metamorphic

Banded limestone or marble pebble

Calcite-rich carbonate rock; likely banded marble (CaCO₃)

AI-generated identification · may be incorrect

Gray-white, rounded and polished-looking, with dark wavy bands and a dull to weakly silky luster. Calcite has Mohs hardness 3, rhombohedral cleavage, and fizzes with dilute hydrochloric acid; marble may show recrystallized interlocking grains.

Identified September 18, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed from layered limestone later altered by heat and pressure into marble, with darker bands from clay, carbon, or other impurities. The visible rounding indicates water or abrasion; exact geological age cannot be determined from the image.

Uses & applications

Suitable as a decorative pebble, paperweight, or lapidary material; carbonate stone is also used for aggregate, lime, cement, and dimension stone. Ordinary pieces have little commercial value.

Geological facts

The banding may represent original sedimentary layers preserved during metamorphism, or compositional banding developed during recrystallization. A simple acid test helps distinguish carbonate rock from quartz-rich banded stones.

Field identification & locations

Common in regions containing folded limestone and marble, including the Appalachians, Alps, and many river gravels. Check for acid reaction, very low scratch resistance, and calcite cleavage; a steel knife should scratch it.