igneous
Quartz-rich rock, possibly pegmatite
Likely quartz–feldspar pegmatite; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectCoarse, uneven white-to-tan grains with a dull to vitreous luster are visible. Quartz is Mohs 7 and feldspar about 6; crystal shapes and cleavage are not clear enough here to confirm the minerals or rock type.
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Physical properties
Coarse, uneven white-to-tan grains with a dull to vitreous luster are visible. Quartz is Mohs 7 and feldspar about 6; crystal shapes and cleavage are not clear enough here to confirm the minerals or rock type.
Formation & geological history
If pegmatite, it formed as water-rich magma cooled slowly in veins or pockets, commonly during the late stages of granite intrusion. Its geological age and formation setting cannot be determined from the image.
Uses & applications
Ordinary quartz–feldspar rock has limited collector value; comparable material is used as a source of feldspar, quartz, and dimension stone when suitable.
Geological facts
Pegmatites can contain exceptionally large crystals and rare minerals, but this specimen does not show a diagnostic crystal or texture clearly enough to identify one.
Field identification & locations
Look for interlocking, unusually coarse quartz and feldspar crystals; a fresh surface or hardness and streak tests could help distinguish pegmatite from weathered quartz-rich rock. Pegmatites occur worldwide, often near granitic intrusions.
