Dovish comments from Federal Reserve Chairman Ben Bernanke sparked a sharp fall in the dollar and a strong rise in commodity prices on Thursday, sending mining equities soaring in London.The FTSE 100 finished the session up 38 points (+0.6%) at 6,543, a level not seen since June 4th, with resource stocks rallying as Bernanke signalled that the US economy still needs monetary stimulus.Last night saw the release of the minutes of the latest Federal Open Market Committee (FOMC) meeting, in which policymakers seemed divided on when to begin tapering asset purchases. The statement reiterated that downside risks to the economy had diminished and activity was picking up, but "many" members wanted to see further progress in the labour market before beginning to 'taper'.However, given the meeting took place before the release of the release of last month's stellar jobs report, many analysts still expect a scaling back of quantitative easing (QE) by as early as September.Nevertheless after the Wednesday's closing bell, the Q&A session with Bernanke caught the attention of investors as the Fed chief looked to reassure markets that short-term interest rates wouldn't be rising anytime soon, even if the unemployment rate falls dramatically. "It may be well sometime after we hit 6.5% before rates reach any significant level," he said."This admission appears to have put the prospects of any tapering programme on the back burner in the short term, and helped drive European equity markets to one-month highs," said Senior Market Analyst Michael Hewson from CMC Markets."There is a school of thought that Bernanke's comments were primarily aimed at the bond markets in an attempt to keep a lid on the recent sharp rise in long-term interest rates, rather than any attempt to suggest that the Fed was stepping back from its intention to taper asset purchases by the end of the year," he said.FTSE 100: Miners surge as metals prices jumpBernanke's remarks saw gold prices jump the most in a year, with futures for August delivery up around 3.0% at $1,284.6 an ounce earlier on. Silver meanwhile gained 4.1%, copper rose 2.6% while platinum was up 2.2%.Gold and silver group Fresnillo was the standout performer of the day on the FTSE 100, rising nearly 13%. Randgold, Anglo American, Antofagasta, Rio Tinto, BHP Billiton, Vedanta and Glencore Xstrata were also higher.Associated British Foods was also putting in a decent performance after total group sales rose 8.0% in the third quarter, as a strong performance from Primark offset weakness in the sugar division. The stock was boosted by an upgrade by Panmure Gordon to 'buy'.G4S declined following reports the private security company was being investigated by the Serious Fraud Office for overcharging millions on government contracts. Britain said it would review contracts held by the company and Serco Group which also saw its shares fall following the news.easyJet was flying higher after shareholders voted in favour of an order for 135 Airbus planes valued at $13bn, a transaction that has drawn fierce criticism from founder and major shareholder Stelios Haji-Ioannou.FTSE 250: Gold miners lead the riseAfrican Barrick Gold was leading the risers on the FTSE 250, followed closely behind by precious metals peers Polymetal, Hochschild, Lonmin and Centamin, as gold prices jumped.Fund manager Ashmore was also higher after reporting that it was able to retain assets under management on last year during the final quarter despite more challenging market conditions.Heading the other way was price comparison site Moneysupermarket.com which revealed slower trading in the second quarter due to ever-changing Google algorithms.FTSE 100 - RisersFresnillo (FRES) 1,018.00p +12.67%Randgold Resources Ltd. (RRS) 4,402.00p +7.24%Anglo American (AAL) 1,337.00p +5.44%Associated British Foods (ABF) 1,907.00p +5.07%Antofagasta (ANTO) 853.50p +4.79%Rio Tinto (RIO) 2,833.50p +4.58%BHP Billiton (BLT) 1,800.00p +4.56%Vedanta Resources (VED) 1,106.00p +4.14%Glencore Xstrata (GLEN) 266.30p +3.36%Tullow Oil (TLW) 1,125.00p +3.21%FTSE 100 - FallersSerco Group (SRP) 626.50p -7.94%G4S (GFS) 213.00p -5.59%TUI Travel (TT.) 370.80p -1.49%Meggitt (MGGT) 555.00p -1.25%Aviva (AV.) 364.00p -1.03%Bunzl (BNZL) 1,378.00p -1.01%BP (BP.) 464.75p -1.00%Reed Elsevier (REL) 791.50p -0.75%GKN (GKN) 326.70p -0.70%Babcock International Group (BAB) 1,176.00p -0.68%FTSE 250 - RisersAfrican Barrick Gold (ABG) 111.00p +12.86%Polymetal International (POLY) 519.00p +8.33%Ashmore Group (ASHM) 376.70p +7.14%Supergroup (SGP) 858.00p +6.06%Hays (HAS) 99.90p +5.16%Ferrexpo (FXPO) 157.00p +4.81%Premier Oil (PMO) 358.30p +4.70%Bwin.party Digital Entertainment (BPTY) 127.80p +4.58%Lonmin (LMI) 287.60p +4.39%Morgan Advance Materials (MGAM) 291.00p +3.85%FTSE 250 - FallersRedrow (RDW) 237.50p -3.02%Informa (INF) 500.50p -2.34%Aveva Group (AVV) 2,494.00p -2.27%Anite (AIE) 132.40p -1.93%Britvic (BVIC) 512.00p -1.92%F&C Asset Management (FCAM) 96.55p -1.88%Tullett Prebon (TLPR) 341.60p -1.73%Moneysupermarket.com Group (MONY) 200.10p -1.72%Dechra Pharmaceuticals (DPH) 688.00p -1.71%Big Yellow Group (BYG) 431.80p -1.64%BC