Calcarenite
“Sandstone made entirely of shells”
Calcarenite is a limestone composed of sand-sized carbonate grains — shell fragments, foraminifera, ooids, and coral pieces — cemented together. Think of it as a 'carbonate sandstone' where every grain is biological in origin rather than quartz, deposited in warm, shallow marine environments.
calcite grains (bioclasts), calcite cement, foraminifera, ooids, peloids, quartz (minor)
Bermuda, Puglia (Italy), Malta, Yucatán (Mexico), Western Australia, Florida Keys (USA)
3-4
The entire island of Bermuda is built from calcarenite — ancient wind-blown carbonate sand dunes that lithified into rock, making Bermuda one of the few places where you can see fossilized sand dunes made of seashells.
Test Your Knowledge
How does calcarenite differ from a typical quartz sandstone in terms of grain composition?
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