The metal didn't react by bubbling when hit with vinegar so am sure it's not magnesium, not sure it's aluminum either seems like a zinc pot metal
or something. I don't believe I've ever seen a white thick corrosion on any thing like that except battery posts,so am wondering about some zinc mix.
More to come.....
I'm no expert, but I believe that zinc alloys were/are used a lot for die-casting of precision parts, models, etc. ?