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Ammonite Dactylioceras UK self prep
Quite a few collectors build the collection in whole or in part by buying fossils. Like many collectibles, there is a flourishing trade in fossils, and especially where the supply is limited and demand is high, prices go up quickly. There are also niche markets (think of exclusive collections, interior decoration, etc.) in which fossils are only interesting if they are in perfect condition; preservation, completeness, preparation and overall aesthetics. Fossils have traveled millions of years folloed by weathering, excavation (often rapidly and ignorant), preparations also, leaving really mint fossils only in exceptional circumstances. Within some markets, the incentives are so high that falsifications are the rule rather than the exception.
Degrees of falsification
First and foremost, it is important to recognize that there are many forms and degrees of falsifications exist, from the slightly improvements of an authentic piece to complete total falsifications. Sometimes a fossil is improved with good intentions, e.g. to fill a missing part. This is sometimes done for pieces that are part of a museum exhibit, but it is generally regarded as an undesirable practice within the scientific community. Often this kind of repairs are done to make the fossil nicer, either for its own collection or display, either to sell the piece more expensively. When the repair is not clearly stated during its sale, this can certainly be regarded as a falsification.
Also totally fakes are sometimes made ??with the best intentions, e.g. used as casts for education, for exhibition, or simply to be traded as a replica. Sometimes this kind of pieces in trade are eventually sold as genuine. In other cases, there are real industries where total falsifications are produced at a large scale. An example is the -now infamous- trilobite falsifications from Morocco, where the markets were at a given moment literally flooded with artificial resin.
A practical overview of the degrees of falsification developed by Udo Resch and Klaus Bartl, and has been published on the magnificent website of Michael Kipping (adapted and copied with permission). For each category, a concrete example is given. Combinations of these classifications are also possible.
|Natural||Completely natural, except for measures to preserve (e.g. strengthening fragile matrix) the Integrity of the piece.|
|Improved||Subject only to a treatment of the surface, such as slightly recoloring or treatment with a contrast-enhancing layer. Also very light polishing of the surface to give shine.|
|Restored||Restauration on a limited scale, such as filling in missing small chips, cracks or parts of shells.|
|Composed||The correct reassembling of disarticulated parts of the same individual, with documentation of the original condition of the find.|
|Reconstructed||Adding missing parts that have not been preserved.|
|Manipulated||Covering the fossil with a colored layer or plaster, often to hide preparation damage or missing parts. Highly polished fossils can also be regarded as 'manipulated'.|
|Assembled||Merging fossils or parts of fossils that are not originally found together, often in an artificial matrix.|
|Art||Fully artificial totally fake, not based on an existing fossil.|
'Natural': This trilobite is not restored or treated. All details are anatomically correct, and the fossil has no unnatural shine or color.
Example of a 'natural' fossil.
'Improved': The surface of this ammonite is polished. As a result the original shell has disappeared (mainly on the ribs), and the fossil exhibits an unnatural shine. Also fine morphological details, such as growth ridges are sanded smooth.
Example of an "improved" fossil.
'Restored': In the example below we see that the cracks are filled with a gray filler. In addition, a relatively small missing part Ammonite bottom also supplemented with the same filler. In some cases, but not in this example, these additions are colored so that they are less noticeable or even become virtually invisible. The latter is commercially interesting, but is usually not done in a 'normal' reconstruction. It's a good thing that it is clear which parts of the fossil are restored.
Example of a 'restored' fossil (photo Derschueler).
'Composed': For composite fossils, the different parts are put together after preparation, possibly in a different position than they are found. The components are found together, and they may belong to the same individual. Examples of composite fossils are found often in museums. Many skeletons you see in museums are often from different individuals (and therefore 'assembled'), and often the missing bones are supplemented (and hence 'reconstructed' and / or 'restored').
Example of a 'composite' fossil.
'Reconstructed': The example below shows the Giraffasaurus brancai as it is placed in the Natural History Museum Berlin. The exposition of the museum works with an exceptionally high percentage of real specimens, and this Giraffasaurus is no exception. Missing pieces of the original skeleton are filled with plastic replicas. This fossil is therefore 'reconstructed', and 'assembled'.
