Pegmatite

Hardness varies by mineral (typically 6-7 on the Mohs scale for the overall rock due to quartz and feldspar content); coloration is generally light, featuring mottled white, gray, and pink tones mixed with darker mineral flecks; luster is vitreous to pearly; crystal structure is phaneritic with exceptionally large crystals (pegmatitic texture); cleavage is distinct in feldspar components; specific gravity is approximately 2.5 to 2.8.

Formed during the final stage of magma crystallization, when water and other volatile elements become concentrated in the remaining melt, allowing extremely large crystals to grow. They typically occur as dikes or lenses associated with large granitic plutons.

Source of rare-element minerals (such as lithium, tantalum, niobium, and beryllium), industrial feldspar and quartz, and collector-grade gem crystals like tourmaline, beryl, and topaz.

Pegmatites are famous for hosting some of the largest individual mineral crystals ever found on Earth, sometimes measuring several meters in length.

Identified in the field by its very coarse-grained (pegmatitic) texture, where interlocking crystals of quartz, alkali feldspar, and micas are conspicuously large. Commonly found in ancient shield areas and mountain belts worldwide associated with granite intrusions.