Kaolinization of Biotite as a Result of Coniferous and Deciduous Seedling Growth1
- D. E. Spyridakis,
- G. Chesters and
- S. A. Wilde2
The rhizospheric activity of coniferous and deciduous tree seedlings grown for a period of 13 months in sand cultures containing biotite (50 to 2µ) as the only source of K and Mg, effected the transformation of biotite to kaolinite. The identity of the kaolinite was established by means of X-ray diffraction and electron microscope analyses. The effectiveness of the seedlings in producing kaolinite from biotite was in the order: white cedar > hemlock > white pine > white spruce > red oak > hard maple [(Thuja occidentalis) > (Tsuga canadensis) > (Pinus strobus L.) > (Picea glauca > (Quercus rubra L. (Q. borealis Mich. x.f.) > (Acer saccharum)]. The conditions prevailing in the cultures accelerated the hydrolytic process and removal of K, Mg, and Fe from biotite and their substitution by H3O causing kaolinization. Electron microscope data revealed the characteristic hexagonal crystals of kaolinite forming on the mica surfaces. Monterey pine (P. radiata) grown in sand cultures converted biotite to vermiculite. The formation of vermiculite rather than kaolinite was attributed to the presence of metal cations in the root remains added to the cultures at the outset of the experiment.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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