The Wisdom Pocket Blog Intro | iRocks Blog

Welcome to the Wisdom Pocket.

We’ve long been looking for the right avenue to add fun content for our customers and the mineral-curious. After rebuilding our database, relaunching, and months of tracking down articles, videos, interviews, photos, and more, we’re finally set to launch our new blog.

For new readers just learning about minerals, you might be curious about the name of our new blog. When searching for fine minerals in mines and mountains, crystals can be found in pockets within the rock. Hot liquids, gases, and molten rock that are produced by various Earth processes, migrate upward from the upper mantle and various parts of the crust and accumulate in pockets located in the Earth’s upper crust. As temperature and pressure is reduced, these liquids, gases, and molten rock, rich in various elements, combine to create the large variety of minerals and crystal shapes that we know and love. Do you know there are almost 5,000 minerals that have been discovered and more are found every year?!

A robust, colorful bluecap mineral specimen from the famous BlueCap Pocket

A Blue Cap Tourmaline from the famous Tourmaline Queen Mine, Joe Budd Photo.

Many of these pockets contain crystals of minerals with distinct characteristics and mineral associations that help make the specimens identifiable from a specific pocket from a particular mine or mineral occurrence. Some pockets and their contained minerals have become world famous for the exceptional color, shape, or crystal size.

These special pockets are often named after the miners or individuals who found them (Charlie Key Pocket of lustrous blue azurite crystals from Tsumeb, Namibia), special characteristics of the specimens found (Blue Cap Pocket – distinct, gemmy rubellite tourmaline crystals with a blue indicolite cap from the Tourmaline Queen Mine, in California), or whimsical memorable jokes (Electric Meatball find of Zunyites).

So now, we present to you the Wisdom Pocket, our own special space to share our knowledge, passion, and insight into the mineral world.

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Rock and Mineral Collecting for Beginners

Rock and Mineral Collecting for Beginners

Assemblage of fine minerals and crystals - thumbnail sized minerals

Assembling little treasures of fine minerals can be a cost-effective and rewarding pursuit.

Collecting rocks and minerals is an exciting and rewarding hobby – full of fun, adventure, and hands-on opportunities to learn more about our world’s geology – all while building an important anecdotal and historical record. 

For those of you beginners who are interested in exploring the amazing world of rocks and minerals – here are some tips for starting and maintaining an excellent collection, sure to bring you joy for years to come!

1. Do the research. Start close to home, by exploring your area’s geology – what minerals and rocks are present in your current locale? Are there any interesting geological features, or caches? By familiarizing yourself with the samples available near your home base, you can get used to using the tools of the trade, and practice your collecting skills, without venturing out into unfamiliar territory. Read The Wisdom Pocket Blog or check out some of our recommended reading lists.

2. Join a club. What better way to learn about collecting, than to connect with others who share your interest? Your local mineral collector’s club is a great place to learn more about your area, as well as the best approaches to collecting. There is no reason to recreate the wheel, when you can benefit from the knowledge of those who are more experienced – and collector’s clubs are also a great way to learn about other gatherings, events, and expeditions. The American Mineral Federation lists contact info for many local collecting clubs. Read More…

Discover Oxide Minerals

Oxide Minerals

Large copper crystal formation from Michigan

This significant copper (over 26 pounds!) on custom base was in the Harvard Museum for decades.

The oxide group of minerals include naturally occurring compounds where oxygen is combined with one or more metals such as iron, manganese, aluminum, chromium, titanium and copper. This major group of minerals is known for their distinct physical properties that include high hardness and density, moderate to high luster, and are refractory. Most oxides are very stable in most geologic conditions as well as in the surface environment. They are found as primary minerals in igneous, sedimentary and metamorphic rock types and can be a major component of the rock or may be just an accessory mineral. Many oxide minerals serve as major ore minerals of economic importance, and some as significant gemstones!

Oxide minerals are very diverse, encompassing a wide range of mineral species ranging from more common minerals such as Hematite, Corundum, Cuprite, Chromite, and Rutile to relatively rare species such as Franklinite, Chrysoberyl, Tantalite-(Fe), and Perovskite, all with varying physical properties and chemical compositions. Oxide minerals can be generally classified into two distinct groups: simple oxides and multiple oxides. Simple oxides include those species in which oxygen is combined with one metal as in Corundum (Al2O3) and Cuprite (Cu2O) whereas multiple oxides have two or more metals combined with oxygen like Ilmenite (FeTiO3) and Spinel (MgAl2O4). Although technically oxides, Ice and Quartz are categorized differently due to their unique qualities.


As a result of their diversity, general convention limits the classification of oxides as non-complex minerals which are characterized by mostly ionic bonding of oxygen to the metal cation. Physical properties of oxide mineral specimens can vary greatly, but most of them have high hardness in common such as Corundum, Spinel and Chrysoberyl which exhibit a Mohs hardness of 8 to 9. Many are opaque and submetallic like Magnetite, Hematite, Ilmenite, Columbite-(Fe) and Uraninite, to those that are translucent to gemmy such as Spinel, Corundum and Chrysoberyl that can constitute precious to semi-precious gemstones!

A developing sixling twin of chrysoberyl from Brazil

Espirito Santo in Southeast Brazil is home to some of the world’s most classic chrysoberyls.

