sedimentary

Fossiliferous Limestone Pebble

Sedimentary Rock (CaCO3)

Hardness: 3-4 on Mohs scale. Color: Grey, tan, whitish. Luster: Dull to earthy. Texture: Fine-grained matrix containing tiny fossil fragments and small pores. Chemical composition: Mostly Calcite (Calcium Carbonate).

Hardness: 3-4 on Mohs scale
Color: Grey, tan, whitish
Luster: Dull to earthy

Identified July 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow, warm marine environments where calcium carbonate shell fragments and skeletal debris accumulated on the ocean floor and were compacted and cemented over time. Smooth pebble shape indicates stream or wave abrasion.

Uses & applications

Limestone is heavily used as crushed stone in construction, concrete, and road base, as well as an ingredient in cement. Small water-worn pebbles like this are collected as natural beach/river stones or used in landscaping.

Geological facts

Limestone covers roughly 10% of the total volume of all sedimentary rocks. When exposed to mild acids like vinegar, the calcite in limestone will produce a mild effervescence (fizzing) as carbon dioxide gas is released.

Field identification & locations

Identified by its dull grey color, soft texture compared to quartz, and small fossiliferous or porous structures. Commonly found along riverbeds, lake shores, ocean beaches, and areas with limestone bedrock exposures.

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