Minerals and gems expo set to sparkle in Chenzhou

May 17, 2018

Latest event will showcase Hunan province city's expanding business opportunities and draw international interest with exciting exhibits and displays

By Zhao Shijun
Originally published on ChinaDaily.com.cn

Stage at the Chenzhou China Mineral and Gem Auction A fantastic stage set the mood for the Fine Mineral Auction at the China Mineral and Gem Expo in Chenzhou, Hunan, China. Monica Kitt Photo.

The China (Hunan) International Minerals and Gem Expo - staged each year in the city of Chenzhou, Hunan province - is set to again draw international interest and showcase the city's bright business opportunities, according to local officials.

This year's expo, the sixth show, will open on Friday and organizers said it will be another dazzling extravaganza.

They said a total of 2,800 exhibition stands, covering about 120,000 square meters, have been booked by more than 1,000 exhibitors from over 50 countries and regions including France, the United Kingdom, Italy, Germany, Belgium and Brazil.

Liu Zhiren, mayor of the mineral resource-rich city, said he believes the expo will continue to play its role as a platform to publicize the city's business environment and forge deals, helping attract overseas businesses and push local companies into international markets.

Read the full story here


10 Facts You Didn’t Know About Gold, Part 1

Feb 27, 2018

Most people understand gold in terms of wealth and investments, but there is so much more to say about the mineral. Gold has had a long history as a currency and as a sign of power. Today, gold’s unique qualities have expanded its role as a conductive material, decorative accent, and a mineral collector’s favorite. Here is part 1 of our 10 facts about gold that you didn’t know:

Gold can be found around the globe

Gold can be found on every continent, including discoveries in Antarctica. However, not all locations hold equal amounts of gold. For centuries, the two largest deposits of gold were found in South Africa and India. Australia's gold rushes began in the mid-1800s. When South African gold began to peak in the 1970s, other locations like Russia and the North American continent began to boom as the leading producers of gold. Brazil recently has hit a small deposit of beautiful crystallized golds.

Several gold crystals from Brazil Brazil recently had a find of beautiful gold crystals.


We’ve produced enough gold to fill two Olympic swimming pools

Two Olympic pools or 5 million liters is a figure that is frequently cited by publications using Thomson Reuters GFMS survey.[1] The truth of the matter is that coming up with an exact number is incredibly complicated, as many countries are secretive about the amount of gold they hold.

Mining for gold has been a practice for growing wealth since before the ancient Egyptians. History holds countless legends of gold hordes like Francisco Pizarro’s treasure exploits filling a 22-ft. by 17-ft. room and hundreds of bullion chests aboard sunken ships like the Nuestra Señora. Still “Two Olympic pools” is a safe estimate with cross surveys by the U.S. Geological Survey and the British Geological Survey.[2]

There is more steel produced in an hour than gold in its entire history

Gold is incredibly rare. In fact, the world produces more steel in an hour than it has ever produced gold since the start of written history. Looking at the number, the world increases the production of steel by 10,500 tons per-hour while gold production increases by 2,000 tons per-year![3]

Platinum from Siberia, Russia. Crystallized platinum, an example of a noble metal is exceptionally rare.

Gold is a “noble metal”

“Noble metals” are a rare group of metals that resist corrosion and oxidation from moisture in the air. This is because gold’s electronic configuration prevents its electrons from reacting with chemicals that would cause base metals to rust or tarnish.[4] Other metals included in the “noble metals” group are silver, platinum, rhodium, and palladium.

Earthquakes can create gold

A recent study by the University of Queensland in Australia discovered that water in faults vaporize and make gold during an earthquake.[5] During an earthquake, water moves from bigger faults to smaller fractures throughout the earth. At around 6 miles below the surface, the intense heat and pressure carries concentrated carbon dioxide, silica, and gold. When the pressure drops, the water is instantly vaporized to forcing out silica and gold.


Gold specimen from California on a custom lucite base Stunning gold from the Eagle's Nest Mine (Mystery Wind Mine) in Mariposa, California

Our fascination with gold has found many incredible facts about its history, uses, and qualities. Be sure to join our mailing list to stay updated.

Looking for gold pieces to add to your growing rare rock and mineral collection? Then 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 updated our galleries with specimens from around the world. You can find our latest collections here.

[1] Ed P. “How much gold is there in the world?”. BBC. http://www.bbc.com/news/magazine-21969100

[2] Ibid.

