Wednesday, January 02, 2019

Geological State Symbols Across America - Alabama

One of my goals for 2019 is to post an in-depth look at the geological and paleontological symbols of each state. I plan on posting 1 state each week for the year, so you can look forward to that. In addition to that I am planning on updating a lot of my Geology of the National Parks Through Pictures to catch up on ones I missed for each of the states as I go through them. Some of the early states have been published before but they will be updated with new and more up to date information. First up on my Geological State Symbols Across America is:

Alabama



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

                                                                    Year Established
State Rock: Marble                                         1969
State Mineral: Hematite                                 1967
State Gemstone: Star Blue Quartz                  1990
State Fossil: Basilosaurus cetoides                 1984

State Rock: Marble

Marble is a metamorphosed variety of the sedimentary rock limestone. This means that the original sedimentary rock underwent periods of increased temperatures and pressures to change the rock itself. The primary mineral in marble is calcite (CaCO3) or dolomite ((Ca,Mg)CO3) but it will usually have other mineral contaminates mixed in as well (i.e., clay, mica, quartz, pyrite, and iron oxide, etc.). Since, the primary mineral in Marble is calcite, most marbles will have a white color with swirls of darker colors (the contaminates) but marbles can be found in many different colors depending on what impurities were present in the initial limestone. During metamorphism of the original limestone, the calcite is recrystallized to form interlocking crystals, which will usually destroy any remnants of the original rock, including any fossils present.


The primary source of marble in Alabama is the Sylacauga marble found in Talladega County. The Sylacauga, or Alabama, Marble has been quarried and used in art and building stones throughout Alabama and the US. The marble is named for the town Sylacauga and has been called the "whitest marble in the world" its purity. The Sylacauga Marble has been used in several famous landmarks including the Washington Monument, the Lincoln Memorial, and the U.S. Supreme Court. The marble formed during metamorphism associated with the Appalachian orogen (mountain building) and is approximately Cambrian to Ordovician in age. Besides the pure white sections of the marble, there are also sections that have green, pink, gray, black, and gold veins in the ~5.5 cubic mile deposit. Official descriptions of the marble state it as "white and pale-blue to light-gray calcite marble, locally containing interlayered dolomite marble and thin phyllite layers" (mrdata.usgs.gov).

State Mineral: Hematite

Hematite is a mineral that is produced from the oxidation of iron, and forms iron oxide in the form of Fe2O3. In everyday language, this means that hematite is more commonly known as rust. Hematite is primarily composed of iron and is abundant on the Earth's surface,resulting in hematite becoming one of our most common sources of iron ore. Although typically found as a red "earthy" deposit, there is also a variety of hematite that has a silver/steel-grey metallic appearance to it (pictured left). Both varieties of hematite can be easily identified by the characteristic bright red streak of the mineral. Hematite has a hardness of 5 to 6, meaning that it is approximately as hard as a plane of glass (5.5). The mineral hematite was originally named "aematitis lithos" in ~300 BCE by the Greek Theophrastus and its name means "blood stone". The name was translated by Pliny the Elder to haematites, meaning "bloodlike", and that name eventually evolved to the modern spelling of "hematite".




The hematite in Alabama was primarily mined from the Red Mountain Formation until 1975, where it became cheaper to import it. At one time it was Alabama's most developed, non-fuel, mineral industry, helping to build up Birmingham as an industrial center. In the 135 years hematite was mined, ~375 million tons of ore was excavated. The Red Mountain Formation is primarily a Silurian interbedded shale-sandstone with some siltstone and limestone deposits intermixed. The hematite is largely from cross-bedded sandstone members of the Red Mountain Formation, which were deposited as shoreface (essentially beach) deposits. The production of hematite within the sandstone was precipitated during periods of sediment starvation and reworking during a regression (sea-level drop). Birmingham is also known for the largest cast-iron structure ever made, the statue of Vulcan (picture right), produced entirely with the Birmingham iron ore.


