igneous
Pegmatitic granite
Granite pegmatite, chiefly quartz, potassium feldspar, plagioclase, and biotite or other dark mica
AI-generated identification · may be incorrectCoarse, interlocking crystals with pink feldspar, pale quartz, and shiny dark mica. Hardness is about 6–7 Mohs; typically nonmetallic, with vitreous quartz and feldspar luster and mica’s perfect basal cleavage.
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Physical properties
Coarse, interlocking crystals with pink feldspar, pale quartz, and shiny dark mica. Hardness is about 6–7 Mohs; typically nonmetallic, with vitreous quartz and feldspar luster and mica’s perfect basal cleavage.
Formation & geological history
Formed as water-rich, silica-rich magma crystallized slowly in veins or pockets near the margins of granitic intrusions. Pegmatites are commonly Precambrian to younger, depending on the host intrusion.
Uses & applications
Granite is used as dimension stone and aggregate; pegmatites are also important sources of feldspar, quartz, mica, and sometimes collectible or gem minerals.
Geological facts
Pegmatites can develop exceptionally large crystals and may host minerals such as tourmaline, beryl, and spodumene.
Field identification & locations
Identify by its unusually coarse, interlocking pink feldspar, glassy quartz, and dark mica; common in granitic regions worldwide, including Brazil, the United States, and Scandinavia. The photo shows a hand-sized specimen, but locality and mineral tests would refine identification.
