Miners were posting impressive gains on Tuesday after China posted a better-than-expected trade surplus. According to analyst Colin Cieszynski from CMC Markets, "This was due to much lower than expected imports suggesting that the Chinese economy remains sluggish and increasing speculation that more PBOC [People's Bank of China] easing may be on the way. Reports that China may improve foreign access to its stock markets may also be helping to turnaround sentiment toward the country."Also helping sentiment was last night's bullish forecast by Alcoa for 7% demand growth in aluminium in 2012. The company also said it expected a global aluminium supply deficit of 600,000 tonnes this year. Kazakhmys, Fresnillo, Antofagasta, Vedanta Resources and Randgold Resources rose between 4% and 6%. Meanwhile, pharmaceuticals were among the few stocks falling with sector giant GlaxoSmithKline finishing in the red.The firm announced yesterday that its once-a-day respiratory drug Relovair is soon to be submitted for regulatory approval but admitted that a 24-week "superiority study" of Relovair against another drug, Seretide, in asthma patients "did not meet the predefined threshold for superiority". Glaxo described this study as "non-pivotal". BCTop performing sectors so far todayForestry & Paper 5,209.03 +4.38%Mining 21,037.36 +3.37%Chemicals 7,051.73 +3.33%Construction & Materials 3,457.80 +3.29%Banks 3,446.03 +3.25%Bottom performing sectors so far todayTechnology Hardware & Equipment 756.28 -1.02%Health Care Equipment & Services 3,390.05 -0.48%Pharmaceuticals & Biotechnology 9,907.69 -0.39%Personal Goods 20,113.64 -0.10%Beverages 10,565.13 -0.03%