Friday, January 18, 2019

Geological State Symbols Across America - Arizona

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: (being updated as I go along this year).

                                                                                        Year Established
State Gemstone: Turquoise                                                        1974
State Fossil: Petrified Wood (Araucarioxylon arizonicum)        1988
State Metal: Copper                                                                    2015

I also have several Geology of the National Parks Through Pictures that I have done for Arizona previously. These include:
Casa Grande Ruins National Monument
Grand Canyon National Park
Hohokam Pima National Monument
Sunset Crater Volcano National Monument
Walnut Canyon National Monument
Wupatki National Monument

State Gemstone: Turquoise
Turquoise is a blue-green mineral made up of copper, aluminum, and hydrous phosphate (CuAl6(PO4)4(OH)). The name turquoise comes from the French expression for "Turkish Stone", illustrating that the early sources for European turquoise were from the Middle East. Turquoise has long been considered valuable and is one of the oldest known gemstones. It has been found in ancient Egyptian and Chinese archeological expeditions, showing that those people used turquoise as far back as 3,000 years ago. It is formed by the flowing of groundwater through copper deposits that eventually react with phosphate and aluminum minerals. Turquoise is also only found in arid (desert) environments because that is one of the few places that allows the groundwater to maintain a high enough copper concentration for long enough to interact with the other minerals. The result is a gemstone unlike traditional, gemstones like ruby or emerald, which is most commonly opaque. The opaqueness is due to the structure of turquoise, which is made up of many microcrystalline structures instead of one large mineral crystal. These microcrystals give the turquoise its appearance, either a mottled look or a smooth finish, which is due to the size of these microcrystals. It is also extremely soft and easy to carve. All of these attributes make it useful for many different purposes from jewelry to architectural adornments.

Turquoise mines can be found all across the southwestern United States, with the largest concentration found in Arizona. As mentioned above, turquoise mines in Arizona are often associated with copper mines (many of them open-pit mines in AZ). The largest and most well known of the turquoise mines is the Bisbee Mine, near Bisbee, AZ, located adjacent to the Copper Queen copper mine. In 1880, the mine was founded as a gold, silver, and copper mine, which are often found together due to the formation of these minerals from the waters associated with subduction zone magmatism. The hydrothermal waters associated with the former subduction zone in the region circulated throughout the rocks depositing the heavy metal deposits within the bedrock. These heavy metal deposits eventually interacted with the local groundwater producing these turquoise deposits. The Bisbee Mine turquoise was discovered in the 1950's and quickly became prized for it's spider-webbing patterns throughout the turquoise stones (pictured left). Although most of the turquoise has been mined out, this has resulted in these variety of the gem to become prized collectors items. Native Americans (primarily the Anasazi and the Hohokam) mined the turquoise in Arizona for use in jewelry and for trade. Arizona is also home to one of the largest domestic turquoise mines, located in Kingman.

State Fossil: Petrified Wood (Araucarioxylon arizonicum)  
Petrified wood is not actual wood, however it was wood at one point. Petrified wood is a fossil that formed from pieces of wood that have been mineralized. Mineralization is a process where groundwater moves through the wood and replaces all of the wood molecules with molecules of other substances, most often silica (i.e. quartz). This means that petrified wood actually isn't wood anymore, but a fossil of the former wood.

The specific species of petrified wood (Araucarioxylon arizonicum) that is the Arizona state fossil is an extinct conifer (like an evergreen) that can been found throughout Arizona and New Mexico. There is a problem with the state fossil though; the original name of the species was based on three different species. This means that although one of the three was correct, two had to be renamed, resulting in several of the trees identified since the initial 1889 description were likely named incorrectly. The problem is that proper identification can only be made with thin sections and close analysis, which is not likely going to happen for a majority of the samples previously identified, at least not any time soon. Arizona is host to one of the largest assemblages of petrified wood logs, with ~20% of all the petrified wood in northeastern Arizona found in Petrified Forest National Park. The concentrations of logs in Petrified Forest was a result of a log jam that flowed down a prehistoric river. The logs where then quickly buried, which allowed the mineralization process to proceed on the logs, converting them into fossils.