Oxide minerals can also vary greatly in color, form, and appearance. Some (for instance, Hematite) have almost a metallic luster, while others (such as Chrysoberyl) form as gemstones. Due to the environment of their formation, it is quite common for several species of oxide minerals to be found in close association. For example, deposits of Ilmenite, Magnetite, and Rutile may be found in locations where Hematite is also present. Several species of oxide minerals are also quite useful for industrial purposes, and hold significant economic value. These include chief ores such as Hematite and Magnetite (Iron), Chromite (Chromium), Manganite (Manganese), Cassiterite (Tin), Ilmenite and Rutile (Titanium), Franklinite and Zincite (Zinc). As precious gemstones, the highest quality gem Corundum (ruby in particular) can command some of the highest prices of any precious gemstone, even more than diamond!

Notable oxide mineral localities for specimens (sometimes in economic concentrations) include the Isle of Elba in Italy and the Kalahari Manganese Field in South Africa for fine and large Hematite crystals; Burma Stone Tract in Myanmar (Burma), Yenbai Province in Vietnam, and the gem gravels of Sri Lanka for stunning gem Corundum (ruby and sapphire) and Spinel; the historic zinc deposits in New Jersey, USA for Franklinite and Zincite; and Mount Kapudzhukh, Armenia and Graves Mountain, Georgia for world-class Rutile crystals.

Zincite with Franklinite crystal fine minerals from Franklin, Sussex County, New Jersey.

This rare zincite with franklinite from Franklin, New Jersey, was found in the late 1800s or early 1900s.

Because of their unique qualities, most oxides are very stable and survive into extreme geologic and environmental conditions and can be concentrated into significant economic concentrations when they weather out of rock and form placers such as ilmenite-rich sands that are mined for titanium. Oxide group minerals are generally stable under normal storage and display conditions, but the same care and considerations given to other minerals in your collection should be followed with the oxides, just on general principle. The biggest consideration, as with all minerals, is limiting their exposure to sunlight; Cuprite is very light sensitive and susceptible to darkening on exposure. Gem varieties of Corundum and Spinel, along with Chrysoberyl, can potentially lose their quality of color with prolonged exposure to light. Thus, enthusiasts and collectors should perform due diligence to determine the sensitivities of their prized specimens, and do their best to avoid exposure to conditions which might adversely affect their value.

Overall, oxide minerals are an intriguing and varied lot – with much to offer the rockhound or collector. To learn more about adding variety and interest to your rock and mineral collection, feel free to explore the Wisdom Pocket’s other informative articles – or browse our current collection of rare oxide minerals, including this unique collection of sparkling Cuprites from the Milpillas locale. They won’t last long!


A special thanks goes out to Tom Campbell for his article contributions.


Pyrite vs. Gold: A Tale of Two Origins

Pyrite vs Gold: A Tale of Two Origins

At a glance, pyrite and gold are nearly indistinguishable from one another. Pyrite, otherwise known as “fool’s gold” has a similar luster and a goldish color that shines like the real deal. In some instances, they can be mined in the same locations. This makes it even more difficult to spot gold from a pile of pyrite (or vice versa). While the two minerals may share a similar appearance, their origins are much different.

This unique pyrite shell photo is great for wall art or as mineral canvas photo prints.

Long ago, pyrite filled in the fossil remains of an ancient creature similar to a large snail. The result is this fantastic work of natural art – a pyrite mineral specimen in a truly unique form.

Creating Pyrite is Complex

Pyrite is a unique metallic mineral made of one iron and two sulfur atoms. The reaction used to form pyrite is highly complex as it involves the decomposition of organic matter in dissolved sulfate within sedimentary rock.

In some instances, pyrite has been found to cover or completely replace the remains of prehistoric creatures like ammonites and trilobites.[1] Many of these specimens are found within layers of sedimentary rock that were once covered by the ocean.

The ancient waters were low in dissolved oxygen, allowing for large numbers of sulfate to grow and reduce bacteria the necessary bisulfide.[2] This byproduct is highly reactive with iron, the most abundant of all metals, to create compound iron sulfide or pyrite that we see today.

Iron sulfide is a special type of compound called polymorphs whose crystal structure creates a multitude of minerals. For example, pyrite and marcasite are both made of iron sulfide, but each have a distinct crystal structure that makes them a unique mineral. Pyrite has a cubic structure with a metallic luster and gold color. Marcasite has an orthorhombic crystal structure and is easily damaged when mishandled.

Despite having a complex formation process, pyrite crystals are found in abundance throughout the world. The most famous mining localities for massive pyrite specimens are in Peru and Southern Europe.


The Ausrox Gold Nugget, one of the largest ever found!

At over 50 pounds, the Ausrox gold nugget has been on exhibit in the Perot Museum, Houston Museum of Natural Science, and the Melbourne Museum.

Gold’s Shine Comes from The Heavens

Despite sharing a similar appearance, gold and pyrite couldn’t be more different. Gold is highly rare and valued for its properties. Unlike other metals, gold doesn’t tarnish and is easy to work with. The mineral is malleable enough to create wire or flatten into thin sheets for detailed shapes.

Another key difference between the two is that gold is an element. The crystals cannot be formed like pyrite, only bound together produce gold nuclei. Some theories suggest that the source of much of Earth’s gold comes from the explosion of distant supernovas.[3] The end of a star’s life is volatile and many elements with high atomic numbers are produced. When the star explodes, these materials are flung into space and some of the product landed on Earth.

Other theories suggest that some of the gold was produced through natural geological forces in the Earth’s core.[4] When molten rock is carried to Earth’s surface, other elements with smaller atomic numbers around bound with free roaming neutrons to produce gold ore. These ores can be found within the veins of other ores like copper and iron.

