sedimentary
Fossiliferous Limestone
Bioclastic Limestone (CaCO3)
Hardness: 3-4 (Mohs scale), Color: tan, grey, or yellowish brown, Luster: dull/earthy, Crystal structure: microcrystalline matrix with visible fossil casts, Specific Gravity: approx. 2.7
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3-4 (Mohs scale), Color: tan, grey, or yellowish brown, Luster: dull/earthy, Crystal structure: microcrystalline matrix with visible fossil casts, Specific Gravity: approx. 2.7
Formation & geological history
Forms in shallow marine environments where organic debris like shells and coral accumulate and are compacted over millions of years, often dating from the Paleozoic or Mesozoic eras.
Uses & applications
Primarily used in the construction industry as aggregate, for architectural stone, and as a source of lime for agriculture; also valued as educational specimens for fossil collectors.
Geological facts
This particular specimen appears to be a 'clast' containing internal molds or impressions of marine organisms. Many such rocks contain fossil fragments like brachiopods, crinoids, or gastropods.
Field identification & locations
Identify by looking for small holes or distinct shell-shaped impressions on a fine-grained, earthy surface. It will fizz when exposed to weak acid (vinegar). Found globally in areas with ancient seafloor history.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
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
sedimentary