sedimentary

Fossiliferous limestone, likely coralline or stromatolitic

Biogenic limestone; predominantly calcite (CaCO₃)

AI-generated identification · may be incorrect

Gray-brown, fine- to medium-grained, dull to weakly earthy luster, with raised irregular fossil or microbial textures and possible bedding. Calcite has Mohs hardness 3, rhombohedral cleavage, and reacts vigorously with dilute hydrochloric acid; specimen-scale identification is uncertain from the image alone.

Identified August 22, 2026More sedimentary →

Explore Fossiliferous limestone, likely coralline or stromatolitic 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 sediments, skeletal debris, or microbial mats accumulate and lithify, commonly during Paleozoic–Mesozoic shallow-marine environments; the exact age cannot be determined visually.

Uses & applications

Used as crushed stone, aggregate, cement and lime feedstock, and dimension stone; attractive fossil-rich pieces are mainly educational or decorative specimens.

Geological facts

The convoluted surface may represent preserved coral, algal/microbial structures, or weathered bedding rather than crystal growth.

Field identification & locations

Look for visible fossil outlines, carbonate texture, relatively low hardness, and acid effervescence; common in ancient marine sedimentary basins worldwide. Avoid acid testing on valuable specimens and confirm with a hand lens or thin section.