igneous
Pegmatite
Igneous Pegmatite (Granitic Composition)
Hardness of 6-7 on the Mohs scale, predominantly pink to white color due to alkali feldspar and quartz, vitreous to pearly luster, coarse-grained crystal structure with exceptionally large crystals, specific gravity around 2.5-2.7.
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Physical properties
Hardness of 6-7 on the Mohs scale, predominantly pink to white color due to alkali feldspar and quartz, vitreous to pearly luster, coarse-grained crystal structure with exceptionally large crystals, specific gravity around 2.5-2.7.
Formation & geological history
Formed from the cooling of the final, water-rich vapor and fluid phase of a magma chamber, typically during the late stages of igneous pluton crystallization.
Uses & applications
Used as a primary source for rare-element ores (such as lithium, tantalum, and beryllium), industrial minerals (mica and feldspar), and specimen/gemstone collection.
Geological facts
Pegmatites can host some of the largest individual crystals ever found, sometimes measuring many meters in length, including giant crystals of spodumene and beryl.
Field identification & locations
Easily identifiable in the field by its interlocking, extremely coarse-grained texture with large crystals of quartz, feldspar, and micas.
