Board Thread:Lore Discussion/@comment-12481512-20130717104617/@comment-4057437-20131228050236

72.74.176.143 wrote: For those saying that it's Bronze, it's not. In one of the books you can find in Markarth, Calcelmo specifically says it's not Bronze, and is "most definitely a distinct type of metal of its own"

Calcimo is only guessing. He has no way to recognize an aluminum bronze as he has no knowledge of aluminum.