sedimentary

Weathered limestone

Calcite-rich limestone (primarily CaCO₃)

AI-generated identification · may be incorrect

Typically white to cream or tan, dull to earthy, fine-grained, and massive; Mohs hardness 3, specific gravity about 2.3–2.7. Calcite-rich surfaces effervesce strongly with dilute hydrochloric acid or vinegar, though a powder test is more reliable.

Identified September 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed mainly from compacted marine shell, coral, or carbonate mud sediments, commonly during Paleozoic–Cenozoic seas; the rounded shape and surface colors indicate weathering or abrasion. Exact age and subtype cannot be determined from the image alone.

Uses & applications

Used for aggregate, cement and lime production, building stone, soil neutralization, and decorative landscaping; ordinary pieces have little jewelry value.

Geological facts

The tan coloration commonly comes from iron-oxide staining, while the white areas may be fresher calcite or weathered surfaces. It may also be a rounded limestone cobble rather than a cut specimen.

Field identification & locations

Look for visible fossil fragments, calcite veins, and vigorous acid fizz; distinguish it from sandstone by its softer texture and acid reaction. Common in marine sedimentary regions, river gravels, beaches, and limestone quarries.