ORAC,
rhenium is in minerals found everywhere, just at concentrations of about 1 part per billion.
Rhenium rarely occurs as a native element or as its own sulfide mineral; most rhenium is present as a substitute for molybdenum in molybdenite. We have molybdenum mines in the US that do not contain rhenium, same is true of some copper mines. Sediment-hosted strata-bound copper deposits in Kazakhstan (of the sandstone type) that contain rhenium also contain harmful impurities that must be eliminated before using the resulting rhenium in superalloys at added costs.
https://pubs.er.usgs.gov/publication/pp1802P