Keywords

Radon is a chemical element with symbol Rn and atomic number 86.  It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as an indirect decay product of uranium or thorium.  Its most stable isotope, ²²²Rn, has a half-life of 3.8 days. Radon is one of the densest substances that remains a gas under normal conditions.  It is also the only gas under normal conditions that only has radioactive isotopes, and is considered a health hazard due to its radioactivity.

Geological keywords, such as “granite”, “lake”.  The definitions are generally taken from the AGI Glossary of Geology.  Keywords with a geographic context (e.g. Cape Smith Fold Belt, Selwyn Basin, Grenville Province) are assigned to a separate category.