Rock Identifier
Fossiliferous Limestone (Calcium Carbonate (CaCO3) matrix with biogenic fragments) — fossil
fossil

Fossiliferous Limestone

Calcium Carbonate (CaCO3) matrix with biogenic fragments

Hardness: 3 on Mohs scale; Color: tan, grey, to light brown; Luster: earthy or dull; Cleavage: none in bulk sample; Specific Gravity: ~2.5-2.7. Contains small shell fragments and marine organism remains.

Hardness
3 on Mohs scale
Color
tan, grey, to light brown
Luster
earthy or dull
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Physical properties

Hardness: 3 on Mohs scale; Color: tan, grey, to light brown; Luster: earthy or dull; Cleavage: none in bulk sample; Specific Gravity: ~2.5-2.7. Contains small shell fragments and marine organism remains.

Formation & geological history

Formed in shallow marine environments where shell fragments and marine organism remains accumulated on the ocean floor and were compacted and cemented together by calcium carbonate over millions of years.

Uses & applications

Used in construction, cement manufacturing, soil conditioning, and as educational specimens or display rocks for collectors.

Geological facts

Limestone covers about 10% of the total volume of all sedimentary rocks on Earth. Fossiliferous limestone often contains fossils of brachiopods, crinoids, bryozoans, and mollusks.

Field identification & locations

Can be identified in the field by its light color, soft nature (can be scratched with a steel nail), effervescence (bubbling) when exposed to dilute acid like vinegar, and visible shell fragments. Common along ancient riverbeds, quarries, and coastal regions.

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