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Wenban - a preparator's nightmare (Viaphacops claviger preparation sequence)

Viaphacops claviger is one of the strangest phacopid species in the fossil record. Known only from Wenban formation, Nevada (USA). This species is large, has strange shaped spines and is rare, so here is a preparation story.

If I had to describe preparation of Wenban in one word: "a nightmare!"

There are different layers, so preparation difficulty can vary, this specimen however comes from a very hard layer. I have prepped many fossils in the past, this was the second Viaphacops claviger I worked on, so I knew what to expect, but probably one of the most difficult bugs I prepped so far. The rock is hard (on a scale from 1 to 10, this is 11) and breaks unpredictably like glass (similar to Jorf, Morocco, but Jorf in my experience is nicer to prep), the skin and matrix are fused together and there is zero separation, so the only way to prep Wenban is sandblasting. Hardness of the rock, glass like breaks, zero separation and close to 0 contrast between matrix and skin (when sandblasted) make Wenban a nightmare to prep (respect to the few american preparators who prep Wenban trilobites)! And like all said was not enough, the break was difficult to work with. Due to the difficulties to prep, dig and find Wenban material these bugs are high priced and rare in the market for a very good reason!

Here are a few step by step photos of the preparation:

Weban Viaphacops claviger positive and negative

Viaphacops claviger positive

The negative side with skin in matrix, this is what is considered not a good break, but hey, you are lucky if you find one

First I started to prep the positive

Both parts before glueing

Positive and negative glued, it's a massive block of rock that needs to be removed from the fossil

Now you can clearly see how much rock needs to be removed

Low contrast between the matrix and skin is a problem; as you can see here, part of the eye, glabela and most of the thorax had to be transfered.

It would have been easier without axial spines

Cutting matrix didn't work, matrix was too hard and started chipping off like glass when pressure was applied, so the extra matrix was first carefully scribed down and then sandblasted under the microscope with different abrasives.

Very hard rock and close to zero contrast made this preparation a difficult task. Like that wasn't enough, due to the split just under the skin there were also few cavities (hollow spots under the skin) which needed to be filled with glue.

Front of the glabella was in another part, so that was glued last.

Took a few weeks, I'm happy it's finished.

Viaphacops claviger, Wenban (prep A.Ž.)

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