With the Federal Reserve pledging to do its best to strengthen the US economy last night, the dollar weakened against the euro, sending metals prices higher. As such, the miners were dominating the risers on Thursday afternoon.Kazakhstan-based copper miner Kazakhmys was in the top spot after saying that it met all of its major production targets in 2011 and expects to maintain similar levels of copper output in 2012. Sector peer Anglo American also rose after it said iron ore production in the final quarter of 2011 increased by 5% from a year earlier to 12.4m tonnes. Sector peers Vedanta Resources, Xstrata and Rio Tinto were also firmer.Polymetal International shares leapt over 9% but were registering more modest gains by the afternoon on rumours that Russian peer Polyus Gold and Polymetal's billionaire owners are considering merging the Russian gold miners to create the world's ninth-biggest producer of the metal. Royal Bank of Scotland was also higher on rumours that US investment bank Jefferies is close to buying the bank's corporate broking arm Hoare Govett. Barclays and Lloyds were also making strong gains.FTSE 100 - RisersKazakhmys (KAZ) 1,196.00p +7.46%Vedanta Resources (VED) 1,226.00p +6.42%Lloyds Banking Group (LLOY) 32.60p +5.42%Xstrata (XTA) 1,133.50p +5.05%Rio Tinto (RIO) 3,892.00p +4.86%Glencore International (GLEN) 437.50p +4.55%International Consolidated Airlines Group SA (IAG) 179.00p +4.25%Barclays (BARC) 226.30p +4.17%Royal Bank of Scotland Group (RBS) 27.85p +4.11%Randgold Resources Ltd. (RRS) 7,095.00p +3.96%FTSE 100 - FallersMorrison (Wm) Supermarkets (MRW) 291.90p -1.29%Vodafone Group (VOD) 173.30p -0.72%Imperial Tobacco Group (IMT) 2,247.00p -0.71%Serco Group (SRP) 510.00p -0.49%British Sky Broadcasting Group (BSY) 669.50p -0.45%Tesco (TSCO) 321.60p -0.39%Hargreaves Lansdown (HL.) 420.60p -0.31%Sainsbury (J) (SBRY) 289.20p -0.17%G4S (GFS) 269.50p -0.11%Compass Group (CPG) 598.50p -0.08%NR