igneous
Pegmatite
Granitic pegmatite, composed mainly of quartz and feldspar with possible mica
AI-generated identification · may be incorrectCoarse, irregularly intergrown crystals; mostly pale pink, cream, gray, and dark brown. Quartz is Mohs 7 and feldspar about 6; luster ranges from glassy to dull, with no visible uniform cleavage in the whole specimen.
Identified More igneous →
Explore Pegmatite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse, irregularly intergrown crystals; mostly pale pink, cream, gray, and dark brown. Quartz is Mohs 7 and feldspar about 6; luster ranges from glassy to dull, with no visible uniform cleavage in the whole specimen.
Formation & geological history
Crystallized from water-rich, silica-rich residual magma, commonly in veins cutting older granite. Pegmatites are generally Precambrian to younger, but this specimen’s age cannot be determined from the image.
Uses & applications
Pegmatite is a source of feldspar, quartz, mica, and specialty elements such as lithium, tantalum, and cesium; attractive pieces are collected or used decoratively.
Geological facts
Pegmatites can contain exceptionally large crystals and rare minerals, though the pictured specimen does not show a diagnostic rare mineral.
Field identification & locations
The coarse, patchy crystals and quartz–feldspar-like material suggest pegmatite, but identification is tentative from the photo; check for hard, glassy quartz and softer feldspar grains. Pegmatite occurs worldwide, especially in granitic regions.
