Gneiss metamorphic rock

Gneiss

Metamorphic rock that forms under intense pressure and high temperature and that is made of quartz, feldspar, amphibole and mica. Gneiss represents the highest grade of metamorphic rock, which is characterized by alternating bands of dark and light-colored minerals, foliation (i.e., parallel alignment of planar minerals) and tight folding. This rock type is common at mid to deep levels of continental crust.

Geothermal Glossary

Word of the Week – Cement Bond Log

Word of the Week – Cement Bond Log

Cement Bond Log A geophysical well log that is obtained using a sonic-type tool on a wireline. The result helps to confirm the integrity of the hardened cement that was injected to form a bond between well casing and the adjacent rock formation.

Word of the Week – Chemical Geothermometer

Word of the Week – Chemical Geothermometer

Chemical Geothermometer A temperature that is calculated based on the chemical composition of a hydrothermal fluid and involves knowing a ratio (e.g., Na/K) or knowing the absolute concentration of a species (e.g., SiO2). Temperature is computed using a simple...

Word of the Week – Chlorite

Word of the Week – Chlorite

Chlorite A micaceous mineral that is commonly green-colored, composed of iron and/or magnesium, and forms due to hydrothermal alteration of amphiboles, pyroxenes, and feldspars.

Utah FORGE

Advancing innovative technologies to unlock Earth’s limitless geothermal energy.