Posted by: Raymond McDougall on 12.07.2013 | Filed under: Collectors | Comments (0)


The following article is based upon a variety of sources of information, personal experience, and the experiences of many other people. McDougall Minerals has not independently conducted tests to establish the information and cannot confirm the natural or unnatural characteristics of any mineral specimen without inspecting and/or testing it (as we do, when we acquire minerals). The goal of this article is not to say all of one type or another are unnatural (although with some things, this is certainly the case), nor it is to tell you what you should or should not enjoy. Rather, the goal here is to help by increasing awareness and discussion around fakes, treatments and alterations.


One of the best things about mineral collecting is that so many specimens are so amazing it is hard to believe that they are real and entirely natural. And yet, when it comes to buying minerals, a surprising number of specimens actually aren’t!

The good news is that it is easy to become knowledgeable and begin to protect yourself from buying something you believe is totally natural when in fact it is not. The lesser news is that there are always new tricks, and, sadly, there many people out there who would happily part you from your money regardless of what you are getting in return, so if you are going to buy mineral specimens from anyone other than dealers you trust, become an expert! There are quite a few different fakes, treatments and alterations out there, but not all are hard to figure out – a lot of them are well-publicized. Some dealers are quite honest about the fact that specimens have been treated, but then many others are not, and usually you have to ask – there is rarely a label to announce the fact.

Constant vigilance is critical, particularly to detect the most rampant practice – that of unlabeled repairs. I have seen countless unlabeled repairs at the big shows, and all over the world. Somewhere in the world right now, as you read this, someone is out there gluing a crystal onto a rock. Maybe gleefully. Likely not a professional, and likely not about to tell you about it. Probably also clasping his or her hands together and saying “Excellent” in the voice of C. Montgomery Burns, but I digress. And if it sounds like I have an opinion on this subject, it’s because it’s impossible to buy thousands of mineral specimens and never find out later that you’ve been sold an unlabeled repair…

By the way, the alteration and even complete creation of mineral specimens for collectors has been going on since the nineteenth century – the fact of it is absolutely nothing new, even if many of the technologies and techniques are more advanced than they were when the first mineral specimens were faked.

One particular personal incident many years ago (let’s call it The Topaz Incident – I will describe in a moment) inspired me to learn very quickly about these issues. I realized that if I was going to be spending money on natural fine mineral specimens, I had to get up to speed. I am not writing this with the goal of providing a comprehensive list by any means, but this whole area of knowledge is such important critical thinking for us all apply to minerals, and I hope to be able help you in developing your critical appreciation of minerals (or at least add specifics you may not yet have seen).

Part I  Specimen Creation and Enhancement

Mineral specimens are considered to have been “faked”, “treated” or “altered” when they have been subjected by humans to a process to alter their natural appearance. Such processes may include irradiation, heat treatment, and physical processes, including the addition of dyes, or even creating specimens altogether. Mineral specimens are also often reinforced, repaired or restored in some way – these practices are different and generally viewed along a more acceptable spectrum than the creation and enhancement techniques, and they are considered separately in Part II of this article. We each need to come to a final personal view on what will and will not be acceptable in our own mineral collections.

1. Fakes

Complete true fakes are not incredibly common in the scheme of things, and many are one-off creations. My favourite contemporary fakes are the perfectly spherical “geodes” from Morocco, lined with beautiful sparkly galena crystals. I think they are a riot – or at least they would be, if not sold as “natural” to unsuspecting buyers. As I understand it, the spheres are created by using a cast around a ball. The cast is then cut around the middle, the ball is removed from the centre and the sparkly galenas are then added to the hollow. These spheres are then sold to tourists. They aren’t really too convincing.

Truly created specimens, such as result from gluing crystals to a matrix to which they do not belong, or even a totally reconstituted unnatural matrix are out there in the market – for example some Colombian emeralds have been subjected to this torture. Other examples have included some malachite stalactites from the Democratic Republic of Congo with crystals on the stalactite surfaces where the coatings of crystals glued onto them. More recent reports have indicated that some clusters of the beautiful orange wulfenites from Mibladen, Morocco, have been created (and have come apart when tested by knowledgable buyers). Classic faked specimens of various kinds from historical times have sometimes been well described in mineral literature.

Other examples of fully constituted fakes are the “iron cross” twins of native gold from Russia. Turns out these were actually gold melted down and poured into a cast in the shape of an “iron cross” twin. Well-known mineralogist John Rakovan did fascinating analytical work and a great Rochester Symposium presentation on these.

