Won't Be Fooled Again: Big Differences between Gold and Pyrite

May 26, 2017

Pyrite is a compound mineral of iron and sulfur. Yet, to the untrained eye, pyrite looks nearly identical to the chemical element gold. There have been countless stories throughout history of grand explorers being fooled by pyrite – earning it the title of “fools’ gold”.

Peru on quartz from Peru bears strong differences when compared to gold specimens. Peru is famous for the remarkable pyrite crystal formations found there.

One such explorer was Sir Martin Frosbisher, an English Privateer, who was one of the first miners in Canada.[1] He found what he suspected was gold on Kodlunarn Island on his first voyage to the New World and shipped 1,400 tons to Europe. However, when the mineral made it to Dartford to be smelted, they learned that the rocks were made of pyrite.

The colonists at Jamestown were also fooled when they rowed up the Potamac river.[2] The sands of the river were glistening with golden pieces, creating a frenzy for Captain Newport and his crew. Believing they had struck it big, Captain Newport shipped 1,100 tons of the shiny sand to England, where it was later found to be pyrite.

How to Spot the Difference

Gold and pyrite may seem similar because of their appearance, but the reality couldn’t be further from the truth. There are distinct differences between gold and pyrite that are discernable with the human eye. Some of the differences are in their:

  1. Density
  2. Color
  3. Hardness

At first glance, spotting the differences between gold and pyrite can be challenging. With enough practice and a sharp eye, you won’t be fooled with “fool’s gold”.

  1. Difference in Densities

Prospectors knew that gold and pyrite behaved differently in a sifting pan because of their densities. Gold in its purest form has a density of 19.3 grams per-cubic centimeter and will tend settle at the bottom of a sifting pan full of sand.[3] Pyrite is a compound of chemicals with a density of 4.8 grams per-cubic centimeters and will rattle around the pan more loosely than gold.[4]

  1. Difference in Color

While both gold and pyrite both shimmer in the sun, pyrite takes on an exaggerated shininess like polished brass because of its metallic luster. Gold also has a metallic luster, but it retains a solid color in direct light better than pyrite. In ideal conditions, pyrite will form isometric crystals with equal faces. This allows for the mineral to shine better than gold, whose malleable form releases less shines.

  1. Difference in Hardness

The most distinct difference between gold and pyrite is in their hardness. Gold is one of the most malleable and ductile metals on earth. The mineral can take any shape when flattened and is easily scratched with a pocket knife.

Pyrite is noticeably harder with a hardness of 6 on Mohs scale while gold is at a 3. Pyrite is not easily scratched and will shatter like glass if struck by a hammer. In fact, if you take a piece of copper and scratch it with a piece of pyrite, it will a scratch on the copper. If you repeat the test with gold instead of pyrite, the gold will be scratched.

Spotting the differences between gold and pyrite takes practice – but a little know-how will take you a long way. Next time you’re digging for treasure and you’ve found a golden nugget, you’ll be ready with the on-site tools needed to tell the difference.

GOLD Examples


PYRITE Examples


Want to see the difference between gold and pyrite in-person? 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] Dana H. “Famous Fools for Fool’s Gold”. Scientific American. https://blogs.scientificamerican.com/rosetta-stones/famous-fools-for-fool-8217-s-gold/

[2] Ibid.

[3] “How heavy is a gold bar?”. Elmhurst College. http://chemistry.elmhurst.edu/vchembook/125Adensitygold.html

[4] “Pyrite”. Mindat. https://www.mindat.org/min-3314.html

Chinese Game Show Promoting Minerals

May 21, 2017

By Dr. Robert Lavinsky and Tom Moore

We recently received a link to an hour-long episode of a Chinese game show (in Chinese, of course) in which a panel of minor celebrities and some experts competes to see who has the most knowledge regarding various objects important in Chinese culture. Objects may include antiquities, carvings, ceramics, bronzes, paintings, calligraphy and, especially, jade -- and also what their retail value might be. Sounds like fun, especially in this case, as they were faced with having to price some very fine Chinese mineral specimens!

The popular show is produced by CCTV (the government-run television station seen by all Chinese households. The featured item in question is a large specimen of inesite from Fengjiashan mine in Hubei Province. The host proceeds to engage the guests in a discussion about "rocks," showing them a range of photos of beautiful specimens. At the end he has them gasping in surprise at the high values associated. This seems to be part of a gradual educational effort by the Government, in concert with the museum building initiative reported in the
January-February 2013 China Supplement, available for reading online (free!) here.

Watch the clip online!

Summer Fun for Rockhound Kids!

May 5, 2017

Summer is flying by, but there's still plenty of time to plan mineral activities for kids.

The summer months are prime season for rock and mineral collecting – but that doesn't mean the professionals should get to have all the fun! In fact, there are many rock and mineral collecting camps which focus on encouraging the development of younger rockhounds.

Youngsters who are excited about pursuing their interest in geology and gemology may benefit greatly from attending a summer camp or field expedition geared towards their age group – and may find themselves gaining the foundational skills and knowledge they need to nurture a lifelong hobby or career.