[3] Vronsky. “History of Gold”. Gold-Eagle. http://www.gold-eagle.com/article/history-gold

[4] Bjørk H. “Why gold is the noblest of all the metals”. Nature. https://www.nature.com/nature/journal/v376/n6537/abs/376238a0.html

[5] Deon W. and Richard H. “Australian research confirms link between seismic activity and gold deposits”. The University of Queensland. https://www.uq.edu.au/news/article/2013/03/australian-research-confirms-link-between-seismic-activity-and-gold-deposits

Visit a Gallery, a Museum and the Dallas Symposium: A Hands-on Education

Feb 22, 2018

There’s no greater fulfillment in collecting rare rocks and minerals than seeing an incredible specimen in person. Not only is it a rare opportunity to engage with scholars, you’re also bound to learn a wealth of information that cannot be found in an article. This is why we at the Arkenstone encourage enthusiasts to visit museums and symposiums to see rare minerals that couldn’t be found anywhere else.

The founder of the Arkenstone, Dr. Robert Lavinsky, has woven this passion for hands on education into the culture of the company with several specimens in display at the Smithsonian Institute, Harvard University, the California Institute of Technology, and many others. In our opinion, here are some reasons to start planning your next museum or symposium visit today:

You’ll See Premier Specimens

Going to a museum or symposium gives you the chance to see some of the finest specimens found on earth and learn from experts. It’s one thing to read about a rare rock in a magazine or online article. Being up close and personal with some of the earth’s rarest minerals like benitoite, red beryl, euclase, and alexandrite is a far richer experience.

You’ll See Complete Collections

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.

The most exciting part of visiting a museum or symposium are its complete collections. Some minerals like sapphires come in a variety of colors with large specimens being incredibly rare. Visiting an exhibit with an entire collection is a unique opportunity to indulge in a collection that would otherwise take dedicated years and resources to complete.

Some museums dedicate entire rooms to collections by world famous hobbyists and researchers like the Smithsonian Natural History Museum’s Janet Annenberg Hooker Hall. The museum is residence to over 2,500 minerals and gems, including the Hope Diamond and the Star of Asia sapphire.[1]

The Hope Diamond is one of the most recognizable gems in the world. The Hope Diamond at the Smithsonian, one of the world's most famous gems. By David Bjorgen - Own work, CC BY-SA 3.0

You’ll Meet Experts in The Field

There’s no shortage of rare rock and mineral experts when you visit a museum or symposium. Museum curators and docents have extensive background knowledge about the rare rocks in display and will happily offer references for further studies.

Symposium events like the annual Dallas Mineral Collecting Symposium and the Tucson Mineral Shows bring hundreds of scholars and enthusiasts to review the season’s most important discoveries and research. These events typically have showrooms available, allowing you to network with other enthusiasts.

Opportunities to Handle Rare Minerals

Sulfur from Sicily, Italy. Photo by Joe Budd, courtesy of The Arkenstone, www.iRocks.com Sulfur from Sicily, Italy. Photo by Joe Budd.

A great way to familiarize yourself with the spectrum of rare rocks and minerals is to observe their physical properties. From the surprising smell of sulfur to the unexpected weight of gold, handling rare minerals provides deeper insight.

Some museums have special exhibits planned that allow visitors to handle specimens. The National History Museum in Los Angeles County encourages visitors to handle their slabs of jadeite – a highly praised material around the world.[2]

Visiting a museum or symposium offers unique opportunities that can’t be experienced anywhere else. So, fit a trip into your next vacation or outing today!

Looking to start your own rare rock and 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 updated our galleries with many impressive specimens from around the world. You can find our latest collections here.


[1] “Museum Event Spaces”. Smithsonian Natural Museum of Natural History. http://naturalhistory.si.edu/specialevents/gems.html

[2] “Gem and Mineral Hall”. Natural History Museum. http://www.nhm.org/site/explore-exhibits/permanent-exhibits/gems-minerals

The Vibrant Glow of Electric Hyalite Opals

Feb 18, 2018

Opals are some of the most unique gems found on earth for their wide display of color. Fire opals are revered for their translucent coloring with flashes of red and yellow hues. Lightning ridge opals are a darker variety with splashes of red and green.

Of the many opal varieties, one of the most unique versions is hyalite opal. But unlike the fire and lightning ridge opal,  hyalite opal’s display of magnificence is best seen in the dark... check out what happens in the video below when the lights go out and a blacklight comes on!

The Opal with a Fluorescent Glow

One of the most captivating qualities of hyalite opal is its fluorescent green glow in shortwave ultraviolet light. All minerals can reflect a degree of light, but some have the physical qualities that allow them to temporarily absorb a small amount of light and releases it in a different wavelength.

While the hyalite opal may appear milky to colorless, with certain "electric" hyalites, the change in wavelength is visible to the human eye as a glow that is intensified just by sunlight or moving into a dark room.

Hyalite Opal, like this specimen from Hungary, shows shocking fluorescence under UV lighting!

