No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
The Ore Minerals and Their Intergrowths
... The pores are generally uniform with a size of nearly 10 µm in diameter. Sintering also results in partial melting and coalescing of the individual Cu2S granules enhancing Densities of the green, sintered, and post-processed specimens are given in Table 1 [38]. During the thermal de-binding process, the binding agent (methylcellulose and water) is volatilized leaving behind pores in the sample. ...
... Printed The literature value for bulk density of Cu 2 S: 5.6 g/cm 3 [38]. ...
... the structural integrity and TE properties of the fabricated specimens. Sulfur infu post-processing performed on the sintered specimens does not lead to any notable m phological changes, as shown in Figure 4. Densities of the green, sintered, and post-processed specimens are given in Tab [38]. During the thermal de-binding process, the binding agent (methylcellulose and ter) is volatilized leaving behind pores in the sample. ...
Copper (I) sulfide (Cu2S) is a low-cost, earth-abundant, and non-toxic thermoelectric material for applications in the middle–high temperature range (>650 K). Although 3D printing these materials can simplify their manufacturing, elevated temperatures observed during sintering impair their crystal structure and energy conversion efficiency. In this study, we demonstrated a novel post-processing methodology to revert the thermoelectric properties of the 3D printed Cu2-xS materials back to the unimpaired state via sulfur infusion. After printing and sintering, sulfur was infused into the specimens under vacuum to optimize their crystal structure and achieve high thermoelectric efficiency. Chemical analysis and X-ray Diffraction (XRD) tests showed that after the sulfur infusion process, the Cu/S ratio was reverted close to the stoichiometric level. The 3D printed Cu2-xS showed p-type thermoelectric behavior with electrical conductivity peaking at 143 S-cm−1 at 750 K and Seebeck coefficient of 175 µV-K−1 at 627 K. The figure of merit (ZT) value of 1.0 at 780 K was achieved, which is the highest value ever reported for a 3D printed Cu2-xS thermoelectrics at this temperature. The fabrication of environmentally friendly thermoelectric materials with extended dimensional freedom and conversion efficiency has the potential to impact the thermoelectric industry with new energy conversion applications and lowered manufacturing costs.
... Gold-brannerite intergrowths are extremely rare and have been found only in ores of the Witwatersrand (South Africa) and Richardson (Canada) in the form of small crystals and grains [54,55]. P. Ramdor (1962) [57] gives a photograph of a polished section (see Figure 288 in p. 332 from [57]) from the Bou-Azzer deposit (Southern Morocco), which shows "cataclastic brannerite is cemented by much gold with a little galena and quartz". The formation of the gold-brannerite association at the Bou Azzer deposit (the polymetallic Bou Azzer Co-As-Fe-Ni(±Ag ± Au) district) occurred at the early pre-arsenide gold-bearing stage of the hydrothermal system [58]. ...
... Gold-brannerite intergrowths are extremely rare and have been found only in ores of the Witwatersrand (South Africa) and Richardson (Canada) in the form of small crystals and grains [54,55]. P. Ramdor (1962) [57] gives a photograph of a polished section (see Figure 288 in p. 332 from [57]) from the Bou-Azzer deposit (Southern Morocco), which shows "cataclastic brannerite is cemented by much gold with a little galena and quartz". The formation of the gold-brannerite association at the Bou Azzer deposit (the polymetallic Bou Azzer Co-As-Fe-Ni(±Ag ± Au) district) occurred at the early pre-arsenide gold-bearing stage of the hydrothermal system [58]. ...
We carried out a comprehensive study of native gold (morphology, composition, intergrowths, and microinclusions) from alluvial deposits of the Kamenny stream (Ozerninsky ore cluster, Western Transbaikalia, Russia). The study showed that there were four types of native gold, which differed significantly in their characteristics and probably had different primary sources from which placers were formed: gold–quartz, oxidized gold–sulfide, gold–silver, and zones of listvenites with copper–gold and gold–brannerite (Elkon-type). Particular attention was paid to the study of unique, both in size and in composition, gold–brannerite nuggets of the Kamenny stream. It was established that the gold in the gold–brannerite nuggets (GBNs) had wide variations in chemical composition and mineral features. According to them, there were five different fineness types of native gold: 750–800‰; 850–880‰; 880–920‰; 930–960‰; and 980–1000‰. The data obtained indicated a multistage, possibly polygenic, and probably polychronous formation of GBN gold–uranium mineralization. The first stage was the formation of early quartz–nasturanium–gold–W–rutile–magnetite association (Middle–Late Paleozoic age). The second was the crystallization of brannerite and the replacement of an earlier pitchblende with brannerite (Late Triassic (T3)–Early Jurassic (J1) age). The third was the formation of the hematite–barite–rutile–gold association as a result of deformation–hydrothermal processes, which was associated with the appearance of zones of alteration in brannerite in contact with native gold with 8–15 wt.% Ag. The fourth was hypergene or the low-temperature hydrothermal alteration of minerals of early stages with the development of iron hydroxides (goethite) with impurities of manganese, tellurium, arsenic, phosphorus, and other elements. The carbon isotopic composition of an organic substance indicates the involvement of a biogenic carbon source. In the OOC area, there were signs that the composition of the GBNs and the quartz–chlorite–K–feldspar-containing rocks corresponded to Elkon-type deposits.
... It also has lower content of As (1.11 wt.%) and higher contents of Fe (up to 9.34 wt.%), Cu (up to 35.27 wt.%), Sb (up to 26.43 wt.%), and S (up to 26.46 wt.%) and contains an impurity of Zn (≤0.88 wt.%). The variations in the Cu and Ag proportions show that the composition of the fahlore significantly deviates from the reference one toward its cuprous varieties (Ramdohr, 1969;Borisenko, 1977). ...