Although pyrite and gold look similar, the way they’re formed couldn’t be more different. Pyrite is highly plentiful and found in virtually all parts of the world. On the other hand, gold is incredibly rare and some scientists are pointing towards space as their place of origin.


Looking to add pyrite and gold to your mineral collection? Follow the Arkenstone on their many mineral shows throughout the year! Information on the shows we’ll be attending can be found on our Mineral Shows page. We’d love to meet with you and talk about the specimens in our collections!

We’ve recently update our galleries with many impressive specimens from around the world. You can find our latest collections here.

[1] “What is pyrite?”. Discovering Fossils.

[2] Ibid.

[3] Joseph S. “All the Gold in the Universe Could Come from the Collisions of Neutron Stars”. Smithsonian Magazine.

[4] Matthias W, Tim E, and Stephan M. “Where does Earth’s gold from?”. ScienceDaily.

The Legends of Beautiful Crystals and Gems

The Legends of Beautiful Crystals and Gemstones

Throughout history, crystals and gemstones have been the subject of great myths and legends. Their natural beauty inspires curiosity in where they came from and mysticism in the power behind their colors.

Custom engraved bases by The Arkenstone,, are one of the most important ways to boost the display beauty of your fine minerals.

While modern science has given us insight on the creation of crystals and gemstones, legends offer an understanding of their value throughout history. Here are some of our favorites:


Amethyst is one of the most recognizable gemstones in the world!

Amethyst from Vera Cruz, Mexico. Joe Budd Photo, Jeff Starr Collection

Amethyst is a purple variety of Quartz with deep lavender to light rose colors. Most Amethyst starts as a clear Quartz, and receives its purple coloring after being exposed to manganese and varying degrees of iron. As more iron is introduced into the clear Quarts, the deeper its purple color.

The ancient Greeks believed Amethyst originated from the tears of the god of wine Dionysus that trickled down the statue of Amethyst.[1] When Dionysus was insulted by mortals, he created tigers to attack the next mortal that crossed his path.

A beautiful young maiden named Amethyst went to pay tribute to the goddess Diana, the tigers charged for Amethyst. The goddess Diana then turned Amethyst into a giant pure crystalline Quartz statue. When Dionysus saw the beautiful statue and realized the consequences of his actions, he wept remorseful tears of wine. It was believed that these tears stained the Quartz statue into the lavender color we see today.


Amber is unique from other rare rocks and minerals, because it’s made from fossilized tree resin. The fossilized resin is an organic compound of progressively oxygenated hydrocarbons over millions of years. In fact, the majority of Amber specimens are found within Cretaceous and Tertiary sedimentary rocks that are aged between 30 – 90 million years old.[2]

Many cultures revered Amber for its sun-like colors and its preservation of plants, insects, and other organic matter. Some Amber specimens take the shape of a teardrop, as tree resin drips from the bark and reta

ins its pouring form. These physical qualities have led to many legends connecting Amber to the sun.

The history of amber (especially those with insects frozen inside!) have fascinated people for centuries.

Amber found in north Poland with insect inside, auctioned on

One legend in Lithuania believed Amber came from the tears of Jurate, a Sea Goddess, who mourned the loss of her beloved.[3]

The ancient Greeks believed Amber was formed after the tragedy of Phaethon, son to the God of Sun.[4] When Zeus the Thunderer threw a bolt of lightning at Phaethon and his flaming chariot, Phaethon was swallowed by flamed and died on the Eridanus River. When his body was found by his mother Clymene and sisters Heliades, their tears fell into the river and hardened into Amber.


Jasper is a type of Chalcedony Quartz that is completely opaque. A pure microcrystalline quartz gemstone is semitransparent, but the Jasper contains enough impurities to change its ability to transmit light. Jasper can come in a variety of colors, ranging from red-orange to a light peach.

Bumblebee Jasper from Indonesia auctioned on

Historically, Jasper gemstones with a blood red color were widely sought after and used in royal amulets. It was believed that the blood red coloring helped women with fertility and stimulated good health. The ancient Egyptians linked red Jasper to the fertilizing blood of Mother Isis. [5]

The Vikings also believed red Jasper held magical properties that strengthened the skills of warriors. One legend believed that a red Jasper was laid in the hilt of the magical sword of Siegfried. The red Jasper gave Siegfried the courage needed in battle to later become a fierce slayer of dragons.[6]

Many legends offer a story of origin for crystals and gemstones. Their striking colors, shapes, and organic qualities are oftentimes connected to forces of nature like the sun. Rare crystals and gemstones are natural works of art that have inspired cultures throughout history.

Want to see these rare crystals and gemstones in person? We’ve recently update our galleries with many impressive specimens from around the world. You can find our latest collections here.

Also, don’t miss our listings for our rare rock and mineral shows. We’d love to meet with you and talk about the specimens in our collections!

[1] “Amethyst”. New World Encyclopedia.

[2] Susan A. “What is Amber?”. Emporia State University.

[3] “Legend of Jurate and Kastytis”. Amber Museum Kaliningrad.

[4] “Myth of Phaethon”. Amber Museum Kaliningrad.

[5] Caroline S. “Isis, Sister of Nephthys, Mistress of Magic”. The Keep.

[6] “Saga of The Nibelung”. The Viking’s World.

