What is that gold square thing around John's neck?

[modernmark1]

Does anyone know what is that gold square thing near the cross that John has as a necklace around his neck in that famous 1974 photo by Bob Gruen? I noticed that it hangs near the cross he has on, but I'm not sure what it is.

[beatler90]

I guess it's some kind of 'guardian angel', I've seen sth like this before.