Industrial metals and mining stocks were again among the worst performers on Monday, bearing the brunt of another market-wide sell-off as concerns over slowing growth in China hit the outlook for demand.Goldman Sachs has joined a growing list of brokers to cut its growth forecasts for the Asian powerhouse for this year and the next owing to tighter financial conditions and reforms.The investment bank now expects China to grow by only 7.4% in 2013 compared to the previous 7.8% estimate. For 2014, Goldman now anticipates a 7.7% expansion compared to the prior 8.4% forecast.Also dampening sentiment in the industrial metals sector today were copper prices which fell to their lowest in nearly three years, weighed down by Chinese concerns as well as the news that copper stockpiles have climbed to a 10-year high. Copper futures for September delivery were down 2.7% ad $3.017 a pound.AIM-listed iron, copper and nickel group Bellzone Mining was among the heaviest faller in the sector today, disappointing with the release of its 2012 results. The company revealed that loss before tax last year totalled $54.2m, worse than the $42.7m loss in 2011, mainly as a result of higher staffing and admin costs.Steel producer EVRAZ, which was recently demoted to the FTSE 250 after its recent weakness, was extending losses today with a fall over of 6.0%. The stock has now dropped a whopping 60% in 2013 alone.Nickel group Talvivaara and iron-ore producer Ferrexpo were also in the red today.Top performing sectors so far todayMobile Telecommunications 4,115.77 +0.11%Industrial Transportation 2,798.61 +0.07%Bottom performing sectors so far todayIndustrial Metals & Mining 1,220.81 -4.25%Chemicals 8,743.55 -2.86%Real Estate Investment Trusts 2,224.12 -2.86%Forestry & Paper 8,170.08 -2.69%Real Estate Investment & Services 2,274.92 -2.41%