Key global markets and the copper price had finished the week higher but the Australian market had lost most of the morning's gains by early afternoon.
IG market analyst Jingyi Pan said a miss in Friday's US industrial production figures reinforced "the expectation of dovishness" from the FOMC meeting.
The gold price was just below US$1,299 an ounce at the time of writing.
Australia's self-styled "third force in iron ore" Fortescue Metals Group (ASX: FMG) was the biggest riser among S&P/ASX200 stocks in afternoon trade, up 4.9%.
BHP (ASX: BHP) was 1.3% higher, after news of Brazil iron ore major Vale facing a multi-billion dollar demand for environmental repairs and further production setbacks.
Metals and mining stocks had closed 0.55% higher in Toronto on Friday, where the acquisitive Barrick Gold (TSX: ABX) finished the week down 1c.
Finally, Rio Tinto (LSE: RIO) had closed down 0.43% on Friday in London, where agreement on a Brexit deal is yet to be reached.