Selective dissolution and difference infrared spectroscopy in quantitative mineralogical analysis of volcanicash soil clays

• Published in: Geoderma 1972-05, Vol.7 (3), p.199-213
• Main Authors: Wada, K., Tokashiki, Y.
• Format: Article
• Language: English
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/0016-7061(72)90005-5

The use of selective dissolution and difference infrared spectroscopy has been studied as a means of quantitative determination of amorphous constituents in volcanic-ash soil clays. X-ray analysis, electron microscopy and thermogravimetry have been used to determine the crystalline and paracrystalline constituents which remain after the treatments and those which are dissolved by them. The contents of the amorphous to paracrystalline constituents dissolved by Na 2S 3O 4NaHCO 3Na citrate 2% Na 2C0 3 and 0.5 N NaOH treatments were estimated to be 18 to 94.5% for the clays examined. Dissolution of allophanes of different composition was indicated for the volcanic-ash soil clays in which these predominated, but not for those in which gibbsite and/or crystalline layer silicates were the principal constituents. Difference spectra proved that halloysite was dissolved by 0.5 N NaOH, but no significant amounts of other crystalline layer silicates.