Influence of aqueous Mg concentration on the transformation of amorphous calcium carbonate

Droplet-based in situ X-ray absorption spectroscopy cell for studying crystallization processes at the tender X-ray energy range

“…38 In this work, aragonite formation was not detected at any stage of the crystallization process because the experiments were done in big droplets, at room temperature and without any aragonitepromoting additive such as magnesium ions. This is consistent with the literature, where at room temperature aragonite formation has been observed to occur either in connement $25 nm pores 39,40 or in solutions containing inorganic additives such as magnesium ions [41][42][43][44][45][46][47][48] or organic additives/solvents. [49][50][51] Carbon dioxide has a strong inuence on the pH of aqueous solutions because it readily dissolves in water to form carbonic acid, which dissociates to bicarbonate and carbonate ions respectively (eqn (1)).…”

Significance of fluid chemistry throughout diagenesis of aragonitic Porites corals – An experimental approach

“…Nevertheless, similar patterns have previously been reported and commonly linked to diffusion‐related processes (Allison, Finch, Newville, & Sutton, ; Watson & Müller, ). The high Mg/Ca ratios used in the burial fluid experiments created not only initial dissolution, but also inhibited calcite nucleation and growth, while favouring the precipitation of aragonite—a commonly observed feature in both laboratory and natural systems (Purgstaller, Mavromatis, Immenhauser, & Dietzel, Mavromatis, Konrad, & Dietzel,; Purgstaller, Dietzel, Baldermann, & Mavromatis, , Purgstaller, Konrad, Dietzel, Immenhauser, & Mavromatis; Konrad et al, ). In contrast, the extensively altered meteoric sample contains relatively lower amounts of Mg and higher amounts of Sr in the neomorphosed primary framework, with relatively higher Mg and lower Sr content in the grain bridges (Figure H and I).…”

In-situ Raman spectroscopy of amorphous calcium phosphate to crystalline hydroxyapatite transformation

“…In geosciences, RS is most commonly used as a fingerprinting tool for identifying and characterizing minerals. As such, time-resolved in-situ RS presents an easy, rapid and reliable tool with a wide range of applications, e.g., identifying aqueous species, monitoring pathways of mineral formation [ 24 , 25 ], quantitative determination of mineral contents as well as studying the exchange kinetics of e.g., O-isotopes [ [26] , [27] , [28] , [29] ]. Further, RS is very sensitive to short-range ordered (amorphous) phases.…”