Oklahoma Trilobites

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Science Section

Production of Oklahoma Devonian Trilobites

Haragan Formation and Bois d' Arc Formation, Coal County, Oklahoma

Also see Oklahoma Trilobites Species by Order Oklahoma Trilobites Gallery

Finding and preparing trilobites in the limestone matrix of coal county, oklahoma differs markedly from collecting in the shale of the western U.S.  The gallery below takes you through the arduous process that Bob Carroll of Black Cat Mountain Trilobites has done for more than twenty years. He does this for a living, but also out of love.
Phase 1: The first process is preparing the quarries for the dig season.
Black Cat Mountain is really a small hill overlooking the Haragan ansd Bois d' Arc Formation.
A large trackhoe is brought in to remove the formation's overburden down to a trilibite bearing level.
Next, a backhoe is used to break up the limestone layer into large slbs.
The backhoe shovel scraps up a bedding plane layer that is typically a few to several inches thick.
Phase 2: Then, the real work begins. Months of back-breaking work follows throughout the wickedly hot Oklahoma summer. Well over a hundred trilobites will be found, but many won't make it through preparation.
A sledge is used to break the big slbs into smaller ones as above.
Here's a day work (above left) of trilobite hunting, as these have to be spilt into smaller yet pieces yielding the tailings pile above right over a month.
Only rarely will a trilobite be found on the layer surface.
Rather, rocks have to be tediously spilt into small pieces in search of a tell-tale trilobite exoskeleton cross sections. This is both art and very hard work. Some trilobites are in multiple pieces. Think practice doesn't make perfect, watch this movie of Bob Carroll breaking rock.
The vast preponderance of these Oklahomo trilobites are found by splitting and resplitting the limestone in search of tell-tale trilobite cross sections, as shown in the Reedops above. It takes a keen eye , and a lot of experience to identify the species. Note the two pieces above left are mirror images. They will be glued together to proceed with preparation.
Phase 3: Laboratory Preparation is a tedious multistep process, with every trilobite requiring many hours with special equipment: 1) an air scribe which is like an itsy bitsy air hammer with a sharp point vibrating at very high frequency; and 2) A mini-sandblaster using a soft matrix operating at up to 100 psi. It is during the early stages of roughing out the trilobite with an air scribe that many are discovered to be too incomplete to finish and must be tossed out.
First, the pieces have to be glued back together.
A large portion of the covering matrix is removed with the air scribe.
The mini sandblaster is operated in a sealed hood utilizing a microscope.
Most of the ones that make it to the sandblaster end up like above.
Various horizons among the many layers of the Haragan and Bois d' Arc Formations that have been worked by Bob Carroll over the last 20 years.
Above to be done: Rough out and finished of several species.
Above to be done: Selected batches of finished Oklahoma trilobites.
Also see this page from a trip we made to visit the Oklahoma trilobite's quarries at Black Cat Mountain.


Oklahoma Trilobites at Fossil Mall