How did ancient cultures first discover iron? It fell from the sky.

Inside a 4,400-year-old royal tomb in Egypt, I studied the walls searching for a particular symbol. The shapes of one of the oldest writing systems—vultures and owls, eyes and feet, snakes and half circles—were etched into the limestone in neat columns. Flecks of brilliant blue pigment, a prized adornment in the Old Kingdom, still lined the crevices of the hieroglyphs.

The symbol I was trying to find looks something like a bowl with a horizontal line just beneath the brim, as if it were filled with water. Fluorescent lights on the floor lit the dim antechamber, casting shadows across the texts as tourists and guides milled about. Rows of carved five-pointed stars covered the vaulted ceiling.

Egyptologist Victoria Almansa-Villatoro scanned the hieroglyphs with two extended fingers. Wearing a white baseball cap, a magenta backpack, and Nike sneakers with a pink swoosh, she cut an image of modernity, striking in that ancient place. A scholar of Old Kingdom texts with the Harvard Society of Fellows, Almansa-Villatoro had agreed to show me the tombs of Saqqara, about 15 miles south of Cairo.

This burial place belonged to Unas, the last ruler of the 5th dynasty from the 24th century B.C. The passages on the walls, called spells by Egyptologists, were intended to guide the deceased king through the perils of the afterlife. They are the oldest such writings, collectively known as the Pyramid Texts.

Almansa-Villatoro’s fingers froze over a column of symbols next to the passageway to Unas’s sarcophagus. “There you go,” she whispered excitedly, pointing to the U-shaped marking.

The symbol, Almansa-Villatoro’s research suggests, was used to refer to iron—a remarkable thing for Egyptians to write about at that time. It would be roughly a thousand years before humans learned to reliably smelt iron. But there is another source of the metal: meteorites.

Within the past decade, studies of artifacts have confirmed that some civilizations used iron from meteorites to craft objects before smelted iron was available. In a cemetery on the Nile called Gerzeh, dated to about 5,200 years ago, archaeologists discovered nine beads made of meteoritic metal. An exquisitely made polished dagger and other meteoritic iron objects were among the treasures sealed in Tutankhamun’s tomb about 3,300 years ago. Ancient jewelry and weapons made from this rare material have also cropped up in other parts of the world: beads in North America, axes in China, and a dagger in Turkey.

In most cases, it isn’t known whether these cultures understood where meteorites came from. In the tomb of Unas, however, the funerary texts tell of metal in the sky, suggesting Egyptians may have not only recognized the phenomenon of falling iron but also incorporated it into their mystical beliefs.

Almansa-Villatoro broke down the semantics of the sentence for me. She pointed out an arched symbol meaning “sky” and a teardrop-shaped glyph indicating “metals.” Together with the bowl symbol, these hieroglyphs refer to a metal belonging to the sky, she explained.

“Unas seizes—grabs—the sky and splits its iron,” she translated.

This line describes the journey of Unas into the divine realm of the sky. The exact meaning is obscure, but Almansa-Villatoro argues the passage reflects a belief that the sky is a great water-filled iron basin from which rain and metal sometimes fall. To reach the afterlife, the Pyramid Texts tell us, the king must sail across this celestial domain.

The texts, which also appear in the tombs of later rulers, include other equally abstruse references. “The iron door in the starry sky is pulled open,” reads one line, according to Almansa-Villatoro’s translations. They also tell of an “egg” of iron, a possible metaphor for the womb of the Egyptian sky goddess Nut. “He will break the iron after he has split the egg,” another line says.

“Iron has all these cosmological connotations with creation and, therefore, resurrection,” Almansa-Villatoro says. To split the iron egg of the sky is to return to the womb to be reborn.

Meteorites: from myth to fact

Rock and metal have pummeled Earth since its earliest days, mostly fragments of planetary bodies pulverized in collisions. Every year, roughly 17,600 meteorites weighing more than 50 grams reach Earth. Most are primarily stone, but about 4 percent are iron-nickel alloys distinct from terrestrial iron. They usually land unnoticed, with people witnessing only about five of these falling objects a year.

The first dated account of a possible meteorite fall appears in the writings of ancient Greeks and Romans. Aristotle, Plutarch, and Pliny the Elder, among others, wrote about a stone landing in 467 or 466 B.C. in what is now Turkey. “It will not be doubted that stones do frequently fall,” Pliny observed.

Plutarch also recounts a Roman military engagement in the first century B.C. that may have been interrupted by a meteorite. “As they were on the point of joining battle, with no apparent change of weather, but all on a sudden, the sky burst asunder, and a huge, flamelike body was seen to fall between the two armies,” he wrote. “In shape, it was most like a wine jar and in color, like molten silver.”

