Yes the USGS has made a mistake. This was by mis-reading and mis-interpreting old CANADIAN reports beyond their jurisdiction. NOWHERE are these results verified by field work. The reports are ' Reading Reports '. Geo_newfie will explain it to you.
This is an interesting tidbit of information that was brought to my attention....
KATX themselves stopped using the term "IOCG" in their PRs after they had finished the drilling starting with the 22 Nov 2010 PR. Prior to that they always used IOCG when describing RR.