igneous
Pegmatite with quartz, feldspar, and mica
Granitic pegmatite, chiefly quartz (SiO₂), feldspars, and mica
AI-generated identification · may be incorrectCoarse-grained, with glassy to milky quartz, pale feldspar, and dark flaky mica; quartz hardness 7, feldspar 6, mica about 2–3. The image suggests intergrown crystals, but specific minerals cannot be confirmed from appearance alone.
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Physical properties
Coarse-grained, with glassy to milky quartz, pale feldspar, and dark flaky mica; quartz hardness 7, feldspar 6, mica about 2–3. The image suggests intergrown crystals, but specific minerals cannot be confirmed from appearance alone.
Formation & geological history
Crystallized from water-rich residual magma slowly cooling in veins or pockets, commonly late in a granite intrusion. Most pegmatites formed during the Precambrian or later; this specimen’s age and locality are unknown.
Uses & applications
Pegmatite is collected for its striking large crystals and may host industrial minerals or gem materials. Quartz and feldspar are used in glass and ceramics; mica has electrical and industrial applications.
Geological facts
Pegmatites can contain exceptionally large crystals and valuable minerals such as tourmaline, beryl, and spodumene.
Field identification & locations
Look for a very coarse, interlocking mix of quartz, feldspar, and mica; quartz lacks cleavage, while mica splits into sheets. Pegmatites occur worldwide near granitic rocks, including in Brazil, the United States, and Scandinavia.
