Plot showing the solubility of amorphous silica in water as a function of temperature

The solubility of amorphous silica (solid silica with no crystal structure) in water as a function of temperature. When deep groundwater flows through hot rhyolite it can remove silica from the rhyolite (dissolve silica). For example, groundwater with a temperature of 250 degrees Celsius (482 degrees Fahrenheit) can dissolve up to about 1230 parts per million of silica (point A). When the water ascends towards the ground surface and cools to about 92 degrees Celsius (198 degrees Fahrenheit) which is the boiling temperature in Yellowstone’s geyser basins, it can dissolve only about 350 parts per million, or about one third of the concentration at 250 degrees Celsius. The plot was modified from a figure presented in Fournier and Rowe (1966).