Mineral Prospecting/Mineral Exploration/Field Geology/Ore mineralogy/Petrography/Ore Deposits Modeling

The rare earth elements and yttrium and several metals, including Ni, Cu and Co, are considered among the promising resources of deep-sea marine deposits, such as polymetallic nodules, ferromanganese crusts and seafloor massive sulphides. Some deep-sea sediments, especially metalliferous clays and REY-rich muds, also have valuable economic potential. Block kriging efficiency and local scale resource estimation of selected critical metals and rare earth elements in surface sediments from the Clarion-Clipperton Fracture Zone, equatorial Pacific Ocean, Interoceanmetal claim area is described. Geochemical data of siliceous clayey silts were acquired by ICP-MS method, with useful results for discussion of economic importance of deep-sea deposits.

Projede Kurşun ve Çinko hazırlama teknikleri kullanılarak Türkiye’deki Çinko’nun katı ile sıvı ayrımının Kızıl Ötesi ışınımla ile yapılabilirliği açısından değerlendirme olanaklarının araştırılması hedeflenmiştir. Bu çalışmada endüstriyi yakından ilgilendiren çinko madeninin, katma değerli ürün kazanımı için geçtiği aşamalar hakkında ve kızılötesi ışınımla kurutucu tasarlanması hakkında ilgili bilgiler ele alınmıştır. Çinkonun hangi sanayilerde kullandığı, işletilmesi ve önemi açıklanmıştır. Kurutucu tipleri hakkında bilgi verilmiş ve kızılötesi ışınımla kurutucunun diğerlerinden avantajları ele alınmıştır. Çinko konsantresinin çıkarıldığı ve işlem gördüğü yerler ile alındığı yer ile ilgili bilgiler verilmiş ve uygulanması istenilen endüstriyel ölçekli kızılötesi ışınımla kurutucu ve deneysel ölçekte kızılötesi ışınımla kurutucu tasarımı yapılmıştır. Çinko cevheri gerekli uygun koşular sağlanarak kızılötesi ışınımla kurutularak bu sistemin fizibilite çalışması ortaya koyulmuştur. Tez kapsamında literatür çalışması olarak Türkiye ve Dünya’da çinko hakkında yapılan yayınlar derlenmiştir. Çalışmanın deneysel kısmında ise Türkiye’nin Balıkesir Balya bölgesinden alınan çinko numuneleri kullanılmıştır. Alınan numuneler üzerinde nem analizleri yapılmış ve tasarlan cihaz içinde kızıl ötesi ışınım ile muamele edilerek nem oranı saptanmıştır.Bu katı sıvı ayrımı sonucunda elde edilen bulgulara yer verilmiştir.Bu alanda yapılabilinecek çalışmalar için bir ön araştırma niteliği ortaya çıkarılmıştır.Bu çalışmanın yapılması sonucu edilecek kâr ortaya koyulmuştur.

The recently-discovered nickel mineralization in Dangoma, Kaduna State, along the southern margin of the Jos Plateau is rare and unique because it contains high grade native nickel that occurs as metallic pellets or "balls" about 0.1 to 5 mm in size, and dispersed within a deeply weathered regolith overlying a serpentinized ultramafic host rock. The deposit is described as "world class and highly unusual"-a type that has not been previously reported. Field investigation shows that the nickel mineralization is localized within a serpentinite body that occurs within the Precambrian basement complex of north-central Nigeria. The basement rocks comprise of Archean migmatites and gneisses, and Proterozoic metasediments and meta-ultramafites that were intruded by Pan-African granitoids and pegmatites around 500 my ago. The Dangoma serpentine, like other similar rocks within the Proterozoic schist belts are slivers emplaced along transcurrent and associated fault systems. The native nickel occurs as a residual deposit within a thick and deeply weathered regolith in which the native Ni occurs probably as awaruite (Ni3Fe) containing an average of 94%% Ni with Fe, and traces of Cu, Zn, Pb and Co. The origin of this unique deposit is attributed to a combination of initial serpentinization of an ultramafic intrusive rock that produced a hydrated, highly reducing and low sulfur fugacity environment in which Ni in primary olivine was remobilized to form blebs of Ni-Fe alloy that grew in size with increased temperature during progressive low-grade metamorphism. The unique roundness of the Ni pellets as "balls" is intriguing, and probably occurred during lateritic weathering and supergene remobilization within an area undergoing regional tectonic uplift.

