Thomas Mountains of Utah - Volcanic Fields for Hundreds of Miles

Thomas Mountains, Utah

This summer when I did my dinosaur expedition to Utah, we took some time to go to the Thomas Mountains in eastern Utah.  We actually went there last year as well.  This place is amazing!  The geology of the region is very complex, with multiple events occurring in the same place over a span of hundreds of millions of years.  The Thomas Mountains are a volcanic mountain range that formed about 50 million years ago to as recently as 1 million years ago, near the time of the end of the formation of the Rocky Mountains.  Numerous volcanoes litter the region and most of them are calderas, giant volcanoes that erupted very violently.  Because of the volcanic activity in this area, gemstones are very common throughout the region. 

Probably the best known caldera is Topaz Mountain, appropriately named because natural amber-colored topaz is found here, along with red beryl, amethyst, garnet, bixbyite, opal and hematite.  The minerals are found in cavities in the rhyolite ash that was deposited when the volcano erupted.  It can be a lot of work to break open the rhyolite to find the cavities with the precious minerals inside.    In the picture, you can see the crater of the caldera.  The area of Eureka is also famous for many metal deposits, including gold and silver.

Topaz Mountain near Eureka, Utah

To the southeast of Topaz Mountain, near the town of Nephi, precious calcite onyx can be found.  The popular flowering tube onyx is from this area as well as yellow, red and white banded sardonyx, which will be available on Ruby Mountain5 Rocks soon.  The onyx forms when geothermal fluids from the volcanoes flowed through calcium-rich rocks in the mountains, depositing bands of colorful silica.

Flowering Tube Onyx

 

Sardonyx

Available at Clidastes Stones

To the west of Eureka is the town of Birdseye, where birdseye rhyolite is found (Utah Birdseye Rhyolite will soon be available at Ruby Mountain5 Rocks, currently you can find Mexican Birds Eye Rhyolite)

Birdseye Rhyolite, Utah

Available at Clidastes Stones

South of Delta is another kind of volcano, Sunstone Knoll is a locality that is andesite lava.  In the cavities in the andesite, you can find small yellow sunstone crystals.  Sunstone is a gem variety of the mineral feldspar, the same class of minerals that includes moonstone and labradorite.

Sunstone knoll is a cinder cone.  Cinder cones are smaller volcanoes that are less explosive and produce more lava than ash.

Sunstone Knoll.  Image from millardcounty.com

Sunstones collected from Sunstone Knoll

My most favorite gemstone from this area is the bacon opal.  Bacon opal is formed when geothermal fluids flow through rhyolite layers and deposit colorful bands of silica rich in iron minerals.  Every piece of this material is unique.  You can find specimens of bacon opal at Ruby Mountain5 Rocks, Bacon Opal.

 

One of the most famous and sought after gemstones from Thomas Mountains is Tiffany Stone.  Tiffany stone is becoming very rare because the locality has not been open to collecting for quite a long time and the only stock available was collected over 30 years ago.  Tiffany stone is opalized beryllium-rich fluorite and bertrandite.  This stone has a cracked marbling of creamy white and purple.  You can get your own Tiffany Stone at Ruby Mountain5 Rocks.

 

Utah is riddled with collecting localities for rock hounds of all types.  Some localities can be found here and here.

By Dr. Janet Bertog, Professor of Geology
Owner of Ruby Mountain5Rocks
Owner of Clidastes Stones

Chert, Flint, Jasper, Agate, Opal .... all so popular, and yet, what's the difference??

Chert, flint, jasper, agate - these are all common semi-precious and precious gemstones found in the lapidary world.  They are all different, they all look different, and yet, they are all the same.  All of these gemstones are made of micro-crystalline or non-crystalline silica grains, similar to quartz.  So, why so many different names for essentially the same material?  Well, it gets even more complicated than that because there are many types of jasper, many types of agate... you get the idea.  

So, to start, what makes them all similar?  Rocks are generally made up of minerals.  Minerals are crystals with an orderly arrangement of atoms.  Some rocks are not made up of minerals.  For example, coal is made up of plant material, which is not a mineral.  No minerals are organic.  Chert, flint, jasper and agate are all made up of micro-crystalline, poly-crystalline quartz, a mineral composed of silica and oxygen.

