Where's the iridium?

In my absence last week I got wind of a new study on where the valuable asteroids be at. (I'd filled up last week higgelly-piggelly. Normally I'd have slotted this in, for later days; as these poasts stand, this one had to await today.)

The study aims at "refractory" metals. Such boiling-points be high; we're talking the famous tungsten, also niobium and others around the lower left of the 'Table. These should, then, condense first, as the solar-system cools. I gather the researchers expected to see more of these metals in S-type rocks down around here at ~1 AU. And we do have quite a bit of titanium on our Moon, which metal is near-enough-refractory we use it for roggets.

Yes yes our Moon is technically not S-type but it's been struck by a lot of S, so... regolith.

It turns out that iridium and other refractories (they're including platinum, I wouldn't) are more common far from down here. The thought is, then, that they formed down here - and moved. Then Jupiter moved inward and opened up the (Kirkwood) gaps, stranding the metal-rich S rocks on the far side.

Future miners should scout for S rocks out by Psyche and beyond. I wonder how much refractory ore remains in the rockier Hildas and Trojans . . .

As to the history of our system, we'd be more WSB 52 less HL Tauri (or βPictoris). Our nebula was a "Doughnut". Rings such as we see at HL Tauri come with Kirkwood, so with Jovians. All this incidentally suggests Jupiter and the others formed much further from our protoplanetary inner parts than is usually assumed. Either that or Jupiter simply wasn't much of a planet until later.