igneous
Weathered quartz-rich rock, possibly granite or quartzite
Likely quartz–feldspar aggregate; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectHardness about 6–7 Mohs; pale gray-white with brown surface staining, granular texture, and dull to weakly glassy luster. Interlocking quartz and feldspar grains are suggested, but crystal structure and cleavage are not clearly visible.
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Physical properties
Hardness about 6–7 Mohs; pale gray-white with brown surface staining, granular texture, and dull to weakly glassy luster. Interlocking quartz and feldspar grains are suggested, but crystal structure and cleavage are not clearly visible.
Formation & geological history
Probably formed as an intrusive igneous rock such as granite, later exposed and chemically weathered; alternatively it may be metamorphic quartzite. Formation age cannot be determined visually and could range from Precambrian to much younger.
Uses & applications
Common granite-like material is used for crushed stone, aggregate, monuments, and building surfaces; quartzite is used for construction aggregate and decorative stone. This small weathered fragment has negligible commercial value.
Geological facts
Iron-oxide staining commonly produces the brown-yellow coating seen on exposed rock surfaces. A fresh broken surface would reveal whether the specimen is quartz-rich and crystalline.
Field identification & locations
Look for visible quartz (glassy, gray grains), feldspar (opaque white or pink grains), and interlocking texture; granite usually shows multiple minerals, while quartzite is more uniformly quartz-rich. Common worldwide in bedrock and stream gravels.
