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Petroleum Geological Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
Silicate groups of minerals are rock-forming material and constitute about 99% of the molten magma of the earth’s mantle and igneous rock. Silicate mineral consists of anions of silicon and oxygen atoms (SiO4)–n together with metallic cations of Al, Na, K, Fe, Ca, Mg and some other metals.
Electrochemical and Physical Properties of Geologic Material
Published in V. P. (Bill) Evangelou, and Its Control, 2018
The silicate minerals constitute the majority of the crystalline natural minerals. They consist of Si-O tetrahedrons in which one silicon atom is centered between four oxygen atoms. These simple structures form chains, rings and sheets by sharing oxygen atoms. As should be expected from the non-homogeneity of nature, minerals of this form are not perfect crystals and have impurities in their structures. The substitution of an aluminum atom for silicon in the tetrahedron is very common. A subgroup of the silicate minerals, the layer silicates or phyllosilicates are of particular importance when considering geologic material because they make up a large part of the < 0.2 μm “clay sized” particles. These minerals are also referred to as clay minerals. For additional information on silicate minerals present in natural geologic environments the reader is referred to Minerals in Soil Environments (Dixon and Weed, 1977).
Minerals
Published in W.S. MacKenzie, A.E. Adams, K.H. Brodie, Rocks and Minerals in Thin Section, 2017
W.S. MacKenzie, A.E. Adams, K.H. Brodie
Although we have defined a mineral as a chemical compound, the word compound is used in a somewhat different sense from that in which a chemist would use the word. To a chemist, a compound usually has a fixed composition which can be represented by a chemical formula. Common minerals, on the other hand, with some exceptions, are rarely of a single composition. A few minerals are virtually pure compounds, e.g. quartz is almost pure SiO2; kyanite, andalusite and sillimanite all have the formula Al2SiO5 and again only have minor amounts of other elements. Silicate minerals commonly show the greatest complexity in chemical composition and almost all of them are solid solutions, i.e., certain elements can substitute for one another in the structure. Thus in the minerals which we call ferromagnesian minerals, magnesium and iron are interchangeable, in the sense that either element may occupy certain sites in the crystal lattice, and in the alkali feldspars sodium and potassium are interchangeable. One of the common minerals, hornblende, embraces a range of chemical compositions in the amphibole group of minerals which represents an even wider range of substitution of different elements in what is essentially one crystal structure.
Mineralogical Control on Ash Fusion Temperatures of some High Sulfur Indian coals by oxides generated during combustion
Published in International Journal of Coal Preparation and Utilization, 2023
B. Mahanta, A. Saikia, P. Saikia, J. Jayaramudu, S. Periyar Selvam, A. Varada Rajulu, E. Rotimi Sadiku
The high-sulfur coals in the North Eastern part of India have been playing an important role for various industries, particularly the metallurgical industries and the thermal plants in the region. These coals are enriched with silicates, carbonates, phosphates, hydroxides, oxides, sulfates and sulfides. The silicate minerals are found in the form of quartz (SiO2), feldspar (KAlSi3O8), mica [KAl2AlSi3O10(OH,F)2], chlorite [(Mg, Fe)5Al2Si3O10(OH)8] and kaolinite [Al2Si2O5(OH)4]. Oxides occur as hematite (Fe2O3) and rutile (TiO2), and hydroxides as gibbsite [Al (OH)3] and goethite (FeOOH). The carbonate group minerals are present as calcite (CaCO3) and siderite (FeCO3), whereas phosphate minerals in these coals occur in the form of monazite [(Ce, La, Th, Nd)PO4] and apatite [Ca5F(PO4)3]. The sulfides present in these coals are pyrites (FeS2), marcasites (FeS2) and sphalerites (ZnS), while the sulfates are present in the form of gypsum (CaSO4 · 2H2O) andbarite (BaSO4) (Nayak 2013; Sharma et al. 2014).
Kinetic and thermodynamic study of potassium recovery from silicate rocks
Published in Mineral Processing and Extractive Metallurgy, 2022
Himanshu Tanvar, Nikhil Dhawan
Silicate minerals are the largest and most important class of rock-forming minerals and makeup ∼ 90% of the earth's crust. In general, the silicate rocks contain ∼5–12% K2O content. The general structural formula of silicate rocks is XmYn(ZpOq)Wr. Where, X is the largest size cation like K+, Rb+, Na+, Ba+, and Ca+2. Y represents intermediately sized cation like Al+3, Mg+2, Fe+2, Fe+3, and Mn+2. Z represents the tetrahedral site containing Si+4 and Al+3. O is oxygen and W is OH−1 and the subscripts m, n and r depends on the ratio of p to q, and its value depends on charge balance. The principal concern with these resources is the complex structure and associated slow leaching rate of macronutrients compared to conventional salts (Manning 2010; Ciceri et al. 2017). Weathering transforms primary minerals (orthoclase) into secondary minerals such as muscovite and is partly responsible for the rate of nutrient leaching into the soil solution from crystals. The dissolution of silicate rocks is a bane for hydrometallurgical heap leach operations as most of the cations (Na, K, Al, and Si) often pile up in the leaching circuit and their dissolution behaviour is highly complicated (Crundwell 2015). On the other hand, these rocks can be a boon for an agricultural-based country like India (Jena et al. 2014; Luo et al. 2015).
Managing hazardous materials in New Zealand’s National Petrology Reference collection
Published in New Zealand Journal of Geology and Geophysics, 2018
Delia T. Strong, Rose E. Turnbull, Andreas Markwitz
In New Zealand, the management of asbestos in a place of work is governed by the Health and Safety at Work (Asbestos) 2016 Regulations (Health and Safety at Work (Asbestos) Regulations, New Zealand Statutes 2016). These Regulations replace the previous Health and Safety in Employment (Asbestos) Regulations 1998 (Health and Safety in Employment (Asbestos) Regulations, New Zealand Statutes 1998) which were revoked in April 2016. The new Regulations define asbestos as the asbestiform varieties of silicate minerals belonging to the serpentine or amphibole groups of rock-forming minerals, including:actinolite asbestosgrunerite or amosite asbestos (brown asbestos)anthophyllite asbestoschrysotile asbestos (white asbestos)crocidolite asbestos (blue asbestos)tremolite asbestosa mixture containing > 1 of the above.The terms ‘asbestos’ and ‘asbestiform’ refer to silicate minerals that occur in polyfilamentous bundles of flexible, long, small-diameter fibres with splaying ends. Respirable asbestos is defined by the Health and Safety at Work (Asbestos) 2016 Regulations as an asbestos fibre that:is less than 3 micrometres wide;is more than 5 micrometres long; andhas a length to width ratio of more than 3:1.Because asbestos is widely known as a hazard to human health, its use is banned as an industrial material in many countries. In New Zealand its use for new construction and disposal is controlled by the Health and Safety at Work (Asbestos) Regulations 2016. The regulations have principally been written to manage the health and safety of workers in construction and demolition industries rather than curators of natural science collections. There is provision, however, for the management of naturally occurring asbestos, defined as the ‘natural geological occurrence of asbestos minerals found in association with geological deposits such as rock, sediment or soil’, in accordance with an asbestos management plan which must be prepared under Regulation 13.