Охарактеризовано Мяучанское рудное поле, расположенное в пределах Омсукчанской зоны Охотско-Чукотского вулканогенного пояса. Составляющие рудное поле Ag-Pb-Zn рудопроявления Коренное и Малютка локализованы в центральной части антиклинальной складки северо-западного простирания, сложенной верхнетриасовыми карбонатно-терригенными толщами, прорванными штокообразными телами и дайками позднемеловых андезитов, монцодиоритов, гранит-порфиров и риолитов. Сульфидно-карбонат-флюорит-кварцевые жилы и жильно-прожилковые зоны с арсенопиритом, пиритом, сфалеритом, галенитом, халькопиритом, Ag-тетраэдритом распространены как в интрузиях, так и в терригенных толщах. Геохимический спектр минерализации As-Sb-Ag-Pb-Au-Bi-Cu-Zn-W. Результаты изучения флюидных включений наряду с данными по распределению редкоземельных и рудных элементов указывают на формирование руд в эпитермальной обстановке гидротермально-магматической системы из хлоридных растворов с участием поверхностных вод. Отложение руд происходило в диапазоне температур 106—287 °С из растворов соленостью от 0.5 до 9.0 мас. % NaCl-экв. Руды, содержащие Ag порядка 70 г/т и Pb до 1.2 %, формировались в условиях выкипания из растворов, обогащенных солями Fe; руды с содержанием Ag менее 7 г/т, а Pb до 25 г/т образовались в условиях разбавления из гидротерм, в составе которых преобладали соли Na с незначительной примесью K. Минерализация Мяучанского рудного поля представляет верхний уровень Ag-Pb-Zn рудной системы, аналогичной месторождению Гольцовое.
The Myauchan ore field located in the Omsukchan zone of the Okhotsk–Chukotka Volcanic Belt is described. The Korennoe and Malyutka Ag–Pb–Zn ore occurrences forming this field are localized at the center of anticlinal fold of NW strike made up of Upper Triassic carbonate-terrigenous deposits intruded by stock-like bodies and dikes of Upper Cretaceous andesite, monzodiorite, granite-porphyry, and rhyolite-porphyry. Sulfide–carbonate–fluorite–quartz veins and vein–veinlet zones with arsenopyrite, pyrite, sphalerite, galena, chalcopyrite, and Ag-tetrahedrite are localized both in intrusions and in terrigenous strata. The field bears As–Sb–Ag–Pb–Au–Bi–Cu–Zn–W mineralization. Study of fluid inclusions and REE and ore element patterns show that the field ores formed from chloride solutions with the participation of surface waters in hydrothermal-magmatic system under epithermal conditions. The ores were deposited from solutions with TDS = 0.5–9.0 wt.% NaCl equiv. in the temperature range 106–287 ºC. The ores containing ca. 70 ppm Ag and up to 1.2% Pb formed through boiling-off of solutions enriched in iron salts. The ores with Ag < 7 ppm and Pb ≤ 25 ppm were generated from diluted hydrothermal solutions with predominant sodium salts and potassium admixture. Mineralization of the Myauchan ore field marks the upper level of the Ag–Pb–Zn ore system similar to the Gol’tsovoe deposit.
... The most common gangue minerals in the studied samples are chlorite, albite, sericite, actinolite, epidote, and quartz Deformed pyrites are the main pyritic generation that was recognized in the Gallala sulfide mineralization. Deformation and fracturing of the ore bodies occurred syn-genetically or epigenetically due to shearing resulting in the brecciated texture of the coarse pyrite grains (Craig et al., 1981, Pracejus, 2015, Awadh, 2006, Ramdohr, 2013 (Fig. 7fc). ...
In this article, a Fe-rich sulfide mineralization hosted within the Walash Group in the Gallala area, on the northwestern side of the Zagros Orogen is investigated for the first time. The mineralization occurs as massive sulfide veins and veinlets, as well as disseminated within volcanic lithologies. The objective of the study is to characterize the sulfide-rich mineralization using petrographical and geochemical methods, applied in both the ores and the corresponding host formations, including the characterization of volcanic rock alteration. Petrographic data indicates the presence of Fe-rich sulfide mineralization in altered basaltic andesite to andesite rocks, which are affected by hydrothermal alteration such as actinolization, chloritization, sericitization, and epidotization. The geochemical analysis of the fresh rock samples reveals enrichment of iron in the suture zones, but low copper and zinc concentrations. The mineralogical and textural signatures of sulfide minerals lead to inferring that the ore mineralization origin is volcanogenic to the hydrothermal type of deposits.
... The production of red blood cells, the development of connective tissue, and the functioning of the neurological and immunological systems all depend on copper. Each mineral serves a distinct purpose, so it is crucial to get enough of them through a balanced diet to preserve optimum health (18). ...
Nutrigenetics and nutrigenomics are two interrelated fields that explore the influence of genetic diversity on nutrient responses and function. While nutrigenetics investigates the effects of hereditary ge-netic variations on micronutrient metabolism, nutrigenomics examines the intricate relationship between diet and the genome, studying how genetic variants impact nutrient intake and gene expression. These disciplines offer valuable insights into predicting and managing chronic diseases through personalized nutritional approaches. Nutrigenomics employs cutting-edge genomics technologies to study nutrient-genome interactions. Key principles involve genetic variability among ethnic groups, affecting nutrient bioavailability and metabolism, and the influence of dietary choices based on cultural, geographic, and socioeconomic factors. Polymorphisms, particularly single-nucleotide polymorphisms (SNPs), significantly influence gene activity and are associated with specific phenotypes that are related to micronutrient deficiencies. Minerals are inorganic elements, vital for various physiological functions. Understanding the SNPs associated with mineral deficien-cies is crucial for assessing disease risk and developing personalized treatment plans. This knowledge can inform public health interventions, targeted screening programs, educational campaigns, and fortified food products to address deficiencies effectively. Nutrigenomics research has the potential to revolutionize clinical and nutritional practices, providing personalized recommendations, enhancing illness risk assessment, and advancing public health initiatives. Despite the need for further research, harnessing nutrigenomics' potential can lead to more focused and efficient methods for preventing and treating mineral deficiencies.
