Hasil untuk "Mineralogy"

R. Folk

R. L. Bates, J. Jackson

F. Barker

C. Feller, M. Beare

J. Mustard, S. Murchie, S. Pelkey et al.

G. McDowell, M. Bolton

Q. Dehaine, L. Tijsseling, H. Glass et al.

Abstract Cobalt (Co) is a transition metal featuring unique physical properties which makes its use critical for many high-tech applications such as high strength materials, magnets and most importantly, rechargeable batteries. The bulk of world cobalt output usually arises as a by-product of extracting other metals, mostly nickel (Ni) and copper (Cu), from a wide variety of deposit types mostly Cu-Co sediment-hosted deposits, but also Ni-Co laterites, Ni-Cu-Co sulphides or hydrothermal and volcanogenic deposits. Significant differences in ore properties (geochemistry, mineralogy, alteration and physical properties) exist between cobalt-containing deposits, as well as within a single deposit, which can host a range of ore types. Variability of cobalt ores makes it challenging to develop a single extraction or treatment process that will be able to accommodate all geometallurgical variation. Overall, there is a lack of fundamental knowledge on cobalt minerals and their processability. The recovery efficiency for cobalt is generally low, in particular for processes involving flotation and smelting, leading to significant cobalt losses to mine tailings or smelter slags. This paper starts by reviewing the main geometallurgical properties of cobalt ores, with a particular focus on ore mineralogy which exerts a significant control over ore processing behaviour and cobalt extraction, such as the oxidation state, i.e. oxide or sulphides which drives the selection of the processing route (leaching vs flotation), and the associated gangue mineralogy, which can affect acid consumption during leaching or flotation performance. The main processing routes and associated specific geometallurgical aspects of each deposit type are presented. The paper concludes on the future cobalt prospects, in terms of primary and secondary resources, cobalt processing and sustainable cobalt sourcing for which further research is needed.

A. Aplin, J. Macquaker

P. Scholle, D. Ulmer-Scholle

B. Figuerola, Alyce M. Hancock, N. Bax et al.

Understanding the vulnerability of marine calcifiers to ocean acidification is a critical issue, especially in the Southern Ocean (SO), which is likely to be the one of the first, and most severely affected regions. Since the industrial revolution, ~30% of anthropogenic CO2 has been absorbed by the global oceans. Average surface seawater pH levels have already decreased by 0.1 and are projected to decline by ~0.3 by the year 2100. This process, known as ocean acidification (OA), is shallowing the saturation horizon, which is the depth below which calcium carbonate (CaCO3) dissolves, likely increasing the vulnerability of many resident marine calcifiers to dissolution. The negative impact of OA may be seen first in species depositing more soluble CaCO3 mineral phases such as aragonite and high-Mg calcite (HMC). Ocean warming could further exacerbate the effects of OA in these particular species. Here we combine a review and a quantitative meta-analysis to provide an overview of the current state of knowledge about skeletal mineralogy of major taxonomic groups of SO marine calcifiers and to make projections about how OA might affect a broad range of SO taxa. We consider a species' geographic range, skeletal mineralogy, biological traits, and potential strategies to overcome OA. The meta-analysis of studies investigating the effects of the OA on a range of biological responses such as shell state, development and growth rate illustrates that the response variation is largely dependent on mineralogical composition. Species-specific responses due to mineralogical composition indicate that taxa with calcitic, aragonitic, and HMC skeletons, could be at greater risk to expected future carbonate chemistry alterations, and low-Mg calcite (LMC) species could be mostly resilient to these changes. Environmental and biological control on the calcification process and/or Mg content in calcite, biological traits, and physiological processes are also expected to influence species-specific responses.

T. Matschei, B. Lothenbach, F. Glasser

Jumana Sharanik, Ernestos Sarris, Constantinos Hadjistassou

Understanding the fluid storage and production mechanisms in sedimentary rocks is vital for optimising natural gas extraction and subsurface resource management. This study applies high-resolution X-ray computed tomography (≈15 μm) to digitise rock samples from onshore Cyprus, producing digital rock models from DICOM images. The workflow, including digitisation, numerical simulation of natural gas flow, and experimental validation, demonstrates strong agreement between digital and laboratory-measured porosity, confirming the methods’ reliability. Synthetic sand packs generated via particle-based modelling provide further insight into the gas storage mechanisms. A linear porosity–permeability relationship was observed, with porosity increasing from 0 to 35% and permeability from 0 to 3.34 mD. Permeability proved critical for production, as a rise from 1.5 to 3 mD nearly doubled the gas flow rate (14 to 30 fm³/s). Grain morphology also influenced gas storage. Increasing roundness enhanced porosity from 0.30 to 0.41, boosting stored gas volume by 47.6% to 42 fm³. Although based on Cyprus retrieved samples, the methodology is applicable to sedimentary formations elsewhere. The findings have implications for enhanced oil recovery, CO₂ sequestration, hydrogen storage, and groundwater extraction. This work highlights <i>digital rock physics</i> as a scalable technology for investigating transport behaviour in porous media and improving characterisation of complex sedimentary reservoirs.

