How Was Iron Smelted in Ancient Israel? Researchers Build Kilns to Find Out

The transition from the Copper Age to harder iron tools was a turning point for the ancient Hebrew kingdoms, but we don't know quite how they did it

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The archaeologists suspect that  iron smelting kilns were disposable
The archaeologists suspect that iron smelting kilns were only used once, and destroyed to get the iron outCredit: Ilan Assayag
Nir Hasson
Nir Hasson
Nir Hasson
Nir Hasson

The Iron Age was a turning point in the history of the Land of Israel. Iron tools began to appear around 3,000 years ago, gradually supplanting the softer copper and bronze tools. It was also a time of dramatic political change, as the Hebrew kingdoms, Judah and Israel began to take shape, which may or may not have to do with the advent of iron.

However, it has never been quite understood how the ancients actually produced their iron.

Regarding the copper that preceded iron, archaeologists know where it was mined and smelted, thanks in no small part to advanced chemical analysis. It has even been proved, for example, that Cyprus was a key source of copper for the northernmost corners of Europe thousands of years ago.

That can't be said for iron. Excavations around Israel have unearthed the rusted remains of ancient iron tools and in some places, slag from iron production as well. But the scientists know little about where the iron ore was mined, how the iron-bearing ore was processed as a raw material, and how it was then smelted.

How to smelt iron using a 3,000-year old techniqueCredit: YouTube
Making Iron like 3,000 years ago: tools used to make iron
Making Iron like 3,000 years ago: tools used to make ironCredit: \ Ilan Assayag

However, there are only so many ways the people in Judah and ancient Israel could have generated temperatures high enough to extract the iron from ore, and last week Dr. Adi Eliyahu of Ariel University set out to recreate the long-forgotten process.

Using the means that could have been available at the time and common sense, Eliyahu – who studied chemistry and archaeology at the Weizmann Institute in Rehovot – and her colleagues set out to make iron the old way.

Hair dryers and the color red

The first stage was to gather iron-rich rocks, which was done from two streams in the Negev, Nekarot and Paran. Rocks with iron can be identified by their reddish hue.

Making iron like 3,000 years ago: Adding ore to the kiln
Making iron like 3,000 years ago: Adding ore to the kilnCredit: Ilan Assayag
Smelting iron in  clay kiln
Smelting iron in clay kiln by Gedera, hopefully recreating a technique dating to the kingdoms of Judah and IsraelCredit: Ilan Assayag

The next stage was to heat the rocks in an open fire, which reached a temperature of about 500 degrees Celsius. Then the hot rocks were pulverized into fine gravel, which was placed into a tall, narrow kiln, made of strong clay, together with coal.

The kiln had an opening for ventilation. At its bottom, this crude furnace could reach a temperature of 1,300 degrees.

It is true that the researchers gave themselves some wiggle room. Their predecessors in smelting 3,000 years ago definitely didn't use electric bellows and hair dryers to create air flow. They would have used slaves or workers wielding bellows made of leather. 

But aside from that, the process Elihayu created was apparently similar to how iron was made in days of yore.

After about four hours of burning ore, occasionally adding more and feeding the kiln more coal as needed, an opening was made in the bottom of the furnace to let out molten slag.

Researchers place pulverized rocks in narrow kiln
Researchers place pulverized rocks in narrow kilnCredit: \ Ilan Assayag

Inside the belly of the kiln was a lump of iron, ready to be worked into tools or whatever. It was rather like a birth, Eliyahu says. Thirty-five kilos of ore produced seven-and-a-half kilos of iron.

One of the team members is Lee Sauder, an American researcher who produces iron using ancient technologies. In a separate workshop, he made a small knife using the smelted iron. Meanwhile, Jake Keen of Britain built a variation on the design of the iron foundry, which was operated by three hair dryers.

It bears stressing again that both these recreations of iron production techniques are ecuated guesses, no more.

A small knife made using the iron smelted by a 3,000-year-old technique (maybe)
A small knife made using the iron smelted by a 3,000-year-old technique (maybe)Credit: Ilan Assayag

Not one single ancient facility to make iron has been discovered in Israel. One theory is that this is because the ancient furnaces were used exactly once: they would be destroyed in order to extract the purified iron from their insides.

That is just theory, for now. Meanwhile, Eliyahu is just happy that she managed to produce iron from three types of ore fed to the furnaces. Other ores will be tried later, and ultimately she hopes the project will teach us more about ancient iron production in Israel.

“This idea is to go through all the stages in the process, from the raw material to the final product, so that we can build calibration tables in order to characterize findings and say where they came from," she says.

She hopes that the research will shed light on how iron tools could have been made in antiquity, and also on why there are differences between the iron tools found at different sites. Ultimately, the hope is to build a database that can facilitate the identification of the ancient tools found around Israel.

Her research, which is being done with Naama Yahalom and Yigal Harel of Hebrew University of Jerusalem and others, is supported by the Israel Science Foundation. The kilns were built in the yard of a house in Moshav Kidron, near Gedera. "There are still many open questions and we aren’t getting answers for everything, but meanwhile it looks promising,” she says.