'Iron Stone' Records

Not so much a Guide yet, as an appeal for help.

Can anyone help?

I have been informed that there is such a thing as the "Iron Stone" Records used for mining/quarrying of steel, and could be the same use as railway plans. Has anyone else heard of them, seen them or know where they are?

My source say that Corus has them but where we don't know.

Matt Brookfield 4/2003