And, here we arrive at The Topaz Incident.  About twenty years ago in Tucson, I was duped by a pretty well-done (of course _I_ will say it was well done!) matrix topaz specimen from a Pakistan dealer. Two topazes were attached to hosting albite and quartz rock that was at least partly reconstructed (some material dissolved overnight when tested, and examination under a microscope then revealed another confirmatory sign… who knows what a longer test would have dissolved(!)…). Thankfully I wasn’t duped long enough to permanently lose my money, as it was not cheap.

In a relatively less sophisticated example, some of the hair-like Zacatecas, Mexico boulangerite specimens include boulangerites that have been glued onto the pyrite matrix to supplement boulangerite that is there. A matted appearance can sometimes be an indicator of the glue on the ones that have been glued (not all have!).

2. Irradiated Specimens

A common practice in the jewellery industry, the artificial irradiation of mineral specimens is also quite common. Subjecting a mineral specimen to radiation may cause internal changes to the crystal lattices and therefore may alter the optical properties of the crystals, which can in turn cause their colour to change. Examples of fakes from irradiation include: some “smoky” or “black” quartz, from Arkansas and also from other localities, including Romania (clear or pale quartz that has been subjected to irradiation); some heliodors from Pakistan (goshenite or aquamarine that has been subjected to irradiation); certain topaz from Brazil (resulting in particular hues of blue or pink); very dark brown, smoky-looking topaz from Pakistan; dark blue (not light blue) barites from Romania; certain aquamarines from Brazil (some began as goshenites or pale aquamarines and many of which faded over time after the treatment); and some tourmalines (particularly certain shades of red) from Brazil. Many others are rumoured or suspected as well, so always keep your ears and eyes open, look at specimens critically, and ask questions.

3. Heat Treatment

Heat treatment can also change a mineral’s colour. Examples of heat treatment include: the ubiquitous dark golden-brown to deep beer bottle coloured “citrine” crystals and crystal cavities from Brazil and Uruguay (these are heated amethyst); and aquamarine from Ukraine (heated heliodor). Tanzanites (beautifully-coloured zoizites from Tanzania) have also been heated – there is always debate about the extent of this as a practice and I would encourage you to read more about them.

4. Dyes

Dying is also common, but fortunately is is limited to relatively few minerals. For example, agates are dyed all kinds of colours using various methods – this is exceptionally common with Brazilian agates, often resulting in bright, very annoying colours that don’t suit agates. Quartz geodes from Morocco have been abused the same way – hot pinks that would look out of place on even the cheesiest Valentine’s card. For another example, some opal from Honduras has been dyed a darker colour (using sugar and sulfuric acid). And poor unsuspecting balls of okenite crystals from India have been dyed absurd colours using common food colouring agents. Dyes and coloured oils have also been applied to some Colombian emeralds, some Brazilian rose quartz and some Chinese fluorites, to name but a few.

5. Specialized Coatings

Specialized coating is another treatment – applied to quartz with different effects. For example, a vapour deposition containing gold will coat quartz crystals with a nice entirely fake light blue colour – these are sold as “aqua aura”. Alternatively, when treated with titanium vapour deposition, quartz looks metallic and colourful, like a prop in a cheap science fiction production. Quartz has been treated in other ways as well. Always ask, if a quartz has an appearance unlike any usual occurrence of quartz described in the literature and documented in online databases like

6. Physical Processes

Many different physical processes have been used to alter mineral specimens – this is very common. Some are easy to detect and some are really hard and require serious analytical work. One that is incredibly common is the grinding and polishing of one or more damaged crystal faces, effectively replacing them with new, smooth faces. A large number of Brazilian quartz specimens have been defaced in this way. Sometimes, it’s pretty obvious – by turning the crystal in the light, you can see that a natural face reflects light in a single, sharp plane, while a polished one often has at least a little bit of curvature. However, this is not always the case. Sometimes faces have actually been faceted onto crystals and do have a sharp plane of reflection, in which case magnification may be necessary to confirm whether it is in fact an artificial face (may or may not help). And all of this is most difficult to notice when the overall specimen is natural and very little about it has been altered. Sometimes the lustre of an artificial faceted face will be subtly different (often brighter) than the natural faces.

