Sedimentary

Limestone (Cliff Formation)

Limestone (predominantly CaCO3 as calcite)

AI-generated identification · may be incorrect

Hardness: 3 (soft to moderate), Color: Typically white, gray, beige, or yellowish, Luster: Dull to earthy (can be waxy or vitreous if crystalline), Crystal Structure: Microcrystalline to macrocrystalline, often granular, Cleavage: Three directions of perfect cleavage (for calcite crystals within), Specific Gravity: 2.7…

Identified October 24, 2025More sedimentary →

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Physical properties

Formation & geological history

Formed from the accumulation of marine organisms' shells and skeletons (calcium carbonate) over millions of years in shallow marine environments. Processes include biological deposition and chemical precipitation. The geological age of such coastal formations can vary widely, from Paleozoic to Cenozoic, depending on the specific location.

Uses & applications

Predominantly used for building materials (cement, concrete, aggregate), historical construction (e.g., cathedrals, ancient ruins), agricultural lime, and as a raw material in various industrial processes.

Geological facts

Limestone is a major constituent of many iconic geological features worldwide, including the White Cliffs of Dover, the karst landscapes of China, and the formations seen in the image. It is susceptible to chemical weathering, forming caves and karsts. It also plays a vital role in Earth's carbon cycle.

Field identification & locations

Identify in the field by its light color, bedding planes (layers), and reaction to acid (fizzing due to calcite content). Often found in marine sedimentary basins and uplifted coastal areas, such as the one pictured. Look for fossil inclusions as a definitive identifier. Collectors might look for interesting fossiliferous samples or well-formed calcite crystals within limestone vugs.

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Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

fossil

Sandstone or Siltstone

Arenite (if sandstone)

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Quartz pebble

Silicon dioxide (SiO2)

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Generic Pebble / Rock Fragment

Lithic fragment / Weathered rock

sedimentary

Sedimentary Sandstone

Arenite (Sedimentary Rock)

sedimentary

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)

sedimentary