Did you know… Alaska uses geothermal energy to produce electricity? It might seem highly unlikely...
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 – Proppant
Proppant Sand-sized solid grains that are injected in a fluid suspension and used to hold open stimulated fractures in a geothermal reservoir.
Word of the Week – Propylitic Alteration
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),...
Word of the Week – Rhyolite
Rhyolite Light colored fined grained volcanic rock composed of glass, quartz, K-feldspar and plagioclase, with relatively high silica (69-77 wt %). The composition reflects partial melting of continental crust. Rhyolitic volcanism is a feature of both Yellowstone...