I have scanned and PDF'd a BICC cables publication, "The Electrician's Mate" showing how to install and use Mineral Insulated cable. It includes a description of Earthed Concentric Wiring (TN-C) which is now no longer permitted to be connected to the public electricity mains.
There's still plenty of it about in the UK. MI used to be the standard for fire alarms and emergency circuits, and although more modern alternatives like Pirelli FP200 are now used instead, MI lasts so long there will be loads of it still in service for many years. It is still used extensively on fuel sites and in other high explosion risk areas.