On the Yorkshire coast, most ammonites are most usually preserved mud-infilled or pyritized. Calcite preservation of a significant part of the whorls is relatively rare, but does occur occasionally, in my experience for example with
- Psiloceras
- Arnioceras
- Euagassiceras
- Pleuroceras
- Eleganticeras
There are rare calcite preserved ammonites where the calcite is so translucent that you can almost look through it – I´d like to show you 2 examples :
The first one is a Psiloceras erugatum from the glacial drift (more on the lower lias ammonites from the glacial drift later) :
Psiloceras erugatum, 3 cm
I photographed it against the light on my light table and pulled up the contrast in Photoshop to maximum to show the most of the translucent chambers.
The second is an Eleganticeras elegantulum that you might have seen earlier in one of my Christmas postings on the UKGE forum,
the resemblance of the sutures with Christmas trees was just too tempting…
Eleganticeras elegantulum, width of ammonite 4 cm
With this one I did a little HDR setup, photographing it with a number of exposure settings and combined the pictures with a software later to capture the maximum dynamic range.
Of course beside the right preservation you also have to prep the ammonite completely free of matrix to see the light shine through – with the two examples shown I was lucky with the Psiloceras, it “jumped” off a multi block matrix free, the Eleganticeras was a lot more work involving air pen, diamond cutter and air abrader to remove all the matrix surrounding it without braking the fragile calcite inner mould.
AndyS
Yorkshire Ammonites (and other fossils ) revisited 