Photo by Jennifer Boyer: Geothermal Greenhouses in Hveragerði, Iceland. Geothermal Greenhouses: A...
Propylitic Alteration
A term borrowed from studies of hydrothermal ore deposits that refers to an assemblage of secondary hydrothermal minerals which forms in igneous rocks. This assemblage is made up of chlorite, illite, feldspar (both Na and K-rich varieties), epidote, calcite and pyrite, imparting a dark green tint to the appearance of altered rocks. It is commonly developed in volcanic-plutonic sequences that host high-temperature geothermal reservoirs.
Geothermal Glossary
Word of the Week – Epidote
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...
Word of the Week – Felsic
Felsic A geological term referring to igneous rocks that are equivalent to rhyolite and granite in composition.
Word of the Week – Flowback
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...