3.8" Agatized Coral Fossil Oligocene and Miocene Epochs Tampa Bay Florida
Location: Tampa Bay, Florida, United States
Weight: 5.1 Ounces
Dimensions: 3.8 Inches Long, 3.6 Inches Wide, 1.1 Inches Thick
The item pictured is the one you will receive.
Oligocene and Miocene epochs, 34 million to 5.5 million years old
Agatized Coral, specifically found in the Tampa Bay region, is a fossilized form of coral where the original calcium carbonate structure has been replaced by silica, primarily chalcedony, a microcrystalline variety of quartz. This geological process, known as permineralization or replacement, occurs over millions of years. The silica infiltrates the porous coral structure, preserving the intricate details of the ancient organism, including its septa and corallites. The resulting material exhibits the hardness and durability characteristics of quartz, making it suitable for lapidary purposes.
The formation of agatized coral in Tampa Bay is linked to specific geological conditions. During the Oligocene and Miocene epochs, Florida was submerged under shallow marine waters, supporting extensive coral reefs. Subsequent changes in sea level and geological uplift exposed these ancient reefs to terrestrial environments. Groundwater rich in dissolved silica then percolated through the coral, leading to the gradual replacement of the organic material. The presence of iron oxides and other trace minerals within the silica can impart a variety of colors to the agatized coral, including white, gray, brown, red, and black.
The term "agatized" refers to the banded or concentric patterns often observed within the chalcedony, similar to those found in agate. These patterns can arise from variations in the silica deposition or from the preservation of original growth layers within the coral. While commonly referred to as "agatized coral," it is technically a pseudomorph, where one mineral has replaced another while retaining the original form. The Tampa Bay area is particularly renowned for its agatized coral specimens, which are often collected from fossiliferous limestone formations and riverbeds in the region.
