Gold is now below $US800 an ounce in price for the first time since December 2007. Aluminium prices have hit their lowest in some six months. Copper also fell.
The price of commodities has fallen on speculation that demand will slow amid a global slowdown.
Another factor has been the stronger US dollar, which has reached a half-year high against the euro.
Three-month copper dropped to an intra-day low $US7,185 per tonne on Friday. Earlier in the week, it fell to its lowest in six months earlier in the week at $US7,120 per tonne. Copper is largely used in the building sector.
Crude oil fell $US1.61 to below $US114 a barrel while Brent oil slipped $US1.69 to $US111.99 a barrel.