igneous
Quartz-bearing feldspathic rock, possibly pegmatite
Granite/pegmatitic granitic rock; primarily quartz (SiO₂) and feldspar
AI-generated identification · may be incorrectCoarse, irregular crystalline texture with translucent gray-blue quartz and white feldspar, plus rusty brown iron-oxide staining; quartz hardness 7, feldspar 6–6.5, vitreous to dull luster, no obvious cleavage in quartz but cleavage in feldspar.
Identified More igneous →
Explore Quartz-bearing feldspathic rock, possibly pegmatite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse, irregular crystalline texture with translucent gray-blue quartz and white feldspar, plus rusty brown iron-oxide staining; quartz hardness 7, feldspar 6–6.5, vitreous to dull luster, no obvious cleavage in quartz but cleavage in feldspar.
Formation & geological history
Likely formed by slow cooling of silica-rich magma, allowing large crystals to grow; the brown coloration reflects later weathering and oxidation of iron-bearing minerals. Exact age and locality cannot be determined from the photograph.
Uses & applications
Commonly used as decorative or dimension stone when sound; attractive quartz-bearing pieces may be collected, but this specimen appears ordinary and has little commercial gem value.
Geological facts
The blue-gray material may be quartz, weathered feldspar, or a surface coating; color alone is insufficient for precise identification. Pegmatites commonly host larger crystals and collectible minerals.
Field identification & locations
Look for interlocking visible crystals, glassy quartz that scratches glass, and feldspar’s flat cleavage faces; a hardness, streak, or acid test would improve identification. Common worldwide in granitic terrains and pegmatite districts.