... It also has lower content of As (1.11 wt.%) and higher contents of Fe (up to 9.34 wt.%), Cu (up to 35.27 wt.%), Sb (up to 26.43 wt.%), and S (up to 26.46 wt.%) and contains an impurity of Zn (≤0.88 wt.%). The variations in the Cu and Ag proportions show that the composition of the fahlore significantly deviates from the reference one toward its cuprous varieties (Ramdohr, 1969;Borisenko, 1977). ...
The Myauchan ore field located in the Omsukchan zone of the Okhotsk–Chukotka Volcanic Belt is described. The Korennoe and Malyutka Ag–Pb–Zn ore occurrences forming this field are localized at the center of anticlinal fold of NW strike made up of Upper Triassic carbonate-terrigenous deposits intruded by stock-like bodies and dikes of Upper Cretaceous andesite, monzodiorite, granite-porphyry, and rhyolite-porphyry. Sulfide–carbonate–fluorite–quartz veins and vein–veinlet zones with arsenopyrite, pyrite, sphalerite, galena, chalcopyrite, and Ag-tetrahedrite are localized both in intrusions and in terrigenous strata. The field bears As–Sb–Ag–Pb–Au–Bi–Cu–Zn–W mineralization. Study of fluid inclusions and REE and ore element patterns show that the field ores formed from chloride solutions with the participation of surface waters in hydrothermal-magmatic system under epithermal conditions. The ores were deposited from solutions with TDS = 0.5–9.0 wt.% NaCl equiv. in the temperature range 106–287 ºC. The ores containing ca. 70 ppm Ag and up to 1.2% Pb formed through boiling-off of solutions enriched in iron salts. The ores with Ag < 7 ppm and Pb ≤ 25 ppm were generated from diluted hydrothermal solutions with predominant sodium salts and potassium admixture. Mineralization of the Myauchan ore field marks the upper level of the Ag–Pb–Zn ore system similar to the Gol’tsovoe deposit.
... This exhibits the stability of pyrite and other ore minerals during metamorphic changes. These primary textures are considered to be the result of colloidal precipitation (Ramdohr 1980), mineral crystallization from supersaturated solution, or rapid nucleation and limited crystal growth . It is suggested that this texture in the Naweoba deposit indicates the interaction of high-temperature mineralized solution with cold ambient seawater, causing rapid precipitation of pyrite on the seafloor. ...
The petrography, mineralization, and geochemistry and isotope studies of sulfide ores were used to determine the genesis of the Naweoba and Bagh Volcanogenic Massive Sulfide (VMS) deposits. These deposits consist of minor stockwork, massive sulfide, and gossan zones. They are hosted by basaltic rocks in the Naweoba Block and Bagh Complex of Zhob Valley Ophiolites, respectively. The host rocks are strongly altered to chlorite and sericite. By using whole rock and pyrite in situ analyses, it is found that the Cu concentration is higher compared to Zn and Pb. Similarly, the primary mantle normalized data of Pb, Cu, Ag, Au, and Zn as well as the high Co/Ni ratios (> 1) in pyrite for both deposits indicate that these deposits have a mafic origin dominated by hydrothermal processes. The trace element signature in pyrite and chalcopyrite in these deposits suggests that mineralization formed at high to moderate temperatures. The δ34S values of pyrite (2.4–4.6‰) and chalcopyrite (2.7–5.7‰) indicate that hydrothermal fluids have derived sulfur largely from basaltic igneous rocks. The above signatures are all consistent with a Cyprus-type VMS ore deposits associated with ophiolites. Moreover, it was found that several trace elements (Ni, Co, Se, Zn, Pb, Sb, and As) show systematic variations in pyrite from Naweoba that are correlated to the stratigraphic depth and can be used as a proxy to separate deeper from shallower sulfide ores.
... In addition, the intergrowth of sphalerite and various mineral inclusions such as chalcopyrite, pyrrhotite and pyrite have been explained by exsolution, coprecipitation, or replacement mechanisms Bortnikov et al., 1991;Nagase and Kojima, 1997;Çi˙Ftçi˙, 2011;Govindarao et al., 2018). Therefore, the combined features of mineral assemblage, textures and chemical compositions of sphalerite and associated mineral inclusions can help understand the Pb-Zn mineralizing process (Ramdohr, 1969;Cook et al., 2009;Ye et al., 2011;Cugerone et al., 2020). ...
