A caveat on metallicity.
I read a science-periodical article [Science, New Scientist, Nature?] in the past two years that puts a damper on the theory of "neutron capture" for the creation
of heavy-elements [Iron to Uranium]. The article in question revealed some serious
problems with the "neutron capture" theory.
That kind of leaves the issue of how those heavy-elements were created
up in the air....At least until another theory emerges.
Jacob