State Metal: Copper
Copper is an elemental metal mineral, meaning that it is entirely composed of one element; copper (Cu) in this instance. It is also the only elemental metal, besides gold, which is not naturally silver or grey. Copper is the oldest known metal to have been manipulated by humanity. The Copper Age took place after the Neolithic (Stone) Age, and lasted from ~4500 BC to ~3500 BC, overlapping with the early Bronze Age. The earliest known Middle Eastern artifact is also made of copper, a pendant dating back to 8700 BC. In the modern day, copper is the third most consumed industrial metal in the world. Mining of copper in the US began with high grade ore deposits found in Arizona and Michigan in the late 1800's, however newer processes that were able to filter the copper out of low-grade deposits made excavating low-grade ores more economical, leading to more abundant uses of strip and open-pit mining for the recovery of copper. These processes enabled the US to become one of the leading producers of copper in the world. 

In the late 1600's, Spanish explorers traveled the west looking for metallic deposits, specifically gold and silver. The association of these metals with copper enabled them to discover numerous copper deposits as well, even though it was not their primary focus. Eventually, the modern age of mining in Arizona was born in 1854 with the creation of the Arizona Mining and Trading Company in Ajo, AZ. Mining for copper was initially restricted to deep mine tunnels of fairly high quality ore. However, the success of the open-pit Bingham Mine in Utah illustrated that open-pit mining and new processing methods for low-grade copper ore worked well and Arizona began using similar processes, increasing their copper yield significantly. Currently, copper is the most valuable metallic commodity in Arizona, followed by gold, silver, molybdenum, and lead. In 2017, the US produced 1.27 million tons of copper with 68% of that coming from Arizona. There are currently over 3,000 Arizona locations that have copper listed as a commodity. These metallic deposits form a northwest to southeast band across the state (as seen on the map to the left). Along this band, most of the copper deposits are found within southeastern portion of the state (red on the map). These deposits are found mostly in granitic rocks that intruded within the region 70 to 55 millions years ago.


Thursday, January 10, 2019

Geological State Symbols Across America - Alaska

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: (being updated as I go along this year).

                                                        Year Established
State Mineral: Gold                                1968
State Gemstone: Jade                              1968
State Fossil: Woolly Mammoth                1986

State Mineral: Gold

The chemical symbol for gold is Au, and gold is one of the unique minerals that, in its pure form, is composed entirely of one element. It has a hardness of 2.5 to 3 on the Mohs hardness scale meaning that it actually is very soft (your fingernail is 2.5). For this reason most gold jewelry is mixed with another metal to prevent scratching and bending easily. The karat rating of the gold represents it's purity, where 24 karat is 99.9% pure, 22 karat 91.7%, 18 karat 75%, and so on. Gold naturally does not corrode or tarnish, so even when it is mixed with other metals it usually has a resistance to tarnishing, enhancing its value for jewelry. When gold is found in place, the highest grade of gold is often found in association with quartz veins. Currently gold is considered one of the most valuable metals on Earth, being used as the standard for most money (gold standard). Gold is often formed initially in relation to volcanic regions, where fluids associated with volcanoes carry the heavy metals up towards the surface and deposit them in rocks. These are found in areas of current or former subduction zones, places where two plates came together forcing one place down and melting it, while the other plate is forced upwards into mountains. Afterwards, erosion will take the gold out of the mountains and carry them down stream. However, since gold is so dense it does not travel easily down rivers and will often settle to the bottom of the river within the rocks and mud within the river sediment. These gold deposits are known as placer deposits and are the primary place where gold panners find gold. They can then use the locations of these placer deposits to backtrack to the original sources of the gold within the streams.