Diamonds in the Rough – Finding a True Gem

Natural diamond found in Mir Pipe, Russia. Joe Budd Photo

Diamonds have long been a symbol of rarity and natural beauty. The phrase “a diamond in the rough” really sums it up perfectly – as these crystals, even in their natural form – are quite stunning. But what makes them so rare, and desirable? Is it merely the value we’ve attached to them? Or, something more?

To begin with, diamonds are the only gemstone comprised of a single element. Their crystals are composed entirely of pure carbon which has been compressed in extreme temperatures and pressure beneath the earth’s surface – resulting in an arrangement of carbon atoms into a unique crystalline structure which lends the diamond unique properties. With a Mohs rating of 10, and a melting point of 3800°C, diamonds are the hardest known natural substance. In fact, even the name “diamond” arises from the Greek word “adamas”, which means indestructible.

The most valuable diamond specimens are those which are clear, colorless, and flawless – though even rough cut diamonds which meet these standards are difficult to find. Variances in color may span the full spectrum of the rainbow, depending on the presence of trace minerals (such as boron, or nitrogen) during the formation process. This can result in hues which range from the very pale, to deep and richly colored specimens. Clarity can also be affected by the inclusion of these trace minerals, as well as the presence of internal fractures which may have occurred during formation. Rough cut diamonds selected for jewelry-making should also be reviewed by a trained eye, as their shape and internal flaws may drastically affect their suitability for trimming.

Still, even the most flawed of natural diamonds hold a distinctive, inherent beauty. The simple miracle of their formation deep beneath the earth’s crust, and subsequent journey to the surface, lends rarity and interest to each unique specimen.

Every diamond has a story which spans millions of years – a timeline which truly boggles the mind. After formation within the Earth’s mantle, diamonds are transported to the surface in pipes of magma, which burst forth in violent eruptions. These stone pipes are usually composed of kimberlite – a weathered, yellow-brown or gray volcanic rock composed of fragments of peridotite and eclogite, embedded in potassic-ultramafic magma. Kimberlite was named after the city of Kimberley, in South Africa, where these diamond-bearing channels were first discovered. The presence of kimberlite (or its cousin, lamproite) is one of the first things geologists search for, when seeking sites where diamonds may be present.

Diamonds naturally display a crystalline habit – still, due to their extreme age, and volatile life’s journey, rough cut diamonds have often lost their naturally sharp faceting, exhibiting a more rounded shape. Eighty percent of rough cut diamonds are unsuitable for use as gemstones, and are separated from higher-quality specimens after mining, to be used for industrial purposes.

Arkansas natural diamond crystals

Arkansas is the most well-known location for American diamonds. Joe Budd Photo

Higher-quality stones are then sorted and graded by hand – separated by size, and other characteristics which lend each specimen a greater or lesser perceived value. Rough cut diamonds are then priced according to their clarity, color, carat, and shape – as these are factors which will determine their price, and suitability for use in jewelry or industrial purposes.

When choosing a rough diamond, you may want to consider factors outside of the typical “Four C’s”. (Learn about why the Four C’s of diamonds don’t apply to natural crystal collecting!) Those purchasing for industrial use will want to consider hardness and shape, whereas those seeking a stone for use in fine jewelry will want to consider the same standards used for assessing a cut stone – but with detailed attention to shape, and inclusions which may affect the resulting shape of the finished stone (keeping in mind that, on average, as much as 50% of the carat weight will be lost in the trimming).

Mineral collectors interested in reviewing these stones for their own personal enjoyment and display will find that rough cut diamonds make a breathtaking addition to any collection. Their rich history adds interest and intrigue to your fine gem and mineral display, and will be an expression of rarity and beauty you value, for years to come.

For those interested in assistance with their final selections, please contact the experts at iRocks, directly. Or, take a look at the Arkenstone’s current collection of rare, rough cut diamonds. We’re sure you’ll find a specimen which sparks your fancy!

Amethyst Geode Themed Wedding Cakes!

Amethyst Geode Themed Wedding Cakes!

The love for rare rocks and minerals has taken over the culinary world with the detailed work of amethyst themed wedding cakes. Recently, The Arkenstone supported the creation of a stunning geode cake for our Dallas Mineral Collecting Symposium as part of a 90th birthday celebration for speaker Bob Jones, but the cake style first hit popularity in Denver.


Using edible sugar, rock candy, dyes and moldable chocolate, Rachael Teufel of Intricate Icings has started an exciting new trend that foodies and rockhounds love. Unveiled at an industry event, the tall white cake sparkles with realistic amethyst crystals hollowed into its side like a geode.

From the Intricate Icings website, Rachael explains her geode inspiration and how the cake was made:

The cake was the centerpiece for one of the three “emotion” inspired vignettes that evening. The stunning ‘Joy’ inspired vignette showcased a variety of geodes. It included rich textures, deep colors and lots of light letting the natural beauty and shape of geodes lead the design. Joy speaks of experiencing something that pleases the eye, warms your heart and soothes the soul.[1]

Rachael’s amethyst geode cake took 16-hours and an eye for details to make. As rockhounds, we can appreciate the dedicated work it takes to replicate one of nature’s most astonishing rare minerals.

Geodes in Nature

Amethyst Geode - fantastic natural art

Amethyst Geodes like this one are a hot trend in home decor and provide inspiration for the popular geode cake trend.

The amethyst inside a geode is a byproduct of mineral deposits lining the interior cavity. It can take thousands to millions of years for massive geodes to form under extreme steady heat and pressure. The exterior of the geode may look like an unimpressive rough stone, but the interior cavity of the geode is lined with a mass of crystalline minerals whose natural beauty inspired the amethyst geode cake.

