igneous
Quartz-rich pegmatite fragment
Granite/pegmatite; chiefly quartz (SiO₂) and feldspar, with possible biotite or tourmaline
AI-generated identification · may be incorrectCoarse-grained, white to gray, vitreous quartz and pearly feldspar with dark inclusions; quartz hardness 7, feldspar 6–6.5, generally massive with imperfect cleavage in feldspar. Specific gravity is approximately 2.6–2.7.
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Physical properties
Coarse-grained, white to gray, vitreous quartz and pearly feldspar with dark inclusions; quartz hardness 7, feldspar 6–6.5, generally massive with imperfect cleavage in feldspar. Specific gravity is approximately 2.6–2.7.
Formation & geological history
Likely crystallized slowly from water-rich felsic magma in a pegmatite vein or granitic body, allowing large interlocking crystals to grow. Such rocks commonly formed during Precambrian to Phanerozoic intrusive events.
Uses & applications
Used mainly as a geological specimen or lapidary material; quartz and feldspar from pegmatites are industrially important in glass, ceramics, and electronics. This small irregular fragment has little commercial value.
Geological facts
Pegmatites can host oversized crystals and rare minerals such as beryl, tourmaline, lithium minerals, and garnet. The dark patches may be mica, iron staining, or another accessory mineral.
Field identification & locations
Identify by its visibly coarse interlocking texture, white quartz, blocky feldspar cleavage, and lack of layering or fossils; a steel knife should not scratch quartz. Common in granitic terrains and pegmatite districts worldwide.
