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Sedimentary Rocks
Published in F.G.H. Blyth, M. H. de Freitas, A Geology for Engineers, 2017
F.G.H. Blyth, M. H. de Freitas
Jurassic ironstones Important bedded iron ores of this age in Britain and northern Europe contain the minerals siderite and chamosite (hydrated iron silicate); some of the ironstones are oolitic and others have small crystals of siderite in a matrix of mudstone. The Cleveland ironstone of the Middle Lias is an oolitic rock containing both the above minerals. A rock of the same age, the marlstone of Lincoln and Leicester, has a large amount of calcite as well as chamosite and siderite. The Northampton ironstones are partly oolitic rocks with chamosite as the chief constituent, and partly mudstones with siderite and limonite.
Sedimentary Petrology
Published in Supriya Sengupta, Introduction to Sedimentology, 2017
Iron-bearing sediments include banded (bedded) iron formations (BIF), ironstones, ferruginous ooids and fossil fragments. The bedded iron formations consist of alternating thin layers of silica and ferruginous minerals of chemical origin. The iron-bearing minerals are mostly oxides (magnetite and hematite). Silica occurs as quartz, chert or jasper. The bedded iron rocks, found in all the Precambrian cratons of the world, are often modified by diagenesis and metamorphism. The ironstone formations, which are of younger age, are composed mostly of iron carbonate (siderite) with some iron silicates (chamosite). Ooids and fossil fragments, often replaced by iron oxide minerals, are also known to occur within ironstones. The siderites are often altered to limonite near the surface.
Whole-rock compositions of Precambrian iron formations and Phanerozoic ooidal ironstones: Comparative considerations and mineralogical differentiation of subtypes
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
In order to explain the distribution of the analytical plots of both the ironstones (Fig. 2) and the iron formations (Fig. 3) general considerations must be presented. Ironstones are classified as Clinton (Silurian) and Minette (Jurassic) types. Apart from differences in their ages other characteristic differences of the two types are unknown. Another classification of ironstones is based on mineralogical aspects (Mücke, 2000). The defined types are the chamosite type and kaolinite type. Both types occur in two subtypes either unaltered or altered due to post-diagenetic ferruginization. Minerals of the ironstones are chamosite, kaolinite, magnetite, side-rite, detrital quartz grains, apatite, organic material, pyrite (mainly framboidal), sulphides and rutile/ anatas. In ferruginized ironstones goethite and/or hematite are the dominating minerals which may be associated with relics of the above-mentioned minerals.
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 analyses undertaken in this study suggests that any propylitic alteration mineralogy did not survive weathering in this landscape. Calcite is only identified in the XRD analysis within soil samples, and chamosite is the only mineral from the propylitic mineral assemblage to be identified within geological exposure samples. However, chamosite was not recognised in any proximal or distal soil samples from these GRV exposures across the study area. As with other alteration minerals in this study, chamosite is easily weathered and breaks down to kaolinite (Anand, 2005), depending on its specific chemical composition. There is some debate concerning epidote weathering mechanisms, but it is considered to be a common constituent of the residual mineral fraction of soils (cf. Price et al., 2005). Therefore, if there were epidote present in the geological exposures, it is likely to be identifiable in soils, even after weathering. There was no epidote identified by XRD or image analysis, which implies that neither chloritic nor propylitic alteration is present in this study area.
In vitro antibacterial activities of selected TB drugs in the presence of clay minerals against multidrug-resistant strain of Mycobacterium smegmatis
Published in Cogent Engineering, 2020
Patrick K. Arthur, Vincent Amarh, Ethel J. S. Blessie, Rebecca Yeboah, Benjamin W. Kankpeyeng, Samuel N. Nkumbaan, Elvis K Tiburu
The elements in the clay materials included silicon (Si), aluminum (Al), iron (Fe), oxygen (O) and carbon (C), as investigated using Energy Dispersive X-ray (EDX) and Atomic Absorption Spectroscopy (AAS) (Figure 1(a)). The based weight percent ratio of Si to Al was found to be 1.5. The Scanning Electron Microscope (SEM) image of the clay revealed an irregular distribution of particles (Figure 1(b)). The X-ray diffraction (XRD) pattern indicates characteristic peaks of d001 and d100 at 7.1 Å and 12.6 Å, respectively, with additional peaks at positions 21 Å and 27 Å at <2θ> angles (Figure 1(c)). The XRD pattern and EDX analysis of the clay material showed characteristic peaks revealing a chamosite clay ore with elevated amounts of iron. Finally, the signature peaks of the clay were confirmed using Fourier Transform Infrared Spectroscopy (FTIR) showing unique peaks at 3695 cm−1 and 3622 cm−1 representing NH2 and O-H stretching vibrations, respectively, whereas the peak at 1635 cm−1 revealed Si-O stretching mode (Figure 1(d)). The bands located within the range of 650–745 cm−1 were assigned to symmetric T–O–T vibrations within the clay. These results confirm a chamosite clay ore with varying amounts of mineral concentrations (Racha et al., 2010). Henceforth, the chamosite clay would be referred to as healing clay in the subsequent sections of the paper.
Ore Pretreatment Methods for Grinding: Journey and Prospects
Published in Mineral Processing and Extractive Metallurgy Review, 2019
Veerendra Singh, Prashant Dixit, R Venugopal, K Bhanu Venkatesh
Omran et al. (2015b) investigated the effects of microwave and conventional heating pretreatment on the liberation of iron-bearing minerals from high phosphorus oolitic iron ore. Scanning electron microscope (SEM) results indicated that intergranular fractures were formed between the gangue material (fluoroapatite and chamosite) and hematite after microwave treatment, resulting in improved liberation of the iron ore. Only a small number of micro-cracks were observed between the oolitic/matrix and in oolitic layers after conventional heating of iron ore. Grindability tests indicated that microwave-treated iron ore could be more easily ground compared with iron ore treated in a conventional furnace. Energy consumption measurements also revealed that microwave treatment consumes much smaller quantities of energy compared with conventional heating ovens. Meikap et al. (2010) studied the influence of microwave pretreatment on the grindability of iron ore. Grindability tests showed that microwave-treated iron ore ground much more rapidly initially than the untreated ore. The results showed that the breakage function of both microwave untreated and treated iron ore was dependent on the particle size. The grindability increased significantly because of microwave pretreatment with the specific rate of breakage increasing by an average of 50%.