At Silex Spring, consider how this hot water arrived at the surface. Deep beneath your feet, heat from partially molten rock beneath the surface is transmitted up through the earth's crust. Ground water circulating through these rocks becomes heated and follows cracks upward. Where the hot water can escape at the surface, a hot spring forms.
Silex is Latin for silica, the major component of rhyolite, the primary volcanic rock in Yellowstone. Hot water dissolves silica, which precipitates as siliceous sinter along the bottom of the spring and in runoff channels.
Thermophiles thrive in the overflow of Silex Spring. They provide food for flies living in and on the hot water. The flies then become food for mites, spiders, insects, and birds.
Mats and flies don't exist in the pool or at the start of the overflow where the water is too hot (167-199°F; 75-93°C) for most thermophiles.
The activity of Silex Spring, like that of other hydrothermal features, can change. For example, after 21 years of dormancy, Silex Spring erupted many times from 2000 to 2006.
Temperature 193°F Dimensions 35.5x39.4 feet. Depth 27 feet. It is unknown when or by whom this colorful blue spring was named, but the name Silex may refer to the word silica. Some believe it may refer to the Silex coffee percolator. The spring boils occasionally and, periodically large bubbles of gas rise to the surface. The 1959 earthquake caused it to erupt and increased the flow. The discharge is now 75 to 100 gallons per minute. There are underground connections to Celestine Pool, a similar nearby hot spring.