Industrial action is set to start today at BHP's remote operations centre in Santiago.
Copper gained 0.6% on the London Metal Exchange to US$9,961.25 per tonne.
Gold rose above $1,900 an ounce in the past 24 hours but has fallen back to $1,893/oz on the spot market.
It was the highest level since January for the precious metal.
Gold majors barely moved - Barrick Gold gained 0.47% in Toronto and Newmont was flat in New York.
However gold explorers were on the rise in Toronto amid "bonanza" drill results, including Allegiant Gold (TSXV: AUAU).
It rose 39.6% on reporting 148m at 2.6g/t gold at its Eastside project in Nevada.
Maple Gold Mines (TSXV: MGM) was up 5.26% on intercepting 132m at 1.58g/t gold at its Douay project in Quebec, a joint venture with Agnico Eagle Mines.
Agnico (TSX: AEM) was up 1.16%.
Finally in London, both Antofagasta and Glencore gained about 0.7%.
