Wackestone
“Mud-supported fossil limestone”
Wackestone is a type of limestone containing scattered fossil grains (shells, coral fragments, foraminifera) floating in a mud-rich carbonate matrix. It forms in relatively calm marine environments where fine lime mud accumulates along with occasional shell debris, capturing a snapshot of ancient sea floors.
calcite mud matrix, fossil fragments (calcite/aragonite), foraminifera, peloids
Bahamas (modern equivalent), Persian Gulf, Great Barrier Reef region, Indiana (USA), Yorkshire (England)
3-4
Wackestone is one of the key rock types in the Dunham classification — a naming system for carbonates that petroleum geologists use every day to evaluate potential oil and gas reservoirs.
Test Your Knowledge
In the Dunham classification of carbonate rocks, what distinguishes wackestone from packstone?
Photo Attribution
Related Specimens
Want to identify rocks yourself?