Some hints as to identifying fake Moroccan trilobites

1. air bubbles in matrix and exoskeleton as signs of resins.

If you discover tiny holes in the matrix or the trilobite exoskeleton you can assume you are dealing with a fake trilobite. These tiny holes, usually less than 0,5 mm in diameter, are the results of bursting bubbles of air that formed during the hardening process of the resin used to cast the trilobite. (see Picture1).

Picture 1: A) simple fake, a Drotops trilobite completely made of resin, the cast trilobite then mounted onto the matrix, the tiny holes in the resin surface can be easily seen. B) magnified view of part of the axis. C) air bubbles in the matrix of a faked Dicranurus indicate that the trilobite including underlying false matrix has been mounted onto a piece of real rock, the resin shows an unnatural brown color, real matrix should be of a dark grey.

2. differences in matrix color frequently with cast trilobites

If you find different colors in the matrix of Devonian trilobites, for example a light brown close to the trilobite while the rock, once you turn it over, is of a dark grey, this indicates there may be trouble ahead.  Usually the rock is of an evenly dark grey (Hamar L’Aghdad), reddish or light yellow (Laatchana) color.  If there are differences in color as described and in addition to that very extensive preparation marks on the surface (to hide tiny holes), then both the trilobite and an underlying layer most likely were cast and later mounted on some real piece of rock.
In Cambrian giant trilobites you can sometimes find color variations of the matrix that may indicate that the specimen was assembled from different individuals.  Look for thin lines were parts may have been glued together with their respective colors.  Trilobites without tampering should have an evenly level and colored matrix.

Picture 2: complete fake of a spiny Moroccan trilobite, Dicranurus monstrosus.  The trilobite plus an underlying layer were cast from brown resin and then mounted on top of real rock.  The “trilobite” was then painted, the surrounding areas covered with preparation marks.  The saw proved it!  Notice the hole underneath the “trilobite” and the color difference between the brown resin layer on top and the real rock beneath which is grey.  Photo taken by Sonntag, sawed up by Horst Burkhard

3. crack line in Devonian trilobites as an indication of authenticity

If you cannot find any crack line in Devonian trilobites that can be followed on throughout the surrounding matrix then be suspicious.  These crack lines are characteristic for authentic trilobites from the very hard rocks of the Devonian of Morocco.  It is hard to find a trilobite without splitting it with your hammer.  The absence of a crack line may be an indication of a fake trilobite so take a close look.

4. color and substance of the trilobite exoskeleton

The exoskeleton of most Moroccan trilobites is of black, in some rare cases of dark brown or olive color. Many faked trilobites show different colors, often brownish, with an unnatural shine to it.  Making careful use of your front teeth, you can test the trilobite for authenticity.  Fake trilobites will feel “soft”, like plastics.  This method is simple and safe at the same time, because the nerves in your teeth are sensitive enough to tell the difference without damaging the specimen.  Authentic trilobites are much harder than faked ones made of resin.  Try it using your toothbrush and some piece of rock.  But please be careful, a slight touch will do, don’t try and bite into it!

As far as trilobites from the Ordovician and Cambrian of Morocco are concerned, their exoskeleton has been replaced with hydrated iron oxides like limonite, the color being a shade of brown or orange rather than yellow or black, as has been seen in some faked trilobites.

Picture 3: these trilobites are authentic specimens, for only if you know what real trilobites look like will you be able to identify the faked ones.  The Paralejurus on the left shows the characteristic crack lines of a Devonian trilobite (marked by arrows), the upper one clearly visible on the cephalon, the lower one not so obvious.  Top right: clearly visible terrace lines on the pygidium of the Paralejurus.  These lines will be missing in faked trilobites or specimens that have been treated too aggressively with a blaster.  Notice the tiny white spots, they are preparation marks resulting from direct hits with the tip of the prep needle but of course, they will also be gone once a blaster has been used in the manner described.  Bottom right: the individual eye lenses of trilobites of the order Phacopida are a sign of authenticity because they are (still) hard to fake. It should be noticed, though, that schizochroal eyes are peculiar to the Phacopina, which are abundant in the Devonian of Morocco but of course there are other trilobites as well (Lichida, Harpetida, Proetida).

5. morphological characteristics, surface details and trilobite eyes

The exoskeletons of real trilobites very often show fine structures, inconsistencies and ornamentations, there are terrace lines (see the Paralejurus above), little knots, knobs and spines.  Taking a close look at the trilobites’ eyes will be helpful as, e.g., the Phacopina have schizochroal eyes, the individual lenses clearly visible to the naked eye.  Faked trilobites usually lack these characteristic details … it is hard to copy nature perfectly.  Faked Phacopina usually have smooth eye surfaces, because the production method of cast trilobites does not allow for such details to be reproduced.

6. UV-lights and solvents as tools to identify resin

If you are not sure whether you are dealing with a fake trilobite a UV-light may be of assistance.  Resin reflects ultraviolet light and therefore starts gleaming when exposed to a UV source.  A real trilobite is mineralized, it has the same reflection habits as the surrounding matrix.  Be careful, however, when testing waxed or finished trilobites like those coming from Russia, they may start gleaming under UV light and still be “real”.  Waxing and finishing is a commonly used method to increase contrast or conceal minor damages to the exoskeleton.
Moroccan trilobites sometimes are covered with an unidentifiable black paste, both real specimens and faked ones.  We use a solvent like Aceton or Bindulin to remove such patinas from trilobites.  Take a paintbrush and confront your trilobite with the solvent and within seconds the paste will come off, as do other artificial colorings.  Use the solvent on real trilobites to remove the paste and see what remains ….. perhaps not too much, if you are unlucky.  If there are restored areas they will appear white because the color came of.

7. The ultimate and final solution – the saw!

If you are still in doubt about the authenticity of your trilobite then saw it up with an appropriate saw (diamond-covered blade).  Is there is a hypostome present?  Bad luck - chances are you just sawed up a real trilobite!  is there a hollow area underneath the trilobite and resin has been used?  Then your trilobite was fake but it should not be necessary to saw up your specimen unless you want to prove its lack of value 100%.

Picture 4: a completely faked Burmeisterella, the hole underneath the cast trilobite can be easily seen, the use of a shiny finish to pretend a real trilobite exoskeleton is evident. This fake was 25 cm in length. Photograph taken by Sonntag, specimen owned and sawed up by Burkhard.




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