Studies on Japanese acid earth

Abstract Japanese acid earth was discovered about fifty years ago, in Niigata Prefecture. The properties of this earth resemble those of Fuller's Earth showing distinct acid reaction; it is believed that it consists of montmorillonite or beidellite.1, 2, 3) The author took samples from lmai, Niigata Prefecture and studied the chemical properties and clay mineral composition of the acid earth. The soil profile of the spot where the samples were taken is shown in Fig. 1. It consists of 12 layers, but the top 7 layers are alluvial deposits unconformably covering the acid earth. The lower earth deposits are divided into 5 layers viz., G1 G2 , H1, H2 and the parent rock P. This mother rock is estimated to be liparitic tuff or glassy liparite by microscopic and macroscopic investigation.