This is a Weird Echinoderm called a Rhombiferan
. Here's the way it looked before Dan started working on it.
Dan began using the air abrasive unit to see how well the shale can be removed from this specimen. Note in the picture below that Dan's hands are in a box under the microscope.
As Dan looks through the microscope, he operates the nozzle with one hand, holds the fossil with the other, and steadies the tool using his fingers. The microscope focuses by moving the fossil closer or farther way. Lots of skill and dexterity is required to use this tool. The picture below is looking down into the box as Dan works on the Rhombiferan.
The test worked pretty well on the Rhombiferan, as shown below. The shale on this specimen contains crystals of Calcite that can stick to the specimen. It didn't cause a problem in this case.
Knowing that the air abrasive machine works on the specimen, Dan finished removing the shale that isn't too thick.
For the thick shale, Dan used the vibro tool that has a needle. (below)
It's getting better...
Finally, Dan uses a manual needle on a handle to poke away some shale in
delicate places. This is done without water.
Here's the final specimen!
Dan had a tiny piece of the specimen fall off while using the needle. As shown below, he dabbed glue on the spot and applied the loose piece with the needle tool. He had some trouble getting it to stay on.
The photo below shows the top of the specimen with the loose piece glued on the right side. Notice the distinct "gear shift" pattern that is characteristic of the "ambulacra" of Cheirocystis fultonensis .
Next Page: A Seastar Gets a Chemical
Table of Contents
Page 1: Introduction
Page 2: A Tour of Dan's Fossil Prep Lab
Page 3: A Fossil Cleaning Demonstration: Rhombiferan
Page 4: A Seastar Gets A Chemical / Cleaning a Phacops Trilobite
Page 5: Other Specimens Cleaned That Day
Back to the Field Trip Index
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