At iRocks, mineral collecting is not just our business – it's our passion! And we strive to fuel the flames of those who seek to take their interest in rock and mineral collecting to a whole new level – no matter their age. That's why we've decided to bring you these tips for finding the right summer learning program for your young rockhound. We hope your whole family benefits!


  • Start locally. Many museums and science centers offer incredible summer camps for youngsters interested in the earth sciences. Local collectors clubs and geology-focused attractions may also be a good bet – so make sure to check out their summer offerings and event schedules!
  • Keep it age-appropriate. There are many types of rock and mineral collecting camps, but the one you choose should depend on the age, independence, and skill level of your youngster. Younger children may be content with an exploratory day program, such as those hosted by your local museum or science center – whereas teens and older youth may be more engaged by a field expedition geared towards their age group.A helpful tip: The online search tools found atKidsCamps or Activity Hero can help you locate independent camps or programs located in your area, and then narrow selections by program type and age group.
  • Search by specialty. Some programs choose a specific focus for their youth programs, such as this Colorado program which focuses on rock and mineral collection in the vicinity of prehistoric evidence and fossils, or GIA's GemKids, which focuses on gemology.If your youngster has a particular interest or area of geology which holds special fascination, try searching for that particular focus or specialty, to see what arises.
  • Get out and about. Consider taking a Geology Adventure , or planning a trip to the closest State Park or National Park for some geology-focused exploration. Contacting your local recreational authority can also be helpful, for those who have interest in a local field expedition.
  • DIY Rock Camp. Unable to find a summer program in your area? Consider hosting a do-it-yourself rock and mineral day camp for your youngster, and a few friends. You can find some simple, kid-appropriate geology experiments and rock and mineral-related projects at com or Science for Kids – or contact your local science center or university to arrange an exploratory field trip, or guided tour of their geological exhibits.

We're confident that with just a little digging, you'll be sure to find an array of programs and adventures designed just for your amateur rock and mineral collector!

Prefer to explore our online collection of gems and minerals? Click here.

How to Build a Great Mineral Collection on a Budget! (Guest Post by Phil Persson)

Apr 24, 2017

By Phil Persson

Mineral collecting is one of the greatest hobbies in the world. I often find that the word ‘hobby’ seems inadequate for what is a lifelong, all-consuming passion for many serious mineral collectors. For as many reasons as there are for collecting minerals, there are ways of acquiring them. Some people are die-hard field collectors and their collections reflect many hundreds of hours swinging hammers and chiseling outcrops, traveling mine-to-mine in search of fine mineral specimens to add to their cabinet. Others attend club meetings, field trips, local rock swaps, and silent auctions where they might spend $10 or perhaps $20 on a modest specimen for their collection. For such collectors, the enjoyment of the hobby may be largely related to the social aspects- the meetings, the club shows; the myriad ways in which we engage and participate with our tight-knit community of fellow rock nuts. For others still, the thrill is in the hunt for a true ‘trophy specimen’ whose value can easily climb into the tens or hundreds of thousands of dollars, and whose acquisition may feel more like an initiation into the secretive and zealous world of high-end mineral trading. Regardless of how and why we collect minerals, with the exception of the field collecting purist, we all want the same thing- to acquire as nice of a specimen for our collections as we can for the least amount of money. For those blessed with the financial means to acquire whatever they desire, the following advice many not be particularly important, but I suspect that most collectors reading this have asked themselves at one point how they can improve their collection and still stay within their budget. I offer here a few bits of advice gleaned from 20+ years of collecting and selling minerals, most of the time on a fairly modest student or self-employed budget.

  • Be mobile. The late Rock Currier, a legend of 20th century mineral dealing and collecting, once remarked that finding good minerals was something akin to the random searches ants will do for food, where they leave the anthill and seemingly wander in circles until something tasty is found. Compared to having lots of disposable income, Rock opined, the ability to do such ‘random searches’ was probably more important in locating and acquiring good mineral specimens. This use to mean that one had to have a lifestyle akin to Rock’s: traveling the world from far-flung recently-overturned dictatorships to musty museums in some forgotten corner of Eastern Europe seeking minerals for sale or trade. In the internet era, however, mobility has taken on a new meaning that is not always physical. We now are connected as collectors more than we have ever been through portals like Mindat.org, the Friends of Minerals Forums, and social media platforms like Facebook (follow The Arkenstone and MineralAuctions.com!) and Twitter. I have acquired many good minerals, particularly from defunct ‘classic’ locales in far-away countries which are difficult to acquire here in the USA, through ‘friends’ on Facebook whom I have connected with via the larger mineral community online. While I know few of these people ‘in person’, we have built relationships online which have enabled advantageous trades or purchases where I was able to get minerals within my budget which I would be unlikely to find at a US show or other venue.Physical mobility in acquiring good minerals on a budget is still important, however. This does not have to mean expensive airfare and uncertain safety in some distant corner of the world- just look at the annual Tucson gem and mineral show. While visiting this event, I have sometimes taken a day trip down to the world-famous locality of Bisbee, Arizona, arguably the most important in Arizona and one of the major mineral locales of the United States. While the mines are shuttered and the town now resembles more an artist community and tourist destination than mineral mecca, good minerals at reasonable prices can still be found for the discerning collector at local rock shops and museums. I have added several very fine Bisbee crystallized native copper specimens to my collection in this manner which would have probably been outside of my budget otherwise.