The northeastern Hunan Province hosts numerous hydrothermal Pb-Zn(-Cu-Co) polymetallic deposits. As a representative example, the Jingchong Cu-Co-Pb-Zn deposit is characterized by the lower Cu-Co and upper Pb-Zn mineralization, whereas little is known about Pb-Zn mineralization. In this study, three generations of sphalerite were identified based on their textural and geochemical differences. The Sph-I exhibits the oscillatory zoning that consists of reddish-brown Sph-Ia (poor in chalcopyrite inclusion) alternating with dark Sph-Ib with zoned chal-copyrite inclusion. Sph-II is composed of honey-brown Sph-IIa (abundant chalcopyrite droplets) and white clean Sph-IIb (rare chalcopyrite inclusion). The black Sph-III is characterized by nano-to submicron-sized chalcopyrite inclusions with typical "dusting" or "watermelon" texture and crosscuts all other sphalerite generations in vein-lets. The electron microprobe and laser ablation inductively coupled plasma mass spectrometry show that Sph-I has higher Fe and Mn contents, but lower Cd, Cu and Ag contents than Sph-II and Sph-III. Sphalerite geother-mometry yields temperatures of 334-346 (±58)°C for Sph-I, 254-289 (±60)°C for Sph-II and 286 (±55)°C for Sph-III. The sulfur fugacity ranges from logfS 2 values of −9.03 to −8.26 for Sph-I to −11.77 to −10.63 for Sph-II and −10.82 for Sph-III. The combined textural features and chemical compositions indicate that the self-organized mechanism forms Sph-I, and that the coupled dissolution and precipitation reactions triggered by the influx of Cu-elevated fluids are responsible for the formation of Sph-II and Sph-III. The associated pyrite and pyrrhotite inclusions in sphalerite are produced by the exsolution mechanism, while chalcopyrite inclusions are formed by co-precipitation due to local supersaturation at the interface of sphalerite with fluid. The 40 Ar-39 Ar dating of muscovite in the Jingchong deposit yields a mineralizing age of ca. 121.1 ± 2 Ma, consistent with the ca. 130-120 Ma Pb-Zn mineralizing events in the northeastern Hunan Province. The sulfur isotopic values (−3.0 to +3.5‰) of the Pb-Zn ores are similar to that of Cu-Co ores, indicating a magmatic sulfur origin. Together with the trace element affinity of sphalerite with magmatic-hydrothermal origin, it was proposed that the Jingchong Pb-Zn and Cu-Co mineralization were formed in the same magmatic-hydrothermal system. The placement of Pb-Zn orebodies at the upward zoning of Cu-Co orebodies could be attributed to the higher solubilities of Pb and Zn chloride complexes in hydrothermal fluids, relative to Cu chloride complex.
... The most common gangue minerals in the studied samples are chlorite, albite, sericite, actinolite, epidote, and quartz Deformed pyrites are the main pyritic generation that was recognized in the Gallala sulfide mineralization. Deformation and fracturing of the ore bodies occurred syn-genetically or epigenetically due to shearing resulting in the brecciated texture of the coarse pyrite grains (Craig et al., 1981, Pracejus, 2015, Awadh, 2006, Ramdohr, 2013 (Fig. 7fc). ...
Petrographical and Geochemical Features of Sulfide Mineralization in the Walash Group, Gallala Area, Kurdistan Region of Iraq
... The mineralogical association, mosaic of arrangement, and their interrelationship described as texture in geological literature is related to their genetic link in geological evolution history. On the other hand, process engineering literature expresses the ore texture in terms of their mineralogical assemblage, such as hematite-goethite texture, martite-goethite texture, etc. [16]. While geological textural terminology (viz. ...
After being subjected to geometallurgical evaluation, the iron ores from Singhbhum Bonai-Keonjhar region, eastern India, have been designated as dense martite microplaty hematite high-strength ore (dM-mH-hs ore), massive dense martite microplaty hematite high-strength ore (mdM-mH-hs ore), schistose microplaty hematite low-strength ore (smH-ls ore), microplaty hematite powdery ore (mH-p ore), vitreous goethitic ore (vG ore), and ochreous goethitic ore (oG ore) end members, with varied strengths attributed to the microporosity levels. The first four variants form typical high-grade run-of-mines (ROMs) (hard, soft and powdery iron ore variants, e.g., ROM-HIO, ROM-SSIO, and ROM-PBD, respectively) with better amenability to beneficiation. In contrast, oG and vG ore end members form ROM lateritic iron ore (ROM-LIO) with poor amenability to beneficiation, having relatively higher concentrates of alumina (~3–6 wt%) due to the complex mineral chemistry of goethite and altered hematite. Banded hematite jasper (BHJ) is a very low-grade siliceous end member. In a mining operation, the ROMs may have the attributes of several combinations of the above-stated end members and ROM variants. The designated end members present in the ROMs determine their liberation, mineralogical processes, geometallurgical characteristics, amenability to beneficiation, product grade and recovery.
... The usually pockmarked titaniferous magnetite (called ''Ti-magnetite'' from now on) shows exsolution textures of an Fe-Al-spinel and locally reaction fronts with homogeneous ilmenite (Fig. 5B, F), indicative of a high-temperature magmatic origin of this assemblage (e.g., Ramdohr 1969). Notably, in addition to olivine, Ti-magnetite and ilmenite may also host idiomorphic inclusions of Pt-Fe alloys (Fig. 5E, F, G). ...
The Mooihoek pipe is one of several platiniferous dunite pipes in the eastern Bushveld Complex that were discovered in 1924 and mined until 1930. It has a diameter of about 180 by 400 m and consists of magnesian dunite that crosscuts a sequence of layered leucocratic wall rocks of the lower part of the upper Critical Zone of the Bushveld Complex. The Mg-dunite pipe at Mooihoek hosts a smaller, carrot-shaped inner pipe, 13–16 m in diameter and cylindrical in shape near surface, consisting of mainly iron-rich dunite/wehrlite pegmatite, comprising the platinum-bearing orebody. Specific characteristics of the mineralization are the near absence of sulfides and Pt being the predominant platinum-group element (PGE).
