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

Refers to non-radioactive isotopes of elements, including those of oxygen, hydrogen, carbon, sulfur, and nitrogen. In geothermal geochemistry, the stable isotope ratios of oxygen (18O/16O) and hydrogen (2H/1H) in thermal waters are used to trace its origin (e.g., meteoric, magmatic).
Epidote Alumino-silicate hydrothermal mineral having a distinctive yellow-green color that is used a mineral geothermometer, forming at temperatures above ~230°C. The first down hole occurrence of epidote commonly coincides with the top of a high-temperature...
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...