How the “Bubbles” Are Formed

At a glance, hyalite opal looks like a cluster of milky bubbles on sedimentary rock. This globular mass comes in irregular shapes and sizes, giving it a weak opalescence (play of color) that is a hallmark of other precious opals. The tiny beads of hyalite contain around 3-8% water and are made of hydrated silicate.[1]

Like other opals, the hyalite opal lacks the crystal structure of most minerals. Instead, they form spherules through the layered massing of silica gel.[2] To form hyalite opals, the layered massing of silica must solidify within its gas phase. Most of this activity takes place within irregular crusts of volcanic and pegmatite environments.

When the exposed lava begins to cool and harden, gasses rich in silica and water travel through the cooling lava and the bodies of rock around it. Some of the silica and water rich gas is trapped in fissures and pockets within the rock, continually cooling and lowering in pressure as it turns into a liquid. The byproduct of this process is a bubbled botryoidal crust of hyalite opal that is less hydrated than precious opal.

This pale yellow opal from Mexico glows neon green under blacklight. Gemmy field of lustrous, green, botryoidal Hyalite Opal that has bright fluorescence. From Zacatecas, parts of this Opal are a full half centimeter thick with plenty of cutting material. These fluoresce in the natural sunlight, just holding it outside!

Hyalite opals can be found in precious opal-rich regions around the world like Australia. The most common regions that produce the most hyalite are Central Europe, Northeastern United States, and Mexico. Recently, major discoveries of hyalite opal have been in the Zemplen Mountains of Hungary and Zacatecas, Mexico.

Opals are revered for their wild display of color. While the hyalite may not have the impressive color splashes of the lightning ridge or the striking yellow of a fire opal, their fluorescent glow is vibrant and must be seen to believe it!


Interested in adding a hyalite opal to your collection? Browse specimens for sale from Mexico and Hungary.


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 updated our galleries with many impressive specimens from around the world. You can find our latest collections here.

[1] “Hyalite”. Mindat. https://www.mindat.org/min-32188.html

[2] Franca C, et al. “Physical and chemical properties of some Italian opals”. Periodico di Mineralogia. http://citeseerx.ist.psu.edu/viewdoc/download?doi=

5 Incredible Minerals Sold in an Auction

Feb 6, 2018

One of the best places to find high quality rare minerals is in an auction. Dealers bring their finest specimens forward for collectors to appraise and cast their bid to take home the prize. Now, with the internet connecting communities from around the world, online auctions like mineralauctions.com are making it easier than ever to bid for incredible rare minerals – bringing more diversity and excitement to the mineral world!

Mineral auctions are growing and sometimes we see news breaking sales of one of a kind minerals and purchases. To celebrate the spirit of mineral auctions and the sought-after minerals ever found, here’s a list of 5 incredible minerals sold in an auction:

The Rockefeller Emerald

The Rockefeller name is woven in the fabric of American history with the Standard Oil Co. Inc. of the 1900s and many other entrepreneurial achievements. Adding to the Rockefeller legacy is the most expensive emerald in an auction, at $305,00 per carat: The Rockefeller Emerald.[1]

The 18.04-carat Rockefeller Emerald was purchased by Harry Winston for $5.5 million at the Christie’s Auction house in New York, New York. The Rockefeller Emerald was first acquired by John D. Rockefeller Jr. in 1930 as a center stone for a brooch. In the 1940s, the emerald was placed into a platinum ring. Images and more details available here.

The Sunrise Ruby

Original work: Société Cartier; Depiction: Justin Tallis Sunrise Ruby - one of the most valuable gemstones sold at auction - weighs in at 25.59 ct. Cartier Photo.

Rubies are one of the rarest minerals in the world with valuable qualities that are increasingly hard to find in nature. As a red variety of corundum, rubies have an intense red color that come from their chromium impurity, separating them from their sapphire cousins. Large carats of rubies are exceptionally rare, so it should be to no surprise that a 25.59-carat ruby called, “The Sunrise Ruby” sold for a record of $30.33 million at Sotheby’s in Geneva.

Praised as “amongst the rarest of all gemstones” by David Bennet, head of Sotheby’s international jewelry division, The Sunrise Ruby is one of the few rubies in the world to have the rare grading of pigeon’s blood color at its size.[2]

Blue Moon of Josephine

Described as “flawless” by the gemstone world, the 12.03-carat Blue Moon of Josephine was auctioned for $48.5 million at Sotheby’s in Geneva.[3] The diamond was bought by Joseph Lau, a billion from Hong Kong, as a gift for his daughter. The Blue Moon of Josephine is an exceptionally rare blue diamond with a hue described as Fancy Vivid by the GIA. Fancy Vivid describes a gemstone whose medium to dark tones are strongly saturated and have only been found in 1% of all blue diamonds.[4] Photos here.

