Somewhere in the United States, there's an airfield (probably military) with a runway made entirely out of metal. I've seen the approach plate for it, but I can't remember the identifier.
What airfield am I thinking of?
You are thinking of Bogue Field (KNJM). It is a Marine Corps auxiliary landing field, currently mocked up to look like a carrier deck, and last I heard it was still active and in use to practice carrier landings.
The runway surface is Perforated Steel Planking (PSP - actually I believe the new stuff isn't "steel" anymore but the name remains) - discrete sections that can be laid out to quickly construct temporary landing strips in forward combat zones.
A search on AirNav for "pierced steel plaking" came up with a couple more military fields:
KNXP Twentynine Palms SELF Airport (Strategic Expeditionary Landing Field) - Twentynine Palms, California, USA
2CA9 Castle Dome Army Heliport - Yuma Proving Ground (Yuma), Arizona, USA
2CA9 says it's a helipad but it's 3000x65. The rest of the results were all (reasonably sized) helipads.