Chert and flint are the most similar.  They really are essentially the same thing.  Chert is the variety that most often forms in nodules in limestone.  The formation of chert in limestone is thought to be a result of sponges (the marine animals).  Sponges make their shells out of tiny spicules of silica.  When they die, this silica absorbs into the water.  Most other animals in the shallow marine environment, including corals and clams, use calcite to make their shells.  The calcite gets recrystallized into limestone.  The silica from the sponges globs together and forms nodules in the limestone.  If you work in limestone, or in caves, this is often called "trash rock" because it is not the main rock that makes the limestone.  Chert is also found in banded iron formations, which are layers of the iron mineral hematite and chert.  Banded iron formations formed during the Precambrian, more than 500 million years ago.  It is thought that the alternating bands of hematite and chert represent seasonal changes.  During the dry season, chert crystallized out of the water and precipitated to the bottom of the oceans.  Sponges are some of the oldest animals on Earth and it is possible that this chert is remnants of these sponges, which were living in the ocean when no calcite-forming animals were around.  Up on land, things were much different.  There were no plants or animals on land during this time, the land was barren and weathering.  During rainy seasons, iron-rich weathered rock would get washed into the ocean as hematite-rich sands, depositing a layer.  This would alternate each season, with a layer of chert then a layer of hematite.  After the Precambrian, with the onset of the Cambrian, there was an explosion of new life, particularly, this was the first occurrence of animals with hard parts, shells made of calcite.  This put an end to banded iron formations.

So, long story short, chert is generally made from tiny pieces of sponge.  So what about flint?  Well, flint is exactly the same thing as chert, but it is usually restricted to the variety found in chalk or marl (marl is chalk with mud in it, chalk is very fine grained limestone - so many subtle variations!).  Some famous flint includes the Flint Hills in Kansas and the Ohio Flint Ridge.

So, what about jasper and agate?  These are also varieties of micro-crystalline,crypto-crystalline quartz, but they form by the replacement of other minerals with the quartz.  The main difference between jasper and agate is that agate is banded and jasper is not.  Jasper will replace grains of minerals in rock very slowly over time.  Petrified wood is a variety of jasper where the wood grains have been completely replaced with silica, or petrified.   There are many other types of jasper as well.  One of the neat things about jasper is that the replacement process usually creates great color patterns in the rock, such as seen in Owyhee Picture Jasper.  You will find that many of these jaspers are very similar!  That is a topic for another post.  Some rocks are mistakenly called jasper.  One example of this is Rainforest Jasper, which is really rhyolite, a type of volcanic ash.

Picture jasper with antiqued copper tree of life

Owyhee Picture Jasper Slab

Brecciated Rhyolite (Jasper)

 

Birdseye Rhyolite (Jasper) Cab

Agate is generally banded and forms as the grains of quartz crystallize out around a rim or precipitate out in cavities.  Crazy lace agate is an example of an agate that forms in cavities and creates nodules that have to be cut open to reveal their beauty.  Moss agate forms from the crystallization of minerals in a mossy pattern within a background mineral.  Again, some rocks are misnamed, like Turitella Agate, which is actually not Turitella and is really a jasper.

Moss Agate Pendant at Clidastes Stones

Montana Moss Agate

Turitella Agate

Some examples of jasper include Bigg's Picture Jasper, Deschutes Picture Jasper, Fantasy Jasper, Kambaba Jasper, Leopardskin Jasper, Mary Ellen Jasper, Ocean Jasper, Owyhee Picture Jasper.

Some examples of agate include Black Plume/Medicine Bow Agate, Montana Moss Agate, and many more!

By Dr. Janet Bertog, Professor of Geology, Northern Kentucky University
Owner of Ruby Mountain5 Rocks lapidary material
Owner of Clidastes Stones, specializing in unique and rare gemstone jewelry and home decor

Utah Dinosaur Expedition and Mineral Collecting

I have returned from another successful trip to my Utah dinosaur excavation.  I have been working at this site for 13 years, studying the animals that are buried there and how they got there.  Every year a group of students from Northern Kentucky University and Marietta College and volunteers from all over join us at this dig.  The site is called the Aaron Scott Quarry and is near Ferron, Utah.  Our main dinosaur at the quarry is the majority of a skeleton of a Barosaurus. The site is in the Jurassic Period.  In addition to the Barosuarus, we have a juvenile Apatosaurus, lots of teeth and some other bones of an Allosaurus, and isolated remains of Dryosaurus, Camptosaurus, Coelurus, and turtles, crocodiles, a small lizard called a sphenodont (related to a tuatara), and a few mammals.For an account of our adventures, you can see my posts on the facebook group Ruby Moutain5Rocks.  Here are some of the highlights.

