Below is an example preparation sequence of a large (2 3/4 inch) Utaspis marjumensis trilobite from the Marjum Formation of Utah. It was personally collected in the spring of 2013 from a lease in the House Range. This shows how much skilled work goes into a quality fossil even after it has been found. Click on the images for larger versions.
Quarrying the interbedded limestone and shale layers of the Marjum Formation. Utaspis with cheeks (not molts) are pretty scarce.
The two halves of the split trilobite have been glued back together and the head is partially exposed after an hour of work using air abrasives under microscope.
About 7 hours in. It is one of the most frustrating trilobite I've ever prepped. I've been ready to chuck it across the room several times. The shell is tissue paper thin, and even using dolomite at 15 PSI causes it to start to flake up. I have to stop every 30 seconds to try and stabilize it with glue. It's nerve racking as I think if I hit it at the wrong angle half the shell will just flake off.
12 hours of work into the Utaspis and it's almost fully exposed.
About 14 hours it's almost done. Just needs more matrix cleanup work, and restoration of some damaged shell.
Completed Utaspis post shell restoration and matrix cleanup. This one is going in the personal collection.