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Found this a number of years ago and just getting around to prepping it.

It's a piece of Frodingham iron stone. 

When it's fully exposed, how do I go about polishing it?


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Gary W
Think carefully about polishing it it would look very good in it's natural state
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Barrow Museum
There are two approaches:

Either you carefully expose the delightful green shell of this Aegasteroceras (I think) and leave it as is (which I prefer).  The shell will always have a rather dull lustre, but the colour and original integrity of the animal itself will be preserved. And, if there is no calcite infill, then you still have a very acceptable specimen.

Or, you remove the shell to let the calcite-filled chambers show.  If you prepare it very delicately, flaking off the shell, the calcite infill will already have a gloss, from the smooth inside of the green shell which you will have removed.  From what I have seen of some of these in collections, a small rotating dental drill tool has been used to grind off the shell and then a fine polishing medium applied after to smooth it all off.  I see you have a Ken pen - he markets dental-style rotating tools too, in case you don't have one.  The only approach I have to these is to take it one rib at a time and gradually work towards the centre.  Seems as if you already have made a good start.  Personally, I would never attack one of these without a binocular microscope, as it is so easy to mark them irreversibly if doing the job with the unaided eye.

As I can see you have discovered, the matrix on these ammonites really sticks hard sometimes, so they can be a beast to prepare to the appearance I think you want.  I have a few that turned out to be incomplete too, so good luck with the rest of the whorls continuing all the way round.
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Thanks both. Will expose it then decide I think.
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No guarantee that it will have nice calcite filled chambers either...
Visit my liassic ammonites (+ other fossils) blog at
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