Abstract
In this study, we investigated the dissolution kinetics of wollastonite, a pyroxenoid with composition CaSiO3, at earth-surface temperatures. We used vertical scanning interferometry (VSI) to quantify the surface normal retreat (or advance) of a crystallographically defined cleavage face on a single wollastonite crystal as a function of time. Nanometer-scale measurements of (100) faces show that the wollastonite surface undergoes a net expansion normal to the surface and relative to the pristine mineral surface. These observations were made during the dissolution process at acidic conditions. The swelling is the result of the formation of a cation-depleted layer at the wollastonite-water interface. We combined VSI measurements with electron microprobe measurements to track the chemical evolution of the leached layer during dissolution, and then used previously reported Ca release rates to calculate the density of the cation-depleted layer. Using an average Ca release of 9.09 × 10-9 mol/m2·s at pH 3 and 25 °C, the density of the leached layer is 1.2 g/cm3, and grows to a thickness of ~50 nm after 20 hours of reaction. Although our observations do show direct evidence of the formation of a cation-depleted layer during dissolution, they do not favor a particular mechanism of formation of this layer. At this time, our results cannot rule out either cation migration through the depleted crystal structure or re-precipitation at the mineral surface.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Presidential Address: Elastic properties of minerals and the influence of phase transitions
- Pressure-induced hydration in zeolite tetranatrolite
- Annealing experiments on induced fission tracks in apatite: Measurements of horizontal-confined track lengths and track densities in basal sections and randomly oriented grains
- Alpersite (Mg,Cu)SO4·7H2O, a new mineral of the melanterite group, and cuprian pentahydrite: Their occurrence within mine waste
- Application of a new vanadium valence oxybarometer to basaltic glasses from the Earth, Moon, and Mars
- Quantitative polarized infrared analysis of trace OH in populations of randomly oriented mineral grains
- Hydrogen incorporation in olivine from 2–12 GPa
- A numerical model for steady-state temperature distributions in solid-medium high-pressure cell assemblies
- Thermodynamics and kinetics of cation ordering in natural and synthetic Mg(Al,Fe3+)2O4 spinels from in situ high-temperature X-ray diffraction
- Kinetics of cation ordering in natural Mg(Al,Cr3+)2O4 spinels
- Equations of state and structures of andalusite to 9.8 GPa and sillimanite to 8.5 GPa
- Equation of state and phase transition in KAlSi3O8 hollandite at high pressure
- A novel arrangement of silicate tetrahedra in the uranyl silicate sheet of oursinite, (Co0.8Mg0.2)[(UO2)(SiO3OH)]2(H2O)6
- Aluminum substitution in stishovite and MgSiO3 perovskite: High-resolution 27Al NMR
- The effect of chlorine on the viscosity of Na2O-Fe2O3-Al2O3-SiO2 melts
- TEM imaging and analysis of microinclusions in diamonds: A close look at diamond-growing fluids
- A partial molar volume for ZnO in silicate melts
- Garnet-spinel intergrowths in ultrahigh-temperature granulite, Eastern Ghats, India: Possible evidence of an early Tschermak-rich orthopyroxene during prograde metamorphism
- The partial molar volume of Fe2O3 in alkali silicate melts: Evidence for an average Fe3+ coordination number near five
- The crystal structure of a second antigorite polysome (m = 16), by single-crystal synchrotron diffraction
- Oxide melt solution calorimetry of sulfides: Enthalpy of formation of sphalerite, galena, greenockite, and hawleyite
- An experimental determination of the effect of pressure on the Fe3+/ΣFe ratio of an anhydrous silicate melt to 3.0 GPa
- Evolution of product phase assemblages during thermal decomposition of muscovite under strong disequilibrium conditions
- Synthetic P21/m amphiboles in the system Li2O-Na2O-MgO-SiO2-H2O (LNMSH)
- Incongruent dissolution of wollastonite measured with vertical scanning interferometry
- Experiments on CaCO3-MgCO3 solid solutions at high pressure and temperature
- Calorimetric data for naturally occurring magnesiocarpholite and ferrocarpholite
- Clinopyroxene exsolution in wollastonite from Namaqualand granulite, South Africa
- Icosahedral coordination of phosphorus in the crystal structure of melliniite, a new phosphide mineral from the Northwest Africa 1054 acapulcoite
- Mechanism for the dissolution of olivine series minerals in acidic solutions
- High-pressure behavior of synthetic antigorite in the MgO-SiO2-H2O system from Raman spectroscopy
- Sinoite (Si2N2O) shocked at pressures of 28 to 64 GPa
- Laser Raman spectroscopic measurements of water in unexposed glass inclusions
- The Mars/Earth dichotomy in Mg/Si and Al/Si ratios: Is it real?
- Equation of state of CaIrO3-type MgSiO3 up to 144 GPa
- Synchrotron infrared spectroscopy of synthetic Na(NaMg)Mg5Si8O22(OH)2 up to 30 GPa: Insight on a new high-pressure amphibole polymorph