Characterization Of Quartz Research Articles

Quartz veins and silver-containing crushing zones in the exocontact of Solur granite stock (Kularsky district, Yakutia)

The purpose of the work is a investigation of quartz varieties present in quartz veins and crushing zones in order to establish the formation conditions and the possibilities of using quartz varieties to study the distribution of mineralization during exploration. The work was stimulated by the discovery of gold and gold-silver mineralization in adjacent areas and the possibility of using some new methods for studying quartz. Research methods. Samples for the study were taken during the mineralogical mapping of the studied area in the course of work to assess the prospects for its ore potential. The characterization of quartz from veins and crushing zones was carried out on the basis of its field descriptions and laboratory microscopic study, as well as measurements of X-ray luminescence (RL) of vein quartz in the region of 350–550 nm. Fluid inclusions in quartz and sulfur isotope composition in sulfides from quartz veins were also studied. Results and conclusions. The granite stock, surrounded by a zone of contact hornfels with cordierite and andalusite, lies among terrigenous sedimentary rocks that have undergone metagenesis (anhimetamorphism). Veins of glassy coarse-grained quartz and recrystallized (granular) quartz are located directly in the granites, partially recrystallized gray quartz – among the contact cornea, and veins of deformed milky-white quartz - in terrigenous sedimentary rocks outside the contact halo. As the transition from veins located among granites to veins located outside the granite massif, the intensity of quartz RL decreases sharply. The nature of the RL indicates the probable presence in the crystal lattice of quartz from veins in granites of their own defects – vacancies of oxygen or silicon, and in gray and milkywhite quartz – cation-compensated [AlO4 /M+]-centers. Sulfide mineralization in quartz veins is mainly represented by arsenopyrite with an isotopic composition of sulfur close to the meteorite standard. In addition to quartz veins, later crushing zones with hydrothermal injection breccias are also common in the area. In breccia cement and in breccia-intersecting veins, early non-split hypidiomorphic quartz and later split comb-shaped and chalcedony quartz are present. In micro-cryptogrаined chalcedony quartz with grain size up to 0.05 mm contaminated with inclusions of finely crushed rock particles and kaolinite grains, the inclusions of the pyrargyrite – one of the main silver-containing minerals on a number of gold-silver deposits of the region – were found. Based on the known vertical zonality of epithermal gold-silver deposits with the confinement of kaolinite-containing ores and chalcedony quartz to the upper horizons of the deposits, and due to the presence of micro-cryptograined chalcedony quartz containing kaolinite and pyrargyrite in the considered crushing zones, it can be suggested that these crushing zones may be confined to the upper parts of the silver mineralization development zone.

Test The Effectiveness and Characterization of Quartz Sand/Coconut Shell Charcoal Composite as Adsorbent of Manganese Heavy Metal

The research on the effectiveness and characterization of quartz sand/coconut shell charcoal composite as adsorbent of Manganese (Mn) heavy metal has carried out. Quartz sand was previously activated by using Na2CO3 while the coconut shell charcoal was activated by using HCl 4 M. The adsorbent characterization was carried out by Fourier Transform Infrared Analyzer (FTIR), X-RayDiffraction(XRD), Scanning Electron Microscopy-mapping Energy Dispersive X-Ray (SEM-EDX), and Surface Area Analyzer (SAA). The adsorption experiment of the Mn metal was carried out by varying the composition of quartz sand/coconut shell charcoal. The variations were in the number of 100:0, 0:100, 25:75, 50:50, 75:25 (b/b) at the degree of pH 1-6 and contact time 10, 15, 20, 30, 45, 60, 75, and 90 minutes by using batch method. The measurement of final concentration at the equilibrium phase was carried out by using AAS. The optimum adsorption condition of the Mn metal occurred in the comparison of quartz sand/coconut shell charcoal 50:50 (b/b), the best condition at the degree of pH 5, contact time during 30 minutes with adsorption capacity of 0.56 mg/gram. The type of adsorption isotherm of composite quartz sand/coconut shell charcoal adsorbent towards the metal of Mn followed the Freundlich isotherm theory.

Characterization of quartz in the Wufeng Formation in northwest Hunan Province, south China and its implications for reservoir quality

Quartz is one of the most important and common minerals in marine shales. This is especially true for the Wufeng-Longmaxi and Niutitang Formations in south China. However, the type, origin and formation mechanism of the quartz in these marine shales are as yet unclear. Thirteen samples of Ordovician shale from the Wufeng Formation in northwest Hunan Province were collected for this study. The quartz within the Wufeng shale was characterized through a series of experiments employing scanning electron microscopy with cathodoluminescence, nitrogen physisorption, X-ray diffraction, and geochemical analysis. The results were then used to assess the implications of the quartz component for reservoir quality. Three quartz types were identified based on scanning electron microscopy and cathodoluminescence imaging. Type I quartz has a relatively large grain size and exhibits bright luminescence, indicative of a terrigenous origin, whereas Type II and Type III quartz is authigenic and has dull or no luminescence. Type II quartz has small grain sizes and may be mainly biogenic in origin. This type of quartz may have formed during early diagenesis, with the silica being sourced from the dissolution of siliceous organisms. Type III quartz generally appears as dark rims on Type I quartz grains; the silica may have been derived from clay mineral alteration, with quartz-formation occurring during middle or late diagenesis. The authigenic quartz (Types II and III quartz) likely formed as a cement and would be expected to generate brittle behavior. The shale with a high content of authigenic quartz has a high Young's modulus and low Poisson's ratio. The biogenic authigenic quartz (Type II quartz) was pore-filling and formed during shallow burial. It would thus have been able to resist further compaction and provide a rigid framework within which the primary pores in the shale could be preserved, controlling the distribution of organic matter and the development of organic pores. The biogenic authigenic quartz has positive relationships with porosity and pore volume and specific surface area. Shale that was high in biogenic quartz had high porosity and adsorption capacity. The characterization of quartz in marine shales has significance for shale gas exploration and development and provides a new angle for evaluating the fracability and storage capacity of shale gas reservoirs.

BENEFICIAMENTO DO QUARTZO DE TANHAÇU/BA VISANDO A PREPARAÇÃO DE SILÍCIO GRAU METALÚRGICO DE ALTA PUREZA

Neste trabalho, as etapas de beneficiamento e de caracterização do quartzo de Tanhaçu/BA foram realizadas com o propósito de utilizá-lo como matéria-prima para a obtenção de um silício grau metalúrgico (SiGM) com baixo nível de impurezas. A amostra de quartzo, após as etapas de britagem, calcinação seguida de quenching e moagem autógena por 2 h resultou num produto com elevado teor de SiO2 (> 99%), isto é, um aumento de aproximadamente 2% em relação `a amostra original e uma considerável diminuição nos teores das principais impurezas, boro e fósforo, além de outras como, alumínio, ferro e cálcio, que também comprometem a qualidade do quartzo. A investigação dos resultados indica que a amostra de quartzo beneficiada possui potencial para ser utilizada como matéria-prima na produção de SiGM de alta pureza, bem diferente do SIGM convencional.