The traditional trading of iron ores is based on chemical specifications and particle size distribution. However, recent characterisation studies, that bring additional information like mineralogical composition and microstructural (textural) aspects, have become important. They contribute to determination of the iron ores downstream beneficiation operations and subsequent steelmaking processing, allowing improvements on both new and existing processes. Despite progress in commercial scanning electron microscope/energy dispersive spectrometer (SEM/EDS) automatic instruments in the last decade, these systems are not capable of performing the identification and discrimination of major iron ore minerals (haematite and magnetite) and the consequent description of its microstructure. On the other hand, reflected light microscopy (RLM) can easily distinguish the iron oxides by their reflectancies, but it cannot discriminate quartz and epoxy resin, which present similar colour on images. The present work proposes an innovative method to perform a quantitative mineralogy characterisation of iron ore based on RLM-SEM co-site microscopy. This technique combines images obtained by RLM and SEM through an automatic registration procedure that accurately aligns the two kinds of images of each field. In fact, it creates multi-dimensional images, which are then analysed using image processing and pattern recognition techniques. The case study is an itabiritic iron ore from Quadrilátero Ferrífero (Brazil) which contains mainly quartz, goethite, magnetite and haematite. The discrimination of phases that are not distinguishable with either RLM (epoxy resin and quartz) or SEM (haematite and magnetite) can be performed through this multimodal approach, allowing the subsequent mineralogical quantification. The mineralogical quantification computed by image analysis was consistent with independently obtained results based on the Rietveld technique.

Computer-controlled microscopes with digital image acquisition and analysis led to the creation of the new field of digital microscopy. These techniques not only allow a certain degree of automation but have also brought new possibilities to microstructural characterisation. One of these new and promising possibilities is co-site microscopy, which links different kinds of information obtained from different microscopy techniques. The present work presents the development and implementation of a co-site microscopy methodology that combines images obtained by reflected light microscopy (RLM) and scanning electron microscopy (SEM). This methodology can improve the SEM analytical capacity by adding colour information from RLM. It involves the whole sequence, from image acquisition at the microscopes to the analysis of the phases using pattern recognition techniques. An automatic registration procedure for the two kinds of images was developed, allowing the adjustment of magnification, translation, rotation and pixel size, and the correction of local distortions. Thus, the images from RLM and SEM can be combined to build a multidimensional data set of each field, which can then be used in a pattern recognition approach to discriminate different phases. The methodology was tested with a copper ore sample, aiming at the discrimination of minerals that are not distinguishable with either RLM or SEM.

Magnesite mineralization of high purity was discovered and described herein for the first time from metamorphosed folded belt from Al-Thanyiah locality in Rub'Al-Khali sector, 360 km east of Sana'a City, northwest Yemen. The magnesite-metamorphic belt, belonging to the Precambrian/Neoproterozoic age? comprises thrust belt, which trends generally N-S direction. Magnesite mineralization was identified in an extended carbonate-metamorphic belt for several tens of kilometers cf. 31 km and occurred in association with 8 stratigraphic units. The thicknesses of pure magnesite bearing units are variable and ranges from 20 to 60 m, associated with dark green chlorite-schist with intersecting huge ultrabasic intrusions. Geochemical, mineralogical and petrographic analyses show that the magnesite concentrations in the stratigraphic units are ranging from 78% up to high purity of 99.6% cf. 35 to 48.9% MgO, with minor dolomite and calcite respectively. Little to rare content of talc and brucite were also recognized. Two thick, productive and high purity magnesite beds, the first is of 40 m thick and the second is 60 m in thickness, which reveals more than 95% MgCO 3 and considered to be economic. The suggested origin of the magnesite mineralization is coming from high stress of regional metamorphism associated with ultramafic intrusions cf. amphibolite and harzburgite associated with diagenetic solutions rich in Mg 2+ , associated with the heat of magma. The alteration of dolomite to magnesite was formed by multiple phases to transform calcite and/or dolomite to magnesite.

