Mining stocks were performing well as investors sought gains after a volatile week for the sector. Vedanta, EVRAZ and Fresnillo were all making decent gains by mid-afternoon. ENRC shares surged Friday after major shareholder Alexander Machkevitch said he was considering a takeover bid for the Kazakh miner.Anglo American was also a high riser after announcing that production at its larger operations of iron ore and copper increased in the first quarter, when compared with last year, despite the company scaling back spending. Tullow Oil was recovering after its shares fell earlier in the week on the back of a well update. There were also some unconfirmed reports surfacing today that the company has announced new oil production from another well. GKN continued to rise one day after the engineering giant said that first-quarter trading met the board's expectations with last year's acquisition of Volvo Aero showing good results.Telecoms firm Vodafone was also in demand as rumours continue to circulate surrounding a buy-out of its 45% stake in its US wireless joint venture with Verizon. According to reports this morning, a deal could happen this year as fears about tax obstacles ease. Meanwhile, GlaxoSmithKline was trading lower ahead of its first-quarter update next week. There were reports this morning that the company is being investigated over claims it paid off firms to delay the launch of cheap versions of its anti-depression drug. IMI was lower, which a number of investors attributed to readacross from a weak quarterly update from Spectris. InterContinental Hotels fell on the back of a rating downgrade from Barclays Capital, which reduced its rating from overweight to equal weight.FTSE 100 - RisersEurasian Natural Resources Corp. (ENRC) 290.90p +26.59%Vedanta Resources (VED) 1,138.00p +4.88%Fresnillo (FRES) 1,116.00p +2.76%Tullow Oil (TLW) 1,049.00p +2.44%Petrofac Ltd. (PFC) 1,296.00p +2.37%Marks & Spencer Group (MKS) 398.20p +2.10%Anglo American (AAL) 1,591.50p +1.89%GKN (GKN) 256.70p +1.87%Evraz (EVR) 159.30p +1.85%HSBC Holdings (HSBA) 675.50p +1.84%FTSE 100 - FallersIMI (IMI) 1,175.00p -1.51%Wolseley (WOS) 3,125.00p -1.26%Polymetal International (POLY) 707.50p -1.26%Carnival (CCL) 2,274.00p -1.13%Tesco (TSCO) 361.70p -1.03%Schroders (SDR) 2,146.00p -0.97%InterContinental Hotels Group (IHG) 1,854.00p -0.96%Aggreko (AGK) 1,761.00p -0.84%Aberdeen Asset Management (ADN) 398.00p -0.77%Capita (CPI) 850.50p -0.76%NR