Yeah, I'm sure Belden happily sells the right cable, for a price. I'm an old miser though.
While Home Depot has a promising candidate, I didn't want a whole spool. CentralComputers sells Cat7 network cables, which are shielded (STP). But are they unplated copper? Meanwhile I learned that copper cable is tinned not (just) for ease of soldering, but to make it resistant to humidity. So I guess cables meant for outdoor applications will be tinned and patch cables not necessarily. One way to find out ...
Turns out, CentralComputers also have spools of network cables, but they were not interested in selling me a few feet (gosh, I miss WeirdStuff, Fry's and Halted/HSC now ...). They suggested that I get a patch cable and cut of the connectors. So I did, you know, for science.
It's nicely shielded (each pair is shielded and all of them once more), I give them that. And it was unplated copper, sadly however tiny (AWG 26, I'd say) and stranded. Guess, the latter I could have figured by the ease of bending it. Oh, well, I needed a cable for a RS-485 connection anyhow ...