I Want To Polish This Ammonite Shell. Where Should I Start And What Do I Need?

[Lawdinfamous]

I've had this ammonite shell in my collection for a while now. I want to shine it up and make the lines on the shell show up and look really nice. How do I go about polishing this to a shiny finish?

[PFOOLEY]

Looks great as it is. Ludwigia uses bee's wax to bring out color and shine. Maybe that's the route.

[Auspex]

There is very little shell present, but a beeswax polish would probably bring out those nice suture patterns.

[BobWill]

Your internal mold looks like limestone. It's probably too soft to buff to produce a shine so a coating of simple floor wax would do and it can be removed easily if you don't like the look. The ammonites that you often see with a high gleam are formed from harder material.

[mammothhunter]

I have to disagree with the limestone cast theory, because you can see on the left side of the photo translucence in the cast material + a druze of aragonite crystals in an open chamber.

So, conceivably, you could polish it with some polishing compound (I used to use dried Brasso polish and a cotton cloth to polish soft minerals), but I think the details are so nice in this one, it would be better to add something light, like what was suggested above.

[Ludwigia]

Ok. To be even more specific: It looks to me like you've got a calcified mould there. There is definitely no shell left, since you can see the impressions which the lobes have left on it. Calcite would take on a polish, but you would need a heck of a lot of elbow grease no matter what kind of polish you use, unless you happen to have a good flexible polishing wheel on a rotating machine. Otherwise you'll have to do hand work. I agree with my predecessors that a coat of wax should bring the desired effect and it's a much more simple solution. But in the end, it's up to you now.

[BobWill]

I have to disagree with the limestone cast theory, because you can see on the left side of the photo translucence in the cast material + a druze of aragonite crystals in an open chamber.

It's an internal mold, not a cast. Crystals are common in limestone, calcite and aragonite, but whether this is limestone can be determined easily with a little diluted acid. I said limestone because it looks a lot like what we find in north Texas. What would you say the mineral on the surface is if not limestone?

Edited May 8, 2014 by BobWill

[mammothhunter]

I've seen a lot of ammonites (Especially from Devon / Dorset that I collected), that have been replaced by aragonite.

If you look at the left-side of the photo, you can see relatively fresh breakage and the internal structure of one of the chambers that shows that the ammonite is essentially aragonite (Or calcite, it's debatable).

How deep it goes is another question, but it seems to be that there is a relatively thick layer, at least.

Aragonite and calcite will both bubble when exposed to acids, the same as limestone, since they are all forms of calcium carbonate.

Edited May 8, 2014 by mammothhunter

[BobWill]

Just saying that whichever one of the crystal forms of limestone that appear inside at the break is not present over most of the fossil, so the rest may be soft enough limestone to wear down if it were buffed to achieve a sheen. That's why everyone is suggesting adding a coat of wax. If you look up aragonite on Wikipedia you will see pictures of it in it's crystal form and a picture of it in a very shiny, thin coating, but most of this fossil lacks either form and is therefore probably just the limestone that calcite and aragonite are usually associated with.