Abstract
From the results of X-ray, chemical, thermal and electron micrographic experiments it is distinct that montmorillonite, hydrated halloysite and small amounts of kaolinite, illite, and gibbsite occur in the soil. Montmorillonite more or less increases at the lower layers. Hydrated halloysite is much more abundant in the finer than in the coarser fractions, and in the latter illite and quartz increase slightly. Though the soil is not a pure one derived from limestone, but is a volcanic ash soil, the soil properties are influenced by the weathering of limestone. It is assumed that in such condition hydrated halloysite is first formed from the weathering products of volcanic materials, and then becomes to montmorillonite with some amounts of gibbsite.