In 861, near a shrine in Nogata, Japan, according to oral traditions compiled in 1927, “a great detonation occurred,” “a brilliant flash was seen,” and “a black stone was found at the bottom of a newly made hole in the ground.” In 1983 Japanese scientists studied the meteorite, which is kept in an old wooden box inscribed with the year. After carbon-dating the container, they concluded the stone likely fell as described.

In Europe, though, until the beginning of the 19th century, most scientists had been skeptical that meteorites were a real phenomenon. In April 1794 German scientist Ernst Chladni published a book that compiled reports of stones and iron dropping from the sky—an endeavor that earned him ridicule.

Then the cosmos intervened. In June 1794 a hail of rocks was seen by witnesses outside of Siena, Italy. The next year a 56-pound stone fell in Wold Cottage, England.

The impacts prompted English chemist Edward C. Howard and French mineralogist Jacques-Louis de Bournon to collect samples from “fallen bodies.” Their analyses, published in 1802, showed that four stony meteorites had compositions and structures unlike terrestrial rocks. Howard also measured high nickel content in three iron meteorites and one stony-iron meteorite, revealing the metal was distinct from that smelted from ore.

But it wasn’t until 1803 that the European scientific community was fully convinced of what Pliny seemed sure of. That year, a meteorite shower pelted L’Aigle, France, with about 3,000 stones.

With that, scientific interest in meteorites grew. English naturalist James Sowerby amassed a collection in his personal museum, including the Wold Cottage meteorite. He was so infatuated with them that he used a piece of an iron one found in South Africa to have a sword forged for Tsar Alexander I of Russia to commemorate the defeat of Napoleon in 1814. The inscription he had engraved on the blade begins: “This Iron, having fallen from the Heavens …”

Rare metal, precious objects

Whether or not they knew it came from the sky, ancient peoples valued meteoritic iron. Copper, silver, and gold exist in metallic form, available to be mined and worked, but on Earth, iron is almost always bound up with other elements, such as oxygen, in minerals called ores.

The oldest known objects fashioned from space metal were ornaments, such as the Gerzeh beads, some of which were strung along with gold and gemstones, including lapis lazuli, carnelian, and agate.

“In the beginning it was used for precious things, beads and representative stuff, because it was so exotic,” says Katja Broschat, a restorer at the Leibniz Center for Archaeology in Mainz, Germany. “It took a while until the manufacturing technique … was good enough to produce a weapon or tool material.”

By the time Tut’s dagger was made in the Late Bronze Age, artisans had learned to grind and polish the meteoritic metal into a fine blade. “It’s very sharp,” says Broschat, who has studied the artifact. “I’m sure you can kill an animal, or whatever, maybe even a man.”

The knife has a gold hilt with stone and glass inlays, a pommel of rock crystal, and a gold sheath with elaborate designs. Found in the wrappings around the mummy’s right thigh, the dagger was “something that he would need in the afterlife to fight against the demons, or whatever dangers the afterlife has, because the afterlife is a dangerous place,” Almansa-Villatoro says. “It’s also a marker of status.”

Tut’s dagger is one of the most expertly wrought objects of its kind, but evidence of ancient cultures using meteoritic iron has been found elsewhere in the region and the world. A likely meteoritic iron dagger from a royal tomb at Alacahöyük in Turkey predates Tut’s knife by about a thousand years.

In China, a knife and a pole weapon with a dagger-ax called a ge, both with meteoritic iron blades, were found in the tombs of two men, possibly brothers, who ruled the Guo state in the eighth or ninth century B.C. The weapons were probably ceremonial, like those with jade blades from this time, says Kunlong Chen, a professor at the University of Science and Technology Beijing.

Similar objects—a ge and a broadax with meteoritic iron blades—were acquired by the Smithsonian Institution in 1934, reportedly from Henan Province, where there are Zhou dynasty sites. The broadax was likely made during the earlier Shang dynasty and may have been passed down as a cherished possession. These types of weapons were used around the time the Zhou state overthrew the Shang rulers and instituted the Mandate of Heaven, the philosophy that the king ruled by divine decree.

Did these rulers know the weapons were made of celestial metal? No contemporary references to meteorites have been discovered, but Chinese texts refer to eclipses and comets. “Astronomy was already quite developed by this point,” says Keith Wilson, a curator at the Smithsonian’s National Museum of Asian Art. “So we do know that there may well have been kind of court astronomers, and they were watching the skies.”

