Chemical Composition of Silica Scales Deposited from Geothermal Waters in Kyushu, Japan

Abstract

Silica scale from geothermal water is not pure silica, but contains various elements. In order to study a role of the elements on the deposition of silica scale, chemical compositions of geothermal water and silica scale were examined. The geothermal water and silica scale samples were collected from four geothermal fields in Kyushu, Japan. The geothermal water was sampled in polyethylene bottle. To obtain silica scale sample whose history was clear, thin titanium plates were immersed in the geothermal water for 1 4.5 months. Silica scale deposited on the plate, growing cylindrically around the plate. After the silica scale samples were taken out of the geothermal water, they were immediately washed with distilled deionized water and methanol, and then were air-dried for a month. The silica scale samples were pulverized and ground into powder with agate mortor.