igneous
Rounded quartz-rich pebble
Likely granitoid-derived quartz–feldspar cobble; exact identification requires testing
AI-generated identification · may be incorrectPale cream-gray, fine to medium grained, dull to slightly sugary luster, with possible quartz and feldspar grains; hardness approximately 6–7 Mohs, no obvious cleavage, and moderate specific gravity around 2.6–2.7.
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Physical properties
Pale cream-gray, fine to medium grained, dull to slightly sugary luster, with possible quartz and feldspar grains; hardness approximately 6–7 Mohs, no obvious cleavage, and moderate specific gravity around 2.6–2.7.
Formation & geological history
Probably a weathered fragment of granite, granodiorite, or quartz-rich metamorphic rock, rounded by stream or shoreline transport. Its precise geological age and source cannot be determined from the photograph.
Uses & applications
Primarily a decorative or collectible pebble; if part of a larger deposit, quartz-rich rock may be used as aggregate or building stone, but this specimen has little commercial value.
Geological facts
The smooth, rounded shape reflects abrasion during transport, while the pale color suggests abundant quartz and light-colored feldspar. Yellow-brown patches may be iron-oxide staining or weathered mica.
Field identification & locations
Look for translucent gray quartz, opaque white feldspar, and scattered dark mica; a steel nail should not scratch it, while glass may be scratched. Common in river gravels, beaches, and glacial deposits.