The present work comprises whole rock analyses, ore microscopy, scanning electron microscopy, and electron probe microanalysis. The main findings are as follows: Chondrite-normalized distribution patterns of the PGE in the Mooihoek samples demonstrate that mainly Pt is strongly enriched relative to the other PGE and Au. The shapes of the patterns are subparallel to each other and also to those of the Onverwacht pipe, indicating a similar mode of origin. Olivine of the ore zone is iron-rich and is frequently accompanied by coarse Ti-magnetite and ilmenite, whereas chromite is rare. Two major generations of platinum-group minerals (PGM) are present at Mooihoek, namely: (1) Early inclusions of mainly ferroan platinum in (magmatic) olivine, Ti-magnetite, and ilmenite, and (2) a later, more complex PGM assemblage, commonly associated with thin veinlets of magnetite, mainly found along grain boundaries of silicates and oxides. This assemblage consists of various Pt-Fe alloys and PGE-antimonides, -sulfarsenides, -arsenides, and -sulfides. Overall, and in line with the geochemical data of the mineralization, Pt-dominated PGM predominate (~70%), followed by Rh, Pd, and Ru species. Pt-Fe alloys are the most frequent PGM (∼44% by number of grains).
Our hypothesis on the genesis of the Mooihoek pipe and its mineralization largely corresponds to that proposed for the Onverwacht pipe (Oberthür et al. 2021): The magnesian dunite pipe was formed by upward penetration of magmas which replaced the existing cumulates. Fractional crystallization of olivine within a deeper magma chamber and/or during ascent of the melt resulted in the formation of a consanguineous residual, more iron-rich, and PGE-enriched melt. This melt also contained highly mobile, supercritical fluids and was continuously enriched in PGE and other incompatible elements. The PGE-enriched residual melts formed and sealed the inner ore pipe. Apparently, the PGE mineralization is not related to the well-established mechanism of sulfide collection. Instead, it was introduced in the form of nanoparticles and small droplets of PGM, which coagulated to form larger grains during evolution of the mineralizing system. Concomitant supercritical magmatic to hydrothermal fluids were continuously active and caused a certain redistribution of the initial PGE inventory and possibly added further quantities of PGE from lower parts of the mineralizing system. Reactions with ligands like Sb, As, and S led to the formation of composite PGM grains and complex intergrowths in a continuous process of mineralization. The present work underlines that sulfide-poor magmas may constitute fertile potential precursors of PGE deposits and, therefore, deserve more attention in future exploration.
... Investigations on ore association, geologic occurrence, country rock and its alteration, total mineral composition of the ore, the likely composition of the ore solution, etc. can be derived from the study of ore texture (Ramdohr, 1969). This is an important genetic interpretation that can possibly yield. ...
The Thanagazi Formation of the North Delhi Fold Belt (NDFB) is extensively explored for copper mineralization. Copper occurs predominantly in quartz veins in volcanic rocks and quartz-carbonate veins hosted in dolomite of the Thanagazi Formation belonging to the Alwar basin. Sulphide mineralization in volcanic rocks includes sulphide ore minerals such as chalcopyrite, galena, sphalerite, and arsenopyrite. This study encompasses the ore mineralogy and textures of sulphide phases associated with quartz veins in the Thanagazi Formation. It is related to chalcopyrite, pyrite, and pyrrhotite mineral assemblages. Secondary alteration products such as malachite and iron oxides are also associated with copper mineralization considered as the surface indicators
The Ain El Bey abandoned mine, in North-West Tunisia, fits into the geodynamic context of the European and African plate boundary. Ore deposit corresponds to veins and breccia of multiphase Cu–Fe-rich mineralization related to various hydrothermal fluid circulations. Petro-mineralogical studies indicate a rich mineral paragenesis with a minimum of seven mineralization phases and, at least, six pyrite generations. As is also the case for galena and native silver, native gold is observed for the first time as inclusion in quartz which opens up, thus, new perspectives for prospecting and evaluating the potential for noble metals associated with the mineralization. Scanning Electron Microscope—Energy Dispersive Spectroscopy and Transmission electron microscopy analyses show, in addition, a large incorporation of trace elements, including Ag and Au, in mineral structures such as fahlores (tetrahedrite-tennantite) and chalcopyrite ones. The mineral/mineral associations, used as geothermometers, gave estimated temperatures for the mineralizing fluids varying from 254 to 330 °C for phase III, from 254 to 350 °C for phase IV, and from 200 to 300 °C for phases V and VI. The seventh and last identified mineralization phase, marked by a deposit of native gold, reflects a drop in the mineralizing fluid’s temperature (< 200 °C) compatible with boiling conditions. Such results open up perspectives for the development of precious metal research and the revaluation of the Cu–Fe ore deposit at the Ain El Bey abandoned mine, as well as at the surrounding areas fitting in the geodynamic framework of the Africa-Europe plate boundary.
