sedimentary
Coquina
Bioclastic Limestone
Hardness: 3 (Mohs scale), Color: tan, cream, or light brown, Luster: dull to earthy, Structure: poorly consolidated mass of shell fragments, Porosity: very high
Identified More sedimentary →
Explore Coquina in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3 (Mohs scale), Color: tan, cream, or light brown, Luster: dull to earthy, Structure: poorly consolidated mass of shell fragments, Porosity: very high
Formation & geological history
Formed in high-energy marine environments like beaches and barrier islands where wave action accumulates shell fragments. Most recognizable deposits are from the Pleistocene and Holocene epochs.
Uses & applications
Historically used as a building material (notably in St. Augustine, Florida), road base material, and in landscaping or aquarium decoration.
Geological facts
The Castillo de San Marcos in Florida was built from coquina; the stone's porous nature allowed it to absorb cannonball impacts rather than shattering.
Field identification & locations
Identify by looking for a 'cereal bar' appearance made of visible broken seashells. Found along coastlines, particularly in Florida, the Carolinas, and Australia.
More like this
Other sedimentary specimens
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