 Gold has an important history in Alaska. Originally when the territory was purchased it was referred to as Steward's Folly because this big hunk of land couldn't be worth anything. That was before gold was discovered. It began in the 1870's and continued through most of the 1900's. The beginnings of many communities in Alaska got their start as gold mining towns. Today Alaska is more known for its oil exploration but gold still holds a prominent place in its heart with Fairbanks remaining as a major gold exploration area. From the 1880's to 2005, Alaska has produced ~1250 metric tons of gold. Even though gold is going by the wayside in Alaska, it is still one of the major producers of gold in the United States, producing the second most gold after Nevada for the last decade. To the left is the major gold mines up to 1897, which follows a similar pattern of known gold deposits today, with a large swath of gold mines spread across the central portion of the country. One of the locations that gold was originally discovered was a placer deposit within the Yukon River and several mines of gold have been discovered from there, expanding ever outwards from the central strip.

State Gemstone: Jade

Jade is a green gemstone that has a bit of an ambiguous mineralogy. It turns out that samples of gemstones that have been called jade actually fall into three different mineral categories. Typically what happens with gemstones, is that they are a name of a specific colored mineral; i.e. purple quartz is known as amethyst. Well in this instance the green gemstone jade can be one of three minerals: jadeite, actinolite, or tremolite. And even the combination of actinolite and tremolite goes by a different name: nephrite. There is a strong physical similarity between all these minerals, hence the confusion of which mineral jade could belong to and so all of these, as long as they are green, can be considered jade.

All of these minerals have a hardness of 6 to 7 on Mohs Hardness Scale and all are silicates, although with significantly different chemical formulas. Jadeite is a aluminum-rich pyroxene (NaAlSi2O6) and actinolite and tremolite are magnesium-rich amphiboles (Ca2(Mg,Fe)5Si8O22(OH)2). All three of these minerals are formed through the process of metamorphism. Jadeite is a metamorphosed variety of albite, a plagioclase mineral and actinolite/tremolite are commonly formed from the metamorphism of ultramafic and mafic igneous rocks, such as those formed in oceanic crust. Due to the durability of the jade minerals, they can be formed into tools, however the green color has caused many artisans to use them more for jewelry and sculptures (such as the Mayan jade sculpture to the right).

Alaska has large deposits of jade throughout the state but its principle claim to fame is an entire mountain made out of jade, aptly named Jade Mountain. The mountain is located far from any road, north of the Arctic Circle, near Kobuk. Very large blocks have been taken out of the mountain and used to create statues including a 3,600 lb block for a police memorial statue in Fairbanks. Currently, jade statues and jewelry produced from Alaska's famed Jade Mountain can be found all over the world, including a plaque embedded in the Washington Monument (pictured left). The mineral tremolite, which is one of the mineral varieties of jade, also can form another similar mineral, asbestos. It is the asbestos from Jade Mountain that received much of the commercial interest in the early days, of the modern "discovery" of the mountain (despite it being known about for thousands of years by the local Eskimos). The jade from Jade Mountain is the nephrite variety, however the amount of jade is dwarfed by the amount of tremolite asbestos in the region, and the quality is often not good enough to be considered gem grade. However, enough of the jade has been mined and used as jewelry and sculptures to warrant recognition. The age of the original, premetamorphosed ultramafic and mafic rocks, are Early to Middle Jurassic. These rocks were likely metamorphosed from contact with hydrothermal fluids associated with plate tectonics along the ocean floors and serpentinized. Eventually, plate tectonics along the convergent plate boundaries caused these deep ocean deposits to be uplifted into the Brooks Range (the mountain range where Jade Mountain is located).

State Fossil: Woolly Mammoth

The Woolly Mammoth, also known as Mammuthus primigenius, is a species closely related to modern day elephants. One notable difference between the extinct species and the modern day elephant is that the mammoth notably was covered with hair, allowing it to thrive in the arctic environments of modern day Alaska, Siberia, and Canada. Unlike most of the other state fossils, mammoths are frequently found as complete specimens, such as the complete baby mammoth found from Siberia (image on the left). They are usually frozen in the snow or buried in an Arctic swamp. Most of the ~100 remains of fully preserved mammoths have been found in Russia and Alaska. Mammoth remains are found throughout the northern reaches of the state as well as scattered throughout other regions. The local prehistoric people were known to have had interactions with the mammoths. Evidence includes tools that were created from their tusks. It is believed that these interactions with prehistoric humans are what drove the mammoths into extinction. A small island off the coast of Alaska is also one of the last remaining locations where woolly mammoths lived (until ~3,750 BC). Since the island was small the mammoths that have been found here evolved into dwarf varieties of the typical continental mammoths (pictured right).

