The S&P/ASX 200 peaked early at 5211 points followed by a consistent sell-off to close 0.5% lower than yesterday at 5165.

The session was marked by a bad day for resource companies, with the basic materials sector losing 2.3% and the major miners unanimously going red.

BHP Billiton fell 0.8% to $A33.76 and Rio Tinto lost 1.9% to close at $54.68.

Newcrest Mining was down 5.3% to $15.02 while Fortescue Metals Group fell 3.9% to $3.45.

Investors grappled with notable overnight drops in silver, gold and nickel as iron ore began to show signs of fatigue, slumping into a bear market on concerns of slowing economic growth in China.

Bloomberg tracked a 20% decline in the price of the metal since February and said the Bank of America cut its China growth rate estimate from 8% to 7.6%.

“It’s in response to recent weakness in Chinese data,” ANZ Bank commodity strategist Natalie Rampono was quoted as saying.

“The market is bearish in terms of demand.”

Weaker European growth and US industrial production also added to concerns over global metal demand as three-month London Metal Exchange copper prices traded around $US7190 per tonne this morning, down 12.5% from the previous period.

Australian copper companies, however, proved able to turn around some recent losses today with OZ Minerals gaining 1.2% to $A4.10 and CuDeco lifting 0.2% to $3.95.

Copper-gold player PanAust closed 7.6% lower at $2.20.

Whitehaven Coal stood out with a 4.6% gain to $2.26.

Pressure from continued price erosion caused iron ore miners to follow FMG into the red with Atlas Iron down 5.7% to 83c, Aquila down 4% to $2.13 and BC Iron down 1.2% to $3.23.

Other iron companies in retreat included Arrium, Gindalbie Metals, Mount Gibson Iron, Jupiter Mines and Grange Resources.