
> is described as the largest metal planetismal body in the solar system
It's "planetesimal" BTW, and please don't imagine some huge cannon ball hanging out there in the void, Psyche is just so dense it's assumed to have a huge proportion of metal (iron-nickel), way more than the standard, garden variety asteroid belt denizens. There is a whole class of those metal-rich asteroids out there, the M-types, and they're what people dream of eventually mining.