Most geodes are found within igneous rock with cavities created by the cooling of lava. The exact process for how these cavities are formed is still somewhat a mystery, but some popular theories suggest the bubbling activity of the lava leaves pockets for gas to escape.[2] As the molten rock of the geode cools and the gas escapes, a cavity is left behind for mineral enriched water to create crystals.

Geodes can also form within sedimentary rock like calcite and limestone. A popular theory for geodes in sedimentary rock suggests ground water drying from the ground and hardening into cavities.[3] This would occur in a cycle with water leaving mineral deposits for the crystals to grow.

The Colors of Quartz Crystals

The chemical composition of the minerals inside a geode are highly representatives of their environment as temperature, acidity, and elements in the water form crystals. The most common mineral found within geodes is quartz since silicon dioxide, or silica, is plentiful in all forms of rock.

South America produces amazing fine minerals, and amethysts are a specialty. This 21cm tall amethyst from Guererro, Mexico is an exceptional example of natural art and fine minerals.

Amethyst crystal from Guererro, Mexico. Joe Budd Photo

Amethyst is a purple variety of quartz crystal. The formation of amethyst in a geode comes from iron impurities in the mineral enriched water. This is where amethyst crystal structures get their color ranges from a light -lilac to deep, royal purple. Depending on the angular zones of the amethyst crystals, angling light in certain directions can help bring out deeper purples of a specimen. 

Twinned citrine crystal, Namibia. The Arkenstone,

Not only is this citrine natural, but it also exhibits twinning.

Another variety of quartz found in geodes is citrine. They’re light yellow to orange in color and are rarely formed in nature. Citrine is a type of amethyst that has been exposed to intense heat, changing its color from purple to yellow. In geodes that have produced citrine, it is common for the citrine and amethyst to blend and create ametrine.

Amethyst geodes are formed through a complex process that can take thousands to millions of years. Whether you’re assembling a collection for a museum or making a wedding cake, the beauty of these rare rocks and minerals is something we can all appreciate.

Love quartz? Explore more about quartz in our blog article, Favorite Types of Quartz!

Searching for geodes to add to your rare rock and mineral collection? We’ve recently added to our collection of rare rocks and minerals for sale after our shows in Denver. You can also find our other rare rock and mineral collections here.

Also, don’t miss our listings for our rare rock and mineral shows. We’d love to meet with you and talk about the specimens in our collections!

[1] Rachael T. “Amethyst Geode Wedding Cake”. Intricate Icings.

[2] Roger W. “Geodes”. Cochise College.

[3] Ibid.

Cursed Gemstones: The Black Prince’s Ruby

Cursed Gemstones: The Black Prince’s Ruby

Black Prince's Ruby is actually a spinel that is currently a part of the British Imperial State Crown.

The gemstone at the front of George V’s Imperial State Crown. G. Younghusband; C. Davenport (1919). The Crown Jewels of England. London: Cassell & Co. p. 6.

The ruby is a unique precious stone that has adorned a massive following throughout human history. Its deep red colors have made it the favorite of royalty across world cultures from India to England. Many cultures have also created dramatic legends around favorite, famous rubies. The Black Prince’s Ruby was a famous ruby with a tragic past, but a surprising discovery changed its image forever.

The Black Prince’s Ruby Is Not a Ruby

The Black Prince’s Ruby has had a long history as a royal gemstone whose incredible size and blood-red color made it the crowning jewel to the Imperial State Crown of the United Kingdom. Weighing in at 170 carats and at about 2 inches long, the Black Prince’s Ruby was long thought to be one of the largest rubies in the world. However, a ruby gemstone of this size would prove too good to be true.

The majority of rough ruby crystals grow in the shape of an elongated carrot and have their pleochroism flowing towards its pointed ends.[1] Pleochroism describes a gradient effect where different colors follow an opposite direction from the crystal. This makes cut ruby gemstones larger than a carat incredibly rare, because the naturally elongated shape of the ruby makes it vulnerable to a low weight retention rate.[2]

While the Black Prince’s Ruby is an impressive specimen in its own right, it is not a ruby. In the 16th century, jewelers found the Black Prince’s Ruby to be a spinel, a mineral that is well known today as “the great imposter” for its deceitful likeness to a ruby.[3] Although they share the same color with the ruby, the spinel has a completely different chemical composition and crystal structure.

The Curse of the Sultan

The legends behind the Black Prince’s Ruby starts with an act of deceit. Prior to being the crowning jewel in the Imperial State Crown of the United Kingdom, the Black Prince’s Ruby made its first known appearance in the 14th century as the gemstone of Abu Said, the last Sultan of Granada.[4] In 1362, Granada was losing territory to King Pedro the Cruel of the Christian Kingdom of Castile through a series of battles. To find peace, the Sultan arranged a peace meeting with King Pedro in Castile.[5]

On arrival to the Castilian lands, King Pedro killed Sultan Abu and all of his accompanying servants. King Pedro had no intention of settling for peace, and some accounts describe the king as the one who killed the Sultan himself. The ruby was then confiscated from the body of the Sultan. This is the first step in a long history of misfortune surrounding the ruby throughout the majority of the Middle Ages.

Cursed Through the Middle Ages

Soon after killing Sultan Abu, King Pedro found himself warring with his brother, Henry of Trastamara for the throne of Castile. To aid in battle, King Pedro enlisted the help of Edward the Black Prince of England. After a series of battles, Henry of Trastamara was kept at bay, successfully preserving the throne of King Pedro. For his service, the ruby was given to Edward the Black Prince.