Freemasons meeting in the Copper Queen Mine, Bisbee, Arizona Ca. 1897. Though many important specimen-producing mines and districts such as this have been closed for many years, they are still world a visit and may occasionally yield great minerals for sale at fair prices. (Photo © Library of Congress) 
  • Be Knowledgeable. This may seem self-evident or at worst patronizing to say, but knowledge truly is power. Nobody, even the most seasoned, well-traveled dealer or Ivy League mineralogy PhD can know everything about minerals, so it’s best to find what really gets you excited and specialize. Perhaps that specialization is regional - after having lived in Colorado for 10+ years I now enjoy collecting and learning about minerals from my adopted state. One could also specialize in one mineral - numerous incredible collections of just quartz, calcite or perhaps tourmaline have been assembled. Chemistry is another great way to build an important specialized collection, whether it be silicates or sulfides. Some people just love all minerals- I confess I am part of this group. For us, knowledge is acquired in bits and pieces, but constantly, and always about something different depending on what we’re been able to buy or collect. Again, the internet age has democratized the education process in new and exciting ways. While an advanced degree in geosciences and a large library of mineral books, journals and other publications might have been the traditional avenue to become a ‘mineral connoisseur’, this same knowledge can now be acquired online if one is patient and committed. I know of a number people within the mineral community whose ‘formal education’ may have stopped after high school but whom possess a breadth and depth of knowledge on minerals which most PhD museum curators would envy. The pursuit of knowledge is not just pedantic either- the more you know about minerals, the more you are likely to recognize a great deal hiding under a mineral dealer or collection heir’s nose, or be able to confidently purchase an unlabeled specimen at a good price which less experienced collectors might shy away from because you know the locality and provenance.
Fine group of golden calcite crystals on sphalerite from the Elmwood Mine, Tennessee USA ~38 cm across, acquired by the author in 2015 while volunteering to help set up a local museum sale- the specimen was part of the sale materials.
  • Be Fair. The mineral community is exactly that- a group of people whose shared interests, passions and obsessions unite them under a common banner. More so than collecting fine art, or stamps, or baseball cards, I would argue, mineral collectors are tight-knit and often nurturing and supportive of each other’s growth as collectors and scientists. As members of a community many in the ‘general public’ would find strange or even pointless, we have developed a certain ‘outsider perspective’ which we combat using the strength of our own community. As such, fairness and honesty are critical in being able to acquire good minerals on a budget. The cynic might argue here that the previous suggestion of ‘recognizing a great deal hidden under a dealer or collection heir’s nose’ requires a certain dishonesty or swindling, but I believe that so long as the collector or dealer operates with integrity, ‘getting a bargain’ does not have to equal ‘ripping someone off.’ Yes, scour the world for former rockshops-turned-garage sales piled with flats in someone’s backyard holding treasures only you can identify. Yes, develop relationships with older or more experienced collectors not only because you can absorb their knowledge but because our time on earth is finite and one day you may be able to acquire those minerals for your own collection. Just do so fairly. The mineral community is surprisingly small for how global it has become, and the flipside to the interconnectedness of our community is that when you lie, steal, or treat people unfairly, your reputation will undoubtedly proceed you. I have been amazed at how when I meet someone in the mineral world and have to mention only the most peripheral details of a certain individual before the person I’m speaking with knows exactly which ‘bad apple’ I’m talking about.
Large group of native copper crystals from the New Cornelia Mine, Ajo, Arizona, 16.5 cm across; acquired by the author from the heirs to a small collection whose gemstone portion a friend had helped appraise.
  • Be Creative. This is perhaps the most difficult piece of advice to give succinctly. For those with lots of money, the flow of ‘good rocks’ usually points towards them anyways, and creativity may revolve more around what to acquire and when versus how. For the rest of us the ‘how’ question is usually central, and revolves around money most of the time. Today, however, between the internet, mineral shows, clubs, museums and events across the world, and our increasingly globalized society, there are many ways to acquire good minerals at modest prices. Cultivating relationships is crucial. Humans interaction is driven primarily by psychology and collecting minerals is no different. Gaining trust and building rapport, while perhaps not resulting in immediate gains to your collection, are important in acquiring good minerals at prices you may not be able to find at a show or online. Browsing venues like eBay, Craigslist, and local garage sale listings may also not yield immediate returns to your collection, but most of us who have been collecting for some years have at least one story of a great “sleeper” specimen or collection acquired in this way. Finally, consider being a dealer yourself. No, I don’t mean quitting your ‘day job’ (though some have ended up doing this in the end) and hustling rocks for your daily bread. I consider a dealer to be anyone who has sold a specimen at some point in their life, which includes most of us.