É comum encontrar inconsistências em requerimentos para aproveitamento de substâncias minerais em função do desconhecimento da legislação mineral vigente bem como das características geológicas da região. O município de Catalão, localizado na região sudeste do estado do de Goiás foi selecionado como área de estudo em função da existência da lavra de substâncias como Nióbio e Fosfato na região além da carência na existência de trabalhos com caráter acadêmico que reunissem informações a respeito da situação de áreas cadastradas junto ao DNPM no município. O objetivo do trabalho foi reunir informações a respeito dos aspectos da legislação do setor mineiro no Brasil além de caracterizar as unidades geológicas do Município de Catalão analisando de maneira qualitativa as informações obtidas nos processos abertos no município junto ao DNPM e as unidades geológicas nas quais estão situadas correlacionando, com a construção de mapas, as substâncias requeridas com os possíveis depósitos minerais existentes na área de cada processo. Foram selecionadas para a caracterização descritiva apenas as áreas que não estivessem em fase de lavra e analisadas de acordo com sua localização, obtida com auxílio de software GIS, nas unidades geológicas do município e possíveis depósitos minerais levantados em pesquisa bibliográfica em busca de possíveis incoerências nas sustâncias cadastradas em cada processo. Constatou-se com a pesquisa a existência 190 processos cadastrados na região para 22 substâncias diferentes além de grande quantidade de processos em fase de autorização de pesquisa mineral e uma quantidade mínima de incoerências cadastrais se comparadas ao número total dos processos analisados, que se observou durante o estudo, estarem distribuídos em todas as unidades geológicas do município de maneira que foi possível estabelecer na análise dos resultados correlação com depósitos minerais teóricos de substâncias diversas.

Garnets are commonly found minerals, being important indicators of regional and local metamorphism and P-T conditions. Their zonal structure and mixed chemical composition, represented mainly by almandine, pyrope, grossular, spessartine end-members, are useful tools for geothermobarometric considerations. The almandine-pyrope is considered one of the most important geothermometers, mainly due to practically undisturbed Fe and Mg partitioning between garnets and other minerals, like biotite and pyroxenes (Koziol and Bohlen 1992).
The crystalline bedrock of central Sweden was formed in the Svecofennian (Svecokarelian) orogenic phase, under conditions of active continental margin subduction zone. Its age is Orosirian, estimated
locally on 1.96-1.75 Ga. Main geological division is here the Bergslagen lithotectonic unit, composed of large variety of metamorphic and magmatic rocks. Several metasedimentary and metavolcanic types
had been here distinguished (Bergman et al. 2012).
Nynäshamn is partially located on the bedrock consisting of migmatisised “older granitoids”, syenites of age 1.89-1.85 Ga and
complex of metagreywackes, mica schists, graphite-sulphide-bearing schists, paragneiss, migmatites, quartzites and amphibolites (Bergman et al. 2012).

The tourmaline supergroup members are extensively studied in recent years, being the most widespread of cyclosilicate minerals, commonly found in several magmatic rocks, especially in pegmatites and aplites (Bačík 2015; Bosi et. al 2017; Bosi et al. 2018;
Pieczka et al. 2018).
The occurrence of tourmalines in the postmagmatic and metamorphic rocks from Strzegom, Poland, is known from several localities and was reported long ago (Traube 1888 vide Pieczka and Kraczka 1988). Local
granites, pegmatites and aplites are the host rocks for some of well known tourmalines, especially from the schorl group (Janeczek 1985).

More information in the full text.

Chemosphere
Available online 21 April 2018
In Press, Accepted Manuscript — Note to users

Geochemical signatures and isotopic systematics constraining dynamics of fluoride contamination in groundwater across Jamui district, Indo-Gangetic alluvial plains, India
S. Kumara, A.S. Venkateshb, , , Rambabu Singhc, G. Udayabhanub, D. Sahaa

