Abstract Local clay mineral was mined from Okpella Town, Etsako Government Area of Edo State, Nigeria. Mineralogical characterization the carried out using X-ray diffraction analyzer. Chemical fluorescence analyzer and pH analysis meter. The mineralogical revealed that majorly a dolomite having 72% dolomite. impurities present are 18% cristobalite, 4.1% garnet, 5% calcite 1% quicklime. acidic a...

The study of silica polymorphs in impactites is important for determining the pressure and temperature impact rock formation. Silica modifications melt rocks Janisjärvi structure (Karelia, Russia) are presented by tridymite, cristobalite, quartz, trace stishovite coesite. were characterized studied scanning electron microscopy (SEM), probe microanalysis (EPMA), Raman cathodoluminescent spectros...

We use molecular dynamics simulations to study the influence of confinement on the dynamics of a nanoscopic water film at T = 300 K and rho = 1.0 g cm(-3). We consider two infinite hydrophilic (beta-cristobalite) silica surfaces separated by distances between 0.6 and 5.0 nm. The width of the region characterized by surface-dominated slowing down of water rotational dynamics is approximately 0.5...

Network-forming oxides with rigid polyhedral building blocks often possess significant capacity for densification under pressure owing to their open structures. The high-pressure behaviour of these oxides is key to the mechanical properties of engineering materials and geological processes in the Earth's interior. Concurrent molecular-dynamics simulations and first-principles calculations revea...

This article reviews the analytical methods for crystalline silica polymorphs and summarizes promising techniques for compliance with health-related regulations. X-ray diffraction analysis appears to be the most promising method of determining quartz and cristobalite content at this threshold in many bulk mineral and chemical systems. Other analytical techniques can be used in some mineral and ...

We analysed the dehydroxylation of 001, 101, and 111 β-cristobalite surfaces using the periodic density functional theory method and established the OH density stability diagrams of these surfaces as a function of temperature and water partial pressure. Our calculations suggest that important surface reconstructions, involving SiO(2) unit migrations, are required to reach the experimentally mea...