Questions about repairing/cleaning an ammonite

[kehaz]

While out on a hunt in the Marias River Shale (Cretaceous) near Fort Benton, MT, I found what I believe to be either a holoscaphites or clioscaphites, based on the research I have done. The rocks in the exposure are quite segmented and eroded and don't take much force to break apart; a few small taps from my hammer made the rock, and the fossil inside, essentially fall apart into several pieces. My question is not one of ID, but rather of how to best prepare this fossil.

 

From looking around this forum, it seems that many people use super glue for repairs that aren't very large. Would super glue be smart to use here, or should I order some Paleo-Bond? My best guess is that this fossil is only about 10 cm across or so, but it's hard to tell because it's in pieces. I am also about 95% sure that I got all the pieces, but I'm sure there's small fragments missing here and there. Is it important/necessary to fill in missing bits with epoxy, clay, etc.?

 

My next question is about the white powder that covers this fossil. Most every fossil I found still in matrix had some amount of white powder on it, so I can assume it's either part of the shell or a chemical/geological effect of the fossilization process. Is this powder important to the integrity/aesthetic of the fossil, or is it something that can/should be cleaned/removed?

 

There are some very neat internal structures visible on the breaks, plus some crystallization.

 

 

The white material rubs off at the slightest touch. I have tried my best to minimize how much white comes off the main segments (this one was a swipe off a piece of the negative).

 

I have not done anything to this fossil except attempted to fit the larger pieces together to make sure I'm not missing any other major pieces; I've already made one return trip to the site to recover some bits that I know I left behind the first time.

 

Please let me know if I need to upload more pictures. I would love to repair this gorgeous ammonite and do it justice by not destroying it even more.

 

Thank you!

[Ludwigia]

Super glue should do the trick, but use the liquid version which allows the best fit. You can fill in any cracks with an appropriate epoxy modelling clay such as Apoxie sculpt. The white powder is indeed the remnants of the original shell and it's your decision whether you remove it or not.

[Ludwigia]

@kehaz PS. It would be of interest to us if you would post a few photos of the specimen once you have finished the repair work.

[RJB]

  Hi newbie.  The white powder simply means that its in a 'not so good' state of preservation.  I used to use a floor wax on this type of preservation applied with a small art type brush.  Your ammo looks to be a bit 'disarticulated', but it very well may be a mariaensis.   oh, and super glue, paleobond and star bond are all Cyanoacrylate.  There may be slight differences between them but I would not no what.  They also come in different viscosities.  I would not use this type of glue to stabilize the white powder, but thats just my oppinion.  Good luck

 

RB

[Thomas.Dodson]

The white powder in these northern Cretaceous ammonites is often the outermost shell layer. Some people remove it but considering how rarely that layer is preserved in other places I like to keep it around. Brushing on a consolidant like Paraloid-B-72 works well to stop it from rubbing off. Some slight discoloration might occur depending on the concentration and how many layers but it isn't too bad. You can use the one below as a loose reference for discoloration. If I recall correctly the two larger ones got more consolidant since I was concerned about the powder rubbing off during preparation. The small one only got a light layer brushed on.

 

For repairs, everyone else has given you good advice on that.