In North America, dozens of beads, earspools, small blades, and other objects of meteoritic iron have been discovered within the burial mounds of the Hopewell, a widespread network of cultures that traded exotic materials. Many of these objects were found at various sites in Ohio, but 22 tubular beads once strung together with shells were found in a grave dated to about 300 B.C. near what is now Havana, Illinois.

A team of researchers determined that the Havana beads were made from iron from a meteorite shower that struck some 400 miles north, near what is now Anoka, Minnesota. The raw metal from the Anoka meteorite was likely traded to the Havana center, where it was fashioned into the beads.

With no written records, it’s impossible to say whether these peoples understood that the metal came from the sky. “We know a lot about the material culture,” says Tim McCoy of the Smithsonian’s National Museum of Natural History. “We don’t know an awful lot about their belief systems.”

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Elsewhere, meteorites themselves provide clues about people’s interactions with extraterrestrial metal. In Argentina, a field of impact craters about 500 miles northwest of Buenos Aires was created by a shower of iron meteorites roughly 4,500 years ago. In the 16th century the Spanish governor of Tucumán Province heard from Indigenous people about hunks of metal that had fallen from the sky.

Guides led Spanish soldiers to the region, reportedly called Piguem Nonraltá by the Indigenous populations and translated as Campo del Cielo, meaning “field of the sky.” The soldiers found a large slab of iron but refused to believe the stories that it had dropped from above. The Indigenous people made weapons from the iron, according to Spanish reports, but none survive.

Campo del Cielo contains at least 26 impact craters. More than 110 tons of iron have been recovered from the area, including two of the largest meteorite fragments in the world—one of which, weighing 34 tons and named Gancedo after a nearby town, was discovered only in 2016.

Researchers with the National University of La Plata in Argentina recently investigated whether Indigenous stories of great cataclysms could be descriptions of the impact. They didn’t find a definitive link but noted that some of the tales include fire or stones falling from the sky. They also concluded the meteorite shower “was of such magnitude that it must have deeply marked the cultures in the area.”

Finding meteoritic metal

How often people used sky metal has proved difficult to puzzle out. Hundreds of iron objects from Bronze Age sites are listed in archaeological records, but most have not been analyzed, and many are no more than small bits of rusted metal that may have been things like pins or rings.

“If you look at what has already been excavated and how little of that even has been studied, that is a scandal,” says Thilo Rehren, an archaeological scientist at the Cyprus Institute. Like many archaeologists, Rehren is interested in distinguishing between meteoritic and smelted iron, not necessarily to discover celestial metal but to figure out how and where the Iron Age began.

Civilizations in West Asia and the Caucasus Mountains began making bronze as early as the fourth millennium B.C. But most experts believe humans would not learn to reliably extract iron from ore until the end of the second millennium B.C. Smelting iron requires temperatures of roughly 2,200 degrees Fahrenheit.

“When you start making smelted iron, it’s a big business, where you can be able to make weapons which are not expensive to produce,” says geochemist Albert Jambon, a professor emeritus at Sorbonne University in Paris. “There is a switch from one economy to a new economy.”

Jambon has spent the past dozen years tracking down iron objects from the Bronze Age and analyzing them. His research brought him to Aleppo, Syria, where he examined a spherical iron pendant found in the ancient city of Umm el Marra, in a tomb dated to 2300 B.C. It was among a woman’s grave goods, which included beads of gold and stone and a piece of lapis lazuli carved into the figure of a goat, all of which may have dangled from a necklace. The museum in Aleppo also had a copper ax-head with an iron blade, dated to about 1400 B.C., discovered in the ruins of Ugarit, a port city.

Jambon measured the chemical composition of these objects with a handheld x-ray fluorescence machine, which looks a bit like a ray gun. His analysis led him to conclude that both artifacts are meteoritic.

I met Jambon in Nicosia, Cyprus, where he was studying the island’s extensive collection of early iron artifacts, which date to about 1200 B.C. This presents something of a mystery, considering the island does not have any typical iron ores, such as magnetite and hematite.

In a dusty storeroom of the Cyprus Museum, Jambon used his x-ray gun and a small magnifying glass to examine dozens of iron artifacts. “Ooh là là,” he murmured as he saw the first one, the end of a sickle. “C’est vraiment bien.”

Despite his excitement, these artifacts weren’t likely to be displayed. Iron rusts when exposed to oxygen, unlike bronze, which develops a green patina, or gold, which does not oxidize at all. Next to well-preserved treasures, corroding metal does not appear so striking. And none, it seemed, were made of meteoritic metal. Most were knives, but a spiral ring and a brooch served as a reminder that even after iron smelting began, the metal was considered precious.