Upon receiving the ruby, Edward the Black Prince returned to England. However, King Pedro’s victory wouldn’t last long as he’d engage in more battles with his brother, resulting in his bankruptcy and death just 3 years later.[6] Edward the Black Prince would also die from a slow disease before he could inherit the English throne, leaving the ruby to his son, Richard II.[7]

Richard II would eventually become King, but he was murdered at the age of 21 by Henry IV Bolinbroke, starting the line of Lancastrian Kings.[8] Shortly after taking the throne, King Henry IV Bolinbroke would die from a slow illness, leaving his son Henry V to inherit the throne and the Black Prince’s Ruby.

This series of kings dying from mysterious illnesses or misfortune in battle would continue through several lineages until the ruby made its way into the hands of the Tudors.

Passed from the Tudors to the Stuarts

The Black Prince’s Ruby was inherited by the Tudors in the 16th century, entering a relatively calm period for the gemstone. Queen Elizabeth I gifted the ruby to Queen Mary of Scots who would pass it down to King James I when the Stuarts took the English throne in 1603. However, the years that followed the exchange saw another wave of misfortune as King James’s son, Charles I, was executed during the Civil War and the Crown Jewels were sold off.

When the Black Prince’s Ruby was being appraised, a jeweler discovered that the stone was not a ruby but a spinel. When the monarchy was restored by Charles II in 1660, the jewel sold to the crown for 15 pounds and was refashioned as the crowning jewel of the Imperial State Crown.[9] The throne was then inherited by Charles’s brother, James II, who was exiled just 3 years after his coronation.

Today, the Black Prince’s Ruby is now on display in the Tower of London with the rest of the crowning jewels. There have been a few notable incidents since, such as when King James II lost the throne. All in all, the long history of misfortune following the stone has made the Black Prince’s Ruby one of the most infamous jewels in English history.

Looking for rare rubies? Then explore our expansive collection of rare rocks and minerals! We’ve recently update our galleries with many impressive specimens from around the world. You can find our latest collections here.

Also, don’t miss our listings for our rare rock and mineral shows. We’d love to meet with you and talk about the specimens in our collections!

[1] Richard H. “Pleochroism in Faceted Gems”. Gemological Institute of America Inc.

[2] Ibid.

[3] “Spinel”. International Colored Gemstone Association.

[4] Desmond S, The Hundred Years War (London: Penguin, 1999).

[5] Ibid.

[6] Christopher H, A Pilgrim in Spain (London: Bloomsbury Publishing, 2011).

[7] Jenny S, Richard II and the English Royal Treasure (Suffolk: Boydell Press, 2012).

[8] Ibid.

[9] Richard H. “The Black Prince’s Ruby”. Ruby & Sapphire.


Collections That Shine: Rare Coins and Minerals

Collections That Shine: Rare Coins and Minerals

To the untrained eye, a coin has two-sides and shimmers in the right light. To an avid collector, a coin is worth more than its printed monetary value and face. Each coin has a unique craftsmanship that details the tools and symbols of their time. The weight and materials used capture a moment in history and the journeys it took to create it.

The excitement that comes from studying the beauty and history of a rare coin is the same felt by rockhounds when they add a rare mineral to their collection. Rare coins and minerals have more in common than one would think, from how a sample is appraised to their collection trends. Both inspire dedicated communities to their craft.

More Than a Shine

Like a rare mineral, the rare and more sought after the coin the greater its potential value. Where a coin and mineral differ is in their creation. Minerals are created naturally within the earth over a span of thousands to millions of years. Coins are minted by people using minerals, which places greater emphasis on the coin’s locality and year of circulation.

When judging a coin, the value is derived from its historical significance and strike. Some important factors include:

  • The issued year or era
  • The overall condition of the coin and its strike
  • The materials used in the coin
1879 Morgan Dollar Coin

1879 Morgan Dollar Coin

For example, a highly popular coin amongst coin collectors is the 1891 Morgan Dollar. The coin was minted between 1878 through 1904 as the first standardized silver dollar, ending the free coining of silver. Coins minted in 1891 were some of the last to be minted under the Sherman Silver Purchase Act of 1890, as silver was soon redistributed to mint dimes, quarters, and half dollars.[1]

1891 Morgan Dollars of the same mintmark, year, and overall condition may appear to have similar values. However, coins with clearer mintmarks, specifically the Carson City “CC” mint, are worth more than those with shallower strikes.[2] This is because the 1891 Morgan Dollars were produced by four minters with different rarities.

Locality Is Essential

Variations of the factors used to judge coins are also used in judging the quality of rare minerals. Some of the physiological features of a mineral that are taken into consideration are:

  • Condition of the specimen
  • Material makeup of the specimen
  • Hues and tones
  • Saturation and variation
  • Aventurization and Chatoyancy
Fine Sapphire Crystal, Sri Lanka.

Natural sapphires like this one are judged on criteria like crystal shape, color, and the rarity of the location. Joe Budd Photo.

In addition to physiological features, there are also major differences between species of minerals in terms of their chemical makeup. Rare minerals like sapphires and opals are chemically unique from one another. Sapphires are a variety of corundum and, depending on its concentration of impurities, can take on multiple colors. Opals are amorphous as they don’t take on a purely crystal structure and can shine multiple colors at once in what is called the “play-of-color”.

