地殻表層の風化環境で生成される非晶質物質

Abstract

Clay minerals are major constituents of the earth's surface materials and are widely distributed as weathering products of interior materials of the earth crust. It is well known that the clay minerals play an important role in environmental processes through its high reactivity with both inorganic and organic ions and/or molecules. Therefore, more studies concerning the earth's surface materials involving clay minerals are strongly required to understand the environments of life support systems. Generally, clay minerals can be divided into the following two categories; 1) crystalline materials, and 2) noncrystalline materials. Extensive studies have been conducted on mineralogy of the crystalline materials, whereas little is known for the noncrystalline materials. In this paper, the author reviews noncrystalline materials formed in weathering environments on the earth crust, and shows some examples of noncrystalline materials formed by natural weathering and artificial hydrothermal reactions. Two different natural materials are described; one is weathering products formed on the surface of volcanic glass in Ito pyroclastic flow deposit, the other is precipitates on the surface of K-feldspar in Yakushima granite. The noncrystalline materials formed by artificial hydrothermal reactions are products of the reaction between volcanic glass and aqueous solution, and precipitates in a oneelemental system of Al and a two-elemental system of Al-Si.