Juvinas

A single basaltic stone that fell in southern France in 1821 and helped show that some asteroids once had volcanoes.

Key facts

Type

Achondrite (eucrite, HED group)

Fell or found

Fell (witnessed)

Year

1821 (15 June)

Country

France

Mass

about 91 kg

Official name

Juvinas

On 15 June 1821, people in the hills of the Ardèche region of southern France, near the village of Juvinas, heard explosions and saw a large stone fall from the sky. It buried itself in the ground, and when it was dug out it weighed about 91 kilograms. It was a single, large stone with a dark fusion crust. It would become one of the most important meteorites for understanding volcanism beyond Earth.

A meteorite that looked like a volcanic rock

When scientists examined Juvinas, they found that it looked strikingly similar to volcanic rocks on Earth. It is made mainly of the minerals pyroxene and plagioclase feldspar, the same minerals found in basalts, the dark rocks formed from lava. In 1825 the German mineralogist Gustav Rose described Juvinas and noted its resemblance to terrestrial volcanic rocks. This was a striking discovery. If a meteorite looked like lava, then its parent body must once have been hot enough to melt.

Juvinas is a eucrite, a type of achondrite. Achondrites are stony meteorites that lack chondrules, the tiny rounded grains found in most stony meteorites, because their parent bodies melted and erased the original textures. Eucrites are basaltic rocks, crystallised from lava or magma near the surface of their parent body.

A monomict breccia

Many eucrites have been battered by impacts on their parent body. Juvinas is described as a monomict breccia: a rock made of broken fragments cemented together, but where all the fragments are of the same kind of rock. Some parts show coarse crystals and others finer grains, reflecting different cooling conditions. Its crust is dark and slightly glossy, while fresh broken surfaces show a speckled texture of pale feldspar and darker pyroxene grains, easy to see with a hand lens. It is a fresh, well-preserved sample, and because it fell as a single large stone, there has been plenty of material available for research.

A piece of Vesta

Eucrites, together with howardites and diogenites, form the HED meteorites, which are thought to come from the asteroid Vesta. Vesta is large enough to have melted early in Solar System history, forming a metal core, a rocky mantle and a basaltic crust. Eucrites like Juvinas are pieces of that crust, and their crystallisation ages show that volcanic activity on Vesta happened within the first few million years of the Solar System's history.

NASA's Dawn mission confirmed in 2011 and 2012 that Vesta's surface is made of rocks with compositions matching the HED meteorites, and that a giant impact near its south pole could have blasted out pieces that eventually reached Earth.

Using Juvinas as a reference

Because it is large, fresh and well studied, Juvinas has been used as a standard reference for eucrite chemistry. Researchers measure elements and isotopes in it to compare with other meteorites, and to understand how the crust of Vesta formed and changed. It has also been used to study radioactive isotopes that decay over time, helping to date events in the early Solar System.

Why it matters

Juvinas helped scientists realise that not all meteorites are primitive fragments left over from planet formation. Some come from bodies that melted, formed layers and erupted lava, just like a small planet. It is one of the best-known eucrites, with specimens held in museums including in Paris.

Its story is a reminder that a single stone, carefully collected and studied, can change the way scientists think about the early Solar System. When you look at a slice of Juvinas, you are looking at lava that cooled on the surface of an asteroid about 4.5 billion years ago.

Did you know?

See more

Juvinas in the catalogue