Example of a 'reconstructed' fossil (Photo Axel Mauruszat)
'Manipulated': The goniatiet in the example, has its entire exterior grinded away, after which it is polished. This results in the visibility of the individual rooms, but the original morphology of the shell and the structure of the exterior is hereby completely lost. This kind pieces are often sold as collectibles, but the added value of a collection is very limited.
Example of a 'manipulated' fossil.
"Assembled": This example is a assemblage of various trilobites, some authentic, others totally fakes, on a atificial matrix. The authentic trilobites are particularly rough prepared, and then restored and reconstructed locally, what they tried to hide by adding a dark color coating. It is therefore a combination of composite, replica, restoration, reconstruction and improvement. In this case, the approach taken is to assemble trilobites who have the same age, and thus the combination of species in itself is plausible. The arrangement of the trilobites in the matrix, all neatly at about the same distance, and the most outstanding in the center, is typical of this type of assemblages. There is a clear difference in color between the matrix around the central 'Dicranurus' (a replica) and the other matrix. Elsewhere on the matrix there are subtle color differences. The full matrix has an illogical composition of scratches, perhaps to hide these kind of color differences. These scratches are largely parallel to the trilobites, a direction that is rather illogical 'real' scratches from preparation go outwards from the fossil. The dealer told this fossil was a composite, but listed all the component fossils as 'authentic'.
Example of an 'assembled' fossil.
'Replica': This example is a replica of Propalaeotherium messelense as exhibited in a museum exhibition. The replica itself is a cast from an original fossil. The use of replicas in exhibitions is common, in this way you will not risk damaging the original, which is safely tucked away in the scientific collection.
Example of a 'replica' (Photo H. Zell).
'Art': This example is a total falsification, which is in no way based on the morphology of an existing fossil. It is a sculpture that is marketed and sold expensively as a fossil snake with medicinal or spiritual qualities (this particular piece of misinformation you get for free). The anatomy is totally incorrect, and a fossil snake with soft tissue preservation looks really different. The experienced collector will not be forged by this. Yet there are plenty of buyers around to be fooled, witness the exorbitant prices charged for this kind of 'fossils' and the fact that a large market has developed around it. That this market is rather focused on the esoteric, perhaps hoping to attract to vulnerable groups speaks volumes.
Example of a 'work of art'.
Information falsification: a different view on the matter
Another risk in the purchase of fossils is that the fossil is not provided with the necessary information (identification, origin, etc.), or even worse, is provided erroneous information. Typically fossils lack accurate and complete information about the origin of a fossil, often because the sellers want to secure their business. When accurate information is given, it is still questionable whether this is correct. Not rarely the name of the nearest town given as location, where perhaps the local markets are located and where the fossils are traded to wholesalers. This kind of information is virtually worthless.
What you're less likely to see is that the preparation, preservation, and any repairs must be documented. Is the fossil impregnated and if so, what materials are used? What kind of adhesives are used to put together parts of the fossil, and in which solvent is necessary to solve this? Is the piece is desalinated, and if so, is this done thoroughly enough?
On the other hand, statements as 'unique', 'pathological', "museum quality", "mint condition", etc., are made without exception, in an attempt to drive up the price. Only rarely are these kinds of adjectives are correct. A bad trend is the use of the term "undescribed species" to drive up the price. This is an attempt to commercialize scientific importance of a specimen. Do not be fooled, even if it is an undescribed species, the piece may not be excavated in a proper manner, and lack the necessary data to be of any scientific significance.
A special form of misinformation is assigning medicinal or meta-physical properties to rocks or fossils. Don't be fooled, no serious study has proved such a phenomenon. Within this kind of esoteric circuits many fakes are sold, and they are almost standard sold at ridiculous high prices. Some minerals and rocks are toxic, harmful or (slightly) radioactive and can actually have an impact on health, but that's another story.
