Question about prepping / polishing ammonites

[acme]

Hello

 

My question is not so much about the process of prepping & polishing Ammonites as it is about the Ammonite Fossil itself and the outer shell.

 

I can see there are dozens of different techniques and philosophies about this process, but the question is:

 

--> Can "almost" any Ammonite be polished if you remove the matrix or does the shell sometimes absorb too many minerals and become like the surrounding rock and it just remains dull ?

 

 A lot of the Ammonites on our property seem to be encased in a white limestone matrix and are very dull looking. They "appear" incapable of being polished, but I haven't tried yet.

 

 

Just curious...

 

I hope this question makes sense.

 

Thanks in advance,

Mike

 

The photo below is not one of my Ammonites, but is a good representation of what mine look like.

I'll try posting a few of mine later.

 

Thanks Again 

 

 

 

[Fossildude19]

@Ptychodus04  @Ludwigia

[Pterygotus]

I’m not a fan of polishing but it really depends what kind of preservation it is. For example, ammonites from a nearby at a location called West Bay are just pure dull sandy matrix while ammonites at another location called Charmouth can be polished to reveal a brilliant green calcite! You can sometimes just remove matrix from an ammonite by giving it a whack but again, it really depends on the preservation. I have a liparoceras ammonite which another collector just whacked it, broke it and just left it there.

[Ptychodus04]

The hardness if the material that has infilled the shell determines whether or not you can polish the ammonite. Sometimes, the shell material is hard enough but often it is very soft and crumbly. 
 

Many ammonites can be polished but only ones that have nice mineral preservation in the phragmacone really look stunning.

[FranzBernhard]

1 hour ago, acme said:

encased in a white limestone matrix and are very dull looking. They "appear" incapable of being polished, but I haven't tried yet.

Probably they don´t have any shell left. If the white limestone is chalky, than there is a high chance that the steinkern (inner mold) of the ammo is also chalky - chalk can not be polished.

 

1 hour ago, acme said:

or does the shell sometimes absorb too many minerals and become like the surrounding rock and it just remains dull ?

Often, the shell is simply dissolved. But if the remaining steinkern is hard enough, it can be polished and it can be quite beautiful with stunning suture patterns.

 

Franz Bernhard

[acme]

Excellent and instructive feedback.

 

Thank You Very Much !

 

Mike

[Ludwigia]

I agree with everything said here so far. As far as I know, most Texan cretaceous ammonites are not worth polishing, since the shell is usually absent and the stone not all that hard.

[Jeffrey P]

What about coating it with beeswax or something like that?

[Ruger9a]

5 hours ago, acme said:

--> Can "almost" any Ammonite be polished if you remove the matrix or does the shell sometimes absorb too many minerals and become like the surrounding rock and it just remains dull ?

 

 A lot of the Ammonites on our property seem to be encased in a white limestone matrix and are very dull looking. They "appear" incapable of being polished, but I haven't tried yet.

 

The Moroccan ammonites I've collected mostly have some minor defects related to age deterioration and didn't seem to do well.  However, I did have some luck for a different species, see photos below.  I did NOT machine polish because it tends to remove too much detail.  Some I have hand polished after applying a lite coat of water soluble wax.