Sometimes a magnified view of a natural face will show natural growth patterns (though not necessarily – sometimes crystal growth causes this and yet very often it does not, so it’s not definitive).

This practice of adding faceted faces has been known with specimens of other minerals, for example certain Brazilian aquamarines and Colombian emeralds.

Among other physical processes, some are pretty inventive, while others are less impressive.

Hollow skeletal-looking galenas from Bulgaria were shown by analytical work to have been normal galenas that had been physically hollowed by microblasting methods using glass beads in some cases and aluminum silicate in others (Jessica Simonoff did the great analysis on this and presented at Rochester). Once upon a time, some of the anglesites from Touissit, Morocco, were soaked in Javex to turn them a pleasing golden-orange colour. And then there is the occasional practice of bending the wires on natural wire silver specimens to enhance aesthetics… if done well, extremely hard to detect.

7. Synthetic Growth

Yes, people have even applied various techniques to simulate natural environments that will allow mineral specimens to grow artificially – these specimens have then been passed off as natural. Or, in some cases, mineral specimens may have grown naturally in an environment created by mining, which is unintentional, but still does mean that they resulted in processes caused by human activity and are therefore not naturally occurring.

Examples of specimens that are reputed to have been grown include some wire silver specimens from Frieberg, Germany (the subject of much debate and controversy – I encourage you to read and learn more) and bright silver wires on black acanthite matrix from Imiter, Morocco (grown by heating the acanthite). Many fine native sulfur specimens from Italy were in fact grown by an individual.

Mineral growth that has been known to occur in mining or post-mining environments has included many water soluable minerals including some halite crystals and colourful growths of chalcanthite. Others have included some zincite crystals, some interesting native copper specimens and some wire silver that has formed in the heat of processing, such as in chimneys.

Minerals are also commonly synthetically grown for use in the jewellery industry and also for industrial applications. Quartz, diamond, emerald and ruby are examples. As a general rule, these (particularly the more precious gemstones) do not commonly make their way into the mainstream mineral specimen market, and many have distinctive features that enable one to easily distinguish them from natural specimens.

Part II  Interventions and Treatments of Natural Specimens: Repairs, Restorations and Reinforcements

We’re now heading into a much greyer area. Well, I say that because these practices are common, and they generate controversy among collectors.

If you accept the basic premise that a key goal of mineral collecting, whether by an institution or an individual, is the preservation of mineral specimens, you have accepted that there is at least some legitimate room for some of the interventions and treatments we’re going to consider next. How much is up to you, and a matter of personal choice.

It’s safe to say that many of the fine mineral specimens in museums and private collections throughout the world have been treated in one or more of these ways. Take, for example, the Alma King rhodochrosite from the Sweet Home Mine in Colorado (now resident at the Denver Museum of Natural History – if you have not yet gone and knelt before that amazing specimen, one of the world’s greatest, you should!). The large crystal on that specimen did not stay attached during extraction. Or, for another contemporary example, many of the tall slender tourmalines from one of the large finds at the Pederneira Mine in Minas Gerais, Brazil were found broken when the pocket was opened. There are too many examples of repaired, restored or reinforced fine mineral specimens to recount.

If no intervention or technique had been applied, these beautiful mineral specimens – including many of the finest known – would be lost forever, discarded. Most people agree that the rejection of any preservation or preparation techniques at all would be extreme and even tragic.

(And if you compare to other important fields of study, such as paleontology, archaeology, and art, for example, preservation techniques can run a full range and can be integral.) BUT… now that you’re here, welcome to one of the slipperiest slopes in mineral collecting…

Let’s start at the least controversial end of the spectrum among collectors, and work our way to some of the tougher stuff.

1. Extraction and Initial Preparation

So basic that it goes without saying – if you have a mineral specimen in front of you, human hands have been involved. Once a specimen is out of the ground, it may need no more than a quick rinse with soap and water, and presto, into the display case it goes. Yay – mineral collecting is so easy! Sigh. Much more often, many cleaning and preparation techniques are involved. These may include baths in one or more chemical treatments to remove undesirable stains or other unwanted mineral material. Often, specimens are also trimmed in a work shop or laboratory using various physical means (hydraulic trimmers, rock saws and drills, for example). In fact, one of the most enjoyable parts of developing mineral collecting skills is learning some of these techniques and applying them yourself to minerals you have collected in the wild and will now preserve. Yes, these are enhancements of a kind, but unless you want a cabinet full of ugly, sludge-covered blocks of mineralized material with no proportions and nominal aesthetics if any, you will be glad for these enhancements – you will likely be grateful to the mineral dealer who invested so much time in careful prep work and eager to do the best you can to prep your mineral specimens to their best advantage. (Of course, feel free to collect a case full of ugly sludge-covered blocks of rock, but I’m not coming there with you.)

