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Water/Rock Interactions
Published in William J. Deutsch, Groundwater Geochemistry, 2020
A word of caution concerning the use of saturation indices to identify reactive minerals is necessary at this point. It is possible that by some fortuitous set of circumstances that the concentrations in groundwater of the components of a mineral will just happen to be at the right combination of values to calculate a saturation index of close to zero even though the mineral is not forming in the aquifer environment. For example, diopside is a pyroxene mineral with a composition of CaMgSi2O6. Diopside forms in metamorphic rocks generally at temperatures greater than 600°C.29 It is very unlikely that diopside would ever form at aquifer temperatures; however, it is possible that the calcium, magnesium, and silica concentrations in groundwater could be in the correct ratios, due to control of solution concentrations by other minerals, to calculate a saturation index for diopside close to zero. In this case diopside is not affecting the concentration of any of its components because it is not forming in the aquifer environment. It is just by chance that the concentrations of the components of diopside happen to be at particular values that calculate a saturation index of near zero for the mineral.
Minerals
Published in F.G.H. Blyth, M. H. de Freitas, A Geology for Engineers, 2017
F.G.H. Blyth, M. H. de Freitas
2. Single Chain Structures (Si2O6) are formed by SiO4-groups linked together in linear chains, each group sharing two oxygens with its neighbours (Fig. 4.20e). This structure is characteristic of the Pyroxenes, e.g. diopside, CaMg(Si2O6). The chains lie parallel to the c-axis of the mineral, are bonded together by Mg, Fe, Ca, or other atoms, which lie between them. An end view of a chain is given at (f) in the figure. The vertical cleavages in the mineral run between the chains, as shown in (f′), and intersect at an angle of 93°. Aluminium atoms, since they have nearly the same size as silicon, may repace silicon in the structure to a limited extent, and may also occur among the atoms which lie between the chains; in this way aluminous pyroxenes such as augite are formed.
Impact of forsterite addition on mechanical and biological properties of composites
Published in Journal of Asian Ceramic Societies, 2020
Rajan Choudhary, Senthil Kumar Venkatraman, Inna Bulygina, Ankita Chatterjee, Jayanthi Abraham, Fedor Senatov, Sergey Kaloshkin, Artem Ilyasov, Maxim Abakumov, Marina Knyazeva, Dimitri Kukui, Frank Walther, Sasikumar Swamiappan
Diopside is the first magnesium-based silicate ceramic which showed bioactivity [11]. Diopside is a chain-silicate mineral which comprises of covalently bonded silica network, interrupted and modified by Mg2+ and Ca2+ ions. Literature suggests that the dissolution of Ca, Mg and Si ions from diopside plays a key role in cell proliferation and differentiation [12]. Amongst all ternary CaO-MgO-SiO2 ceramic materials, the diopside possesses slower degradability, improved mechanical property and good cytocompatibility [13,14]. Previously diopside was incorporated in the different ceramic matrix (alumina, HAp, forsterite) for preparing composites. These results indicate that an increase in diopside content in the composite improves the reactivity of these composites in the physiological environment [15–17].