Tuesday, June 23, 2020

Geologic State Symbols Across America - Florida

The next state up for the Geological State Symbols Across America is:


You can find any of the other states geological symbols on my website here: Dinojim.com (being updated as I go along).

                                                                             Year Established
State Stone: Agatized Coral                                          1976
State Gem: Moonstone                                                 1970

I also have some Geology of the National Parks Through Pictures that I have done for Florida previously. These include:

DeSoto National Memorial

State Stone: Agatized Coral 
Title IV
Chapter 15

15.0336 State stone.
Agatized coral, a chalcedony pseudomorph after coral, appearing as limestone geodes lined with botryoidal agate or quartz crystals and drusy quartz fingers, indigenous to Florida, is hereby designated the Florida state stone.

History.—s. 1, ch. 79-278.
An example of some brain coral, still alive (pre-fossilization). Image from UNC.edu.

Coral is an invertebrate animal that belongs to the group Cnidaria. Cnidaria also includes the well known jelly fish and sea anemones. Corals are a sessile organism, meaning that they live most of their life in one location, mainly rooted to the ocean floor. The coral animal, called a polyp, is a tiny organism that secrets a calcium carbonate "shell" around itself, like a clam. The accumulations of many of these shells is what most people think of when they think of coral. Neighboring polyps also secrete a shell and attached themselves to other polyp shells. This creates an apartment building type complex with tiny animals, each about the size of a nickel, living within each shell all attached to one another. Over time the animals die and new corals attach to the upper surfaces creating new structures. The coral animals themselves actually form a symbiosis with an algae called a zooxanthellae, where the algae creates the food from the sunshine and the corals eat the food. The corals then provide the algae with protection within their shell. Corals are generally found within fairly shallow and warm waters. These waters allow many corals to grow and the algae to create food. Over time the coral skeletons/shells can eventually build up and form a reef.

A piece of agatized coral from Florida. Image from Imagineyourflorida.com.

The agatization process is twofold. The first part is replacing the original skeleton of the coral, the calcium carbonate, with silica, typically known as the mineral quartz or chalcedony. This processes is referred to as "silicification". The second part is filling the hollow interiors of the coral with banded chalcedony, which is the actual agatization of the coral. Although living coral can be found in modern day Florida, the agatized coral would have to be much older to have gone through the agatization/fossilization process. The agatized coral are fossils that lived during the Oligocene to Miocene periods (38-25 million years ago). The corals originally formed on an ancient sea bed when most of Florida was under water as part of the continental shelf. The waters of the sea were rich in silica and other trace minerals, giving the agatized corals a large variety of colors including white, pink, grey, brown, black, yellow, and red. Within Florida, the agatized coral is most often found in the Tampa Bay area, the Withlacoochee/Suwannee River, and the Econfina River. Besides just a valued collectors item, the agatized coral was first used by the early inhabitants of Florida to make tools such as arrow heads and knives nearly 7,000 years ago.

State Gem: Moonstone
Title IV
Chapter 15

15.034 State gem.
The moonstone, a transparent or translucent feldspar of pearly or opaline luster, is hereby designated the Florida state gem.

History.- s. 1, ch. 70-53.
Moonstones exhibiting the optical property of adularescence. Image from Geologyin.com

The term "moonstone" actually applies to the mineral orthoclase (formula KAlSi3O8) that exhibits certain optical properties. Othoclase is a mineral within the Felspar group, one of the largest groups of minerals, representing over 60% of the rocks in the Earth's crust. During formation of the Moonstone, as the mineral crystallizes the feldspar minerals orthoclase and albite (another feldspar mineral) separate into alternating layers. When the light falls between these layers it produces a scattering of the light called adularescence. In short, adularescence is specifically the metallic glow of a mineral that originates from below the surface, which is caused by light reflecting off the layers within a mineral. 

A gem of Moonstone that resembles the moon. Image from myflorida.com

The effect of the adularescence produces a schiller, or a milky bluish luster, that emanates from below the surface of the moonstone. One of the most remarkable properties of the Moonstone, is that the schiller appears to move as the gem is moved. This gives it the effect of lunar light floating on a surface of water, which gave the gemstone its name. Because of the visual effect of the gem, it was once thought to have been formed by the capturing of the moonbeams in Hindu mythology. The gemstone is also often associated with artistic creations, as well as the 1960's "flower child" apparel. The moonstones themselves can be found in colorless, white, grey, green, peach, and brown varieties. However, even though the moonstone is the State Gem of Florida, it is not found in Florida. It was chosen as the State Gem based on its name. In 1970, one year after first landing on the moon by the Apollo 11 crew, the Moonstone was chosen by lawmakers as the State Gem to honor this accomplishment, which launched from the Kennedy Space Center on Merritt Island, Florida.


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