Project Airless

Project Airless’ is a three year venture that began in August 2015 at the Natural History Museum (NHM) in London, with the objective of treating and preventing pyrite decay in the Museum’s historic earth sciences collections.

Pyrite Decay

Pyrite, or ‘fool’s gold’ (iron sulphide), is a common mineral of varying crystal structure (though cubic is common) that can often be found in or around fossils. It can occur in a compact, crystallized and stable form – or as a porous, microcrystalline and unstable form.

Pyrite oxidation, or ‘decay’, can occur when the mineral reacts with atmospheric oxygen in relative humidities (RH) above 60%. The resulting by-products of this oxidation depend on the mineral composition of the fossil and matrix, but often comprise sulphuric acid and hydrated ferrous sulphates, which can be very harmful to specimens, labels, and storage media. Once pyrite has begun to oxidise, mineral hydrates will form at as low as 30% RH. Signs that pyrite oxidation is occurring include expansion cracks, white or yellowish acicular crystal formations, and a sulphurous odour.

Distressing scenes for fossil enthusiasts: a drawer of fossils with pyrite decay

Distressing scenes for fossil enthusiasts

Method

Three conservation technicians have been surveying the collections and recording where pyrite decay is occurring amongst the NHM’s 7 million fossils and 500,000 mineralogical specimens.

Hunting high and low for signs of pyrite oxidation; conservators check drawers for suffering specimens

Hunting high and low for signs of pyrite oxidation

Affected specimens are temporarily removed from the collection, photographed, and a condition report created for the specimen on the Museum’s collections database. Following this, any remedial treatments are undertaken as necessary (ammonia gas treatment, for example). The fossil is then placed in an acid-free tray within a Plastazote inlay for protection. To prevent further oxidation, the specimens are heat-sealed in a NeoEscal barrier film bag with oxygen scavenging sachets, forming an anoxic microenvironment. Once sealed, the technicians complete a process report and return the fossil to the collections. This work is being undertaken in advance of the development of a new Earth and Planetary Science building, which will have a more efficiently controlled environment.

Specimens re-housed in an anoxic microenvironment, sealed in a bag

Specimens re-housed in an anoxic microenvironment

Treatments

Once a specimen has been assessed for pyrite decay, there are some remedial treatments the conservation technicians can undertake, depending on the severity. The first of these is the removal of any white/yellowish crystals by dry brushing, followed by consolidating any cracks in both the fossil and the matrix with Paraloid B72 in Acetone.

If a figured or type specimen is exhibiting signs of severe pyrite oxidation, a cast can be made in order to preserve morphological detail before it deteriorates further. However, moulding and casting carry risks for fragile specimens.

Ammonia gas treatment is a method that successfully neutralizes sulphuric acid produced by pyrite oxidation, and involves exposing specimens to the vapour emitted by a mixture of ammonium hydroxide and PEG 400 (polyethylene glycol) within an enclosed polyethylene or glass container. The vapours from the ammonium hydroxide react with the decay products, turning the affected areas a brick-red colour.

Team Airless to the rescue!

Team Airless to the rescue!

The Future

According to current estimates, 14,000 specimens at the Museum are in urgent need of this protective measure. As the project progresses, the team hopes that they will be able to share knowledge and expertise with other museums and institutions that may be facing the same problems as the NHM. Images generated for each specimen during the project should vastly improve the Museum’s collection database – and may even limit the need to open the bags. While ensuring that these valuable specimens remain intact, and of use for years to come, the project is also increasing digital access and reducing unnecessary handling by using a web based application to associate images with each specimen’s unique barcode.

Kieran Miles, Matthew Porter, and Amy Trafford

NHM, London

Night at the Museum, Uni Week

“Every night all the specimens in the museum come alive and instantly drown in industrial methylated spirits or silently scream without flesh”

Mark Carnall, Grant Museum.

Most people’s experiences of museums after dark differ to Ben Stiller’s. Mine last night was no exception. I visited the Natural History Museum, London, to see what science’s next generation are doing with our natural science collections.

It didn’t take long to wade past the cultural historians and robot musicians to find a relevant stand:

The University of Leicester

These guys have been studying the process of organic decay. Their stand, titled “Rotten Fish and Fossils – Resolving the Riddle of our Earliest Vertebrate Ancestors”, showcased photographs of a series of exquisitely preserved fossils – many from the Royal Ontario Museum, Toronto. I was shown a 300 million year old relative of the lamprey who stared lifelessly back at me from deep time. His modern counterpart lay equally lifeless in a nearby vacuum bag.

As part of their research, the team have been deliberately decaying various modern vertebrates in an attempt to better understand the process. One thing their team found was that the order in which structures decayed seemed to be a reverse mirror of the order in which they evolved. The implication: if you don’t identify how far along something is in the rotting process, its evolutionary relationships could very easily be misdiagnosed. You can read more about this on their site. This includes citations of published material (£).

The University of Cardiff

Project Splatter is a relatively new endeavour to track the location, variation, and frequency of road kills around the UK. Roadkills are a daily occurrence and form an important part of the corvid and fox diet. The University of Cardiff are asking for your help using social media to crowd source the data.

Most of the time all they want is the species, location, and date but, if it’s a bird of prey or an otter, they need the carcass too. As we know all too well from the DDT egg shell research, if there’s toxins in the environment it’s the top predators who get the most concentrated dose. Here’s the best part: after they have finished analysing the specimens, their remains are sent to the National Museum, Scotland to contribute to their natural science collection. With around 200 otter fatalities on the road per year, the NMS is fast becoming the best place to go for otter variation studies.

You can help out via Twitter, Facebook. They even have an Android app.

Middlesex University

Andrew Greenhargh has been playing with some fun toys involving biomechanics. While his current research is predominantly aimed at humans, the technology has been used to analyse obstacle avoidance techniques in running guineafowl during his stint at the Royal Veterinary College.

Andrew was squeamish until he met John Hutchinson: one elephant dissection later and he was a new man. One thing I learned talking to Andrew is that, when you have to euthanise a sick elephant, it is important to do it in front of the remaining elephants and give them time to grieve. They are very emotional and social animals. If you don’t do this, the other elephants can often become violent. He also talked about the keepers sitting vigil with the deceased elephant: despite recent tabloid stories to the contrary, most zoos care deeply for the animals in their care.

That’s all for my round-up of natural science university research. I did take a look at the other stands ad am happy to talk about what those institutions are up to. If you missed it and want to know more, do ask.