Oppenheimer Blue Diamond

While the Blue Moon of Josephine broke records for being one of most expensive blue diamonds per-carat ever auctioned, at $4 million per-carat, the record for most expensive blue diamond ever auctioned goes to the Oppenheimer Blue. The 14.6-carat blue diamond was auctioned at Christie’s in Geneva for $57.5 million, making it the largest Vivid Blue diamond sold at an auction.[5]

The Oppenheimer Blue diamond was named after Philip Oppenheimer of the De Beers Diamond Jewelers. Blue diamonds are an exceptionally rare type of diamond with only 10% of all found blue diamonds being larger than a carat.[6] The Oppenheimer Blue is truly a one-of-a-kind gem with qualities that place amongst the rarest of the rare. View the amazing photos here!

Pink Star Diamond

Earlier this year, the attendees of Sotheby’s in Hong Kong witnessed history as the world record for the most expensive gemstone ever sold at auction took place. The 59.6-carat Pink Star Diamond, a diamond recognized as the largest Internally Flawless Fancy Vivid Pink by the Gemological Institute of America (GIA), sold for $71.2 million.[7]

According to Sotheby’s, The Pink Star Diamond was mined by De Beers in Africa in 1991 and was 132.5-carats. The rough diamond was then “meticulously cut and polished over a period of two years.” View the results!


Want to stay up-to-date on the latest news and events about the mineral world? Register for the Arkenstone’s mailing list for information on the latest findings, news, and many mineral show announcements throughout the year!

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

[1] Roberta N. “Harry Winston Pays $5.5 Million For Rockefeller Emerald: Most Expensive Per-Carat Emerald Ever Sold”. Forbes. https://www.forbes.com/sites/robertanaas/2017/06/21/harry-winston-buys-worlds-most-expensive-emerald-at-auction-5-5-million-rockefeller-emerald-christies-auctions-highest-priced-emerald-world-records-for-emeralds-john-d-rockefeller/#39e7b5c464b2

[2] “This ‘pidgeon blood’ ruby sold for a record $30 million’. Business Insider. http://www.businessinsider.com/afp-pigeon-blood-ruby-sells-for-record-30-million-2015-5

[3] “Tycoon buys $48m blue diamond at auction for daughter”. BBC. http://www.bbc.com/news/world-europe-34795005

[4] “World Auction Record Price-Per-Carat for a Diamond or Gemstone”. Sotheby’s. http://www.sothebys.com/en/auctions/ecatalogue/2014/magnificent-jewels-and-noble-jewels-ge1505/lot.513.html

[5] “The Oppenheimer Blue”. Christie’s. http://www.christies.com/features/The-Oppenheimer-Blue-Diamond-7197-3.aspx

[6] Cecilia J. “’Oppenheimer Blue’ diamond sets new record, fetches $57 million”. Mining. http://www.mining.com/oppenheimer-blue-diamond-sets-new-record-fetches-57-million/

[7] Merrit K. “’Pink Star’ Diamond Sells for $71 Million, Smashing Auction Record”. NPR. http://www.npr.org/sections/thetwo-way/2017/04/05/522739361/pink-star-diamond-sells-for-71-million-smashing-auction-record

The Rarity of Tanzanite

Jan 17, 2018

By Robert Gessner BSc GG, Gessner Gems
Reprinted with express permission from the author

In 1967, blue-violet crystals of the mine- species, zoisite, were discovered south of Mount Kilimanjaro in northeast Tanzania. The host rocks of the discovery, which are orders of magnitude older than Africa’s highest mountain, form part of the Lelatema Mountains which are located very near the town of Merelani. In 1968, Henry Platt of Tiffany & Co. christened the new and remarkably beautiful zoisite gem,Tanzanite, to honor its single-source discovery in Tanzania. The 50th anniversary of its discovery is marked in 2017 and is the most notable and exciting event of the gemstone industry of the 20th Century.

Bright blue tanzanite crystals are rarely found in sharp crystals like this. Orthorhombic crystal termination seen on the blue axis of a Tanzanite crystal. Robert Gessner Photo.

What makes this gemstone even more interesting and unique, and sets this beautiful stone apart from all others, is its remarkable rarity. Crucial in understanding its rarity is that this stone is the only one (or, one of the few) that evolved from a collector’s stone, only available to a few, to a commercially available stone. But this is only for a limited time: our generation. Tanzanite is found and mined in only one place on earth: a 7 square km area that outcrops near the town of Merelani in northeast Tanzania.