One of the common questions that comes up when discussing mammoths, is "What is the difference between a mammoth and a mastodon?". Although they are fairly closely related, and all related to modern day elephants, there are a few significant differences between the two species. The easiest feature to identify in a fossil specimen is the huge difference in their teeth (pictured below). These differences were due to the way that they ate their food. The cone-shaped molars of the mastodon were used to crush leaves, twigs, and branches, while the flatter ridged molars of the mammoth were used to cut through vegetation and graze similar to modern day elephants.


Saturday, January 05, 2019

Geology of the National Parks Through Pictures - Russell Cave

You can find more Geology of the National Parks Through Pictures as well as my Geological State Symbols Across America series at my website

This post relates to the geological state symbols post that came out earlier this week. 

Unfortunately this is the only National Park I have visited in Alabama but eventually there will be more.

During a trip to Chattanooga for my wife's Ironman race, we took a tour of some of the nearby National Parks. This included a brief foray into Alabama to see the small, but cool Russell Cave.

Entrance Sign

Within the museum and visitor's center there are several panels of artifacts explaining about the Native People who used to live in the caves and how geology was related to their lives. Here the first farmers are mentioned who used nearby flint (a silica/quartz based rock that is very hard and can be broken to have very thin and sharp edges) and limestone (the rock the caves were formed within) as materials to make tools.  

More use of geology, this time for of weapons and more tools. These were also used from nearby flint deposits.

Here are the remains of many of the animals found within the caves that the Native People used for food.

 Here is the main mouth of Russell Cave as you walk up to it from the trail. The entrance has a very large cave mouth and was primarily the place where the Native People resided. Despite Russell Cave being the 19th longest cave in the US, most to nearly all of the activity was at the mouth.

 Here is another shot of the cave right before going in. 

 View from the edge of the cave. Most caves are formed by the dissolution of limestone from running water. In this instance the creek is visible in the previous photo which caused the dissolution. The limestone here can be broken up into three different rock units: the Monteagle Limestone, the Bangor Limestone, and the Pennington Formation. All of these units are Mississippian in age (over 300 million years old). The overlying rock is a sandstone. The overlying rock is a very important part of cave formation because without a sturdy roof rock that resists fracturing, the dissolution of the cave would just cause the entire ground to collapse and no cave could be form. The sandstone is younger than the limestone (hence it being on top) and is Pennsylvanian in age and called the Pottsville Formation (

 This sign within the cave explains that cave roof collapses made it possible for people to live within the cave, causing the floor of the cave to rise above flood waters. The cave was inhabited from about 11,000 years ago to 9,000 years ago.

A couple of hundred feet away from the main entrance is this sinkhole that you can see within the forested area. Here the cave roof, the sandstone, was not strong enough to hold itself up over the dissolved rock and collapsed into the hole below.

Now this is an interesting rock that was just outside the visitor's center. The park service people placed it here on purpose right near a sign explaining it. It is a rock filled with these features called septarian concretions. Concretions are blocks of rock that form from the continued precipitation of minerals along the outer surface of the rock. They often form from hard minerals in softer rocks (such as calcite in a shale) and then when the softer rocks erode away, it leaves behind the concretion. Septarian concretions form in a similar manner, except that they have periods of contractions and expansions which produced cracks or stress fractures within the concretions themselves. These fractures will also fill with the precipitated minerals, producing these banded concretions of different minerals. As these minerals erode, they will erode at different rates all in relation to the hardness of the mineral being eroded producing this onion effect in the rock.

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:


You can find any of the other states geological symbols on my website here: (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" (

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.

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