Hi, Bryan.
No, I don't know what lamination material is, but the fella I got them from told me the laminations were special somehow... not a typical material, and in fact, most of the transformers made got scrapped (I guess the project they were made for didn't materialize?) specifically to reclaim the lamination alloy. I would love to know what it is, but I can't find any info.
They sound great though!
JC