Falling metals prices and some disappointing trading updates from Antofagasta and Randgold Resources were weighing on the mining sector today.Copper prices were at a one-week low today after mixed economic data from the US and concerns over the Eurozone debt crisis - fuelled by some gloomy manufacturing and unemployment figures yesterday - dampened the outlook for demand.Chilean-based copper mining company Antofagasta was a heavy faller, down nearly 4% in afternoon trade, after the firm said that production dropped sharply in the first three months of 2012 as maintenance work, lower ore grades and technical problem hampered activity.Meanwhile, gold miner Randgold fell 3% as investors shrugged off impressive year-on-year production and profit growth in the first quarter with the group reporting that both elements were sharply lower then the fourth quarter of 2011.Sector peers Vedanta Resources and Rio Tinto were also firmly out of favour, trading down 1.2% and 1.1%, respectively.In contrast, health care equipment and services stocks were in demand after a strong first-quarter report from sector giant Smith & Nephew.The medical devices maker was the best performer on the FTSE 100 index today after revealing that profits beat both its own and consensus forecasts in the first three months of the year, which it said was down to the actions being taken to reshape the company.Top performing sectors so far todayHealth Care Equipment & Services 3,550.79 +3.80%Personal Goods 23,648.18 +1.79%Tobacco 37,355.96 +1.51%Mobile Telecommunications 4,021.69 +1.02%Food Producers & Processors 5,692.28 +0.87%Bottom performing sectors so far todayIndustrial Metals & Mining 3,739.33 -1.92%Industrial Engineering 7,802.18 -0.90%Mining 20,494.81 -0.68%Forestry & Paper 6,101.97 -0.61%Insurance (non-life) 1,445.67 -0.50%BC