General Considerations for recognizing falsifications
With the advance of the internet, also a thriving online trade of fossils exists. Transactions are often based on photos. We can certainly say that most photos provided by merchants are not sufficient to judge the quality and authenticity of a fossil unless you have a very good knowledge about the fossils in question. For transactions where significant amounts of money are involved, it is an absolute requirement to see the fossil yourself before you buy. You can (and should) also rely on the reputation of the seller. References are only meaningful when they come from an independent third party. Also, reputable dealers sometimes sell fossils of dubious quality.
How can you distinguish an authentic fossil from fakes yourself? Or rather, what should you look for to place a fossil in one of the above mentioned categories? Below we give some general tips, but it's largely down to have a good eye for details, and knowledge and experience with the fossils in question.
Anatomical accuracy: this is one of the major concerns, and immediately a difficult one because it requires a thorough knowledge of the fossils in question. Please look at both the anatomy as a whole and in fine detail. Below we see a Paralejurus trilobite as offered in a market.
This Paralejurus has a lot of unnecessary ballast.
At a glance it is clear that something is not right with this trilobite. In a normal specimen, the head (cephalon) and tail (pygidium) should be the same size. In addition, this one has one segment too many: 11 rather than the usual 10. At this trilobite we expected to see the characteristic terrace lines. Fine lines, which are particularly evident at the head and tail. The picture is not good enough to evaluate this, but we see effectively a trail of terrace lines on the pygidium. On the cephalon we see lines, but they are scratchings from a hasty and crude preparation. This trilobite we can classify as 'assembled': the piece is a composition of parts of at least two different individuals.
Material Differences: Note different texture, structure, or color differences in the fossil itself or in the matrix. Sometimes you can see tiny bubbles that remain after pouring the resin. Too smooth or rough texture, or a different shine, may be suspicious, especially if it is accompanied by the lack of fine detail that you might otherwise expect. On the shark tooth below a lot of plaster was added. This technique is used to assemble a complete fossil together from a number of fragments. In this case, the ratios between the components are right, so it is possible that all the fragments originated from the same sharktooth.
Hold the mouse over the image to see the artificial filling (shaded).
Matrix Properties: The matrix, the rock in which the fossil is embedded, may also yield indications for possible falsifications. Look for the matrix near the fossil, where small differences in color and texture may indicate the use of artificial substances and fillers. In the example below, there is a subtle color difference noticeable between the body of the 'trilobite' and the stone. This trilobite is a total fake. The whole stone is scratched in an attempt to mask this transition of materials. You can see also that the anatomy is totally wrong. For example, between the segments are no seams.
Hold the mouse over the image to see the line between rock and plastic.
In the following 'trilobite' we do not even have to indicate the separation between stone and artwork. During drying, the plastic was reduced in volume, resulting in a clear shrinkage crack, which is exposed. Again, it is a total fake where the anatomy is totally wrong.
A clear shrinkage crack immediately takes away all doubt - again a totally fake
Multiple fossils together: Beautiful fossils into context with multiple pieces in the same matrix (an "association") can be very interesting. Also commercially sought after, and often fossils that are found separately, are puzzled together to form false associations or composites, in a partially or entirely artificial matrix. It is also common practice that individual parts are assembled into one fossil such as a 'jaw with teeth' that consists of loose tooth crowns and fish bones.
Often, however, it fails to make a coherent puzzle. Such composite fossil contains fossils from different periods that can never be found together. Or what about a 'jaw' with teeth belonging to different species?
The example below is interesting, because it is a composite of 3 total forgeries of trilobites. These are Crotalocephalina, a Zlichovaspis, and Walliserops falsifications. The latter is, however, not found in association with the other two. This fact alone should refrain you from buying, but it does require knowledge of the different faunas, and that is not always evident. But the dull, grainy texture of the trilobites is wrong. The shape of the trilobites is not what it should be (especially the fork Walliserops) and the spines are not fine or pointed enough. The latter is a clear hint that the spines are made of plastic. It is very difficult to manually imitate good spines. The trilobites are very nicely spread over the stone. In real associations this is rarely the case, and the fossils are ofted against or over eachother. Also other fossil parts are often present in the matrix. Here too, the whole matrix covered with 'preparation scratches', with the intention of masking glue joints and transitions. Yet you see color differences between the matrix in the immediate vicinity of the trilobites, and other matrix. On the 'scorpion' bottom right, we will remain silent...
