M.M. Reddy
J.I. Drever
A.R. Hoch
1996
<p>Dissolution experiments using augite (Mg<sub>0.87</sub>Ca<sub>0.85</sub>Fe<sub>0.19</sub>Na<sub>0.09</sub>Al<sub>0.03</sub>Si<sub>2</sub>O<sub>6</sub>) and diopside (Mg<sub>0.91</sub>Ca<sub>0.93</sub>Fe<sub>0.07</sub>Na<sub>0.03</sub>Al<sub>0.03</sub>Si<sub>2</sub>O<sub>6</sub>) were conducted in flow-through reactors (5-ml/h flow rate). A pH of 5.8 was maintained by bubbling pure CO<sub>2</sub> through a solution of 0.01 <i>M</i> KHCO<sub>3</sub> at 25°C. Two experiments were run for each pyroxene type. In one experiment dissolved O<sub>2</sub> concentration in reactors was 0.6 (±0.1) ppm and in the second dissolved O<sub>2</sub> was 1.5 (±0.1) ppm. After 60 days, augite dissolution rates (based on Si release) were approximately three times greater in the 1.5 ppm. dissolved O<sub>2</sub> experiments than in the sealed experiments. In contrast, diopside dissolution rates were independent of dissolved O<sub>2</sub> concentrations. Preliminary results from the augite experiments suggest that dissolution rate is directly related to oxidation of iron. This effect was not observed in experiments performed on iron-poor diopside. Additionally, dissolution rates of diopside were much slower than those of augite, again suggesting a relationship between Fe content, Fe oxidation and dissolution rates.</p>
application/pdf
10.1016/S0009-2541(96)00050-2
en
Elsevier
The effect of iron content and dissolved O<sub>2</sub> on dissolution rates of clinopyroxene at pH 5.8 and 25°C: Preliminary results
article