View of Mount Kilimanjaro from Block C overlooking Block D. Robert Gessner Photo

It is found in only one place on earth because of a very complex and unique set of geological conditions that came together during the breakup of the supercontinent, Gondwana, between 1.5 and 2.5 billion years ago. My intention is to not get too technical, but the geological origins are so interesting, and for me, the start of the story that I want to share, creating excitement for current and future owners and highlighting the fact that this gemstone is only available for a single generation: our generation.

The most striking feature of Tanzanite is its color. Or colors. It is a pleochroic gemstone. More specifically, a trichroic gemstone simply means that it naturally displays a different color in each direction, or on each axis.The fine crystals display intense, well-saturated and deep colors. The color-causing element (or chromophore) of Tanzanite is vanadium. Think of it the same as the element chromium giving Rubies their red color. The vanadium is responsible for the blue-violet color in Tanzanite. If any geological history needs to be mentioned, it is this because the rare availability of the vanadium during Tanzanite’s formation is what ultimately is responsible for what makes this gemstone so beautiful, desirable, and popular.

Tanzanite crystal in a pocket in Bravo Shaft. Robert Gessner Photo.

The vanadium is a trace element that came from the organic (tree and plant) material that was deposited with eroded silica-rich sands and calcium-rich (shell and ocean-life) material in a deltaic/shallow sea environment over millions of years during the gradual break up of Gondwana.This accumulation of layers was subsequently buried and metamorphosed at high temperatures and pressures.The organic material became graphite, the silica-rich sands became the schist and gneiss, and the calcium-rich material became dolomite (an impure marble). All these rocks are seen in the deposit.

At 500 million years, a geological event resulted in the crystallization of Tanzanite. Erosion on the surface on the earth and the natural upliftment of continental crust (in respect to the denser and heavier oceanic crust) brought this deposit to the earth’s surface where Tanzanite was found for the first time in 1967.

Pocket containing Tanzanite in Bravo Shaft. Robert Gessner Photo

The transition from a collector’s stone to being commercially available started in earnest in the late 1990s when the Tanzanian government started adequately regulating the deposit by subdividing the 7-kilometer section into Blocks A, B, C, D, and D-Extension, respectively, and granting mining licenses to companies and individuals at different levels of investment ability. Block C, the largest 2 km 2 of the 7 km 2 , was awarded to African Gem Resources Limited (Afgem), a private South African company, after winning the tender in 1998. Only in the early 2000s did the company start investing heavily in geology and mining as production was decreasing and becoming more haphazard after an initial and significant bulk sample that raised millions of dollars for Afgem.

The investment in geology and mining resulted in a better understanding of the deposit’s geology and the Tanzanite-bearing structures, and in turn increased the company’s production. The increased production resulted in increased revenues that were put back into the mining. More shafts were sunk, more mining faces were created, and from a geo - logical point of view, more geology was exposed on the sidewalls. With all this work, a geological model was created, as well as an understanding that was never in place before. Another result was production areas could now be proactively planned as opposed to a history of reactive mining. Essentially, we were able to get the mining into the right places. As a result, from 2005–6, production from the company improved to more consistent commercial volumes. It must be noted that at no point can a geologist predict the gemstone; we are always predicting the geology in which the gems are formed. From mid-2000, the consistent production from the mine was a result of having the mining faces in the right areas. If one face was not producing, another one was.

In late 2004, Afgem become a publically traded company, TanzaniteOne Mining Limited (TanzaniteOne), and listed on the London Alternative Market (AIM).

Self-portrait taken August 2005 from the largest pocket of Tanzanite I have seen in the deposit! Robert Gessner Photo.

Large-scale mining operations generate not only more production volume, but also more volumes of all grades, more consistently. As a result, a master grading set was created. For the first time, rough Tanzanite could be parceled for size, colour and quality to its sightholders. By definition, this system of product presentation for rough sales could only work with regular and good volumes of production from the mine. This was a direct result of the size of the deposit being professionally mined, with regular production and future exploration.

Afgem initially, but then TanzaniteOne, took a collector’s gemstone to one that became commercially available around the world. But the story does not end there. Because it is commercially available does not mean that Tanzanite is any less rare than it originally was. It just became accessible to everyone; but only for a limited time: our lifetime. Found for the first time in 1967, it can be estimated that the gemstone will no longer be accessible, particularly commercially, within a single generation of its discovery. The most common understanding of this is that the deposit gets physically exhausted (mined out), but the actual concept is that the costs to mine become too high versus the income from sales (i.e., the gemstones are still in the ground but are physically too deep to mine–too expensive). This factor highlights its generational rarity, which the current market and value of Tanzanite do not indicate. The market and consumers think that because there are high volumes of Tanzanite available at the moment this will continue; but this not the case.

