igneous
Pegmatite
Granite Pegmatite
Hardness of 6-7 on the Mohs scale, predominantly pink to salmon-colored due to potassium feldspar, with translucent grey quartz and dark biotite or tourmaline. Luster ranges from vitreous to pearly, with interlocking coarse-grained crystal structure (often giant crystals).
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Physical properties
Hardness of 6-7 on the Mohs scale, predominantly pink to salmon-colored due to potassium feldspar, with translucent grey quartz and dark biotite or tourmaline. Luster ranges from vitreous to pearly, with interlocking coarse-grained crystal structure (often giant crystals).
Formation & geological history
Formed from the water-rich, late-stage crystallization of magma cooling slowly deep within the Earth's crust, often containing rare elements.
Uses & applications
Used as a source for rare earth elements, gemstone mining (such as tourmaline, beryl, and topaz), and occasionally crushed for aggregate.
Geological facts
Pegmatites can contain some of the largest individual mineral crystals found on Earth, sometimes measuring many meters in length.
Field identification & locations
Easily identified by its extremely coarse, interlocking crystals of feldspar, quartz, and dark mica. Commonly found in ancient shield areas and mountain-building belts.
