Keywords

An exceptionally coarse-grained igneous rock, with interlocking crystals, usually found as irregular dikes, lenses or veins, esp. at the margins of batholiths.  Although pegmatites having gross compositions similar to other rock types are known, their composition is generally that of granite.  Pegmatites represent the last and most hydrous portion of a magma to crystallize and hence contain high concentrations of minerals present only in trace amounts in granitic rocks.

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.