sedimentary

Tumbled limestone pebble

Limestone, primarily calcite (CaCO₃)

AI-generated identification · may be incorrect

Pale cream, fine-grained, matte to weakly waxy luster; calcite has Mohs hardness 3, rhombohedral cleavage, and specific gravity about 2.7. The rounded shape indicates natural water abrasion or tumbling; subtle pores and weathering are visible.

Identified August 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted carbonate mud or marine skeletal debris, commonly during the Paleozoic–Mesozoic eras, then rounded by stream, beach, or deliberate mechanical tumbling. Exact age and provenance cannot be determined from the photograph.

Uses & applications

Used for aggregate, cement and lime production, soil neutralization, decorative stone, landscaping, and craft or specimen collecting. This piece has little jewelry value unless it is unusually patterned or fossiliferous.

Geological facts

Limestone effervesces visibly with dilute hydrochloric acid or strong vinegar if freshly scratched, because calcite releases carbon dioxide. It is softer than steel and can be scratched by a knife.

Field identification & locations

Common worldwide, especially in former shallow-marine regions; major sources include the Mediterranean, Caribbean, North America, and Europe. Identify it by its pale carbonate appearance, softness, and acid reaction, while distinguishing dolostone by its weaker reaction.