igneous
Pegmatitic granite (quartz–feldspar rock)
Granitic pegmatite, composed chiefly of quartz (SiO₂) and feldspar, with possible mica
AI-generated identification · may be incorrectCoarse, irregular interlocking grains; cream, tan, and brown with glassy quartz and reflective mineral faces. Quartz is Mohs 7, feldspar about 6; the rock has no single hardness or crystal structure and typically shows no strong cleavage at specimen scale.
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Physical properties
Coarse, irregular interlocking grains; cream, tan, and brown with glassy quartz and reflective mineral faces. Quartz is Mohs 7, feldspar about 6; the rock has no single hardness or crystal structure and typically shows no strong cleavage at specimen scale.
Formation & geological history
Formed as late-stage, silica-rich magma cooled slowly in veins or pockets within older intrusive rocks. Pegmatites are generally Precambrian to recent, depending on the host intrusion.
Uses & applications
Quartz and feldspar are used in glass and ceramics; attractive pieces may be collected or cut for decorative objects.
Geological facts
Pegmatites can contain exceptionally large crystals and valuable minerals, though this small specimen does not show an identifiable gem mineral.
Field identification & locations
Look for coarse quartz and feldspar grains, often with mica; common in granitic regions and pegmatite veins worldwide. The photo supports a granitic pegmatite identification, but mineral confirmation would require closer inspection.