The current prices of Tanzanite, particularly at the wholesale level, are actually too low; too low for how rare the gemstone is, and too low for future mining. The amount of Tanzanite on the market currently should be seen as a bubble and temporary; it will not continue. There has been a lot of recent supply due to many miners being in the right areas and producing, with this product subsequently making it to the wholesale market. This is the reason for the low wholesale prices, but with the mines getting deeper, and the natural pocket effect of Tanzanite, this will not continue. The reality is that the deeper the mines get, the more expensive it will be to mine. For future years of supply, the wholesale prices need to increase.

Tanzanite crystal in Main Shaft. Robert Gessner Photo.

Single generation is a phase coupled with Tanzanite since its marketing in the 2000s, and this itself, evokes its own romance, beauty and rarity. Trying to tie the availability to a number of years should not be the discussion point, and according to me, less importance and significance should be given to it. The history of the talk of only available for another 10 years, or 15 years ties in to large-scale public mining at companies attempting to quantify its resource for value purposes and investment, which the previous owners in the 2000s took to the market to create desire and indicate its rarity. There are too many factors that affect a number like this, so it should only be seen as guide and less importance should be given to it. No one asks how many years are left of the Colombian emerald deposit, or the Burmese Ruby deposit. It cannot be defined, so why should the Tanzania Tanzanite deposit be defined? The famous Brazilian Paraiba Tourmaline and Russian Demantoid Garnet deposits are now mined out, and very little or no material is available anymore; nothing significant in recent years anyway. Old stock or old mined material that do become available command extremely high prices today. We can only look back and say that we should have bought then. This will be the same for Tanzanite. Buy now, as the prices are low–for the moment. All gemologists know that Tanzanite is trichroic. It is also part of the orthorhombic crystal system. As Tanzanite extracted from the earth is often in its perfect rectangular crystal shape, it is easy to see its trichroism (meaning you can see a color on each axis, or side of the gemstone). These natural rough crystals can show either a 3-colour trichoism combination of blue, violet, and brown (combination of red/yellow/green) or a 3-colour trichroism combination of blue, violet, and violet (so two violet axes, or sides), respectively. The reason for the two combinations of trichroism is due to natural (in the ground) heating that a percentage of the natural crystals were locally subjected to. The natural heating has removed the original red/yellow/green on the “brown” axis to colorless, and so the (second) violet color is seen. Technically, this has been achieved by an intervalance charge transfer during heating of Ti3 + to Ti4 +, which is colorless. [As all chemical equations require balance, the second change is a slightly stronger blue-violet (so the V4 + to V3 +). The colour change due to heating is a stable change. As this heating takes place naturally, it is impossible to distinguish between post-extraction (or by man). The result of this means that there are only two realities to label a tanzanite gemstone: no heat or no heat treatment by man. The first is that the gemstone in question displays its blue, violet, and brown trichroism, and the second condition is that a strict and traceable provenance of no heating by man exists of a blue, violet, and violet trichroism gemstone directly from the earth, through the trade to the wholesaler/retailer.

Trichroic pleochroism of Tanzanite under incandescent light. Robert Gessner Photo.

This second condition may be a potential option but is strictly tied to a person’s honesty, because it is scientifically impossible to prove. Another wonderful and valuable characteristic of Tanzanite is that there is only natural Tanzanite in existence. Man cannot create Tanzanite due to its unique formation in the earth and its chemistry. Imitations, by definition any material that looks like a natural gem and is used in its place, do exist but any trained gemologist would be able to confirm whether it’s natural or not with a few simple gemological tests. Tanzanite is a rare gemstone with both a remarkably unique geological history and a success story in the jewelry market and in our homes; a story of rarity that needs to be shared; a story that is hidden within each piece of Tanzanite worn by its owners.

By Robert Gessner BSc GG,Gessner Gems

Article as published in AGTA Prism, Volume 4, 2017, viewable online here.

Article adapted from its original as it appeared in the GemGuide, Gem Market News, November/December, Volume 36, Issue 6 published by Gemworld International.


About the Author: I am geologist by profession having completed my BSc Degree in Geology at the University of Cape Town (UCT), South Africa, in 2002, and completed my post-graduate Honors Degree at the University of Stellenbosch, South Africa, in 2004. My first colored gemstone industry opportunity was in Tanzania in 2003, which has become my specialization and career. I have over 13 years of colored gemstone geology and mining experience in East Africa working specifically with Tanzanite, Tsavorite, Zambian Emerald. In 2016, I graduated as a Graduate Gemologist (GG) from the GIA in Carlsbad, USA. Today, I am based in Los Angeles, and have my own business offering consulting, training and gemstone sourcing. www.gessnergems.com

The New iRocks.com

Jan 8, 2018

Mineral lovers-

We're excited to bring a new iRocks.com experience to the web with improved features, faster speeds, and mobile responsive design for mobile and tablet users.

