The Tampa Member (formerly Tampa Limestone) of the Arcadia Formation is a white to light gray, fossiliferous, Upper Oligocene to Lower Miocene marine limestone containing variable amounts of dolostone, sand, clay, and phosphate. The Tampa is usually a hard, massive crystalline rock and in some areas it contains small cavities called molds where shells have been dissolved out of the rock. Fossils include mollusks, foraminifera, and algae. The classic outcrop areas are at Ballast Point and Six-Mile Creek areas in Tampa, Hillsborough County. This unit is well-known for its silicified fossils, including agatized coral, Florida’s State Stone.