The dissolution of naturally weathered feldspar and quartz

Anbeek, Chris; Breemen, N. van; Meijer, E.L.; Plas, L. van der

doi:10.1016/0016-7037(94)90194-5

Cited by 47 publications

(26 citation statements)

References 44 publications

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“…For example, Gautier et al (2001) observed that the increase in BET surface area arising during the laboratory dissolution of quartz consists of non-reactive etch pit walls and Anbeek et al (1994) reached the same conclusion for a naturally weathered mineral assemblage of quartz and feldspar. Finally, a compilation of kinetic models reviewed by White and Peterson (1990) indicate that reactive surface areas are commonly one to three orders of magnitude lower than specific BET or geometric surface areas, respectively.…”

Section: Discussionmentioning

confidence: 72%

The dissolution rates of natural glasses as a function of their composition at pH 4 and 10.6, and temperatures from 25 to 74°C

Wolff-Boenisch

Gíslason

Oelkers

et al. 2004

Geochimica et Cosmochimica Acta

333

246

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Section: Discussionmentioning

confidence: 72%

The dissolution rates of natural glasses as a function of their composition at pH 4 and 10.6, and temperatures from 25 to 74°C

Wolff-Boenisch

Gíslason

Oelkers

et al. 2004

Geochimica et Cosmochimica Acta

333

246

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“…The shape of etch pits is controlled by the relative dissolution rate in different crystallographic directions, just as final crystal shapes are determined by relative rate of growth in different directions. These features are also observed on quartz grains Investigations of etched pit densities on naturally weathered surfaces suggest that dissolution from etched pits increase with long exposure time to weathering conditions (Anbeek et al, 1994). Bennett (1991) asserted that, the organic acids appear to increase dissolution rates.…”

Section: Discussionmentioning

confidence: 99%

The Origin of Etch Pits Recorded on Residual Grain Surfaces from Kaolinized Granitic Rocks West Region Cameroon

Wouatong¹,

Yerima²,

Fouateu³

et al. 2013

ESR

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The weathering of some granitic rocks in the West Region of Cameroon (Central Africa) was examined by X-ray diffraction (XRD) and X-ray fluorescence Spectrometer (XRF) in conjunction with Scanning Electron Microscopy (SEM). Kaolinite and illite were the most predominant weathering products whereas gibbsite, goethite and maghemite were also found in small amounts; only residual quantities of quartz and potassium feldspar were observed. The geochemical study shows the mobility of major elements during the progressive kaolinization of granitic rocks. The main trend is the loss of elements, with high losses of CaO, Na 2 O and MgO, slight losses of SiO 2 while Al 2 O 3 and K 2 O appear to increase with weathering intensity. Chemical index of alteration (CIA) shows a high value (68-95%). The scanning electron microscope analysis reveals the existence of several surface features that reflect the effect of mainly chemical actions on the quartz and K-feldspar grains. Quartz and K-feldspar crystals from kaolinized granitic rocks show low to very high chemical etching attributed to weathering under moderate to severe environmental conditions such as low pH, high temperature and humidity and extreme leaching typical of tropical climatic conditions. Etched pit densities on quartz surfaces increase with weathering, as a result of increasing silica concentrations in pore fluids.

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“…However, the mineral components of rock materials show very different affinity toward weathering. Ample information exists about weathering and the weathering rates of minerals such as quartz (Anbeek et al 1994;Langmuir 1997;Rovira et al 2000) or feldspars (Huang and Kiang 1972;Petrovic 1976;Anbeek et al 1994). Goldich (1938) developed a weathering sequence of common rock-forming minerals.…”

Section: The Geochemical Problemmentioning

confidence: 97%

Formation of iron-containing colloids by the weathering of phyllite

et al. 2006

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The formation of colloids during the weathering of phyllite was investigated by exposing ground phyllite to Milli-Q water. Secondary mineral colloids of 10 1 -10 2 nm were detected in significant concentrations. At pH of about 8.5, the solution concentration of these colloids reached up to 10 mg/L (however, acidification to pH 4.0 prevented the formation of the colloids). The mineralogical composition of the secondary mineral colloids is assumed to be a mixture of ferrihydrite, manganese oxyhydroxides, aluminosilicates, amorphous Al(OH) 3 and gibbsite with possible additions of iron silicates and iron-alumino silicates. The colloids were stable over longer periods of time (at least several weeks), even in the presence of suspended ground rock. Direct formation of iron-containing secondary mineral colloids at the rock-water interface by the weathering of rock material is an alternative to the well-known mechanism of iron colloid formation in the bulk of water bodies by mixing of different waters or by aeration of anoxic waters. This direct mechanism is of relevance for colloid production during the weathering of freshly crushed rock in the unsaturated zone as for instance crushed rock in mine waste rock piles. Colloids produced by this mechanism, too, can influence the transport of contaminants such as actinides because these colloids have a large specific surface area and a high sorption affinity.

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The dissolution of naturally weathered feldspar and quartz

Cited by 47 publications

References 44 publications

The dissolution rates of natural glasses as a function of their composition at pH 4 and 10.6, and temperatures from 25 to 74°C

The dissolution rates of natural glasses as a function of their composition at pH 4 and 10.6, and temperatures from 25 to 74°C

The Origin of Etch Pits Recorded on Residual Grain Surfaces from Kaolinized Granitic Rocks West Region Cameroon

Formation of iron-containing colloids by the weathering of phyllite

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