Start off by registering using the button in the top right.

Once you finish creating your account and logging in, take advantage of the new wishlist feature (click the purple heart when you're browsing specimens) so you can create your own virtual collection, track specimens to see if they go on sale, and easily access your favorite saved minerals.

If you're looking for a good place to start browsing our minerals for sale, visit our galleries of newly added specimens or visit our themed galleries.

If you are looking for a specific mineral, our search engine can narrow down the hunt by species, locality, size, and more!

As always, if you're looking for a specific specimen that doesn't appear online, don't hesitate to get in touch with us at info@irocks.com, since we have a wide range of inventory here in our new headquarters in Dallas.

Rock on, Mineral Lovers!

The New Arkenstone Gallery

Jan 4, 2018

2017 brought a lot of changes to The Arkenstone. We added a new full-time employee (hi Tom Campbell!), purchased several new collections (have you explored the Kay Robertson selections?), but most significantly, we moved to our new headquarters featuring over 7,000 square feet of mineral display space and plenty of other new features for new enthusiasts and long-time mineral lovers.

Lobby Entrance

Lobby at The Arkenstone Gallery of Fine Minerals Large decorative pieces, important lapidary art (lapis), and amethyst are featured in the front lobby.
A pair of backlit Persian onyx slabs totaling 2,200 pounds and nearly 6,000 pounds of reclaimed 150-yr old Northeastern red oak timbers line the mine shaft "Portal" into the gallery.

The Collector Gallery

Display cases of fine minerals in the Wood Room
Fine minerals from around the world are for sale in the gallery.

Gem & Jewelry Salon

Our new Gem & Jewelry Salon is ready for visiting jewelers for events and trunk shows.

The Jewelry Salon connects natural crystals and the wearable art that results.
Paula Crevoshay displayed her impressive jewels at our Grand Opening

The Design Showroom

If you're looking for larger home or office accents, visit our Design Showroom.

The Museum Gallery

The Trophy Room

Sleek black pedestals display large museum-sized specimens.

Sleek black pedestals display top collector specimens.

The Book Store

Add to your library with our selection of literature, including rare and out-of-print volumes, periodical issues, DVDs, and more. Looking for something specific? E-mail us at info@iRocks.com.

If you're in the Dallas area, send us an e-mail to schedule your private visit to info@iRocks.com.

Tips for Buying Rare Rocks and Minerals Online

Dec 23, 2017

A major part of being a mineral collector is building relationships with vendors and hunting down the best specimens. Chances are you’ll want to grow your collection over time, and there are plenty of online vendors with vast collections to choose from. With so many options, how do you know which online vendors to focus on?

Here are a few tips to help you find a great online vendor:

Tip #1: Stay Informed About Your Specimens

Before deciding on a vendor, it’s important to have a clear idea about the rare rocks and minerals that you want to add to your collection. There are many species to choose from, each with unique properties, colors and luster that all work into its price.

If you’re unsure about what rare rocks and minerals you want to start your collection, look at complete exhibits and make a list of species that capture your interest. You’re likely to trade and upgrade your collection overtime, so feel free to experiment with your interest. For example, you may start your collection with a type of quartz crystal and move into rarer species months or years down the road.

Chinese minerals from Mount Xuebaoding in Sichuan Province often have a deep orange color. Gemmy clear quartz and muscovite accent an orange scheelite crystal.



Tip #2: Look at the Display

When shopping online, the best vendors will have a professionally taken photograph for each of their specimens. You’ll want to be weary of vendors who use generic photographs, as mineral colors can vary depending on lighting.

Take into consideration how the specimen will fit into your existing display space. If you’re using a glass cabinet, use the photograph provided as a reference to see if you like how well it sits with your collection.

Keep in mind that you’re free to ask the vendor for other photographs of the piece for sale. For example, crystalline structures can come in many shapes and clusters. Looking at the specimen from different angles can help you determine if it fits with your collection.

In fine mineral photography, it's often necessary to take many pictures in your quest to produce the best fine mineral photographs. Sometimes photos showing multiple angles of a specimen help determine if the piece is a right fit.


Tip #3: Be Intentional about Building Relationships with Vendors

After researching species and are settling on a budget, you’ll be more informed and comfortable shopping for your collection. You can shop from an online catalog, specialized vendors, a club’s collection or an exhibit.

Well-established vendors will have variety in the specimens available for you to choose from. When getting to know an online vendor, look for their archive of specimens and any published work. This will give you an idea of the types of species that they specialize in, helping you with price bargaining.

The key is to build relationships with these vendors. Over time, they’ll add new species to their collections and you’ll be on the shortlist of people to contact before specimens go on sale.

