sedimentary
Coquina
Biochemical Sedimentary Rock (CaCO3)
AI-generated identification · may be incorrectMohs hardness 3, multicolored ranging from white to tan, dull to earthy luster, fragmental texture with visible shell debris, specific gravity 2.5-2.7.
Identified More sedimentary →
Explore Coquina in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Mohs hardness 3, multicolored ranging from white to tan, dull to earthy luster, fragmental texture with visible shell debris, specific gravity 2.5-2.7.
Formation & geological history
Formed by the accumulation and cementation of mostly whole, water-worn shells and coral fragments in high-energy marine beach environments.
Uses & applications
Used locally as an inexpensive building stone and in road construction; historically significant for constructing old Spanish forts like Castillo de San Marcos.
Geological facts
Coquina derives its name from the Spanish word for cockle shells. It is a highly porous limestone variant.
Field identification & locations
Easily identified by its distinct 'hash' of cemented fossil shells and strong reaction to hydrochloric acid due to its calcite composition.
More like this
Other sedimentary specimens
Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image
fossil
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary