Meteoric iron

Rock Low Classical

Also known as

kamacitetaeniteWidmanstatten iron

Crystal system

cubic

Hardness

4–5 on the Mohs scale

Lustre

metallic

Colour

Metallic grey, often with a fusion crust

Where it forms

In the cores of asteroids large enough to have differentiated, then broken apart. The crystal pattern requires cooling at a few degrees per million years.

Chiefly from

Campo del Cielo, ArgentinaGibeon, NamibiaSikhote-Alin, RussiaCape York, Greenland

Why it is that colour

Metallic. Cut and etched with acid, it reveals the Widmanstatten pattern — interlocking bands of two nickel-iron alloys that cannot be reproduced on any human timescale.

Safety

Safe to handle, but it rusts aggressively — meteoric iron contains chlorides that drive corrosion, and untreated specimens can degrade badly in humid air. Keep dry.

Where it comes from

Meteorites are collected and traded, and provenance matters legally as well as scientifically — several countries prohibit export, and material from Antarctica and from some national parks cannot lawfully be collected. The Cape York meteorite was removed from Greenland by Robert Peary in 1897 and sold to the American Museum of Natural History; the Inuit who had used it for generations were not compensated, and Peary also brought six Inuit people to New York, four of whom died there.

Historical use

Tutankhamun’s dagger is meteoric iron, confirmed by X-ray fluorescence in 2016 — its nickel content matches iron meteorites and no terrestrial source of the period. Iron objects in Bronze Age contexts are frequently meteoric for the simple reason that nothing else was available.

Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.

What is attributed to it, and since when

Genuinely ancient and genuinely well founded: before smelting, this was the only source of metallic iron, and cultures that had it knew it came from the sky. The Egyptian term for iron translates roughly as metal of heaven. Inuit at Cape York worked iron from the Cape York meteorite into harpoon blades for centuries.

Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.

Worth knowing

The Widmanstatten pattern is a genuine certificate of extraterrestrial origin. Etch a cut face of an iron meteorite with dilute acid and interlocking bands appear — two nickel-iron alloys, kamacite and taenite, that separated as the metal cooled. The bands are broad because the cooling was extraordinarily slow: a few degrees per million years, which only happens inside a body large enough to insulate its own core.

No terrestrial process makes it, and no forgery can, because the required cooling rate is not available on any human timescale. If a piece of metal shows the pattern, it came from the core of a shattered asteroid.

The Cape York story deserves its place. For centuries the Inuit of northwest Greenland had the only iron in their region and worked it cold into tools. Peary took the three largest masses in 1897, sold them, and took people as well.

Identity checked against IMA-CNMNC master list, June 2025.