Minerals structure

J.E. Post andC.W. Burnham, Ionic modeling of mineral structures and energies in the electron gas... 

Boskey A (2006) Mineralization, Structure and Function of Bone. In Dynamics of Bone and Cartilage Metabolism, 2nd edn. Seibel MJ, Robins SP, Bilezikian JP (eds), San Diego, Academic Press,201-212... 

However, the question must always be asked as to whether these processes could have taken place on the primordial Earth in its archaic state. The answer requires considerable fundamental consideration. Strictly speaking, most of the experiments carried out on prebiotic chemistry cannot be carried out under prebiotic conditions , since we do not know exactly what these were. In spite of the large amount of work done, physical parameters such as temperature, composition and pressure of the primeval atmosphere, extent and results of asteroid impacts, the nature of the Earth s surface, the state of the primeval ocean etc. have not so far been established or even extrapolated. It is not even sure that this will be possible in the future. In spite of these difficulties, attempts are being made to define and study the synthetic possibilities, on the basis of the assumed scenario on the primeval Earth. Thus, for example, in the case of the SPREAD process, we can assume that the surface at which the reactions occur could not have been an SH-containing thiosepharose, but a mineral structure of similar activity which could have carried out the necessary functions just as well. The separation of the copy of the matrix could have been driven by a periodic temperature change (e.g., diurnal variation). For his models, H. Kuhn has assumed that similar periodic processes are the driving force for some prebiotic reactions (see Sect. 8.3). 

Chromium has a similar electron configuration to Cu, because both have an outer electronic orbit of 4s. Since Cr3+, the most stable form, has a similar ionic radius (0.64 A0) to Mg (0.65 A0), it is possible that Cr3+ could readily substitute for Mg in silicates. Chromium has a lower electronegativity (1.6) than Cu2+ (2.0) and Ni (1.8). It is assumed that when substitution in an ionic crystal is possible, the element having a lower electronegativity will be preferred because of its ability to form a more ionic bond (McBride, 1981). Since chromium has an ionic radius similar to trivalent Fe (0.65°A), it can also substitute for Fe3+ in iron oxides. This may explain the observations (Han and Banin, 1997, 1999 Han et al., 2001a, c) that the native Cr in arid soils is mostly and strongly bound in the clay mineral structure and iron oxides compared to other heavy metals studied. On the other hand, humic acids have a high affinity with Cr (III) similar to Cu (Adriano, 1986). The chromium in most soils probably occurs as Cr (III) (Adriano, 1986). The chromium (III) in soils, especially when bound to... 

Clay minerals are structure of aluminum- and silicate-oxides. Such structures have free bond and vacancies on selective site of the mineral structure allowing them to participate in both physical adsorption and chemical reactions modifying the available concentration of the chemicals in the environment. 

Broadly speaking the classification of meteorites follows the geological mineral classification and with 275 mineral species reported so far this quickly becomes complex some classes of meteorite have only one member. The mineral structure does convey essential information about the temperature at which the meteorite formed as well as the reduction-oxidation (redox) environment was the environment in which it formed rich in oxygen Meteorites have been classified into three broad classes ... 

In Dzombak and Morel s (1990) development, hydrous ferric oxide holds two site types, one weakly and the other strongly binding. In their uncomplexed forms, the sites are labeled >(w)FeOH and >(s)FeOH the notation > represents bonding to the mineral structure, and (w) and (s) signify the weak and strong sites. 

Use of weak leach methods shows that mobile ion concentrations in the upper soil horizons can be used for tracing mineralization or mineralized structures in... 

Why might one be specifically interested in the chemistry of a particular species in soil From a positive perspective, it is desirable to provide plants with nutrients in forms that are available and yet are not present in concentrations high enough to cause environmental harm. Potassium ions are found in the soil solution and on exchange sites. Both species are available to plants. It may also be part of the mineral structure of soil, as in muscovite,... 

Soil solids are either inorganic or organic, and each requires different analyses. Direct measurements on whole soil are not as common as indirect measurements. Direct measurements are limited to X-ray, IR, and NMR analysis. X-ray analysis is commonly used to investigate mineral structure, while IR is used to... 

A broadening in Mark s intellect is shown clearly in his publications of this period. The topics in 1926 and 1927 alone ranged from atomic structure and quantum theory (1), and Compton radiation (2) to the scattering of x-rays by an ideal gas (3) and mineral structure (4). The shear diversity of his contacts and interests made him qualified for expanded responsibilities. 

Biomineralization. In biomineralization, inorganic elements are extracted from the environment and selectively precipitated by organisms. Usually, templates consisting of suitable macro-molecules serve as a substrate for the heterogeneous nu-cleation of bulk mineralized structures such as bone, teeth and shells. Biological control mechanisms are reflected not only in the type of the mineral phase formed but also in its morphology and crystallographic orientation (Mann et al., 1989 Lowenstamm and Weiner, 1989). Two examples (perhaps oversimplified) may illustrate the principle (Ochial, 1991) ... 

The two types of clay mineral structures which are of interest in the present discussion are the expanding 2 1 structures (the smectites and vermiculites) and the 1 1 structures (the kaolins). 

XPS is able to distinguish between metal ions in a mineral structure and those adsorbed on the surface with the same oxidation state. As an example, the Mg Is photoelectron- and Auger electron-spectra of Mg montmorillonite reveal considerable differences in the electronic states of the exchangeable and skeletal Mg (45), the former being similar to typical ionic compounds, such as magnesium fluoride, whilst the latter resembles magnesium oxide. 

Embedded within the protein-mineral structure are the three types of bone cell osteoblasts ( bone builders which form new bone matrix), osteoclasts (which degrade... 

Zvyagin B.B. (1967) Electron diffraction analysis of clay mineral structures. New-York, Plenum. 

Clay Group Mineral Structure Composition (idealized) (meq/IOOg) Remarks... 

Kieffer (1982) suggests a set of rules describing expected frequency shifts for different types of vibrational modes upon substitution of a heavy isotope into the mineral structure. Kieffer s (1982) rules for substitution in silicates are as follows. 

Tossell J. A. (1985). Ab initio SCF MO and modified electron gas studies of electron deficient anions and ion pairs in mineral structures. Physica, 131B 283-289. 

The phyllic alteration zone coincides with a subtle but consistent shift in the dominant AlOH peak in the short-wave infrared spectrum ( 2210 nm) to slightly lower wavelengths, consistent with an inner white mica-ferroan carbonate mineral assemblage. A preliminary analysis of hyperspectral data over the visible to near infrared range suggests that ferroan carbonates may be detected but not reliably quantified. However, TIR data allow calcite and ferroan carbonate to be distinguished, and may also detect increasing Fe content in ferroan dolomite as mineralized structures are approached. 

Brcck, D. R. (1974). Zeolite Molecular Sieves. Wiley-Interscience, New York. Brenner, S. S. (1958). Growth and properties of whiskers. Science 128 569-575. Brindley, G. W. (1980). Order-disorder in clay mineral structures, pp. 125-195. In Brindley, G. W. and G. Brown, eds. Crystal Structures of Clay Minerals... 

Ar. Because Ar is from conversion of the concentration of Ar is proportional to that of Because is part of the mineral structure, its concentration may be treated as uniform throughout the mineral. Hence, Ar concentration is also uniform in the mineral. On the other hand, °Ar concentration reflects the growth and diffusive loss and would not be uniform. 

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