sedimentary

Fossiliferous limestone

Calcitic limestone, primarily CaCO₃ (calcite), with visible fossil fragments

AI-generated identification · may be incorrect

Typically gray to bluish-gray, fine- to medium-grained, dull to weakly earthy luster, and commonly layered or weathered. Calcite has Mohs hardness 3, rhombohedral cleavage, and reacts vigorously with dilute hydrochloric acid; fossils appear as pale circular or shell-like patches.

Identified August 16, 2026More sedimentary →

Explore Fossiliferous limestone in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when marine carbonate mud, shells, and skeletal debris accumulate and lithify in shallow seas; the visible structures likely represent fossil organisms or burrows. Age cannot be determined from the image, but such limestone commonly ranges from Paleozoic to Cenozoic.

Uses & applications

Used for crushed aggregate, road base, cement and lime production, building stone, and landscaping; attractive fossiliferous slabs are collectible or used decoratively.

Geological facts

The pale round markings may be crinoid fragments, shell sections, or weathered burrows, but exact identification requires a closer view and acid testing.

Field identification & locations

Common in former marine sedimentary basins worldwide, including the United States, United Kingdom, and Europe. Look for bedding, fossils, and acid effervescence; distinguish it from dolostone, which reacts weakly or slowly.