The Neoproterozoic peridotites of Abu Dahr, Eastern Desert of Egypt, consist mainly of highly depleted harzburgites that have experienced multiple stages of serpentinization (lizarditization and antigoritization) and carbonation/listvenitization in a forearc environment. The Abu Dahr forearc harzburgites are more oxidized than oceanic mantle, with the oxygen fugacity (fO2) values ranging from FMQ+0.41 to FMQ+1.20 (average = +0.60 FMQ), and were equilibrated at temperatures of 910–1217 °C and pressures of 4.1–7.8 kbar. This study has documented for the first time the presence of various Ni-rich Ni-Fe (-Co) sulfide and metal phases along with Fe-oxides/oxyhydroxides in serpentinized-carbonated peridotites of the Abu Dahr forearc. Here I concentrate on the relationship between redox state and Fe-Ni-Co-O-S minerals with emphasis on the role of hydrothermal processes in upgrading magmatic sulfide tenors, desulfurization (sulfur-loss) of magmatic pentlandite and hydrothermal upgrading of the sulfide phases in Abu Dahr forearc environment. The minerals involved are high-Ni pentlandite (Fe4Ni5S8), cobaltian pentlandite (Fe3.47Ni4.78Co0.75S8), heazlewoodite (Fe0.07Ni2.93S2), godlevskite (Fe0.26Ni8.73Co0.01S8), millerite (Fe0.01Ni0.98Cu0.01S), awaruite (Ni75Fe21) and native Ni (Ni93Fe5), and nickeliferous magnetite and goethite. Chalcopyrite is a rare mineral; other Cu-phases, Fe-sulfides and Ni-arsenides/phosphides are not present. Texturally, Ni-sulfide and alloy minerals occur as interstitial disseminated blebs of either solitary phases or composite intergrowths with characteristic replacement textures, documenting strong variations in oxygen and sulfur fugacities (fO2-fS2). Sulfide assemblages are divided into three main facies: (1) pentlandite-rich; (2) godlevskite-rich; and (3) millerite-rich. Textural relationships imply the following sequence: (a) primary pentlandite → cobaltian pentlandite, with partial replacement of the latter by awaruite and/or heazlewoodite along with magnetite; (b) heazlewoodite is replaced by godlevskite, which in turns is replaced by millerite; (c) Ni-rich awaruite breaks down to millerite; and finally, (d) magnetite is completely replaced by goethite. The sulfide mineralogy reflects the magmatic and post-magmatic evolution of the complex. The primary magmatic processes gave rise to pentlandite, whereas the secondary Ni-sulfides together with the metallic alloys formed in response to changing fO2 and fS2 conditions associated with post-magmatic serpentinization and carbonation. Serpentinization-related Ni-Fe-Co remobilization from magmatic olivines resulted in; (1) upgrading the Ni-Co tenors of pre-existing primary pentlandite, and desulfidation to form low-sulfur sulfides (mainly heazlewoodite) and awaruite under extremely low fO2 and fS2 conditions; (2) in situ precipitation of secondary Ni-sulfides in the presence of extra sulfur as aqueous H2S derived from the desulfurization of magmatic pentlandite or native Ni when fS2 approaches 0; (3) transformation from low-sulfur pentlandite- and godlevskite-rich assemblages to the high-sulfur millerite-rich assemblages related to later carbonation with increasing fO2; and (4) partial dehydration of antigorite serpentinites under high-pressure conditions (>1 GPa) generated Ni-rich awaruite in equilibrium with the prograde assemblage antigorite-metamorphic olivine at higher fO2 and fS2 within subduction channel. The mineralogical, chemical, and thermal similarities with other serpentinite-related Ni-sulfides worldwide suggest that Ni minerals in the Fe-Ni-Co-O-S system record changing fO2 and fS2 during progressive serpentinization and carbonation.
The Churan gold deposit is located 70 km from Sirjan in the Dehaj– Sarduyeh structural subzone from Orumieh-Dokhtar magmatic arc. The mineralization in the Churan is classified as an Intrusion-related gold deposit and Hydrothermal alterations associated with the mineralization contain silicification, sulfidation, tourmalinization, and sericitization. Based on paragenetic and mineralogical relationships, quartz veins have been grouped into seven distinct categories;i) sulfide and sulfosalt minerals vein and veinlets, ii) base metal ore mineral vein and veinlets, iii) Arsenopyrite veins and veinlets, iv) tourmaline-rich vein and veinlets (and sericite), v) quartz-tourmaline veins and veinlets, vi) Pyrite quartz vein and veinlets, vii) The late stage quartz vein and veinlets jarosite. Investigating of relationships and mineralogical characteristics of quartz-tourmaline veins and veinlets shows that containing significant amounts of arsenopyrite (and pyrite) in veins and veinlets is associated with higher amounts of gold in the Churan deposit, higher contents of pyrite and arsenopyrite in the Churan deposit different types of porphyry and epithermal deposits. Keywords: Churan deposit, gold and copper vein and veinlets, arsenopyrite and pyrite, Intrusion-related gold.
In equatorial and tropical regions, supergene mineral deposits created during water/rock interactions are found. Simply put, these supergene deposits are formed through the accumulation of low solubility ions or through the preservation of primary minerals. The supergene manganese (Mn) deposits are examples of the economic importance associated with the chemical weathering processes. In Brazil, the Southern Brasilia Orogen (SBO) was generated during the collision between the Paranapanema Craton and the passive margin of the São Francisco Craton. In the southern Minas Gerais (MG), several supergene Mn occurrences are hosted in the SBO, which were originated during the chemical weathering of gondites belonging to the Amparo Complex. Here, we studied the supergene Mn occurrences in the southern MG, more specifically in the municipalities of Ouro Fino and Careaçu. The MnO contents ranged from 25.50 to 28.40 wt% at Ouro Fino and from 16.80 to 21.20 wt% at Careaçu. These supergene Mn deposits have a diverse mineral assemblage, being composed of spessartine, quartz, Mn-oxides, goethite and kaolinite. The various Mn minerals formed due to spessartine incongruent dissolution were hollandites, cryptomelanes, romanechites, pyrolusites and lithiophorites. Both study areas are relevant for the possible opening of mines for the commercialization of Mn.