There is a spectrum among prep techniques, as well, and again, up to you as to what you choose. Most collectors feel strongly that any prep technique should either be unnoticeable or not visually distracting when looking at the final specimen. Often this is true. However, if we take certain techniques, life can get a little uglier. Most collectors will not have any issue knowing that a saw was used in extracting their specimen. Many will have no issue with a saw cut that is entirely invisible or unobtrusive from the viewing angle. On the other hand, some mineral specimens have saw cuts all over them and look like irregularly-cut blocks of cheese with crystals poking out. Not cool. One does have to consider that in some cases, the minerals are simply too fragile to have any hope of preservation without more saw cuts – and sometimes these are rare minerals and preserving them is most important – and so it’s not always easy to make generalizations about what you will personally accept, without context.

But in any event, it can be visually distracting and a factor to consider.

2. Reinforcement

Ok, so we agree that the initial prep work is important. Many mineral specimens, either during initial extraction or during prep work, become incredibly fragile. The matrix rock may be fractured, or the specimen may just naturally not have much that was ever holding it together in the first place. It is therefore quite common that mineral specimens are reinforced.

Again, this is the case with many specimens in museums and collections all over the world, and most would say that not to reinforce a specimen to make sure it holds together could be seen as failing to take reasonable steps to preserve it.

Many advanced collectors in the field, who know how difficult it can be to collect and preserve excellent mineral specimens, include, among their field collecting tools, materials to enable field reinforcement of a specimen that might otherwise not survive the trip out and home.

Similarly, once the specimen has arrived for other cleaning and preparation work, it may be reinforced before it is subjected to any work.

If done properly, most reinforcement can be undetectable to the naked eye.

Some reinforcement can involve more significant intervention, such as the stabilization of minerals that would otherwise deteriorate with exposure to the display/collection environment. This can involve the coating or impregnation of mineral specimens, and would usually be considered to be different from a drop of super glue into a crack on the back of a specimen, but all are on a spectrum.

3.  Repairs

Sadly, minerals sometimes just break. Collecting in the field with a hammer and a chisel, sooner or later you will in all likelihood bellow a profanity that would wake the dead. Or, in fact, be so unhappy that you just sit there silently in disbelief, as the crystal specimen you were working on extracting for the last hour has now zinged off into the wild blue yonder in several pieces, or developed a crack right through the middle.

Sometimes mineral specimens have broken before we are even on the scene, as can be the case collecting in an active mine or quarry where blasting causes breakage.

In any event, a repair is simply that – re-attaching something that has broken. The only foreign element added is the glue (whatever glue type is being used) and the sole aim is to put the specimen back to the way it occurred naturally before it was unnaturally destroyed. Repairs are common. Many among the world’s fine mineral specimens have been repaired. Many among the world’s least specimens have too!

Be careful! Use your loupe when buying specimens. Know what you are buying. Assume that everything from the top specimens to the least expensive need checking. Remember, if an unlabeled repair can turn a specimen from being worth zero to being worth anything, it may be worth it to someone somewhere to do it. And in some places it may not be considered unfair practice or offside in any way to repair something and not label it…

4. Restoration

So, let’s say that conceptually you accept at least most reinforcements, and some repairs (assuming they are labeled, unobtrusive and well done), and you’re still not overly squeamish. I think that could be said of a very large number of serious mineral collectors. Now comes the tougher stuff. Let’s take the same example of the broken crystal – either you broke it when you were collecting it, or perhaps you were collecting at an active quarry and the specimen had been broken in the pocket before you ever got there. You still want to preserve it. If the break is a completely clean break, then no problem, it’s a repair. But what if the break is not perfectly clean? Maybe a tiny chip is missing. Maybe more than that is missing. Is the specimen to be discarded? Well, what if you were just to fill that little chip or gap with a substance that appeared as close to the real thing as possible? All you’re really doing is trying to put the specimen back the way it was naturally, the best you can, isn’t it?

And isn’t it even an amazing and admirable skill if you can do that? Of course it is.

So why is this “tough stuff”?