Buying ‘in bulk’ not only can get you a deal on an individual specimen you want for your collection which might be out of your reach otherwise, it can establish valuable relationships with suppliers and collectors that will pay for themselves many times over in the future. Selling minerals can be a great way to finance your future acquisitions, as well as connect on a new level with the mineral community.  Finally, be creative with how you ‘stretch your dollar.’ Perhaps you really want a good Sweet Home rhodochrosite for your collection and are dismayed to find that even a thumbnail which looks like it took a trip through the rock tumbler will now run you a thousand dollars or more. But, you have a friend who has a friend who has some Colorado minerals for sale. They are only a small part of a once great collection she has which she has sold to various dealers over the years.  You meet at a mineral show and strike up a friendly conversation that leads to a casual friendship. One day, she invites you over to her house and shows you a flat of minerals she has- some pyrites, a calcite or two, some nice thumbnails, and then a very fine Sweet Home rhodochrosite. Bingo! She discloses she wants a fairly large sum of money for the specimen, but after researching the locality extensively, you are now knowledgeable enough to know it is a good deal and one you are unlikely to find again. You take out a small loan from a friend to acquire the lot from her, sell the other specimens, pay back your friend, and the Rhodo is now yours for a modest end-cost. A lot of work, you may say, but to myself and many others this is part of the fun of the mineral world, the ways we build community and find clever and creative ways to add to our never-ending collections.

“De Re Metallica” by Agricola, published in 1556, at the time the leading source of knowledge on minerals and mining. While texts like this are still critical in building a knowledge of minerals, the internet has become just as important. (Photo © Drek Gee/Buffalo News)

In closing, I firmly believe we live in the “Golden Age” of mineral collecting. Never before has the pace of mining and discovery been so synchronized with ease-of-access and the interconnectedness which defines our global mineral community. Yes, prices for fine minerals, particularly at the top of the spectrum, have risen dramatically over recent decades, but this is turn has popularized collecting to a new group of privileged people who in turn support and justify specimen mining operations and specimen recovery from active mines around the world. This may be one facet of life where ‘trickle-down economics’ actually has some effect. One can visit a mineral show in Tucson, Denver or Munich and in an afternoon be transported around the world to what is new (sometimes very new) in the mineral world, and often have the luxury or ‘price comparison’ between dozens of dealers offering specimens from the same find or pocket until you find the specimen that speaks to your aesthetics and your budget. Most of all, stay inspired, stay excited, and know that staying within your budget as a collector does NOT mean staying at the same level of minerals or collecting!


Special thanks to Phil Persson for giving us permission to post this great article! 

Kay Robertson: A Treasure in the Mineral Collecting

Apr 13, 2017

- Memories from Dr. Robert Lavinsky

Kay Robertson collected from the age of 8 for nearly 9 decades. Cases of fine minerals are featured decor in Kay Robertson's home.

I will say that, in a world full of characters and crazy collectors, Kay stands out as one of the most passionate collectors I have had the privilege to know - to this day, at 97, she is as passionate about minerals and the glory of knowledge that comes from them, as she must have been 90 years ago when she started.

Kay is a collector from another era of mineral collecting, when thousands and thousands of old classics were recycling from old collections in Europe, and the mineral collecting market (and prices) was in its infancy. Many mineral collectors were academics, or affiliated with museums, and most collectors pursued minerals of their local area. She was hooked in 1928 at the age of 8 and collected for over 80 years - always a purist, collecting for the enjoyment and intellectual sport of it, with no regard to minerals as a longterm investment (though they came to be, anyways!). She pursued mineral collecting as a stress release from her world of high end art dealing in Europe and the USA, never spending the money on minerals that she spent on old tapestries and textiles, but perhaps spending more time. Her collection eventually ballooned to 13000 specimens at the time I bought it (she is 97 now). Until the 1990s, she forced herself to keep to collecting as a fun hobby, not an investment, by setting a price limit to what she would spend ($35 per piece went far in 1950; not so far by 1990). Despite her discipline, friends sometimes found ways to evade her price radar by giving her suspiciously good deals or trading to her benefit. I see many specimens from Scott Williams and Walt Lidstrom in her collection that really should have been priced more than she paid. Peter Embrey of the British Museum seems to have gone out of his way to give her oddly generous "house gifts" or trades of $5000-plus specimens on his visits to her home in Los Angeles over the years (including a number of old classics like German Mimetites and a Kongsberg silver). She once so desired a specimen of samsonite, lacking a good one in her otherwise comprehensive German suite, that Embrey trimmed off a 1 cm crystallized piece from the holotype specimen in the BMNH, and gave it to her as a gift (I have now repatriated this piece back to a friend in Germany where it belongs, she was happy to hear).

The Arkenstone's Dr. Robert Lavinsky met with collector Kay Robertson with a serious note to take care of many of the precious old labels accompanying her specimens. Kay Robertson made sure Dr. Rob Lavinsky was given a stern warning to take care of her precious minerals and the historic labels that accompany them.

