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?
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.