COQUINA
Coquina
is a distinctive variety of fossiliferous limestone. Coquina is composed of finely-busted up
seashells, typically clam shells & snail shells (bivalves &
gastropods). Coquinas have high porosity, that is a significant amount of
empty space between the grains. This
results in coquina having a "spongy" appearance. As are all
limestones, coquinas are composed of calcite (CaCO3) and they bubble
in acid.
Coquina had military significance in early American
history. Some military forts in Florida were constructed with coquina
walls. The coquina "sucked up"
cannonballs that were shot at fort. Coquina is a fairly common
sedimentary rock in the Pleistocene of southeastern America (e.g., Florida).
Coquina
from the Anastasia Formation (Upper Pleistocene to lower Holocene) of Florida,
USA.