Aleksandr B. Vrevsky, Anastasiya V. Yurchenko, Shauket K. Baltybaev

The petrogenesis and evolution of metamorphic rocks of the volcano-plutonic units of the Kaskama block of the Inari Terrane in northwestern Russia were studied. A petrographic and mineral study and modeling of igneous and metamorphic mineral formation were performed. PT-conditions of rocks, along with previously known data, including geochronological ones, do not allow us to correlate the studied units with rocks of the Belomorian complex, as previously thought. Modeling of igneous and metamorphic mineral shows good convergence with the fields of stability of mineral parageneses and quantitive ratio of minerals with those observed in the real samples. The early mineral parageneses of the magmatic stage corresponds to the crystallization of rock-forming and accessory minerals from the komatiite melt, and mineral parageneses of progressive and regressive metamorphism stages are superimposed on them. Relic igneous minerals (olivine, clinopyroxene, orthopyroxene, magnetite-spinel) in metaperidotites make it possible to estimate their liquidus temperatures in the range of 1,480-950 °С. The progressive stage of metamorphism is characterized by the development of mineral parageneses: garnet + amphibole + plagioclase + quartz ± biotite, amphibole + plagioclase + quartz. The late low-temperature regressive stage of metamorphism is characterized by the development of epidote-, zoisite-, actinolite-containing associations and a number of other low-temperature minerals. Peak parameters of progressive metamorphism are estimated as Т = 600-700 °С, Р = 5-9 kbar and for the regressive stage as Т = 400-500 °С, Р = 3-5 kbar. The identified thermodynamic conditions for the Kaskama block should be considered when determining whether the studied volcano-plutonic and metasedimentary units belong to the Paleoproterozoic terranes of the Kola-Norwegian Region of the Fennoscandian Shield.

R. Schaetzl, S. Anderson

P. Hartlieb, M. Toifl, F. Kuchar et al.

Abstract This paper deals with experimental studies regarding the thermo-physical properties of granite, sandstone and basalt in the temperature range of 25–1000 °C. It is shown how phase transitions (e.g. α-β quartz phase transition) influence the texture and stability of these rock types. The results of these measurements and analyses are linked to microwave irradiation tests at 17.5 kW power. The measurements demonstrate the strong variation of effects depending on the parameter rock/mineralogy showing possible applications in a mineral processing environment.

G. K. Kome, R. K. Enang, F. O. Tabi et al.

Clay minerals constitute an important component of the soil system and knowledge of their role in soil fertility is imperative for sustainable soil management and productivity. The aim of this work is to overview the influence of clay minerals on some major soil fertility attributes. The rationale for carrying out this work is that most soil fertility studies rarely incorporate soil mineralogy. Clay minerals, through their physical and chemical properties, affect soil fertility by controlling nutrient supplies and availability, through the sequestration and stabilization of soil organic matter, by controlling soil physical properties through microaggregate formation, by influencing soil acidity and controlling soil microbial population and activity. The main processes involved in these relationships are dissolution-precipitation and adsorption-desorption processes, alongside mechanisms involving the formation of short-range-ordered phases. Although the determination of soil mineralogical properties is very costly and time-consuming, information about a soil’s mineralogy is imperative for a holistic understanding and proper management of soil fertility. Therefore, the development of rapid, low-cost, reliable and efficient techniques of soil mineralogical analysis, directly applicable to soil fertility investigations, constitutes a major challenge. Also, future research should investigate the relationships between clay minerals and soil nitrogen vis-a-vis sequestration and stabilization. Lastly, clay minerals should be considered in studies dealing with soil quality assessment, especially in the choice of soil quality indicators.

X. Li, H. B. Li, Jian Zhao

Abstract The aim of this study is to understand the effects of micro-heterogeneity, such as grain size, morphology and mineralogy, on the initiation, propagation and coalescence of microcracks in heterogeneous materials. A multiscale grain-breakable continuum–discontinuum model incorporating realistic micro-heterogeneity reproduction method is proposed to investigate the fracturing behaviours and confinement mechanism of rocks. Crack initiation and damage stresses are intrinsic properties of rocks determined by grain-scale heterogeneity. Intergranular tensile cracks are primarily initiated as a result of local stress heterogeneity along grain boundaries. The subsequent generation of transgranular shear cracks implies a rapid proliferation of grain-crossing fractures, leads to large-scale crack interaction and coalescence. The effect of confinement inhibits crack extension and increases the appearance of shear-induced grain pulverizations. Furthermore, the effects of grain size, grain morphology and mineralogy on macro mechanical properties, including crack initiation stress, crack damage stress, uniaxial compression strength and elastic modulus, are discussed. The simulated results indicate that the larger grain size contributes to stronger local stress heterogeneity, which results in a lower failure strength of rocks. The crack initiation stress is determined by local heterogeneity and is less affected by the change in average grain size. Grain morphology plays an important role in grain interlocking while a reduction in grain size variance leads to a more homogeneous stress field. The mineralogy is evaluated with the aid of a quartz-mica-feldspar diagram, and the quantitative relationships between mineralogy and the macro-scale mechanical properties of rocks are discussed.

R. Milliken, J. Grotzinger, B. J. Thomson

O. Tschauner, Shichun Huang, E. Greenberg et al.

T M Blattmann, Z. Liu, Y. Zhang et al.

Bound to rock Organic matter binds to phyllosilicates, a process which affects both its transport and chemical stability. How does that affect the fate of terrestrial organic carbon that enters the ocean? Blattmann et al. show that organic carbon derived from soils is stripped from mineral surfaces upon discharge and dispersal into the ocean, whereas organic matter derived from ancient rocks is preserved there. Their results show that preservation of continentally derived organic matter in marine sediments is controlled largely by phyllosilicate mineralogy. Science, this issue p. 742 Phyllosilicates transport and preserve continental organic matter in the oceans. First-order relationships between organic matter content and mineral surface area have been widely reported and are implicated in stabilization and long-term preservation of organic matter. However, the nature and stability of organomineral interactions and their connection with mineralogical composition have remained uncertain. In this study, we find that continentally derived organic matter of pedogenic origin is stripped from smectite mineral surfaces upon discharge, dispersal, and sedimentation in distal ocean settings. In contrast, organic matter sourced from ancient rocks that is tightly associated with mica and chlorite endures in the marine realm. These results imply that the persistence of continentally derived organic matter in ocean sediments is controlled to a first order by phyllosilicate mineralogy.