She still has, to this day, the first major specimen of her collection, a remarkable German Sylvite specimen given to her by a Prince of some kind, when she was 8 years old and living in a grand old mansion while her father was the German diplomat to Venice. It sits in her living room where she sees it every day. It started a love of German and European classics that lasted her whole career, and she has built a trove of the kinds of rare old locality pieces available in the 1950s-70s and completely unseen for sale today. She used the collection as a study collection, and invited select collectors and academics to do so as well, eagerly participating in the discovery of new species and the identification of German classics from others' collections. She is probably the single most knowledgeable person today on the German classics, I would guess (she even got the best of Mark Feinglos in a trade once, on a rare German copper - and he definitely knows his stuff!). She speaks romantically of all the decades of travel to Europe, where she visited the museums, the collectors, and many of the mines before they were lost to history. She had a particular love of Hagendorf, and the new mineral Kayrobertsonite was recently named in her honor for amateur contributions to systematic mineralogy by Tony Kampf, and comes from Hagendorf.

I first met Kay in Tucson in the early 1990s ( I had gone since 1991, but she has gone since the 1960s!). I only knew her then as the "German lady who knew way more than I did" about pretty much all minerals. I was lucky enough to get to know her better after I moved to San Diego for grad school in 1995, and saw her at the local shows 3 or 4 times each year. I must have passed her test because I was invited to see the collection in 1997 for the first time, and I know that few had the privilege. For all her gregariousness at shows, she let few into her home. In those few visits in the 1990s, I learned an enormous amount about the old classics, about silver species, German rarities, and the thrill of collecting intellectual old oddities as opposed to only trophy species. She helped teach me to appreciate the micro as well as the macro, and her stories about the labels and the history of each piece convinced me of the value of provenance to specimens (as you will see in our updates of the collection, we tried to document and pass on all the information she gathered). A collection like this is impactful in sheer massiveness of the accumulated information and importance, and takes time to digest even on a quick skim. (Usually, 2 days at a minimum, and she was happy to talk the whole time about it all. ) While not full of trophy display specimens, every drawer had something that blew me away, especially as I had a lot to learn about the classics at the time. All of her minerals were stored in custom cabinets, with crammed drawers, mostly of wood and lovingly made by her husband for her over 50 years ago.

Decades of acquiring fine minerals filled custom-made drawers. Drawers upon drawers of fine minerals fill Kay Robertson's home, many in drawers and cabinets custom-built by her husband.

Kay's priority for the collection was to make it a reference suite and a teaching collection for those who needed it. She worked on several mineralogy projects, including a study of xanthoconite and the Hagendorf phosphates. Kay intended for the last 40 years of  her life that this collection would be her legacy to mineralogical education and to the museum of Los AngelesCounty, specifically. (Believe it or not, she actually curated their world textiles exhibit back in the late 1940s, before she was known as a collector!). She became lifelong friends with curator Dr. Tony Kampf, and promised them the collection. Much to her surprise, she has outlived her other assets and is in excellent mental health, and remains in her home with healthcare assistance. She recently made the difficult decision to sell the collection instead of donate it, as intended.

Obviously, this was not her initial plan, but she said to pass on that she takes comfort in knowing that her pieces will be shared with other passionate collectors around the world - the next best thing to going into a museum study room, in her mind. I knew that she felt conflicted about this, and so Tony Kampf and I met at her home one day in December of 2016 to present a proposal to her: I would buy the collection with the express intent of then donating a section of the value to the LA County Museum myself: the important Hagendorf reference suite; the micromounts; the major California pieces (save only one stibnite); and most of her more modern acquisitions of common species that they could have a use for in exhibits or outreach programs. Tony (now curator emeritus) and his colleague Alyssa Morgan, current collections manager, came and helped us pack at Kay's home. They returned to the museum with a moderate sized SUV vehicle, stuffed to the gills with mineral flats. So, in the end, a part of the collection is in museum now as we speak.  (see photo of smiling curators doing the hard and glamorous work of packing thousands of specimens, the bane of the the modern "international mineral dealer," in the LA heat).

Kay Robertson owned thousands of minerals, and many of them have been relocated to the LA County Museum. Tony Kampf and Alyssa Morgan assisted with packing up a large portion of Kay Robertson's collection to add to the LA County Museum's collection.


Carl Acosta, mineral collector, assists The Arkenstone in packing Kay Robertson's collection. Mineral collector Carl Acosta assisted with packing Kay's collection (and went home with a few new specimens, as well!)

Our good friend, LA-area collector Carl Acosta joined us for the packing, and to make deli runs for Reuben sandwiches to Famous Deli on Pico, nearby (he is really good at making food runs!). I'll admit here, that he took an awfully long time to pack the garnet drawer and probably would have been more efficient if I had not told him he could buy a few...

Kay's own life story can be found in wonderful prose, here, written up by the Mineralogical Record far better than I could do it justice now in a piece featuring her collecting history. Additionally, her granddaughter has launched a Facebook page to share details and stories regarding special pieces.

I am honored to announce that we have agreed with her family and Rainer Bode, editor of MINERALIEN WELT in Germany, to publish an extended issue (with dozens of pages dedicated to the Robertson collection) of the magazine in German, her native tongue, on her collection and her life. Although many Americans and curators know her collection, few Europeans have seen the specimens and visited her home, and she wants to share it with the larger world of collecting. Look for this extended edition to come out at the Munich show or soon after, of 2017. It is a small and long-deserved tribute to a passionate collector and her legacy, and deserves to be shared.