Like a coin, the locality or where the mineral was formed plays a major role in its value. Minerals are created through natural processes within the earth over a span of thousands to millions of years. With earth hosting a variety of climates, specimens from certain parts of the world will slight variations in their qualities.

For instance, 90% of the world’s opals are mined in Australia.[3] Another producer of opals is Ethiopia. Although both countries produce the same silica-based opal, Ethiopian opals are found to contain half the amount of water of Australian opals. [4]

To the avid coin collector and mineral enthusiast, there are few things better than learning more about the samples in their collection. In many ways, collecting coins and rare minerals share the same enthusiasm for history, beauty, and the hunt for their next piece.

Explore our expansive collection of rare rocks and minerals! We’ve recently update our galleries with many impressive specimens from around the world. You can find our latest collections here.

Also, don’t miss our listings for our rare rock and mineral shows. We’d love to meet with you and talk about the specimens in our collections!


[1] William R. Supplement to the revised statues of the United States (Washington, D.C.: United States Government Printing Office, 1891), 806—807.

[2] Daniel H. “1891 Morgan Silver Dollar Value”. CoinStudy.

[3] “The History of Opal”. Opals Dow Under.

[4] ­Eloise G. “Loving Ethiopian Opals”. National History Museum of Los Angeles County.

Famously Misidentified Gemstones – iRocks

Famously Misidentified Gemstones

Gemstones catch the eye of Rockhounds for their unique shapes and colors. Yet, some gemstones are nearly indistinguishable, even to the trained eye. Until the introduction of chemical properties, classifying rare stones was a challenging process that relied heavily on observing physical properties.

Qualities like color, hardness, streak, and diaphaneity were some of the properties that were readily observable to merchants, miners, and jewelers. With modern gemology, the chemical composition and crystal structures of a stone are taken into account. While these properties help us understand the differences between specimens, it has also uncovered identification errors made of famous gemstones.

Black Prince’s Ruby

Black Prince's Ruby is actually a spinel that is currently a part of the British Imperial State Crown.

The gemstone at the front of George V’s Imperial State Crown. G. Younghusband; C. Davenport (1919). The Crown Jewels of England. London: Cassell & Co. p. 6.

The Black Prince’s Ruby is an egg sized gemstone that was originally owned by the Moorish Prince of Granada, Spain in the 14th century. The gemstone was received by the Prince of Wales in 1367 as payment for a victory in battle and later given to King Henry V of England in 1415.[1]

The massive gemstone soon became legendary when it saved King Henry’s life from an axe blow to the head during a battle with French Prince Duc d’Alencon.[2] The Black Prince’s Ruby has since adorned the Imperial State Crown of the United Kingdom, having been passed down to numerous British kings and queens.

In the 16th century, it was found that the Black Prince’s Ruby was not a Ruby after all, but a Spinel instead.[3] The Spinel earned a reputation as “The Great Imposter” by English jewelers as its physical properties are nearly indistinguishable to that of the Ruby.


The Delhi Purple Sapphire

This purple amethyst was originally believed to be sapphire

The Dehli Purple sapphire – revealed later to be an amethyst. Source: Natural History Museum (London)

The Delhi Purple Sapphire is a large gemstone set in a silver ring with alchemic and astrological signs decorating its band. The Sapphire was thought to be a “cursed gemstone” for its curious history of unfortunate events befalling its owners.

Records show that The Sapphire started its journey in India where it was stolen from the Temple of Indra in 1855.[4] The Sapphire eventually found its way into the hands of Edward Heron-Allen, an expert in paleontology and author of many archaeology books, who would immediately find himself in the way of bad luck.[5]

Incidents from bad investments to friends suffering bodily harm convinced Heron-Allen to distance himself from the stone. When Heron-Allen tried to get rid of the gemstone by throwing it into the Regent’s Canal, it was mysteriously returned to him a few months later by a local jeweler.

In January 1944, the Heron-Allen family gave the Delhi Purple Sapphire to London’s Natural History Museum where the stone was found to be an Amethyst.[6] Curators at the Natural History Museum believe these claims were started by Edward Heron-Allen to give credibility to the Amethyst.


Alexandrite gemstone in different lighting - pink and blue coloring

Alexandrite exhibits amazing color-change properties. This is the same stone under different lighting.

Russia became a major source of Emerald gemstone in the 1830s when deposits were found along the Tokovaya River.[7] The discovery then attracted miners to the river and the nearby Ural Mountains where reports of sizable Emerald gemstones were also found.

The Ural Mountains supplied the area with many large gemstones, including a notable discovery by French scientist Nils Gustaf Nordensköld. In 1834, Nordensköld was inspecting Emeralds found in the Ural Mountains when he found some of the stones had a chromium bearing, pleochronic variety of chrysoberyl.[8]

This discovery gave birth to a new gem quality stone, the Alexandrite, whose color would change from a deep emerald green in daylight and red in nightfall. Alexandrite, having been discovered in Russia and found to be one of the rarest colored gemstones, then became the official gemstone of Imperial Russia’s Tsardom.[9]

Despite the misidentification of these gemstones, their rich history and lore is what truly makes them some of the world’s most valued gemstones. After all, beauty is in the eye of the beholder.


Have you seen our expansive collection of rare rocks and minerals?  We’ve recently updated our galleries with many impressive specimens from around the world. You can find our latest collections here.

Also, don’t miss our listings for our rare rock and mineral shows. We’d love to meet with you and talk about the specimens in our collections!