Interpreting ancient texts

Artifacts that could help piece together the puzzle of the Iron Age’s origins are gradually corroding, but additional clues about iron are still being discovered in early texts.

Between the 20th and 18th centuries B.C., the Old Assyrian city-state of Assur in modern Iraq established trade colonies in what is now Turkey. Some 20,000 cuneiform tablets found at Kültepe-Kanesh, the site of the primary outpost, reveal details of this trade. The records include multiple terms connected to iron, such as the Akkadian word parzillum, which is also used in later periods. One of the most common, however, is the term amūtum, which appears with cuneiform signs that can mean “metal” and “sky.”

Whether this term refers explicitly to meteoritic iron, or if it could simply be the word for a type of metal, is unclear. “Whatever it is, it’s super expensive,” says Gojko Barjamovic, an Assyriologist at Harvard University. The records from Kültepe-Kanesh show that this sky metal was traded for as much as 40 times the price of silver.

Parzillum appears again in two cuneiform tablets sent to Egypt in the 14th century B.C. The tablets, among 382 found in the ancient Egyptian capital of Amarna, describe three daggers with iron blades as well as bracelets of iron and an iron mace covered in gold.

These objects are included on lists of gifts sent from Tushratta, the ruler of the Mitanni kingdom in what is now Syria and Turkey, to the Egyptian Pharaoh Amenhotep III. Tutankhamun is believed to have been Amenhotep III’s grandson, which has led some scholars to argue that Tut’s iron dagger could be one of those mentioned in the lists, perhaps passed down as an heirloom.

More terms for iron appear in records from the Hittite Empire, which became the dominant power in much of present-day Turkey and Syria around the 14th century B.C. These include “good iron,” “black iron,” and possibly “white iron,” apparently to distinguish different types. A ritual preserved in several texts describes the gods building a temple. In one version, a line states: “They brought black iron of the sky”—a possible reference to the black crust that coats meteorites after their fiery plunge through the atmosphere.

“This kind of thing does indicate that they seem to know that it’s coming from the sky,” says Mark Weeden, a scholar of Hittite texts at University College London.

Hittite inventories mention hundreds of iron objects, including blades, jewelry, statuettes, and a 66-pound basin. The amount of iron described in these texts, as well as descriptions of people working iron, have led some scholars to conclude the Hittites may have developed iron smelting by this point. But only about two dozen artifacts of rusty iron have been discovered at Hittite sites, and they have not been analyzed to determine if they are meteoritic, leaving the extent of ironworking at this time a mystery.

The right order of things

At the Egyptian Museum in Cairo, I admired two iron objects found with Tutankhamun’s mummified remains that were recently confirmed as meteoritic. One is a pendant of the Eye of Horus hanging on a gold alloy bracelet, discovered near Tut’s right rib cage in the wrappings. The icon is one of the most recognizable from ancient Egypt, used continuously for more than 2,000 years. It comes from an Egyptian saga of the struggles between Horus, a god of order, and Seth, a god of chaos. Seth rips out Horus’s eye, which is later restored. The symbol represents a return to the right and proper state of things.

The other is a small charm in the shape of a headrest, like the full-size ones made of wood that the Egyptians used when they slept. It was found in the back of Tut’s funerary mask. These headrest amulets served as symbols of rebirth. The image of a round head on a curved headrest evoked the rising sun, the god Re, who was birthed by the sky goddess Nut each morning and swallowed by her each night.

I couldn’t help but wonder if the people who made these talismans knew where the otherworldly material came from. While carefully filing the lines of Horus’s eyebrow, did the artisan think about how the metal had come into his hands from the realm of the gods? When the small bit of iron was bent into the shape of a headrest, did the curved amulet remind the metalworker of the great basin in the sky?

We will never know, but we do know that descriptions of metal in the sky would endure in Egyptian writings for thousands of years. The funerary spells in the Pyramid Texts evolved into the Coffin Texts, painted on caskets inside and out. “I know the Field of Reeds of Re,” reads one line repeated on several coffins, referring to a region in the sky. “The wall that goes around it is of iron.”

By the 13th century B.C., a more direct way of writing “metal of the sky” came into use. Funerary spells then were written on papyrus and today are known as the Book of the Dead. In one spell, a great fishing net is described—a barrier the deceased must navigate in their journey to the afterlife. “Do you know that I know the name of its weights?” the Book of the Dead intones. “It is the iron in the midst of the sky.”