https://doi.org/10.1016/j.chemosphere.2018.04.116
Highlights
F− contamination along the groundwater flow direction and discharge areas (Na+ HCO3- facies).
Elevated F− alongside enriched δ18O advocates longer residence time of water.
CaCO3 precipitation and CaF2 dissolution constraining solute acquisition.
Silicate weathering by water-rock interaction coupled with ion exchange.
Chemometric analysis testifies plausible geogenic origine of F− in Groundwater.
Abstract
A data set of 76 water samples are obtained from surface and sub-surface water bodies to investigate chemical parameters and stable isotopic signatures in order to drive factors leading to fluoride (F−) contamination in groundwater of parts of Jamui district, India. Hydrochemical facies reveals that F− concentration is lower in Ca2+ HCO3- facies representative of recharge area, while discharge area has a tendency towards Na+ HCO3- facies with elevated F− concentration. The ionic ratios Na+/Ca2+>1, Na+/Cl−>1, (Ca2++Mg2+)/HCO3−<1, Na++K+ = 0.5TZ+ and Ca2++Mg2+ = TZ+ witness silicate weathering by water-rock interaction coupled with ion exchange and prolonged residence time, are the principle factors for fluoride contamination (3.6 mg/L to 5.8 mg/L) in 67% of deeper bore wells. Geochemical modelling testifies excess of alkalinity due to the dominance of bicarbonate ion leading to calcite precipitation and dissolution of fluoride in solution contributing to fluoride contamination. The chemometric analysis reveals that the water chemistry of the study area is controlled by both anthropogenic and natural sources, and enrichment of fluoride in groundwater is possibly from geogenic source (fractured granite gneiss). The stable isotope plot shows that most of the samples fall along local meteoric water line indicating that the groundwater is originated from local precipitation with a possibility of evaporative enrichment. Groundwater enriched in δ18O is positively correlated with F− suggesting evaporation and longer residence time of water. Spatially elevated F− prevails in the eastern bank of Kiul River and along the groundwater flow direction, which is attributed to control of dynamics of hydrogeological conditions.

The Kambale graphite deposit is located within the Wa Lawra ‐ greenstone belt in NW Ghana. Historical records, recent exploration, unpublished material and accessible surface and subsurface exposures provide a valuable preliminary case study of the deposit. Examination of three transversal trenches and re-logging of eleven Rotary Air Blast (RAB) drill holes in the western part of the deposit reveal moderately to intensely sheared metasedimentary rocks of the lower Birimian formation such as mica schist, graphitic schist, quartzite, and a few pegmatite intrusions. Optical microscopic studies show that the deposit occasionally occurs in a complex mineral paragenesis of quartz ± calcite ± hornblende ± magnetite ± pyrrhotite ± rutile ± chalcocite ± graphite and other gangue minerals, often found around the boundaries of large magnesian ferrohornblende minerals, which tend to form quartz crystals. The Kambale deposit is characterized by numerous faults and shears, associated with brittle-ductile deformation at the NE part of the main shear with fewer faults and shears at the southern and western zones, generally trending E-W between 150ånd 320˚, dipping in NE-SW direction at an average of 060˚. The rocks have undergone medium-high grade metamorphism under high T/medium P facies typically estimated as (∼600-750 • C, 5.0–8.0 kbar), in amphibolite-granulite facies. The genesis of the flake graphite in Kambale is believed to be as a result of the high grade metamorphism, where deep-seated CO 2-rich fluid phase of crustal origin invaded the metamorphosed rocks. The intensity of the pore fluid pressures aided in the genesis of the graphite by hydraulic fracturing of the underlying rocks under regional syntectonic deformation.

Malumfashi schists which occur in association with migmatite-gneisses and biotite granite, occupy
about 60% of Tandama area, north-western Nigeria. These rocks were studied with a view to
evaluate their compositional characteristics and their evolution.
The lithology revealed from systematic mapping and petrographic examinations shows that the
schist is mica schist, which is part of the Malumfashi Schist Belt of Nigeria. The mica schist consists
of greater than 50% micaceous minerals and less than 50% quartz and feldspar. It is light grey to
silver grey in colour, well foliated and mostly weathered to rusty brown or reddish brown.
Mineralogical determinations from optical studies show a high proportion of biotite and minor
amounts of plagioclase and quartz. Chemical analysis of the samples obtained by Inductively
Coupled Plasma Mass Spectrometry (ICPMS) instrumentation method, involving major and trace
elements reveals the nature of the mica schist. The A-CN-K diagram reveals a shale protolith which
suffered moderate to high chemical weathering, prior to being metamorphosed. Obtained Rb/Sr ratio
(>0.4%) and SiO2/Al2O3 values support the shale protolith hypothesis for the schist, diagnostic geochemical features like the Na2O/Al2O3 values, trace element ratios such as Th/U and REE
patterns suggest that the protolith are predominantly derived from felsic igneous sources.
Tectonically, SiO2/Al2O3 versus K2O/Na2O plot revealed the protolith to have evolved within passive
margin environment.

