Hi I'm Ashley, from Bishop Vesey's in Sutton
Coldfield and I'm volunteering here throughout
the summer.
This may look like your bog standard piece
of sandstone but actually, as you can see,
it's flexible.
It was found in Jhajjar, in India near Delhi,
and has been lying here in the stores for
a very long time.
The flexibility of these sandstones has puzzled
geologists for many years and led to much
discussion about why it's so wobbly.
Flexible sandstone was first discovered in
the small area of Morro do Itacolomi in Brazil
in 1822.
It was thought to be a new type of rock, gaining
it the name Itacolumite.
Unfortunately it wasn't a new rock and it
was actually a sandstone formed from the decomposition
of gneisses which contained feldspar grains.
This sediment accumulated together just like
any old sandstone, but the feldspar grains
continued to decompose.
This would have left lots of empty spaces
within the rock leaving it a lump of loosely
interlocking grains of quartz.
Where the quartz grains interlink with their
neighbors, quartz crystals have grown creating
joints, these are like your elbow or knee
and allow the rock to manoeuvre like a wobble
board.
But in case you were wondering, the whole
cliff or bed where this was lying wasn't all
wobbly, it's only flexible when you cut it
into thin sheets like this.
Platy minerals such as micas are sometime
found in these sandstones but they don't affect
the flexibility.
In some cases these sandstones are found to
lose their flexibility as they dry out.
So you better make the most of it while it's
still limber.
