Pegmatites

Pegmatites are extreme igneous rocks that form during the final stage of a magma’s crystallisation.

To be called a “pegmatite,” a rock should be composed almost entirely of crystals that are at least one centimetre in diameter. The name “pegmatite” has nothing to do with the mineral composition of the rock.

Pegmatites are economically important because they can host a wide range of minerals, serving as primary commercial sources for lithium, beryllium, tantalum, niobium, feldspar, mica, and various gemstones.