Copper(I) sulfide (Cu2S) is a low-cost, earth-abundant, and non-toxic thermoelectric material for applications in the middle-high temperature range (>650 K). Although 3D printing these materials can simplify their manufacturing, elevated temperatures observed during sintering impair their crystal structure and energy conversion efficiency. In this study, we demonstrated a novel post-processing methodology to revert the thermoelectric properties of the 3D printed Cu2-xS materials back to the unimpaired state via sulfur infusion. After printing and sintering, sulfur was infused into the specimens under vacuum to optimize their crystal structure and achieve high thermoelectric efficiency. Chemical analysis and X-ray Diffraction (XRD) tests showed that after the sulfur infusion process, the Cu/S ratio was reverted close to the stoichiometric level. 3D printed Cu2-xS showed p-type thermoelectric behavior with electrical conductivity peaking at 143 S-cm-1 at 750 K and Seebeck coefficient of 175 µV-K-1 at 627 K. Figure of merit (ZT) value of 1.0 at 780 K was achieved which is the highest value ever reported for a 3D printed Cu2-xS thermoelectrics at this temperature. Fabrication of environmentally friendly thermoelectric materials with extended dimensional freedom and conversion efficiency has the potential to impact the thermoelectric industry with new energy conversion applications and lowered manufacturing costs.
In nature, minerals are usually found in association, forming rocks. Ores are no exception: they are almost always composed of different species, forming intergrowths. The study, description and interpretation of these intergrowths is the objective of textural analysis and is very important for mineralogy, both from a scientific point of view (e.g. mineral genesis) and for a practical approach (e.g. mining exploration and minerallurgy).
This chapter describes Rutile (abbrv. rt), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 14 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as new quantitative specular reflectance information and graphs (visible and near-infrared ranges: 400–1000 nm).
This chapter describes Stephanite (abbrv. stp), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 8 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as some comparative specular reflectance graphs (visible range: 400–700 nm).
This chapter presents the main concepts and the observation methodology applied for optical ore microscopy. It also introduces the reader to its industrial applications. The state of the art shows the need and the recent progress of automation, an aspect addressed in Part II, vol. 2. Although the ore minerals are numerous, those which are either interesting for the industry or important due to their abundance are not so many, their number varying roughly, according to different sources, from some 30 to about 100 species. These are identified as common ores, even if some of them are actually scarce. The practical selection criteria applied limit their number to some 150 ores which define the scope of the book, adding some frequent gangue minerals. To facilitate consultation, a systematic description plan is followed. This includes a practical guide for the microscopic characterisation of ores, comprising observations with single polariser/crossed polars, both in air/oil, as well as the presentation of data and the identification methodology. A set of full-coloured, systematic photomicrographs provide for each ore an additional characterisation tool, completed by multispectral reflectance information and comparative graphs. To conclude, the use of determinative tables for ore identification is discussed, referring to the materials presented in the Annexes. Even if the text addresses primarily senior professionals, the practical guidelines included should also ensure students and junior mineralogists can make good use of it. The metallic ores are grouped according to their priority for training, either professional training (i.e. lifelong learning, LLL) or academic teaching. A paragraph with practical recommendations (or learning strategy for beginners) and two boxes with schemes for ore characterisation complete the chapter.
This chapter describes the very common ore Pyrite (abbrv. py), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 20 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as new quantitative specular reflectance information and graphs (visible and near-infrared ranges: 400–1000 nm).
This chapter describes Mackinawite (abbrv. mck), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 7 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as quantitative specular reflectance information with comparative graphs.
This chapter describes the aurian silver Ag–Au, traditionally known as electrum or gold-silver alloy (abbrv. el), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks). The microscopic description of the ore is then presented, following a systematic scheme. This comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives). The description is illustrated by four selected, high-quality full-colour photomicrographs under the four settings (d/osp, d/o+p), enriched by a discussion of paragenesis and of the diagnostic properties for identification of the ore, and supported by quantitative specular reflectance information, mostly new spectra in the visible and near-infrared (VNIR) ranges, unpublished to date and useful for automated identification with computer vision (AMCO System).
This chapter describes the important copper ore Chalcocite (abbrv. cc), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks). The microscopic description of the ore is then presented, following a systematic scheme.This comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives). The description is illustrated by 9 selected, high-quality full-colour photomicrographs under the four settings (d/osp, d/o + p), enriched by a discussion of paragenesis and of the diagnostic properties for identification of the ore, and supported by quantitative specular reflectance information, mostly new spectra in the visible and near-infrared (VNIR) ranges, unpublished to date and useful for automated identification with computer vision (AMCO System).
This chapter describes Safflorite (abbrv. sf), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 8 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as new quantitative specular reflectance information and graphs (visible and near-infrared ranges: 400–1000 nm).
This chapter describes Stibarsen (abbrv. sba), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 7 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as some comparative specular reflectance graphs (visible range: 400–700 nm).
This chapter describes Pyrochlore (abbrv. pyc), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 4 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as new quantitative specular reflectance information and graphs (visible and near-infrared ranges: 400–1000 nm).
This chapter describes Platinum (abbrv. Pt), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by ten selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as new quantitative specular reflectance information and graphs (visible and near-infrared ranges: 400–1000 nm).
This chapter describes the iron oxide compound known as Limonite (abbrv. lim), as seen with optical, reflected light microscopy. The presentation, including a discussion of composition, types and meaning of limonite for exploration, follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 14 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification.
This Chapter describes Isocubanite (abbrv isc), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 5 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification.
This chapter addresses the concept of gangue minerals, as an unavoidable company of ores, and comprises some introductory remarks to address the difficult problem of gangue characterisation by reflected light, RL, microscopy. Most of the gangue is composed of transparent minerals and consequently the most straightforward method of optical microscopy should apply transmitted light, as is done in petrography. However, the gangue minerals are also present in the polished section whose ores are to be studied. Therefore, to optimise the information gathered from microscopy, even these transparent minerals should be characterized as far as possible. So, after showing the problems of the RL microscope to define transparent minerals, the chapter proceeds to define and select the common gangue minerals (≈ 50, compiled in Table 133.1). Most of them belong to the Berzelius classes VIII (Silicates) and V (Carbonates, Nitrates, Borates). Nevertheless, some gangue minerals are found in other classes as well, e.g. Class III (Oxides and Hidroxides), Class IV (Halides) or Class VI (Sulphates, etc.), or even as the particular (often ill-defined) products grouped as Organic Matter and Coals.