State Gemstone: Star Blue Quartz

star blue quartz
Quartz is one of the most common minerals on Earth, primarily due to its simple structure and chemical formula, SiO2. Quartz also has an extremely high hardness, 7 on Mohs hardness scale, meaning that it doesn't scratch very easily and therefore does not break down easily. As the rocks on Earth are slowly eroded over time, most of the other minerals will break down into clay while quartz grains will generally just gets smaller and smaller. The result is that most beach sand is composed of quartz that has a slight hematite (rust) stain to it to give the sand grains their slight yellowish color. Although quartz is a simple mineral, it can come in a variety of colors depending on what type of impurities are present in the crystal structure; pure quartz crystal is clear, milky quartz is white, smoky quartz is grey, amethyst is purple quartz, citrine is yellow quartz, rose quartz is pink, as well as some other colors and varieties. Quartz does not have any cleavage, meaning that when it breaks it doesn't form along perfect surfaces. Instead as the quartz crystals grow, individual mineral molecules of quartz are added to the outside of the crystal from water rich in dissolved SiO2 or mineral melt (liquid rock like lava or magma).

Unlike the other varieties of quartz (such as citrine or amethyst), pure blue quartz has not yet been found in nature. Instead, the quartz crystals appear blue because of the inclusions of other minerals or properties of the mineral itself that make the light reflect through the mineral and makes it appear blue. The reason that Star Blue Quartz is blue is that it contains little bits of amphibole (another type of mineral) and displays asterism (a star pattern in the light) when polished. The problem with this variety of quartz though is that there is little to no information on where to find it or why it was even listed as the state gemstone. The best that I can find is the constantly rehashed phrase from when it was promoted to the state: "(star blue quartz) is one of the most beautiful gemstones on earth, and the cheapest because there are so many." It appears that this very common mineral is rare to non-existent in Alabama. There have been reports of it along the Flint River, but most of those occurrences are generally in neighboring Georgia.


State Fossil: Basilosaurus cetoides



Basilosaurus is a member of the whale family (Cetacea) first discovered in Alabama in 1834. It was originally thought to be a swimming reptile but was later discovered that it was indeed a whale from the Eocene period (40-35 million years ago). Unlike modern day whales, Basilosaurus still retained its hind limbs. These were thought to be mostly nonfunctional, however there is a theory that they could have been used during sex. Basilosaurus is one of the closest related animals to modern day cetaceans (dolphins, whales, etc.) that still retains their hind-limbs, although the pelvis is not connected to the vertebrae, limiting any function that it could provide.



The group Basilosauridae contained a few other species that had body proportions similar to modern day dolphins but Basilosaurus had an "exceptionally long body and tail" resulting in the animal having a more snake-like appearance. The body length ranged from 49 to 59 ft and is one of the largest known animals during the Paleocene-Eocene time period. Basilosaurus is most abundant in Alabama and has been found in Clarke, Choctaw, and Washington counties.

References
https://statesymbolsusa.org/states/united-states/alabama
http://www.sylacauga.net/library/sections/Sylacauga%20Marble%20Fiestival/Marble%20Fiestival%202010.htm
http://en.wikipedia.org/wiki/Vulcan_statue
http://geology.about.com/od/regional_geology/ig/stategems/stateblueqtz.htm
http://www.encyclopediaofalabama.org/face/Multimedia.jsp?id=m-3931
http://legacy.decaturdaily.com/decaturdaily/news/050206/marble.shtml
https://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=ALsgq%3B7
http://geology.com/rocks/marble.shtml
https://www.mindat.org/min-1856.html
https://geology.com/minerals/hematite.shtml
https://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=ALSrm%3B3
https://en.wikipedia.org/wiki/Basilosaurus
Chowns, Tim & Rindsberg, Andrew. (2015). Stratigraphy and depositional environments in the Silurian Red Mountain Formation of the southern Appalachian basin. 10.1130/2015.0039(04). 
Houssaye A, Tafforeau P, de Muizon C, Gingerich PD. Transition of Eocene whales from land to sea: evidence from bone microstructure. PLoS One. 2015;10(2):e0118409. Published 2015 Feb 25. doi:10.1371/journal.pone.0118409

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