Crystal Geyser, Cold-water geyser in Utah, United States

Crystal Geyser is a cold-water geyser on the east bank of the Green River that shoots water and carbon dioxide under high pressure through an abandoned oil well shaft. The phenomenon originates from a pressurized groundwater reservoir located deep below the surface.

The geyser's current form comes from an exploration well drilled in 1935 in search of oil. The well reached 2,600 feet deep, but a later owner partially filled it, leaving it only a couple hundred metres deep. The first written record of the site is the July 13, 1869 entry of John Wesley Powell's expedition, noting mineral spring deposits no longer flowing.

The geyser sits on land where the Frutexites-like iron-rich laminae of the travertine are probably the work of Leptothrix bacteria, and green patches elsewhere come from microbes. Metagenomic studies found archaea of the Diapherotrites and Altiarchaeota groups in the aquifer. Visitors often watch the pre-eruption bubbling, which alternates between the main vent and natural side-pools.

The geyser sits on the east bank of the Green River, about 9 miles (14 km) downstream from the town of Green River, reached by dirt roads off Interstate 70. Eruptions are unpredictable, spaced 8 to 27 hours apart, so check recent activity before setting out. The surrounding travertine is uneven and slippery when wet; stay back from the vent and the riverbank.

The underground reservoir holds trapped carbon dioxide within ancient sandstone layers that powers the eruptions without any geothermal heat. This natural gas source makes it fundamentally different from true geothermal geysers.