Explore fine minerals from Kay Robertson's collection now for sale.



The Ammonite: A Glimpse into The Past

Apr 11, 2017
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. Joe Budd Photo

Few places on earth hold as many mysteries as the ocean. Much of our understanding about the history of the deep ocean comes from studying fossils like the ammonite and the rocks where they rest.

The ammonite was a warm sea mollusk creature that lived between 200 to 140 million years ago, during the Jurassic Period.[1] Their soft protruding bodies resembled the modern-day octopus or squid with a hard-coiled shell (like the nautilus) that would make up half its total length.

Paleontologists believe the ammonite spent most of their life in shallow waters. The thin plating that sealed their 26 chamber walls were made of mantle tissue, allowing the soft body to retract for protection. This structure made it unlikely for the shell to sustain the high pressures of the deep sea.

Being a warm shallow sea creature, geographers use the ammonite as an index fossil when determining the age of rock layers. To be an index fossil, a specimen will need to meet four criteria:[2]

  1. Must have a wide distribution
  2. Must be found in various parts of the world
  3. The species must evolve quickly
  4. Must be easy to recognize

The Fossilization of Ammonites

When some people think of fossils, the first image that comes to mind is the tall skeleton of a tyrannosaurus rex. While all fossils are the remnants of an organism like bones, shells, and leaves, this includes remnants of activities like burrows and footprints.

Ammonites are more likely to create a fossil because of their hard shell. After the decomposition process, the shell is buried under sediment where chemical alteration or replacement and compaction occur. These shells have been found to survive tens of millions of years without damage.

Skeletons and shells containing calcium carbonate are replaced with calcite or aragonite to preserve its newfound shape. However, aragonite is unstable and more likely will dissolve away overtime than calcite, leaving behind a mold of the fossil. The empty molds that are left behind are likely to take in new minerals like silica or pyrite, creating intricate ammonite-shaped mineral pieces.

Natural ammonite from Calgary, Canada with rainbow coloring Ammonites found in Canada can have a unique iridescent, colorful appearance that is often used in the creation of ammolite jewelry.

Mythical Ammolites

In rare instances, an ammonite is opalized by minerals coating and replacing the organic material through the veins of sedimentary rocks. Opalized specimens shine the same colors as an opal with flares of red, yellow, green, and blue. These ammonites were given the name “ammolite” in 1981 by the World Jewelry Confederation.[3]

There have been famous instances in history where the discovery of ammolite specimens would spur legends of dragons and serpents. In the Middle Ages, ammolites were thought to be “draconites” – a mythical gemstones from the head of dragons.[4] In 7th century Ireland, ammolites were thought to be the “snakestones” cast away by St. Patrick.[5]

Ammonite fossils give collectors a glimpse into an ancient earth where the climate was warmer and ocean front were full of life. The ammonites were quick in adapting to their environment, allowing a variety of shell shapes and sizes. Some ammonites like the parapuzosia seppenradensis grew to a diameter of 11 feet, making them a fearsome creature of the ancient sea.[6]


Interested in adding an ammonite to your 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!

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

[1] “Ammonites”. British Geological Survey. http://www.bgs.ac.uk/discoveringGeology/time/Fossilfocus/ammonite.html

[2] “The Rise And Fall of The Ammonites”. Fossil Facts and Finds. http://www.fossils-facts-and-finds.com/ammonites.html

[3] “Ammolite”. Alberta Geological Survey. http://ags.aer.ca/ammolite

[4] “Ammonite Gemstone Properties”. Shimmerlings. http://www.shimmerlings.com/gemstones/ammonite/

[5] Alfred K. “Ammonites, legends, and politics”. Academia. http://www.academia.edu/2325235/Ammonites_legends_and_politics_the_snakestones_of_Hilda_of_Whitby

[6] “Museum of Comparative Zoology”. Biodiveristy Heritage Library. http://www.biodiversitylibrary.org/page/3199542#page/115/mode/1up

Gem & Mineral Spotlight: The Perot Museum

Apr 8, 2017
Perot Museum, The Mamones Photography. The Perot Museum features a unique glass escalator, which is especially stunning at night. The Mamomes Photography.

Rockhounds, geologists, and gem and mineral enthusiasts of all levels will be excited to view the new collection of fine rocks and minerals on display at the Perot Museum in Dallas, Texas. The Perot Museum's Lyda Hill Gem and Mineral Hall hosts a breathtaking array of rock and mineral specimens – most of which are on permanent or semi-permanent loan from the private collections of some of the world's most renowned gem and mineral enthusiasts.

The Gem and Mineral Hall was founded through the generosity and organizational efforts of oil fortune heiress Ms. Lyda Hill, who was inspired to begin her own collection after viewing a traveling gem and mineral exhibit hosted by the Houston Museum of Natural Science.

