Active from 1900 to 1904, the Waimangu geyser is the most powerful geyser in history, approximately 20 kilometers southeast of Rotorua on the northern island of New Zealand.
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 – Diorite
Diorite Dark colored, coarse grained, intrusive rock that contains less silica than granite and that is mostly made of plagioclase, biotite, hornblende, pyroxene, and minor to nil quartz.
Word of the Week – Direct Use
Direct use The utilization of geothermal heat as an energy resource, e.g., to heat (or cool) a building such as a greenhouse, for drying, for manufacturing.
Word of the Week – Directional Drilling
Directional Drilling The practice of steering the trajectory of a well during drilling from vertical to a deviated angle, including horizontal drilling used for oil and gas production from poorly permeable rocks. Directional drilling may also be used to maneuver...