Several ancient Egyptian coffins and mummy cases have been found covered in a mysterious 'black goo'.
Dr Kate Fulcher, Research Assistant in the Museum's Department of Scientific Research, explores what this goo is made from, why it may have been used and what it can reveal about Egyptian funerary practice.
Ancient Egyptian coffins and mystery of ‘black goo’
Djedkhonsiu-ef-ankh lived and died almost 3,000 years ago in ancient Egypt. We don't know a lot about Djedkhonsiu-ef-ankh's life, but we do know he was a priest in the temple of Amun at Karnak. Here he had two main roles – one was 'Opener of the Doors of Heaven', which meant he was one of the priests who was entitled to open the doors of the shrine in the temple sanctuary, containing the cult image of the god.
After Djedkhonsiu-ef-ankh died, he was mummified, wrapped in fine linen and sewn into his plaster and linen mummy case. This case was beautifully painted in bright colours and gilded with gold leaf over the face. At the time of his funeral, he was lowered into his coffin, and carried to his tomb. Then several litres of warm black 'goo' were poured all over the mummy case, covering it completely, effectively cementing the case into the coffin. The lid was then placed on the coffin, and he was left to journey forth to the underworld.
Djedkhonsiu-ef-ankh was not unique. Though not used by everyone – there are a number of instances of this 'black goo' being used in Egyptian burials. But what is it? And if we find out what it was made from, can we learn more about why the Egyptians used it?
There are many texts that deal with spiritual preparations for death in ancient Egypt, but very few texts that deal with practical aspects. Knowledge about the practices around mummification and burial appear to have been restricted. So one of the best ways to learn more about this black goo is to chemically analyse it to find out what it is. We can do this in our science labs hidden underground the Museum.
What is 'black goo'?
British Museum experts have analysed more than 100 samples of black goo from twelve coffins and mummy cases, all dating to the 22nd Dynasty in the Third Intermediate Period (c. 900–750 BC). To do this, we take tiny samples and conduct a form of chemical analysis called 'Gas Chromatography - Mass Spectrometry (GC-MS)'. This involves vaporising each sample and pushing it through a long tube, which separates the molecules in the sample. At the end of the tube, the molecules go into a mass spectrometer which separates them according to their mass to charge ratio. From this we can tell which molecules are present and in what quantities.
We discovered that the goo is made of a combination of plant oil, animal fat, tree resin, beeswax and bitumen – which is solid crude oil. The exact ingredients vary from one coffin to the next, but the goo was always made from some of these ingredients. It is possible there were other ingredients as well, that we can no longer detect, because they were volatile and evaporated, or have degraded to undetectable levels over the 3,000 years since the goo was applied.
Where did the ingredients come from and how were they sourced?
Some of the products we have identified only naturally occur outside of Egypt, indicating that these were imported. The two tree resins we often find in black goo are pistacia tree resin and conifer tree resin. Tree resin is a liquid that trees produce in response to injury, which hardens to a brittle solid.
Pistacia trees grow around the Mediterranean, from Greece to Western Asia. Amphorae (pots) that contained resin from pistacia trees have been found at Amarna, the Egyptian royal city from 1347 to 1332 BC, and in the Uluburun shipwreck (off the coast of west Turkey) from approximately the same date. Analysis of the ceramics shows that these pots were most likely made in the region around Haifa in modern Israel, which is probably also where the resin was collected. Pistacia resin was also used as incense in ancient Egypt, and as a golden varnish on painted coffins, so we know it was being imported in reasonable quantities.
Conifer resin may come from a variety of trees, including pine, cedar, fir and juniper, but it's difficult to distinguish between these resins after so many years. The furthest south that these types of tree grow is Lebanon, which indicates that this resin was also imported into Egypt from somewhere further north. Conifer resin has also been found in jars relating to other ritual or funerary uses, again suggesting it was a common import.
Bitumen is an umbrella term for crude oil products. There are many sources known to have been used in ancient times, some liquid and some solid. Bitumen is made from living things (like plants, animals and single-celled organisms) that have died and been compressed over millions of years. Because these living things vary due to the local environment, bitumen also varies from place to place.
Examining the remains of these livings things, which we call 'biomarkers', is the key to finding out the source of the bitumen. By comparing the biomarkers in the goo sample to those from known sources, we can see that the bitumen came from the Dead Sea. This makes sense as ancient Greek texts refer to solid blocks of bitumen floating to the surface of the Dead Sea and people rowing out to these to hack pieces off and sell them in Egypt.
What was it used for and why?
We can't say for certain but, significantly, previous analyses of mummification balm (used on the bodies themselves) have shown it to be made of the same ingredients as the black goo that we have been studying on the outside of coffins and mummy cases. This means the black goo was being used at different points in the burial process – during the preparation of the dead body, and then again during the funeral, on top of the mummy case or coffin.
When someone died, they were said to become a form of the god Osiris, who is associated with death and rebirth. Osiris was called 'the black one' in various funerary texts and is often depicted with black skin and in the guise of a mummified body. Black is also the colour associated with the alluvial silt deposited on the banks of the River Nile after the annual flood receded. Since this fresh and fertile soil provided the ideal environment in which seeds for crops could germinate and grow, it was viewed it as being inherently magical and regenerative. Clay and wooden seed beds in the shape of Osiris, filled with black soil from the Nile and sown with germinating seeds, were sometimes included with the funerary equipment in New Kingdom burials. So, we have interlinking concepts of black, Osiris, and regeneration. It could therefore be reasoned that the practice of coating coffins in black goo links the coffins to regeneration associated with Osiris.
In addition to mummy cases, black goo was also painted on funerary statues of deities. There are several examples of this in the British Museum from the tombs of New Kingdom kings from about 1300 BC, including the seated figure pictured below. Many statues from the tomb of Tutankhamun were also covered in black goo, although these examples have not been analysed. Some shabti boxes (boxes used for holding figurines to be left in the tomb of the deceased) were also coated in black goo. So, it appears that the goo was a ritually important anointing fluid used for a range of purposes, all relating to the burial of the deceased and their transformation into Osiris.
But not everyone got the goo treatment. Evidence suggests that it was likely to have been reserved for social elites. Some of the earliest examples are from royal burials. Tutankhamun's innermost gold coffin was cemented into the middle coffin with 'bucketfulls' of black goo (since cleaned off). The black goo was also available to non-royals but the family had to be able to afford the treatment. Even among social elites, not everyone had black goo, and it seems to have been a matter of personal choice. Examples of the use of black goo are more common in the Third Intermediate Period (c. 1069 BC–c. 664 BC), which may be related to changes in funerary practices, or because more coffins are preserved from this time.
Recent excavations at the ancient town of Amara West, conducted by the British Museum in collaboration with the National Corporation for Antiquities and Museums (NCAM) in Sudan, have uncovered a crumbly black substance in a tomb dating to the end of the New Kingdom c. 1100 BC. Analysis of this black substance found that it contained oil, wax, pistacia resin, and bitumen, which means that this is an example of black goo. Amara West is in Nubia, an area to the south of Egypt that the Egyptians sought to control because of its gold deposits. This is the first example of black goo being found in Nubia and shows Egyptian funerary rites being used far away from the centre of power in Egypt.
There is more to be discovered. Most of the research so far has been into later examples of black goo, we hope that looking at examples from earlier times will tell us how the ingredients changed over time. We also hope to make some of the black goo ourselves to enable us to think more about how it was stored, transported and poured, what it smelt like, and how hot it had to be. This will help us to reimagine what a funeral might have been like in ancient Egyptian times.
The Department of Scientific Research and Dr Kate Fulcher's work are supported by the Wellcome Trust.