sedimentary

Weathered limestone

Calcite-rich limestone (predominantly CaCO₃)

AI-generated identification · may be incorrect

Light tan, very fine- to coarse-grained, dull to earthy luster, massive texture, and no obvious cleavage; calcite has Mohs hardness 3 and typically fizzes with dilute hydrochloric acid or vinegar. The porous, irregular surface suggests weathering or slight recrystallization.

Identified August 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented marine carbonate mud, shell debris, or precipitated calcium carbonate, commonly during the Paleozoic–Cenozoic eras. Exposure to groundwater and weathering produced the rounded, rough surface.

Uses & applications

Used as aggregate, building stone, cement and lime feedstock, soil conditioner, and sometimes as a decorative or fossil-bearing specimen; this example appears mainly of collecting or teaching interest.

Geological facts

Limestone is commonly composed of calcite and may contain dolomite, clay, quartz, or fossils. Acid reaction and a powdery white streak are useful confirmation tests.

Field identification & locations

Common worldwide in marine sedimentary basins, including the United States, Europe, and the Middle East. Test an inconspicuous spot with vinegar or dilute acid; a strong effervescence supports calcite-rich limestone, though the image alone cannot exclude weathered dolostone or sandstone.