How best to preserve a largeish oxynociteras found in blue lias at Bishop's Cleeve in Gloucestersgire? Having done a bit of research i now know there are different types of pyritization (but not which this is) and that THE best way to preserve pyrite fossils is
You get my drift. I've several small pyritized ammonites from Lyme Regis/ Charmouth which have shown no sign of deterioration in the 3 years I've had them. So I'm unsure what to do.
Thanks in advance
Best practice in the curation of minerals (and fossils) is elusive. That's partly because it depends on budget. But in general, the best you're going to get is opinion, and the more-informed the opinion the better.
Bear in mind that when you find a sparkling fresh specimen made of pyrite, it has somehow managed to survive for millions of years like that without PVA/hairspray/etc! That points to the key to long-term conservation being recreation of the physical and chemical conditions that pertained before you scrounged it. Museums can control the environment to a large extent (humidity, acidity, light, etc.), but that can be expensive. And even if you do that, taking specimens out to work on them will still gradually lead to their decay.
Hence the cheaper and easier approach of coating them.
But before applying a coating it is important to try to reduce/eliminate salt levels (a problem where specimens are collected on the beach) then reduce the humidity. Some specimens may need gluing back together; that is also best done before coating. Immersing in oil is in some ways similar to coating; primarily it is a means of keeping the humidty low within the specimen. WD40 is just a thin oil, though it is particularly good at penetration.
Desalination: I suspect you will be familiar with the method of putting a specimen in nylon tights/stockings and immersing in a toilet cistern - whereby the occassional flushing will replenish the slightly salinated water with fresh water, leading to progressive desalination over the course of a week or so.
When drying a specimen, do it slowly and gently; heating can cause damage.
(Of course, some specimens are just too fragile; they'll fall apart almost whatever you do.)
So much for the background/basics, all of which applies to pyrite.
- 'Dreamweaver' (Gethin): hairspray in preference to PVA (http://www.nhm.ac.uk/natureplus/thread/8782)
- me: ditto
- you may get a posting from Tabfish, who posts here
- try dropping an email to Prof. Hetherrington, Head of Earth Sciences at the NHM but with a speciality in ores
Let us know how you get on and what you decide. Your research and opinion will probably be of interest to somebody else in future.
Thanks for the detailed reply, Mike. I'm coming round to the idea that sealing it some container with some dessicant is the best way forwards. I'd hoped to have these on display but seems a bad idea now! As these aren't beach finds do the still need desalinating? I've attached a pic to show state fossil is in now which seems good.
That's a great specimen.
Sealing it in a container including desiccant (silica gel) is a reasonable idea. Bear in mind that, to start with, the desiccant will have work to do absorbing moisture released from the specimen. If you can, use some that changes colour (pink-blue) depending on its water content. Otherwise, include a humidity indicator strip. That way you won't have to wonder if/when it might need changing. Also, any time you open the container, you'll be changing some of the air, so keep an eye on the desiccant again.
How much silica gel? As a rough and easy rule of thumb, 100g per litre.
But before you containerise it, I suggest you take high quality photos (high resolution, good lighting, all angles, any bit of detail that might be of interest in future, etc.). You would not be able to photograph it as well afterwards, through the side of the container.
There is quite a lot of useful information here, archaeologically oriented but very pertinent to specimens such as yours:
That includes discussion of desalination. I won't repeat it all here, but it is important to note that we are talking about soluble salts in a general sense - not just the sodium chloride type of salt. Soluble salts can occur in specimens from locations other than beaches.
Please let us know how you get on.
Hi Alice, very nice ammonite.
I can only speak about the pyritic fossils that we find on the Holderness coast, East Yorkshire.
I personally don't try to preserve them because I know the type that will not rot, the type that will rot and them that will rot if you wash them!
Small Kimmeridgian and Oxfordian ammonites from the Holderness that I have in my collection have never rotted, but on the other hand Cretaceous sponges from the Flamborough chalk if washed rot!
And finally a bit of a mystery, could be a sponge or a Bryozoan, this one is almost certainly going to end up in a pile of dust, unfortunately.
Any IDs would be welcome.
I'll throw in my penny worth Like Tabfish some pyrites rot and some do not
Just took this picture sorry about the quality The pyritic Ammonites were found at Hock Cliff Framton on Severn I imagine from the same bed as the original poster they were just dried and put in a picture frame 47 years ago just one appears to be deteriorating
PS Ihave just noticed the rotting one looks like the original specimen lol
Very nice presentation, our's are just in draw's.
What's the middle ammonite? thought it was a Arnioceras sp, but looking closer - Arietites? Paracoraniceras?
Good ammonites, displayed better than most!
I must admit I have forgotten I have not had that frame out for 15 years it was your post that promted me to go and look for it in the attic/Bat room ( its home to over 50 Horseshoe Bats ) I will have to identify it now or post it here lol