Almost 500 blue artefacts have linked Iron Age Iran with ancient Egypt

Vivid blue minerals are relatively rare in nature, so producing a stable blue pigment was no easy task for ancient artisans.

Egyptian blue became one of the first examples of how people did not simply grind natural minerals to produce pigment, but deliberately created a new material.

To do this, the craftsmen mixed a substance containing copper, quartz sand, an alkali — such as plant ash or natron — and limestone. The mixture was ground and then heated to a specific temperature.

This resulted in the formation of crystals that gave the material its characteristic blue colour.

In terms of its chemical composition, the resulting substance corresponds to the extremely rare natural mineral cuprivite. However, the vast majority of known samples of this material are of artificial origin.

In Ancient Egypt, Egyptian blue was widely used in painting, and later it was also used to make small objects, including beads and amulets.

Details

Archaeologists made particularly interesting discoveries at the sites of Hasanlu and Dinh-e Tepe in north-western modern-day Iran.

Excavations were carried out by expeditions affiliated with the Penn Museum from the 1950s to the 1970s. Among the finds were nearly 500 objects made from Egyptian blue paste, dating from the Iron Age.

It was the scale of the material’s use that surprised modern researchers.

In Egypt and other parts of the Middle East, Egyptian blue was often used as a pigment or to make small objects. At Hasanlu, archaeologists discovered not only beads, but also bracelets, anklets, vessels, decorative wall tiles and even large pieces of furniture.

It appears that this material, the production technique for which originated in Egypt some two millennia earlier, was used very widely in Iran.

Now, archaeometallurgist Vanessa Workman and conservator Alexis North, together with their colleagues, are re-examining the finds.

One of the distinctive features of Egyptian blue makes it much easier to detect. When exposed to visible light, the material emits a characteristic glow in the infrared spectrum. Thanks to this, experts can identify even small traces of the pigment without damaging the objects.

After cataloguing the finds, the scientists began a more detailed analysis.

They are studying the chemical differences between the samples, examining the material’s structure under a microscope and attempting to understand the production techniques used. A separate area of research focuses on the composition of the raw materials.

Its characteristics may indicate the origin of the materials used by ancient craftsmen, thereby narrowing down the possible region of manufacture.

One of the key questions is whether Egyptian blue was imported into what is now Iran, or whether local craftsmen learnt to produce it themselves.

If the analysis shows that the pigment was produced directly in north-western Iran, the finds could represent the earliest known evidence of Egyptian blue production outside Egypt, notes Vanessa Workman.

But for now, this is just one of several hypotheses being tested.

The researchers also need to understand another point: if local craftsmen did indeed master the technique, where did they obtain the recipe and the necessary knowledge?

Egyptian blue required not just the haphazard mixing of readily available substances, but a rather complex sequence of steps and careful control of the heating process. Therefore, the spread of such technology can reveal a great deal about the contacts between ancient societies.

Chemical analysis of the finds allows us to study more than just the objects themselves.

By comparing the composition and origin of raw materials, archaeologists can reconstruct the trade and cultural links that existed thousands of years ago. Such data helps us understand how far people, goods and technologies travelled.

This is precisely why the hundreds of blue artefacts from Hasanlu are of particular interest. If scientists succeed in identifying where the material was produced, they will gain further insight into just how closely interconnected the various regions of the ancient world were.

As Workman notes, modern methods are increasingly showing that, in the past, people moved and interacted over much greater distances than researchers had previously assumed.

Why this matters

Egyptian blue is not merely a paint of an unusual colour. Its emergence was one of the earliest examples of how people deliberately employed complex processing of raw materials to produce a substance with specific properties.

Finds from Iran show that, some two thousand years after this technology first appeared in Egypt, the material was already being used far beyond its borders, and on a significant scale.

Now, scientists must determine the key question: did the pigment itself travel, or did knowledge of how to create the colour blue practically from scratch spread across the ancient world alongside trade and cultural contacts?

Source

An article in Penn Today, University of Pennsylvania, based on the work of archaeometallurgist Vanessa Workman from the School of Arts & Sciences and the Centre for the Analysis of Archaeological Materials at the Penn Museum, and conservator Alexis North. Experts are examining around 500 objects made of Egyptian blue, found at Hasanlu and Dinh-e Tepe in north-western Iran, to determine the technology and possible place of production of the material.