sedimentary

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with Biogenic Inclusions

Hardness: 3-4 (Mohs scale); Color: White, off-white, or light gray; Luster: Dull to earthy; Crystal Structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral in calcite crystals; Specific Gravity: 2.5-2.7

Hardness: 3-4 (Mohs scale)
Color: White, off-white, or light gray
Luster: Dull to earthy

Identified June 30, 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 warm, shallow marine environments through the accumulation of shell, coral, algal, and fecal debris. It is primarily biogenic but can include chemical precipitates.

Uses & applications

Used widely in construction as aggregate, road base, and in the production of cement. Finer specimens are used as architectural stone or for soil pH adjustment in agriculture.

Geological facts

Limestone covers about 10% of the Earth's land surface and contains the vast majority of the world's accessible carbon sink. This specific specimen appears to contain small fossil fragments or 'vugs' where fossils once were.

Field identification & locations

Identify in the field by checking for the presence of fossil fragments and its reaction (fizzing) when exposed to dilute hydrochloric acid. It is common in regions that were once ancient seabeds.

Other sedimentary specimens

See all

Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

Cone-in-cone structure (Limestone)

Cone-in-cone structure (Secondary Sedimentary Structure)

sedimentary

Chert Breccia

Brecciated Chert (Microcrystalline Silica)

sedimentary

Sandstone Grain

Clastic Sedimentary Rock Grain (SiO2 dominated)

sedimentary

Shale or Slaty Mudstone

Argillaceous sedimentary rock

sedimentary

Sandstone

Arenite (primarily SiO2)

sedimentary