igneous
Pegmatite with quartz and feldspar
Granitic pegmatite, chiefly quartz (SiO₂) and feldspar (likely potassium feldspar or plagioclase)
AI-generated identification · may be incorrectCoarse, irregular intergrowth of pale gray, translucent quartz and white-to-pink feldspar, with dark mineral bands or inclusions. Quartz hardness 7; feldspar 6; both have vitreous luster, but feldspar commonly shows cleavage while quartz fractures unevenly. Exact mineral identification is limited by the photo.
Identified More igneous →
Explore Pegmatite with quartz and feldspar in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse, irregular intergrowth of pale gray, translucent quartz and white-to-pink feldspar, with dark mineral bands or inclusions. Quartz hardness 7; feldspar 6; both have vitreous luster, but feldspar commonly shows cleavage while quartz fractures unevenly. Exact mineral identification is limited by the photo.
Formation & geological history
Likely crystallized from the last, water-rich melt of a granitic magma, allowing large crystals to grow. Pegmatites are generally Precambrian to recent and occur in granitic intrusions and surrounding metamorphic terrains.
Uses & applications
Pegmatite supplies quartz and feldspar for glass and ceramics; attractive pieces are collected or used decoratively.
Geological facts
Pegmatites can contain exceptionally large crystals and rare elements, including lithium, tantalum, and beryllium.
Field identification & locations
Look for unusually coarse crystals and a mix of quartz (no cleavage) with blocky, cleaved feldspar; dark bands may be separate minerals or inclusions. Common worldwide near granite bodies; a photo alone cannot establish locality or identify the dark bands.
