The engine's main bearings have copper in them. The bearing
is a steel shell, electroplated with copper, and coated with a lead/tin
(and sometimes antimony) mix that forms the actual bearing surface.
It's intentionally soft so that abrasive contaminants are absorbed into
it to keep them away from the journal as much as possible.
Seeing that the lead and tin (Pb and Sn) counts were also up at
the same time as the copper, I'd wonder if there's a main bearing
giving trouble.
That said, the usual source for copper is either wrist pin
bearings or rocker shaft bushings. Lycoming's rocker bushings tend to
wear too easily.

Dan