Well, now we’re adding foreign substances to structure the specimen – restoration – and that crosses a line for many people. Yes, it can be done incredibly professionally, it can be very minor, and many of the world’s great mineral specimens have been restored this way.

For example, some Californian and Brazilian tourmalines in museums around the world have sometimes been restored, to beautiful effect, with a colour-matched polymer filler and striations to match the original.

Again, these would be lost for eternity if this was not done. But many people ask where does this end: Is it ok if the filler is in a tiny gap (and what is tiny?) or is it ok if a small section of the crystal is filler (and how small)? Does it become a problem when the gap is larger or many gaps are filled on he same specimen? What about the termination? At some point, we’ve moved even further down the spectrum into reconstruction, which would now make many more collectors uneasy.

The Key Questions for Mineral Collectors

1. What is ok? What is not ok?

Everyone answers these questions a little differently for themselves. Most of the techniques discussed in Part I ( Specimen Enhancement and Creation) section are beyond the scope of what most serious mineral collectors would add to their collections, if they detected the treatment, (unless they are adding them out of interest to illustrate what can be done to alter natural specimens). Some may make exceptions, for example for some heated specimens.

On the other hand, in general, most (not all) mineral collectors will accept some level of reinforcement or repair, while restoration is perhaps less agreed among collectors. Again, all of this is provided that the collector is aware of the treatment.

Which leads to the real issue at the heart of this discussion. The securities lawyer in me can’t help but end up at the view that in the context of buying mineral specimens as when you are buying securities, it comes down to disclosure. When an investor makes an investment decision to buy securities, that decision is made on the basis of all available information about risks and so on, all of which a company is legally required to publicly disclose. And after that, absent fraud, the investor had all information and made a decision based upon that information.

Minerals aren’t regulated the way the securities industry is. Understatement.

So, whatever level of critical thinking you might otherwise apply, triple it! Many mineral dealers do their very best to make sure they have disclosed one of the treatments discussed here, and they are as careful as possible when they buy in the first place. It can be incredibly hard to detect some one-offs and well done repairs, and sometimes even the most conscientious dealers may miss something.

However, there are many who don’t do this. They may either not be as careful, or as knowledgeable when buying, such that they may not always detect treatments, or they may be moving so much material that they just don’t have the time to check everything, or they may even turn a blind eye. And unfortunately, some may be trying to deceive.

Of course, the reason this matters so much is money. A collector may well decide not to buy a specimen at all, or may not pay a high price for one, if it has been repaired or subjected to any other treatment. In a great article in the publication Emeralds of the World  – extraLapis English No. 2: The Legendary Green Beryl (published by Lithographie LLC), Marc Wilson from the Carnegie Museum of Natural History in Pittsburgh said it best: “Legitimate enhancements are rendered illegitimate by non-disclosure.”

As for the pricing of specimens where treatment has been disclosed and described to the potential buyer, we can let the free market sort that one out – for example, it used to be said that a repaired specimen should be priced at major reduction of the retail price that would have been asked, had it not been repaired – but what that number used to be and what it is now, seems to vary considerably. More recent trends in the asking prices in the market would suggest that maybe repaired and/or restored specimens are no longer so deeply discounted, although I’m not sure why. Who knows what the right price is, but the prices paid and not paid will answer any debate. On a very positive note, whatever your own view for your own collection, many collectors (and institutions) that could not otherwise afford certain specimens have access to more specimens if they are willing to buy repaired specimens, labeled and sold at an appropriately discounted price.

Most great collections do include specimens that have been subjected to one or more of these techniques.

2. How Do You Tell?

Having said all of the above, the simple fact is many of these treatments are just not well disclosed. And there is no great framework of protective laws to regulate and protect you. My Topaz Incident almost permanently parted me from a lot of money. (I can’t say whether that one was intentional or accidental on the part of the dealer – who was not a major dealer at the time and who I would not recognize now if he is still selling mineral specimens – the dealer said it was accidental and the money was refunded, and I have no knowledge to the contrary.) That year in Tucson I ultimately bought specimens from trusted dealers instead. That experience led me to realize that:

(a) the way to tell you’re not buying something that has been treated, or to know when something you are being offered has been treated, is to become as knowledgeable about these things as you can and be super careful (read, share, ask questions, keep your ear to the ground and a critical eye wide open at all times – preferably with a loupe in front of it and some good lighting!); and

(b) there is real benefit in buying from mineral dealers you trust.