igneous
Quartz–feldspar pegmatite
Granitic pegmatite, chiefly quartz (SiO₂), feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, irregular interlocking crystals with pale quartz and feldspar and brown mica or iron staining. Quartz has Mohs hardness 7 and vitreous luster; feldspar is about 6–6.5 and commonly shows cleavage. Exact minerals and properties are uncertain from the image.
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Physical properties
Coarse-grained, irregular interlocking crystals with pale quartz and feldspar and brown mica or iron staining. Quartz has Mohs hardness 7 and vitreous luster; feldspar is about 6–6.5 and commonly shows cleavage. Exact minerals and properties are uncertain from the image.
Formation & geological history
Forms when volatile-rich, silica-rich magma crystallizes slowly in veins or dikes, often late in the evolution of granite intrusions. Pegmatites commonly formed during Precambrian and younger geologic episodes.
Uses & applications
Used as a source of feldspar, quartz, mica, and sometimes lithium or rare-element minerals; attractive pieces may be collected or used decoratively.
Geological facts
Pegmatites can contain exceptionally large crystals and may host tourmaline, beryl, spodumene, or other valuable minerals.
Field identification & locations
Look for very coarse, interlocking quartz and feldspar crystals, often with mica; common in granitic terrains worldwide. The pictured specimen appears pegmatitic, but the image alone cannot confirm its mineral identities.
