We measured noble gases in amorphous silica of geothermal origin. These samples were formed by precipitation from geothermal water in neutral pH, and by the leaching of rocks in acid hot springs. The concentration of 132Xe has a negative correlation with the temperature of geothermal water although 36Ar and 84Kr show no such correlation. The relationship between 132Xe content A (¿10-8 cm3STP/g) and temperature T(¿C) is approximated by the equation A=-(4.5¿10-3)T+0.50. The obtained equation should be useful for estimating the silica-forming temperature that cannot be easily measured by other methods. ¿ American Geophysical Union 1988