This chapter describes native Silver (abbrv. Ag), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 8 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as new quantitative specular reflectance information and graphs (visible and near-infrared ranges: 400–1000 nm).
This chapter describes Chlorargyrite (abbrv. cag), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks). The microscopic description of the ore is then presented, following a systematic scheme. This comprises observation under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives). The description is illustrated by 4 selected, high-quality full-colour photomicrographs under the four settings (d/osp, d/o+p), enriched by a discussion of paragenesis and of the diagnostic properties for identification.
This chapter describes Psilomelane (abbrv. psi), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by ten selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as new quantitative specular reflectance information and graphs (visible and near-infrared ranges: 400–1000 nm).
This chapter describes Polybasite (abbrv. plb), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by ten selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as new quantitative specular reflectance information and graphs (visible and near-infrared ranges: 400–1000 nm).
This chapter describes Pyrrhotite (abbrv. po), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 10 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as new quantitative specular reflectance information and graphs (visible and near-infrared ranges: 400–1000 nm).
This chapter describes chromite (abbrv. chr), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks). The microscopic description of the ore is then presented, following a systematic scheme. This comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives). The description is illustrated by 10 selected, high-quality full-colour photomicrographs under the four settings (d/osp, d/o+p), enriched by a discussion of paragenesis and of the diagnostic properties for identification of the ore, and supported by quantitative specular reflectance information, mostly new spectra in the visible and near-infrared (VNIR) ranges, unpublished to date and useful for automated identification with computer vision (AMCO System).
This Chapter describes the important ore Columbotantalite-cbt (abbrv. cbt), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks). The microscopic description of the ore is then presented, following a systematic scheme. Columbite, tantalite and other members of the group are discussed as well. The scheme comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives). The description is illustrated by 20 selected, high-quality full-colour photomicrographs under the four settings (d/osp, d/o +p), enriched by a discussion of paragenesis and of the diagnostic properties for identification of the ore, and supported by quantitative specular reflectance information, mostly new spectra in the visible and near-infrared (VNIR) ranges, unpublished to date and useful for automated identification with computer vision (AMCO System).
This chapter describes the important silver ore acanthite (abbrv. ac), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks). The microscopic description of the ore is then presented, following a systematic scheme. This comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives). The description is illustrated by nine selected, high-quality full-colour photomicrographs under the four settings, enriched by a discussion of paragenesis and of the diagnostic properties for identification of the ore, and supported by quantitative specular reflectance information.
This chapter describes Cosalite (abbrv. cos), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks). The microscopic description of the ore is then presented, following a systematic scheme. This comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives). The description is illustrated by 6 selected, high-quality full-colour photomicrographs under the four settings (d/osp, d/o+p), enriched by a discussion of paragenesis and of the diagnostic properties for identification of the ore, and supported by quantitative specular reflectance information, mostly new spectra in the visible and near-infrared (VNIR) ranges, unpublished to date and useful for automated identification with computer vision (AMCO System).
This chapter describes the important copper ore Bornite (abbrv. bn), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks). The microscopic description of the ore is then presented, following a systematic scheme.This comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives). The description is illustrated by 10 selected, high-quality full-colour photomicrographs under the four settings (d/osp, d/o+p), enriched by a discussion of paragenesis and of the diagnostic properties for identification of the ore, and supported by quantitative specular reflectance information, mostly new spectra in the visible and near-infrared (VNIR) ranges, unpublished to date and useful for automated identification with computer vision (AMCO System).
This chapter describes Sternbergite (abbrv. stb), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by 7 selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as some comparative specular reflectance graphs (visible range: 400–700 nm).
This chapter describes Bournonite (abbrv. Bnn), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks). The microscopic description of the ore is then presented, following a systematic scheme. This comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives). The description is illustrated by 4 selected, high-quality full-colour photomicrographs under the four settings (d/osp, d/o+p), enriched by a discussion of paragenesis and of the diagnostic properties for identification of the ore, and supported by quantitative specular reflectance information.
This chapter describes the important manganese ore Pyrolusite (abbrv. prl), as seen with optical, reflected light microscopy. After summing up compositional data, main properties and optical parameters, the presentation follows a systematic scheme to facilitate consultation and comparison with other ores. The description comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives), illustrated by seven selected, high-quality full-colour photomicrographs. It also includes a discussion of paragenesis and diagnostic properties for identification, as well as new quantitative specular reflectance information and graphs (visible and near-infrared ranges: 400–1000 nm).
This Chapter describes Enargite (abbrv. en), as seen with optical, reflected light microscopy. Compositional data, main properties and optical parameters are first summarized (introductory table and preliminary remarks). The microscopic description of the ore is then presented, following a systematic scheme. This comprises qualitative observations under the four common microscope settings (single polarizer/crossed polars; dry/immersion objectives). The description is illustrated by 8 selected, high-quality full-colour photomicrographs under the four settings (d/osp, d/o+p), enriched by a discussion of paragenesis and of the diagnostic properties for identification of the ore, and supported by quantitative specular reflectance information, mostly new spectra in the visible and near-infrared (VNIR) ranges, unpublished to date and useful for automated identification with computer vision (AMCO System).
ResearchGate has not been able to resolve any references for this publication.