At 10:15am AEST, the benchmark S&P/ASX200 was down 64.7 points, or 1.61 per cent, at 3952.5, while the broader All Ordinaries shed 60.1 points, or 1.5 per cent, to 3949.2 points.
On the Sydney Futures Exchange, the June share price index contract was 67 points lower at 3956 on a volume of 7867 contracts.
Mining giant BHP Billiton plunged $1.41, or 3.81 per cent, to $35.62, while rival Rio Tinto dropped $2.88, or 4.02 per cent, to $68.72.
The major banks were mixed. Commonwealth Bank put on 12 cents to $36.92, Westpac was down 14 cents at $19.03, ANZ fell two cents to $16.34, while NAB dropped 94 cents, or 4.07 per cent, to $22.17.
US stocks stumbled overnight as cautious investors locked in profits after hefty gains in the last four sessions and as new data underscored a weak job market.
The Dow Jones Industrial Average shed 65.59 points, or 0.75 per cent, to 8,675.28.
The tech-rich Nasdaq fell 10.88 points, or 0.59 per cent, to 1,825.92 and the broader S&P500 index was down 12.98 points, or 1.37 per cent, to 931.76.
