igneous
Pegmatite
Igneous Pegmatite
Hardness varies by mineral content (typically 6-7 Mohs for quartz/feldspar components); color ranges from white and pink to multicolored; luster is vitreous to pearly; crystal structure is exceptionally coarse-grained with individual crystals often exceeding several centimeters in size.
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Physical properties
Hardness varies by mineral content (typically 6-7 Mohs for quartz/feldspar components); color ranges from white and pink to multicolored; luster is vitreous to pearly; crystal structure is exceptionally coarse-grained with individual crystals often exceeding several centimeters in size.
Formation & geological history
Formed from the water-rich, volatile-element-enriched residual melt of a cooling magma chamber, typically during the final stages of crystallization of granitic magmas.
Uses & applications
Source of rare-element minerals, gemstones (such as tourmaline, beryl, and topaz), and industrial minerals like quartz and feldspar.
Geological facts
Pegmatites are famous for hosting some of the largest individual crystals ever found on Earth, including spodumene crystals over 10 meters long.
Field identification & locations
Easily identified in the field by its extremely coarse-grained texture, often contrasting sharply with surrounding finer-grained host rocks, containing giant interlocking crystals of quartz, feldspar, and mica.
