Gibeon

A prehistoric shower of iron across southern Namibia, whose crystal patterns now gleam on watch faces and rings.

Key facts

Type

Iron, IVA (fine octahedrite)

Fell or found

Found

Year

1838 (first scientific report)

Country

Namibia

Mass

about 26 tonnes recovered

Official name

Gibeon

Across a huge area of the dry Hardap region in southern Namibia, around the town of Gibeon, lie scattered masses of iron that fell from the sky in prehistoric times. The local Nama people knew them well and used the metal to make tools and weapons. Europeans began reporting the irons in the 1830s, and Gibeon has since become one of the most famous iron meteorites in the world, prized by scientists and admired by anyone who has seen its beautiful internal pattern.

A gigantic strewn field

When a meteoroid breaks apart in the atmosphere, its fragments rain down over an oval-shaped area called a strewn field. Gibeon's strewn field is one of the largest known, stretching for well over 200 kilometres. Well over a hundred individual masses have been recovered, ranging from small pieces to masses weighing several hundred kilograms, with a total of about 26 tonnes. No crater has been found; the fall probably happened so long ago that any small craters have been worn away.

Crystals that took millions of years to grow

Gibeon belongs to the IVA group of iron meteorites, which are thought to come from the metal core of an asteroid that melted early in the Solar System's history. When a specialist cuts a slice, polishes it and etches it with a weak acid in a laboratory, an extraordinary geometric pattern appears: the Widmanstätten pattern. It is made of thin plates of a nickel-poor metal called kamacite, interwoven with a nickel-rich metal called taenite, crossing one another at precise angles.

This pattern is a kind of clock. It can only grow as molten metal cools incredibly slowly, over millions of years, which is why it has never been reproduced in ordinary laboratory metal. In Gibeon the kamacite plates are thin, giving a delicate 'fine octahedrite' pattern. Studies of IVA irons suggest their parent body had a turbulent history, possibly including a violent collision that stripped away its rocky outer layers and changed how fast its core cooled.

Etching uses acids and is a job for trained adults with proper safety equipment. Children should never cut, heat or put chemicals on meteorites.

From desert to jewellery

Because Gibeon's pattern is so attractive and the metal is less prone to rusting than many iron meteorites, slices have long been used for jewellery, rings and watch dials. Much of this material comes from older collections. Namibia now protects its meteorites as part of its national heritage: collecting or exporting Gibeon without official permission is illegal. In the capital, Windhoek, a group of large Gibeon masses is displayed in a public street, where passers-by can see and touch them.

Why Gibeon matters

Gibeon is one of the clearest examples of how much information is locked inside an iron meteorite. Its chemistry records the slow crystallisation of a molten core; its pattern records cooling over millions of years; and its huge strewn field records the break-up of a large metal body high above southern Africa. It also shows how meteorites become part of human culture, from Nama tools to modern design, and why countries increasingly treat them as heritage to be protected rather than simply as rocks to be carried away.

Gibeon also shows how iron meteorites change on Earth. A freshly fallen iron has a thin, dark fusion crust, but after a very long time in the desert the Gibeon masses have weathered to a dull brown or grey skin. Some contain rounded nodules of troilite, an iron sulphide mineral that appears as bronze-coloured patches on cut slices, and these too carry chemical clues about the molten core in which the metal formed.

Next time you see a watch or ring with a shimmering silver-grey lattice, look closely. If it is Gibeon, you are looking at crystals that grew in the heart of a small world more than four billion years ago, long before Earth had oceans full of life.

Did you know?

See more

Gibeon in the catalogue