sedimentary
Coquina
Coquina (Bioclastic Limestone)
AI-generated identification · may be incorrectHardness: 3 (Mohs), Color: Cream, white, or light tan, Luster: Dull to earthy, Structure: Fragmental/Bioclastic, composed of poorly cemented shell fragments, Cleavage: None.
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), Color: Cream, white, or light tan, Luster: Dull to earthy, Structure: Fragmental/Bioclastic, composed of poorly cemented shell fragments, Cleavage: None.
Formation & geological history
Formed in high-energy marine environments (beaches) where waves accumulate shell fragments and coral debris, which are then lightly cemented by calcium carbonate (calcite). Generally recent to Pleistocene in age.
Uses & applications
Used as a construction material (historically for forts due to shock absorption), road base material, and in landscaping.
Geological facts
The Castillo de San Marcos in Florida is famously built from coquina; its porous nature allowed it to absorb cannonball impacts rather than shattering.
Field identification & locations
Identified by its 'oatmeal' appearance consisting almost entirely of crushed shells. Found primarily along coastal regions and barrier islands.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary