Pegmatites form from waters that separate from a magma in the late stages of crystallization; this activity often occurs in small pockets along the margins of a batholith. Pegmatite can also form in fractures that develop on the margins of the batholith. This is how “pegmatite dikes” are formed.

Because these dikes and pockets are small in size, the mining operations that exploit them are also small. The mining of pegmatites might be done in an underground operation that follows a dike or exploits a small pocket. It can also be done at an outcrop where the pegmatite is easily discovered by people. Pegmatites usually do not support large mining operations that employ dozens of workers and have continuous activity of many years.