sedimentary

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs); Color: Tan, buff, or gray; Luster: Dull to earthy; Structure: Clastic with visible fossil molds and casts (brachiopods/bivalves); Texture: Clastic or bio-crystalline; Specific Gravity: 2.3-2.7

Hardness: 3-4 (Mohs)
Color: Tan, buff, or gray
Luster: Dull to earthy

Identified June 22, 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

Formed in shallow marine environments through the accumulation of shell fragments and calcium carbonate precipitates. The holes (vugs) are likely created by the leaching of fossils, leaving behind molds. Age varies, often Carboniferous to Devonian for such specimens.

Uses & applications

Primarily used in construction (crushed stone, cement), landscaping (ornamental rocks), and as geological study specimens for paleontologists.

Geological facts

This specific piece is a 'fossil hash,' meaning it contains a densely packed mixture of several types of marine organisms from a prehistoric seafloor.

Field identification & locations

Identify by looking for distinct impressions of shells (brachiopods, mollusks) and a vigorous reaction (fizzing) when exposed to a drop of weak acid (vinegar or HCl). Commonly found in sedimentary basins worldwide.