Secara geografis lokasi penelitian berada pada koordinat 49 M 409513 9137374 UTM (Universal Transverse Mercator). Lokasi penelitian terdapat pada peta geologi lembar Yogyakarta, dengan luas daerah penelitian adalah 1km2. Berada di Desa Banyuroto, Kecamatan Nanggulan, Kabupaten Kulon Progo, Provinsi Daerah Istimewa Yogyakarta. Morfologi daerah penelitian berupa perbukitan bergelombang sedang, dengan slope 13o. Penelitian yang dilakukan pada lokasi ini bertujuan untuk mengetahui batuan apa saja yang berkembang pada daerah tersebut sehingga peneliti dapat menarik kesimpulan bagaimana proses awal terjadinya batuan tersebut untuk kemudian dianalisa. Pengamatan secara mikroskopis dilakukan dengan cara mengambil 5 titik pada sayatan tipis kemudian dilakukan deskripsi, perhitungan butiran (point counting), penamaan batuan, dan penyusunan petrogenesa. Berdasarkan hasil pengamatan secara megaskopis dan mikroskopis didapatkan batuan yang berkomposisi butiran allochem berupa fosil foraminifera, micrite berupa lumpur karbonatan, serta sparite karbonatan.

The Sabzevar ophiolite, with its colored mélange zone, is a highly disintegrated ophiolite complex located at the northern boundary of the central Iranian microcontinent. A large number of chromite pods occur in this area, which needs to be explored. In this study, a mathematical – geological genetic model is advanced as an exploratory tool that provides information for further exploration activity. A petrogenetic model of chromite ore was established on the basis of a geodata information database. This database consists of information from similar chromite mines from around the world. A detailed investigation of the geological, mineralogical and petrological characteristics of chromite pods in the Sabzevar region was conducted along with detailed petrological samplings , thin section studies and mineralogical analysis. In the next step, we developed a conceptual genetic model that defines areas with a high probability of the existence of chromite pods. The model was later refined using such parameters as a critical genetic factor (CGF) and critical reconnaissance criteria (CRC). Next, a linear function, which is a combination of these factors, provided promising regions as intrinsic geological units (IGU). Finally, a 3D model of lithological units depicting the IGU for chromite pods exploration is proposed.

Lenses of radioactive Quartz Pebble Conglomerates (QPC) and associated quartzites are exposed along western margin of Archean Bonai Granite in Singhbhum-Orissa Craton, eastern India intermittently spreading over a strike length of 8–10 km. QPCs are radioactive while quartzites are mostly non-radioactive in nature. The purpose of the research is to investigate and characterize the radioactive QPC and quartzites geochemically to decipher their paleo-weathering conditions, provenance characteristics and possible tectonic setting of deposition. Geochemical data suggest moderate to high chemical weathering conditions in the provenance areas of QPC and quartzites. Major, trace and REE data indicate predominantly felsic to partly mafic-ultramafic sources for the deposition of radioactive Quartz Pebble Conglomerates from the surrounding Archean terrain. Elevated values of Th, U, Pb, La, Ce, Y and low Sc with high critical trace elemental ratios of Th/Sc, La/Sc, Th/Cr and Zr/Sc in radioactive QPC indicate their derivation from felsic igneous source. Low concentration of Th and Sc in quartzites compared to QPC and their variable Th/Sc ratios indicate both felsic and mafic sources for quartzites, albeit their preferential felsic affiliation. Higher Cr/Th ratios in quartzites (18.4), moderate Cr/Th in QPC (5.42), low to moderate Y/Ni in QPC (0.36–12.4) and quartzite (0.29–1.88), along with Au ranging from 30 to 1527 ppb, Pt up to 188 ppb and 682 ppb in QPC and quartzites respectively point towards some contribution from mafic-ultramafic source as well. REE patterns and in particular negative Eu anomalies for both QPC and quartzites further support their derivation from felsic rocks and could possibly linked to some of the phases of Archean Singhbhum Granite and Bonai Granite. Granitic to pegmatitic source for QPC is also revealed by the presence of rounded to sub-rounded mon-azite, zircon and thorian-uraninite grains in their matrix. Study indicates that QPC and quartzites were deposited in a passive margin tectonic setting developed during Archean between a span of 3.3 and 3.16 Ga along the western margin of Bonai Granite when the reducing condition was prevalent as indicated by their low Th/U ratios (<4.0) and presence of detrital grains of uraninite and pyrite in QPC. Radioactive QPC from western margin of Archean Singhbhum-Orissa Craton bears broad resemblance with QPC from Witwatersrand basin of South Africa and Elliot Lake, Canada and thus appears to be ideal sites for exploring QPC hosted U (+Au-PGE) mineralization in the analogous areas.