The Lyda Hill Gem and Mineral Hall's collection is truly the first of its kind. Its specimens are of truly exceptional quality, and many have previously been featured in various professional publications, such as The Mineralogical Record and Rocks and Gems (2014 articles in Rock and Gem can be read here: Part 1 | Part 2 with additional features about our annual Dallas Mineral Collecting Symposium.)

But the quality of specimens is not the only thing which makes this exhibit unique. Ms. Hill's vision for the Gem and Mineral Hall was focused on the concept of motivating youngsters to learn more about the fascinating world of gems and minerals. In hopes of exciting and inspiring younger generations, emphasis was placed on the design of an engaging exhibit, with plenty of interactive features.

Boy with amethyst geode at Perot Museum Due to a special hydraulic system, Dr. Lavinsky's son, Logan, is able to turn the wheel to open and close the giant "Grape Jelly" amethyst geode on display in the museum.

Visitors to the Lyda Hill Gem and Mineral Hall are greeted by a five foot tall specimen, lovingly nicknamed the “Grape Jelly Geode” - which can be rotated (via a hand-cranked wheel) to reveal a stunning interior, lined with amethyst crystals. Throughout the exhibit, touchable specimens, digital puzzles, and interactive audio and video components encourage in-depth exploration of the specimens on display. Visitors are invited to participate in an engaging journey through the world of fine gems and minerals – familiarizing themselves with the qualities and concepts which define high-quality specimens, from lustrous pyrite to glowing fluorescents.

The unique structure of the mineral collection there pulls from the local community. Lyda Hill's collection forms the backbone, while local collectors of these world-class natural art pieces regularly loan pieces for exhibit. Not only does this ensure that the material is always new and changing, but it also allows the Perot to exhibit high-end examples of minerals without concern for securing funding to purchase pieces.

The building which houses the Lyda Hill Gem and Mineral Hall is also incredibly unique. Founded through the generosity of private donations, no expense was spared in the design and construction of the building – resulting in the creation of 11 state-of-the-art interactive exhibits, all housed within a sustainable structure, which leverages its own design to showcase the usefulness and practicality of eco-conscious improvements such as rainwater collection and catchment, a 1-acre “green roof” drought-resistant garden, off-grid energy, solar-powered water heating, and more. The building's architecture integrates concepts of technology and nature, in order to demonstrate scientific principles of conservation, and act as a tangible and functional example of conscious engineering, technology, and sustainability.

The Perot Museum's Lyda Hill Gem and Mineral Hall is incredibly popular – which means it is important to plan your trip in advance. Detailed information regarding scheduling and visitation can be obtained through the visitor's page, here.

Brucite - A Chemist's Treasure

Apr 2, 2017

The United States is home to many rare and unique minerals. From the benitoite of California to the turquoise of Nevada, there is plenty in the states to excite collectors. While these minerals have a lengthy history in the U.S.,  brucite is a mineral that doesn’t get talked about enough

Scan from Mineralogical Record volume 38, Brucite from Pennsylvania Brucite - 15.4 cm. Woods Chrome mine, Lancaster County, Pennsylvania. Specimen from the Kay Robertson Collection, perhaps the most aesthetic surviving example from the 1800s era. Scan from the Mineralogical Record, Volume 38, March-April. Photos by Jeff Scovil.

A Rough, Yet Fragile Mineral

Brucite has been found to take on a spectrum of colors. From light blue to milky white to lemon yellow, a specimen’s concentration of sulfur is the key factor to its color brightness.

Most brucite crystals have a pearly to chalky luster with a fibrous body. At a glance, the brucite looks rough and rocky. Yet, the brucite scores a 2.5 to 3 on Mohs scale.

Discovered in the United States

Brucite was named in 1824 after Archibald Bruce, an American mineralogist and chemist.[1] The first specimens were described as a “native magnesia” of Hoboken, New Jersey, until its unique properties were studied in Maryland. The best later came out of the Wood's Chrome Mine in Pennsylvania, and one of the best of those is in the Kay Robertson collection, recently acquired by The Arkenstone.

The most interesting quality of brucite is its crystal structure. The mineral consists of magnesium hydroxide, which results in a chemical bond whose charge is canceled. In other words, the chemical properties of the brucite’s crystal structure is only held together by weak residual bonds. In addition to its crystal cleavages laying parallel to their plates, brucite is known to sheer perfectly into flat sheets.

Brucite such as this fine mineral are for sale on iRocks.com. Woods Chrome mine, Lancaster, Pennsylvania Green brucite from the famous Woods Chrome Mine, Pennsylvania

Brucite Crystals Are Hard to Come By

Although brucite is a common mineral, there are few locations that produce showcase quantities of crystals found in the world today. The majority of brucite can be found in the Wood’s Chrome Mine of Pennsylvania (over 100 years ago) and, recently, the Killa Saifullah District of Baluchistan, Pakistan. Mountainous and hard to reach, this material has been slowly trickling out for two years, and we have been buying up as much of it as we could, as it is significant and beautiful, both.

Many specimens of brucite are found as part of the structure of other magnesium rich minerals like serpentine. Small specimens of brucite can form within wedges of phyllite and metamorphosed Magnesian limestone.