Price: the price can sometimes give an indication that something is not right. Although for falsifications usually a lot of money is required, it is often a lot less than an original. Indeed, it is often intended to seduce you to a quick decision for a 'good deal'. Is the price very low, be aware.
Other offers: Also look at the other advertisements from the same seller. If you see suspicious specimens, it is best not to buy. Note also repetitive items: often the same mold used for molding. A number of different almost identical pieces can also indicate falsification.
Testing of falsifications
There is no definitive test that can detect any falsification. However, we present a number of general tests that may be discover several types of falsifications.There are notes with this kind of 'general' tests. First, you could say you can never rule out the chance of a false negative. If these tests are positive, you can be sure with great certainty that something is not right. But if the test is negative, this does not guarantee that the piece is not falsified. A second observation is that the use of these tests can be done rarely discrete, and can possibly be interpreted by the trader as a sign of mistrust or insult. Finally, these tests are not possible when you purchase from a distance (e.g. over the Internet).
The 'hot needle'-test: this test is to heat a needle to above the melting point of the plastic which is used in the falsification. The tip of the needle can then be pressed into the plastic. Observe the deformation, discoloration and / or burnt odor. Condition is of course that the needle is hot enough.
UV light: Some plastics glow or fade under UV light. This is a relatively simple test, if they have a suitable UV lamp. These lamps are quite expensive to purchase.
Density: If the fossil is composed of a homogeneous solid, such as amber, a test of the specific gravity can sometimes give a definite answer. The specific gravity is the ratio between weight and volume, and is temperature dependent, so to test at the temperature indicated by the data that you used as a reference (typically room temperature, about 20 ° C) . The weight is adjusted using an accurate scale (for larger pieces suffice a kitchen scale). The volume can be adjusted by immersing the piece in water in a container with straight walls and registering the level before and after.
Solvent: Often repaired parts or total fakes are dyed to match the color of an authentic fossil. Most of these dyes allow to smoothly dissolve in a solvent such as acetone. A drop of acetone on a cotton swab and rubbing as is sufficient, if a color comes along then something is wrong. Please note that original specimen are also sometimes dyed, e.g. to hide preparation scratches.
In the example below, the fracture at the splitting passed through the fish, and only a limited number of bones, particularly in head and tail are still present. The matrix is ??bleached and the fish is painted. The color brown is unnatural and completely smooth, and the shape of the fins is not correct. A bath in acetone or similar solvent quickly makes it clear that the fossil is a print more than anything else. A quick wipe test with a drop of acetone (or nail polish remover) on a cotton swab should produce a brown color on the swab. But it is generally not preferred to do this type of testing in a fair.
Fish are often painted. Hold the cursor over the image to see the result after an acetone bath.
It should be clear that the use of this type of test procedures was not always possible. However, when you are about to pay a decent amount of money for a fossil, it is not unreasonable that the trader would allow you to test the specimen in a discrete manner (e.g. behind the scenes) with a number of non-destructive tests, or at least for another good look. Make sure you always have a loupe wth you, and that there is sufficient light, preferably daylight. Keep in mind that if you have enough experience, the gut feeling is one of the best tests. Do you feel that there is something wrong in the fossil, please refrain from purchasing, even though the deal may be very attractive.
Additional information and examples of common forgeries
Thanks to Gunther, Aaron, Mendel and Nikola for providing or referring to examples, and Michael Kipping of www.trilobita.de for the scheme. And of course a big hug to the dubious dealers whose photos we present here -without source reference- for everybody to learn.
Do you have additional information for this article? Please contact the Fossiel.net Team.