Financeroll.com – Oil prices slumped on Tuesday as investors locked in profits from recent sharp gains. A stronger dollar helped push down gold and crude oil futures on Tuesday, with crude retreating back below the $80-a-barrel level. The U.S. dollar index rose 0.5% to 80.75, with the greenback pulling investors away from commodity futures. Gold futures dropped 80 cents to $1,112.30 an ounce.