Tip #4: Look for Detailed Specimen Descriptions

The single most important feature in any online sale is a detailed description about the specimen. Information about a specimen's size, properties, condition, and origin should all be available to the customer.

For example, benitoite is a rare barium titanium silicate mineral that has grown in popularity for its deep blue, purplish colors. Authentic specimens of benitoite are only found in the mines of San Benito County, California. Knowing where a specimen comes from can have a major influence over its described authenticity and price.

Benitoite crystal from Dallas Gem Mine area in San Benito, California. Copyright The Arkenstone, Joe Budd Photo.


Tip #5: Know Where You’re Shipping From

Understand that rare rocks and minerals can get heavy and shipping prices can go up, depending on where it’s being shipped from. Keep in mind that exceptionally fragile specimens may find it more challenging to ship, and the vendor may recommend that you pick it up in person.

Some vendors will go to various mineral shows, showing their collections in exhibits and galleries. Keep track of vendors who are hitting the road and inquire about picking up your specimens along their travels. The Arkenstone is flexible with bringing specimens for delivery at shows in Denver, Tucson, Munich, and even China! Plus we host a semi-annual San Francisco Road Show.

There are many great online vendors that sell expansive collections of rare rocks and minerals. The hobby is also made of many close communities and clubs where rockhounds come together and talk about each other’s collections. Ask your fellow club members or rare rock and mineral collecting clubs about any vendors that they recommend.


Our favorite learning opportunity is the annual Dallas Mineral Collecting Symposium, sponsored by The Arkenstone and friends. The symposium will feature an expert speaker series about word-famous collections and also provide opportunities to mingle with top mineral dealers, collectors and enthusiasts.

Don’t forget to check our listings for our other shows. The Arkenstone is proud to offer specimens in many displays around the world.


Art Soregaroli: October 19, 2017

Oct 20, 2017

An introduction of Dr. Art Soregaroli's Fine Mineral CollectionWe learned with great sadness of the passing of Art Soregaroli on October 19, 2017. The Arkenstone acquired his collection several years ago, and he took a few moments to share some of his thoughts with us. They are shared here, below, along with a personal note from Peter Megaw.

"The mineral specimens you see here now have been liberated from my collection of the past 6+ decades, rescued from my favoured lair in the recesses of a Vancouver home sold and slated for demolition. This move has forced my hand to make the difficult decision to find new homes for these many precious friends I have spent a lifetime collecting.

From my early youth, collecting agates and arrowheads in rural Iowa quarries and stream beds, to kicking up rocks with pack mules in Idaho as a graduate student, to my doctoral work at the University of British Columbia in Canada (where I’ve made my home this past half-century), and throughout the career that followed in exploring the world for precious metals and commodities to mine, I’ve rarely met a specimen I didn’t like. And, as much as each specimen holds a special place in my heart, I suppose what I am most grateful for in having been captivated by this esoteric hobby is the people I have met who share my passion for minerals and geology, and the many friendships that have been forged at the rock-face, at the bargaining table, with the Mineralogical Record and at Tucson, and in peering through the glass of a display case.

So, now, as I continue my journey, I hope these specimens will continue theirs and bring joy and gratification to the ardent mineral collectors fortunate enough to make them their own."

-Dr. Art Soregaroli


"Sadly, Art passed away peacefully surrounded by family on October 19, 2017.  With his passing the mineral world lost a great geologist/mineral scientist, staunch friend and true gentleman - the outpouring of tributes from those whose lives he touched has been impressive.  His work getting the Pinch Collection to the Canadian Museum of Nature was mentioned by many, as was his work with the Brittania Mine mining museum near his home in British Columbia, and his manifold contributions to mineral symposia...especially the Pacific Northwest FM Symposium that closed just 2 days before his passing. Jodi Fabre noted that Art was single-handedly responsible for guiding the famous Panasquiera Mine in Portugal back into the black so that could not only thrive as a metals mine, but continue to produce quantities of excellent specimens to this day.

Those who wish to express condolences to the family can do so to his beloved wife Rosalie remembering.art@gmail.com.  She will share them with daughter Carla, son and daughter in law Brian and Michelle and the grandchildren he doted on so fondly.

Those who wish to honor his memory can do so by visiting/supporting the Canadian Museum of Nature, the Brittania Mine Museum or attending next year's Pacific Northwest FM Symposium.  Adding a specimen from Panasquiera to your collection would work too!"

- Dr. Peter Megaw


Peter Megaw's original tribute (published in 2015) is available here.

Have stories about Art that you'd like to share? E-mail them to info@iRocks.com, and we will happily add them here.


View Art Soregaroli's Collection