Science Questions

I saw iolite in a jeweller’s window recently. It was a mauve coloured stone but I’ve never heard of it before. What is it? Mariana

We put this question to Ian Mercer:

This is an interesting stone.  This forms at very high pressure.  This isn’t a volcanic stone, this is a gemstone that forms as a mineral in rocks that are squeezed in between something.  This is a stone which is intensely dichroic.  It changes colour completely as you turn it round.

Chris: Where do you find it?Ian: That comes form all sorts of places like Norway and Africa.  Anywhere where deep-seated rocks are pushed up towards the surface.

April 2008