Word of the Week – Stable Isotopes

Stable Isotopes

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).

Word of the Week – Normal Fault

Normal Fault

High angle fault that results from extensional stress and forms a steeply dipping planar structure. Slip movement during an earthquake is vertical and down dip. The down-dropped block is called the hanging wall and the uplifted block is called the footwall.

Word of the Week – Zircon


Zirconium silicate (ZrSiO4) is a minor or accessory mineral in igneous and metamorphic rocks. It contains measurable albeit minor amounts of uranium and lead, which make it amenable for radiometric dating. Zircons are some of the oldest dated minerals on Earth.

Word of the Week – Granite


Light colored, coarse grained, intrusive rock with a felsic (silica-rich) composition that is mostly made of quartz, sodium and potassium-bearing feldspar, and plagioclase. Minor amounts of other minerals can include mica (muscovite, biotite), hornblende, magnetite (iron oxide), and ilmenite (titanium-iron oxide).