Occurrence of gibbsite in weathering of volcanic materials at Kuroishibaru, Kumamoto

White concretions and coatings have been found in weathered volcanic sand and gravel layers at Kuroishibaru Branch of Kyushu Agricultural Experiment Station. Their identity has been questioned by attendants to the field trip of the FAO Soil Correlation Meeting on volcanic ash soils in June, 1964. This paper reports results of urineral identification of these concretions and coatings together with associated weathering products. It also includes those of the comparative analyses of one of the upper volcanic ash layers in which gibbsite accumulates to a greater extent.