Elements Concentrated into Siliceous Deposit Formed from Geothermal Water, and Their Distribution

Abstract

Siliceous deposits were prepared by dipping the titanium or copper plates in neutral geothermal waters. Chemical analyses were carried out for the geothermal waters and the deposits. The deposits were essentially amorphous and their ignition loss and content were in the range 5.6 - 16.0 and 71.8 - 91.7 respectively. A layer structure was observed on the crosssection of the deposits and a black layer was present near the surface of the deposits, In the black layer nodules of and Fe were observed by EPMA. Some elements were concentrated in the outermost portion of the deposit containing black layer. This suggests that a part of the elements uptaken into the deposit moves to the surface during the growth of the deposit. The existing state of and Fe in the deposit was measured by and spectroscopy, respectively. Aluminium existed as 4- and 6- coordinated species and The may be present as aluminium substituted for Si in tetrahedra and may be present as aluminium hydroxide. Iron existed as pyrite and iron hydroxide.