igneous
Quartz–feldspar pegmatite
Granitic pegmatite, likely quartz and feldspar with mica
AI-generated identification · may be incorrectCoarse, irregular intergrowths with pale quartz/feldspar and brownish mica or iron staining. Quartz is Mohs 7, vitreous, and lacks cleavage; feldspar is Mohs 6 and commonly shows two cleavage directions. The photo does not resolve individual crystals well enough for a definite identification.
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Physical properties
Coarse, irregular intergrowths with pale quartz/feldspar and brownish mica or iron staining. Quartz is Mohs 7, vitreous, and lacks cleavage; feldspar is Mohs 6 and commonly shows two cleavage directions. The photo does not resolve individual crystals well enough for a definite identification.
Formation & geological history
Likely crystallized from water-rich residual magma in a granitic intrusion, allowing unusually large crystals to grow. Pegmatites range widely in age and occur in many geologic provinces.
Uses & applications
Pegmatite is mined for feldspar, quartz, mica, and specialty minerals; attractive pieces are kept as specimens. This rough fragment appears to have modest display value.
Geological facts
Pegmatites can host lithium, beryllium, tantalum, and other economically important minerals, though none can be confirmed from this image.
Field identification & locations
Look for coarse, interlocking crystals and distinguishable quartz, feldspar, and mica; the specimen’s brown color may be surface staining. Pegmatites commonly occur near granitic bodies worldwide.
