uniform regulatory framework, is regarded as one of the conservations success stories in the global effort to protect biodiversity

Elemental and phase characterization of quartz samples from Meliti (Florina, Greece)

In this work, a geological, phase and elemental characterization of quartz samples, deriving from Meliti area, is presented. The bedrock of the investigated area belongs to Pelagonian Nappe (Middle Triassic – Lower Jurassic) and consists predominantly of metamorphic basement including mainly mica schists where biotite dominates in relation to muscovite. Specifically, the quartz samples investigated in this study were collected at Moutsouna (Roudina) site about 3,5 km NNW of Meliti village. SEM-EDS, ICP-MS and XRD results indicate that quartz mineral originating from Meliti area is free from other microcrystalline phases. Hence, the quartz mineral found is highly pure and can be used for production of ultra-high purity quartz for special applications, as long as the deposits are found to be exploitable

Elemental and phase characterization of quartz samples from Meliti (Florina, Greece)

In this work, a geological, phase and elemental characterization of quartz samples, deriving from Meliti area, is presented. The bedrock of the investigated area belongs to Pelagonian Nappe (Middle Triassic – Lower Jurassic) and consists predominantly of metamorphic basement including mainly mica schists where biotite dominates in relation to muscovite. Specifically, the quartz samples investigated in this study were collected at Moutsouna (Roudina) site about 3,5 km NNW of Meliti village. SEM-EDS, ICP-MS and XRD results indicate that quartz mineral originating from Meliti area is free from other microcrystalline phases. Hence, the quartz mineral found is highly pure and can be used for production of ultra-high purity quartz for special applications, as long as the deposits are found to be exploitable

New data on the cathodoluminescence of white marbles: Interpretation of peaks and relationships to weathering

This work focus on the Thermoluminescence (TL), the Spatially Resolved Spectral Cathodoluminescence (CL) and Raman spectroscopy (Raman) of white marble specimens collected from the archaeological park of Aiani (Greece) and from patterns of Iceland calcite and Macael marble for comparison purposes. The spectra CL were measured with a high sensitivity cathodoluminescence spectrometer MonoCL3 of Gatan (UK) attached to an FEI-ESEM microscope (CL-ESEM). The experimental set of spectra CL curves of Aiani white marbles suggest that the blue band is more resistant to weathering in comparison with the red band which drops down easily under weathering. The comparison among CL spectra of CaCO3 patterns give a slight difference between the small 330 nm peak, detected in marble and not observed in the monocrystal pattern of Iceland calcite. The Backscattering Electron Dispersed (BSED) images of the white marble are similar to the CL monochromatic plots at 330 nm which highlight the surfaces with remarkable clarity, suggesting a CL emission-defect associated to the marble crystal interfaces, such as protons or hydroxyls. Conversely, the 395 nm monochromatic mapping depicts a CL image emitting from bulk and not from interfaces attributable to point defects or cationic activators in Ca2+ positions. The blue band of the spectra luminescence of marble is composed by several peaks associated to very different types of luminescent defects. This statement is not inconsequential since in archaeological TL dating of marbles the regenerated luminescence in the blue region of the spectrum is a serious difficulty and further research on this topic is necessary