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Basic characteristics of soils
Published in Jonathan Knappett, R. F. Craig, Craig’s Soil Mechanics, 2019
Jonathan Knappett, R. F. Craig
The structures of the principal clay minerals are represented in Figure 1.8. Kaolinite consists of a structure based on a single sheet of silica combined with a single sheet of gibbsite. There is very limited isomorphous substitution. The combined silica–gibbsite sheets are held together relatively strongly by hydrogen bonding. A kaolinite particle may consist of over 100 stacks. Illite has a basic structure consisting of a sheet of gibbsite between and combined with two sheets of silica. In the silica sheet, there is partial substitution of silicon by aluminium. The combined sheets are linked together by relatively weak bonding due to non-exchangeable potassium ions held between them. Montmorillonite has the same basic structure as illite. However, in the gibbsite sheet there is partial substitution of aluminium by magnesium and iron, and in the silica sheet there is again partial substitution of silicon by aluminium. The space between the combined sheets is occupied by water molecules and exchangeable cations other than potassium, resulting in a very weak bond. Considerable swelling of montmorillonite (and therefore of any soil of which it is a part) can occur due to additional water being adsorbed between the combined sheets. This demonstrates that understanding the basic composition of a soil in terms of its mineralogy can provide useful clues as to the geotechnical problems which may subsequently be encountered.
Rock Forming Minerals
Published in Aurèle Parriaux, Geology, 2018
Before studying all the varieties of rocks, we should spend some time describing minerals, the units that make up rocks. Mineralogy is the science of minerals. It is related to inorganic chemistry and petrology, the scientific study and description of rocks.
Engineering Behaviour of Clays: Influence of Mineralogy
Published in C. Di Maio, T. Hueckel, B. Loret, Chemo-Mechanical Coupling in Clays, 2018
The large variations in the surface area and charge characteristics of different clay minerals result in a variety of clay particle arrangements (termed clay/soil fabric). The clay fabric together with the interparticle forces (termed soil structure) determines the consistency limits, volume change, permeabilty and shear strength behavior of clayey soils. The clay size fractions are present in natural soil, can thus influence its behavior to an extent much greater than in simple proportion to the amount present depending upon their mineralogy. Thus mineralogy can be considered fundamental to the understanding of geotechnical properties. Atterberg limits, shrinkage limit and free swell index can to a great extent reflect the mineralogical characteristic of the clay size fraction. In this paper the role of type of clay minerals and the science behind them in influencing the physical and engineering properties of clay soils have been brought out. Since the extreme type of clay minerals could be identified as kaolinite and montmorillonite, discussions are centred around these two clays.
Engineering properties of fine-grained red mud
Published in International Journal of Mining, Reclamation and Environment, 2023
Hua Tian, David J. Williams, Keith Mandisodza, Chenming Zhang, Sebastian Quintero Olaya, Wenqiang Zhang, Chongyi Tang
Many geotechnical soil properties depend on their constituent mineralogy. Significant quantities of iron minerals were found in both red mud and sand, present as haematite (Fe2O3) and goethite (FeO(OH)), respectively, whereas the main mineral composition of bentonite was smectite, followed by quartz. Smectite often referred to as a ‘swelling’ or ‘expansive’ clay mineral contains interlayer spaces and exhibits a high expansion (swelling) capability in the presence of water [50]. Thus, the absence of smectite and other claylike minerals indicates that red mud is similar to ‘sand’ sample, yet it undergoes essentially infinite swelling as the limited expansion of composition occurs with hydration, which has been proven in related literature [10]. Apart from iron minerals, the red mud featured significant quantities of nosean (Na8Al6Si6O24(SO4)), distinguishing it from the ‘sand’ sample wherein large quantities of gibbsite (Al(OH)3) were present.
Airborne hyperspectral characterisation of hydrothermal alteration in a regolith-dominated terrain, southern Gawler Ranges, South Australia
Published in Australian Journal of Earth Sciences, 2021
A. S. Caruso, K. D. Clarke, C. J. Tiddy, M. M. Lewis
The main mineralogy identified across both exposure and soil samples were quartz, kaolinite, muscovite, microcline and calcite. Full XRD semi-quantitative results for each sample can be found in online data. The spatial distribution of XRD results for six key minerals, kaolinite, alunite, pyrophyllite, dickite, illite and chamosite (Fe-chlorite), are shown in Figure 12. The most widespread mineral was kaolinite, recognised within 41 samples that range from 4.5% to 23.3% (Figure 12a). Alunite occurs within two samples, one with 0.90% and the other with 24% both located at Nankivel Hill (Figure 12b). Pyrophyllite occurs in three samples, containing 22%, 30.7% and 98.4% (Figure 12c). Dickite was identified in two samples at 7.6% and 45.8% (Figure 12d). Illite occurs in five samples, which are distributed across the centre of the study area (Figure 12e) with proportions ranging from 17.4% to 30%. Chamosite was recognised in four samples in the north of the study area and one sample south of Peterlumbo Hill (Figure 12f). The proportion of chamosite ranges from 9.7% to 22.3%.
Mineral and mineralogy in late Qing China: translations and conceptualizations, 1860s–1910s
Published in Annals of Science, 2021
The terms mineral and mineralogy had been widely used across Europe for many centuries. Since the eighteenth century, mineralogists have looked back to Agricola (1494–1555), a German physician-natural historian who published his book in 1546, as the founder of modern mineralogy.37 But not until the beginning of the nineteenth century did mineralogy establish its stature as an independent modern discipline of science. The turning point came in the late eighteenth century when the European understanding of mineral and mineralogy experienced a significant revolution that rendered the two terms closer to their modern meanings.38 As summarized by Rachel Laudan, a historian of mineralogy, the term mineral today refers to the chemical compounds making up the rocks of the earth’s crust, and mineralogy is restricted to the investigation of these chemicals, particularly the complex silicates. But in the eighteenth century and before, mineral referred to all the naturally occurring, non-living, and solid objects on the globe, divisible in four main categories: metals, earths and stones, salts, and sulphurs.39 In general, mineral in a modern sense differs from earlier meanings in having a narrower scope, not extending to rocks and earths.