metamorphic

Rounded white pebble, likely limestone or marble

Calcite-rich carbonate rock; possibly micritic limestone (CaCO₃) or marble

AI-generated identification · may be incorrect

White, opaque, matte to faintly waxy surface with rounded edges and a small natural fracture/vein. Calcite has Mohs hardness 3, rhombohedral cleavage, and specific gravity about 2.7; exact identification requires an acid test and closer examination.

Identified September 14, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed as carbonate sedimentary rock (limestone) or recrystallized metamorphic marble; age and formation environment cannot be determined from the photograph. Its smooth shape indicates water or abrasion during transport, or intentional tumbling.

Uses & applications

Common limestone is used for aggregate, cement, and building stone; marble is used for sculpture, tile, and decorative stone. This small piece has minimal commercial value unless it proves to be an unusual marble or collectible specimen.

Geological facts

Calcite effervesces visibly in dilute hydrochloric acid; powdered calcite reacts more readily than an intact surface. White carbonate pebbles can also resemble quartz, gypsum, or manufactured ceramic.

Field identification & locations

Test a hidden spot with vinegar or dilute hydrochloric acid, check hardness against a steel nail, and inspect for calcite cleavage or crystalline grains. Common in stream beds, beaches, limestone regions, and glacial deposits.