『Abstract
Leachability of major elements from common silicate and oxide
minerals has been determined experimentally. K-feldspar, plagioclase,
biotite,muscovite, chlorite, hornblende, epidote, sphene, rutile
anatase and ilmenite were leached in aqua regia, nitric acids,
and hydrochloric acids in varying concentrations.
The results revealed appreciable differences in the leachability
of major elements from different minerals. Biotite was completely
soluble and chlorite almost completely soluble in the strong acids
used in this study, and the yield of elements was nearly complete.
For less soluble minerals, such as feldspars and hornblende, grain
size is of great importance for the resulting yield. By using
＜63 μm instead of ＜2 mm fractions, the leachability of major elements
can be increased from 2-3 up to 7-fold. In some cases, strong
acids with a hydrochloric component are more effective the pure
nitric acid for leaching major elements from the minerals. Leaching
of a ＜2 mm fraction rather than finer grain size fractions is
recommended if the chemical analyses are intended to provide data
for mineralogical interpretations.
The results obtained in this study are suitable for geochemistry,
environmental geology and forestry, where the elemental concentration
in till, based on acid leaching, is frequently presented. The
varying solubility of the minerals can be exploited in many way,
e.g. for determining the content of readily soluble minerals in
the samples and as a starting point for calculating the total
mineralogical composition of soil samples, provided that the data
on total concentrations of elements and acid-leached fractions
are available. A high content of readily soluble minerals and
consequently with high leachability of elements indicates high
resistance to acidification and high soil fertility.
Keywords: leaching studies; leachability of elements; strong acids;
minerals; silicates; oxides』
『For the minerals leached in strong acids in this study, the
following ranking of solubility was obtained for fractions of
equal size:
biotite＞chlorite＞sphene＞ilmenite＞epidote＞hornblende＞muscovite＞plagioclase（albite-oligoclase）＞microcline＞rutile＞anatase』
1. Introduction
2. Materials and methods
2.1. Mineral specimen
2.2. Preparation of samples for leaching
2.3. Leaching
2.4. Measurement of element concentration
2.4.1. Total concentration
2.4.2. Leached fraction
2.4.2.1. Potassium
2.4.2.2. Sodium
2.4.2.3. Calcium
2.4.2.4. Magnesium
2.4.2.5. Iron and aluminium
2.4.2.6. Titanium
2.4.2.7. Leachability of minerals
3. Discussion
4. Conclusions
Acknowledgements
References