When you engage with an exhibit in a museum, you learn where
it’s from and the part it plays in history, culture or nature. It
may link in with other exhibits to tell a more wide-ranging story.
But often the story of the object’s journey before its inclusion in
the museum is equally fascinating.
As Peter Davidson, Curator of Mineralogy explains, “Our Earth in
Space gallery will explore the origins and growth of the Universe
and the place of the Earth through exciting static and interactive
displays on subjects such as ‘matter’, ‘space’ and the ‘origins of
life’. We will use meteorites to show that matter from Space is the
same as matter on Earth. We wanted to find a large meteorite which
could go on open display so that visitors can touch a real
extra-terrestrial object, feeling both the strangeness and
familiarity of these rocks from space.”
And so a fragment of the Muonionalusta meteorite was collected
from a dealer in Denmark. It takes its name from the parish around
the village of Kitkiojöki in northern Sweden, where a number of
large meteorite fragments have been found since 1906. This piece
was uncovered in 2004 and weighs a hefty 170kg. It was part of a
much larger meteor which broke up as it entered the Earth’s
atmosphere about 800,000 years ago.
Earth in Space tells the story of the three main meteorite
types: irons, stony-irons and stony. The names reflect their
compositions: mainly metal for irons, principally rock for stony
meteorites and a mixture of the two for stony-irons. The
Muonionalusta meteorite is an example from the iron group.
Iron meteorites are thought to have formed at the core of a
small planet or large asteroid and may be similar to the material
at the core of the Earth. Staff at the National Museums Collection
Centre found the meteorite to be highly corroded and their primary
concern was to halt the corrosion before too much damage was done.
They placed it in a protective polythene enclosure with dry silica
gel. However, corrosion continued to develop so it was agreed there
was a need for a specific project between the Natural Sciences
curators (Peter Davidson and Vicen Carrio) and the Conservation and
Analytical Research Department (Theo Skinner, Jane Clark, Lore
Troalen and a student from Paris Sorbonne University, Gaëlle
Giralt).
It’s very common for archaeological iron artefacts buried in
soil or found underwater to suffer from active corrosion.
Treatments to stop such corrosion have been studied extensively.
However there has been less research carried out into the corrosion
of meteorites and what has been done relates to smaller scale
specimens. Dr Jim Tate, Head of Conservation and Analytical
Research says, “The stabilisation treatment of a piece as massive
as 170kg was very challenging, but fortunately the conservation
workshop at the Collection Centre has the capability to deal with
large-scale object conservation.”
The question remained: which stabilisation treatment to use?
Jane Clark, Artefact Conservator explains, “We decided on alkaline
sulphite treatment because of its proven efficiency and
affordability. The meteorite was then immersed for several months
into a treatment bath.”
Lore Troalen, Analytical Scientist, continues the story, saying,
“In order to understand the nature of the corrosion, flakes of
corroded metal from the meteorite surface have been scientifically
investigated by means of elemental and structural analysis. This is
helping to assess the efficiency of the stabilisation treatment and
to decide on the final display plans for the conserved meteorite so
that it can star for many years to come as the only out-of-this
world hands-on display in the National Museum of Scotland.”
The Muonionalusta meteorite really has two stories to tell: one
about meteorites and the other about the skill of the geologists,
scientists and conservators who worked together to prepare it for
its first public appearance.