Photo by Jennifer Boyer: Geothermal Greenhouses in Hveragerði, Iceland. Geothermal Greenhouses: A...

Unconventional geothermal resources that contain heat similar to conventional hydrothermal resources but lack the necessary groundwater and/or rock characteristics (e.g., permeability) to enable energy extraction without stimulation.
Felsic A geological term referring to igneous rocks that are equivalent to rhyolite and granite in composition.
Flowback Return flow of slickwater that was injected during a stimulation. This is a highly controlled process in which well head pressure is reduced to allow managed fluid recovery. Fluids are commonly sampled and chemically analyzed to determine the effects of...
Fumarole A steam vent and surface thermal feature that is commonly associated with steaming ground and mud pots in hydrothermally and volcanically active areas.