The most successful way to split an ironstone concretion is to set it on edge, long axis horizontal, on any fairly large rock and strike the upper edge with the hammer. If the concretion is one that developed around a fossil nucleus, it generally will split along the plane of weakness, revealing the fossil. Sometimes one side of the concretion will break off in the middle, in which case the remainder should be tapped firmly but gently on the upper edge until the fossil is completely uncovered. Pieces of the broken half should be glued together neatly with waterproof cement so that the entire specimen can be retained.
Fossils embedded in shale may be recovered by the same method or by repeatedly tapping a chisel inserted along the bedding plane. If the fossil is exposed, the matrix can be chiseled away by slow, painstaking effort.
The usual method of wrapping plant-bearing nodules is to place the end of a sheet of newspaper between the two halves of the nodule, fold the paper over the nodule, and roll it up in the sheet.
How to Wrap a Fossiliferous Concretion
When several localities are visited in one collecting trip, the fossils from each should be kept separate; cloth bags are convenient for this purpose. Notes about the locality should be put in the same bag as fossils from that locality so that there is no possibility of confusion.
Some fossils are so fragile or porous that they should be covered with a hardening protective coat of crude gum arabic solution. (Refined gum arabic will not serve.) This may be applied with a fine brush in successive layers, or sturdier fossils may be dipped in it.
When a fossil is so delicate that the surface tension of the gum arabic solution causes the fossil to “spread,” celluloid (not plastic) dissolved in acetone should be substituted. Before this solution is used, the specimen must be completely dry or the coating will become cloudy or opaque.
If the specimen is pyritized, it should be sprayed with lacquer or shellac to prevent disintegration. If these protective sprays are used they must be applied to dry specimens during dry weather or the coating will remain sticky.