Yellow brucite crystals from Pakistan for sale from iRocks.com Brucite from Killa Saifullah District, Balochistan, Pakistan

The Yellow Brucite of Pakistan

A recent major discovery of yellow brucite was found in the mountainous region of Pakistan. The yellow variety of brucite are extraordinarily rare in comparison to the more common pearly and colorless varieties.

The rarest specimens have a distinguishable bright lemon color that shine under display lights. Naturally, brucite crystals are highly fragile and the mining process is often done by hand. This has also resulted in some incredibly preserved specimens that are highly translucent – offering a richer yellow glow.

Brucite mine pockets in Pakistan Brucite from Pakistan is found in remote, sparse, mountainous areas requiring skill and a lot of luck!

Mining for Brucite in Pakistan from The Arkenstone - iRocks.com on Vimeo.

Interested in seeing the deep lemon color of yellow brucite? The Arkenstone has recently added yellow brucite to its listings.



Don’t forget to 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] Mark Shand, The Chemistry and Technology of Magnesia (New York: John Wiley & Sons, 2006), 33.

Rock and Mineral Collecting for Beginners

Mar 18, 2017
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.

3. Gather the tools. If you decide you want to self-collect, acquire some basic equipment – though you don't need to invest in expensive tools to get started. A great beginner's toolkit should include safety glasses, a short-handled shovel, a good rock hammer or geologist's pick, a mallet, a chisel, a bucket, work gloves, and a pair of sturdy boots – all of which can be found at most hardware stores, or your local tool shop. Don't worry about advanced equipment – you can always add more sophisticated items to your toolkit as your collection of specimens grows, and hone your collecting technique.

4. Catalog your collection. As early as possible, begin keeping a catalog or database of your specimens. At the very least, maintain a record which identifies each specimen by a unique name or number, its mineral and varietal names, the year mined, and locale details (including the mine name, as well as specifics such as depth of find or level). Including the price paid for purchased specimens, and any other details regarding their previous history or display can also be helpful in determining the value of your collection, in future. If you like digital cataloging, new cataloging software options are coming to the market, including MineralDesk, which launched at Munich Show 2014.

This label from the Sir Robert Ferguson Fine Mineral Collection dates to the late 1700s/early 1800s. An old label from the collection of Sir Robert Ferguson, a Scottish noble. Keeping old labels add history and significance to specimens.

5. Keep the labels. When acquiring specimens from others, make sure you save any identifying labels, records, or information which accompanies them. The history of your specimens is what makes them unique – and, in some cases, distinguishes them as rare. This information adds to the story or provenance of your collection, and helps add additional interest and value to your collection.

6. Use reliable reference sources. It's a great idea to invest in a good reference book, or other resource materials and publications. John Sinkankas' book, Field Collecting Gemstones & Minerals is an excellent choice, as is the periodical publication The Mineralogical Record. For a list of other recommended sources on rock and mineral collecting, visit our reference page here.

Aquamarine mineral specimen from Shigar, Pakiston, 15cm showing an example of a custom lucite base created by The Arkenstone7. Learn how to properly trim and display your collection. Study the display of pieces you admire, and you'll learn a lot about how to trim your pieces properly. By learning what helps make a quality specimen stand out, you'll begin developing an eye for display which will help you trim and balance your display pieces, when you're ready to invest in the tools. Contact us if you need advice or recommendations on cleaning or trimming fine mineral specimens. We also have a custom base lab located in The Arkenstone's Dallas gallery. You can view examples of the bases on our custom base page.

8. Limit the size of your mineral collection. It may sound counter-intuitive, but invest in a nice display cabinet or case, and limit your collection to what fits inside. This will help you select your specimens with discernment – and avoid the all-too-common scenario, in which a collection becomes unmanageable. There is no point in collecting pieces which lie unseen for years in storage – if you can't find the space to show off your collection, you may as well not own it! And, if you find yourself in need of a good downsizing – don't discount the opportunity for trade. You may find that by bundling your less desirable pieces, you are able to obtain one or two choice display specimens.

9. Develop your relationships. Many dealers travel far and wide, attending the best shows and symposiums, as well as visiting specific locales and interacting with other collectors. Once you've decided to define the focus of your collection, whatever that focus may be – develop your relationships with a few respected dealers. When you let them know what specimens you are interested in, you may find them willing to let you know when they come across a good deal, or an item of particular interest. Many dealers also maintain their own websites, which can be a wonderful resource for photos, articles, and news about recent finds.

10. Purchase quality. It may take you a while to develop an eye for fine quality stones and minerals – but as you learn more about the characteristics you are seeking, make sure you are buying the best you can afford. It is far better to own a collection with just a few stunning, high-quality display specimens, than to hold onto a large collection of mediocre pieces. Hold out for the finest specimens you can afford!

Above all else – have fun! Rock and mineral collecting is an adventure which allows plenty of opportunity for enjoyment. If you aren't having a good time, you're doing it wrong!

To view specimens of popular species, visit our Themed Galleries!

Discover Oxide Minerals

Mar 13, 2017
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.