metamorphic

Likely granitic gneiss pebble

Quartz–feldspar–biotite gneiss (visual identification; exact type uncertain)

AI-generated identification · may be incorrect

Gray, rounded, fine-to-medium-grained stone with pale minerals and scattered dark flecks; likely quartz and feldspar with minor biotite or other dark minerals. Quartz hardness is 7 Mohs, but the rock’s overall hardness varies; its sparkle may come from reflective mineral grains.…

Identified September 29, 2026More metamorphic →

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Physical properties

Formation & geological history

If gneiss, it formed when pre-existing rock was recrystallized under high heat and pressure, commonly deep in continental crust; its age cannot be determined from the photograph.

Uses & applications

Comparable material is used as crushed aggregate and decorative landscaping stone; this rounded pebble is mainly suitable for collecting or display.

Geological facts

Its rounded shape suggests prolonged abrasion in a river or on a beach. The image does not show clear mineral banding, so a granitic or other feldspar-rich rock is also possible.

Field identification & locations

Look for interlocking pale quartz/feldspar grains and dark flecks; a hand lens can help distinguish minerals. No location is provided, and the visible sparkle alone cannot identify the rock precisely.