Sites from the quarry:

Students and volunteers excavating the quarry

Small bones from the quarry

Bones are wrapped in plaster to protect them

Students and volunteers excavating the quarry

We camp at the site and it is such a beautiful place.  Here is the sunrise to the east and the reflection off the hill to our west.

 

We also take in some of the geological and cultural history of the area.

Students and volunteers at the Little Grand Canyon of the San Rafael

The Spanish Trail passes very close to our site. These monuments mark one of the places they passed through

The Fremont Culture carved these petroglyphs about 1000 years ago

The Barrier Canyon Culture painted these pictographs about 2000 years ago

In the Thomas Mountain Range, volcanic activity was prevelent about 50 million years ago.  This deposited a lot of volcanic ash and lava flows and a great deal of mineralization is present as a result.   Some well known gemstones come from this mountain range including Tiffany Stone, Flowering Tube Onyx, Calcite Onyx (coming soon), Birds Eye Rhyolite (coming soon), and this trip we collected sunstones and hyalite bacon opal, which will soon be available.

Sunstones from near Delta, Utah

Hyalite bacon opal from near Milford, Utah

On the way home, we stopped at the Last Chance Mine in Colorado.  This area of the San Juan Mountains is again a giant volcanic field with several calderas. A lot of mineralization has taken place in this area including gold, silver, copper and zinc and it has been heavily mined.  The Last Chance Mine was a silver mine and the “waste rock” is sowbelly agate, or banded lace agate.  I collected a bunch of this material to make available soon as well!

Banded lace agate

Sowbelly agate

Volcanic ash from calderas in the San Juans

Overall, a very successful trip and I look forward to making all this new material available to you soon!

Visit http://www.rubymountain5rocks.com for lapidary slabs from these and other locations and http://ClidastesStones.etsy.com for cabochons and jewelry made from this material.

Ruby Mountain5 Rocks Under New Ownership

Welcome to Ruby Mountain5 Rocks Rock Shop.

Hello!  I have recently taken over new ownership of Ruby Mountain5 Rocks.  I promise to maintain the same quality products at reasonable prices.  I have recently implemented a new, lower pricing scheme, and free shipping still applies in the US, and now Canada!  Free shipping on orders over 5 items internationally.

So, a little about me.  I am a professor of Geology at Northern Kentucky University.  My specialty is vertebrate paleontology,  but I teach classes in introductory geology, field paleontology, stratigraphy and sedimenation (the study of rock units deposited in different environments and what they tell us about the environments), mineralogy and petrology (the study of the identification, characterization and interpretation of all rock types).  I have been teaching at NKU for 14 years and recently received full professorship.

In January 2016 I started an Etsy business, Clidastes Stones, selling stone crafted wire wrap jewelry and home decor.  I began to brach out within this business and started selling mineral specimens, rock slabs and cabochons.  I really enjoyed finding unique stones for people and sharing them.  I have done most of my business on Facebook through this company.  I have made hundreds of sales this way and have many repeat customers.

About a month ago, I saw Sharon's post about selling this business so they could retire.  I decided this fit perfectly with the direction I was taking my business and so  I offered to buy it.  Now, here I am, surrounded my thousands of rocks that I love and am excited to share them with you.

As you peruse the website, please keep in my mind that I have thousands of slabs of inventory to post, and I am working on this as quickly as possible.  In the meantime, if there is anything you are interested in that is not posted, please check the bulk spreadsheet lists for available items and contact me to see some of what I have available.

I know there will be some bumps in the road as I adjust the website to my settings, but I try to keep these to a minimum and will be happy to assist with anything that might come up.

I look forward to working with you to provide you with quality materials for your jewelry making or personal collections.

Please visit my websites Ruby Mountain5 Rocks and Clidastes Stones!