[1] Byashley F. “Spinel”. Sothesbys.

[2] Richard H. “The Black Prince’s Ruby”. Ruby Sapphire.

[3] “Spinel”. International Colored Gemstone Association.

[4] Amy F. “Specimen of the Month #1: The Cursed Amethyst”. Natural History Museum.

[5] John S, Haunting Museums (London: Macmillian, 2009), 206.

[6] Amy F. “Specimen of the Month #1: The Cursed Amethyst”. Natural History Museum.

[7] Richard H, John K, and Waren B. “Emerald & Alexandrite from Russia”. Lotus Gemology.

[8] George F, The Curious Lore of Precious Stones (Philadelphia: J. B. Lippincott Company, 1913) 55-56.

[9] Ibid.

November 2016: Minerals in the News

November 2016: Minerals in the News

The field of mineralogy and earth sciences is flourishing with discoveries and collection announcements. There is always something new to pique your interest. Here are some of our favorite news stories for November 2016:

Feldspar Sheds Light on the Mohorovičić discontinuity

A study published in Science Daily by Mainak Mookherjee, Assistant Professor of Geology at Florida State University, sheds light on the presence of the Mohorovičić discontinuity by observing how feldspar reacts to changes in pressure.[1] Discovered in 1909 by Andrija Mohorovičić, the Mohorovičić discontinuity is a layer between the Earth’s crust and mantle at around 8 kilometers beneath the ocean basin.[2]

Feldspar is a type of igneous rock made of aluminum, silica, oxygen, and potassium, and it is found in more than half of the Earth’s crust. When minerals are under pressure, they typically become stiffer as they’re forced to compact. Yet, Mookherjee’s studies show that feldspar becomes soft and decomposes into denser materials like quartz under extreme pressures.

According to Mookherjee, this discovery “provides very new insight and a novel way of accounting for the sharp Mohorovičić discontinuity.”[3] By observing how Earth materials are react under extreme conditions, it is possible to gain further insight into deep Earth dynamics.

The Gia Museum Acquires Joel Hauser Mineral Collection

The Gemological Institute of America (GIA) received an exceptional donation of 63 ornamental minerals from the collection of Joel Hauser.[4] Many of the minerals in the collection are from highly restricted localities or are no longer in production. The GIA plans to use the minerals as learning tools on mineral formation and lapidary artistry.

The collection has been Joel Hauser’s pride and joy with over 60-years’ worth of ornamental minerals, petrified woods, agates, and geodes.[5] Hauser was also highly regarded as a skilled lapidary who mastered the art of contour polishing.

“His freeform, undulating polishing style adds interest and texture while removing blemishes, without having to grind away more material than necessary. Joel’s expertise, guided by an artistic eye and perspective, revealed the lovely patterns, markings and colors in the minerals,” says Terri Ottaway, GIA’s museum curator.[6]

The donation was made by his wife Barbara Hauser and their four sons to help the GIA fulfill its mission to educate and inspire the public about gemology. Nearly 50 of these minerals will be available for viewing at the GIA’s Carlsbad museum, starting early November.[7]

Fourteen-Year Old Jessica Simonoff Discovers Merelaniite

In 2011, Jessica Simonoff was studying a piece of tanzanite for her internship with mineralogist Mike Wise at the National Museum of Natural History in Washington, D.C. when she noticed black wire-like structures covering the mineral. When the then fourteen-year old Simonofff showed her observations to Wise, he was surprised to find that he couldn’t identify the wire-like structures either.

After a field of tests in a lab at Michigan Technological University in Houghton, they found that the black wire-like mineral had a crystal structure that contained a never-before-seen combination of molybdenum, sulfur, lead, and other element traces.[8] This led Wise and Simonoff to the conclusion that they’ve discovered an entirely new mineral.[9]

To be accepted as a new mineral, the sample will go through an approval process by the International Mineralogical Association’s (IMA) Commission on New Minerals, Nomenclature, and Classification (CNMNC). Scientists from around the world will study the sample for its crystal structure and properties like density, opacity, reflectiveness, hardness, tenacity, and others.

Four-years and several months of intensive testing and deliberation, the CNMNC has acknowledged the sample as a new mineral and has approved the name “Merelaniite”.[10] Simonoff, now eighteen-years old was delighted to hear that her discovery has contributed to science and opened a new door for research.

John Jaszczak, a scientist who helped the CNMNC study the Merelaniite believes other scientists can use this discovery to study naturally occurring crystal structures to synthesize new materials. “It’s new knowledge that adds to the understanding of how our planet works,” he said.[11]


Feel inspired to start your own rare rock and mineral collection? Then look no further! We’ve recently added to our collection of rare rocks and minerals for sale after our shows in Denver. You can also find our other rare rock and mineral collections here.

Also, don’t miss our listings for our rare rock and mineral shows. We’d love to meet with you and talk about the specimens in our collections!

[1] Kathleen H. “FSU geologist explores minerals below Earth’s surface”. Florida State University News.

[2] Hobart K. “Mohorovičić Discontinuity”. Geology.

[3] Ibid.

[4] “GIA Museum Acquires Highlights of the Joel and Barbara Hauser Mineral Collection”. GIA.

[5] Ibid.

[6] Ibid.

[7] Ibid.

[8] JoAnna W. “Whiskers on Familiar Crystal Revealed as New Mineral”. American Geophysical Union.

[9] Ibid.

[10] Ibid.

[11] Ibid.