London's FTSE 100 finished Thursday's session in positive territory, registering moderate gains as a strong performance in the mining sector and results from Aviva helped the index rebound slightly after a four-day losing streak.Forecast-beating trade figures from the world's top metals user, China, gave the heavyweight mining sector a boost today as resource stocks recovered after recent weakness. Rising copper prices also lifted equities as the metal jumped to an eight-week high.The General Administration of Customs said that Chinese exports jumped by an annual rate of 5.1% in July, better than the 2.0% rise expected, while imports surged 10.9% (forecast: +1.0%)."[The data] has helped spawn a recovery in mining stocks ahead of Chinese July industrial production data tomorrow morning," said Senior Market Analyst Michael Hewson from CMC Markets. "This improvement in imports, if it is to be believed, should translate into a good number here also."The FTSE 100 finished Thursday up 18.47 points at 6,529.68, though well below its intraday high of 6,557 after better-than-expected US economic data heightened speculation that the Federal Reserve would soon begin to scale back stimulus.US jobless claims rose to 333,000 last week from 328,000 the prior week, according to the Labor Department. However, the figure came in under the 335,000 expected by analysts and remains near a five-and-a-half-year low.FTSE 100: Aviva jumps as first-half results impressAviva's share price surged on Thursday after the insurer beat forecasts in the first half as its turnaround continues. The firm reported a five per cent rise in operating profit to 1,008m pounds, ahead of the 933m-pound estimate, while the value of new business jumped 17 per cent to 401m pounds."In the first half we have taken a number of steps to deliver our investment thesis of cash flow and growth. These results show satisfactory progress in Aviva's turnaround," said Chief Executive Mark Wilson. The savings, insurance and asset management firm Old Mutual was also a high riser, extending gains made yesterday after investors cheered its own first-half report. Not all financial stocks were in demand though today, with fund manager Schroders failing to please with a 25% increase in first-half profits as markets focused on £1.1bn of net outflows in the second quarter, all of which occurred in June.Insurer Standard Life was also lower after a 6.0% rise in operating pre-tax profits to £304m in the first half missed the consensus forecast of £320m.Mining stocks were performing well today, rebounding after some heavy falls over recent days, after the data from China. Anglo American, Antofagasta, Glencore Xstrata and BHP Billiton were all higher in afternoon trade. Even Vedanta edged higher as it shrugged off a downgrade from Liberum Capital to 'hold'. Rio Tinto also gained despite recording an 18% drop in underlying earnings in the first half due to lower market prices and a higher tax rate, partly offset by record iron ore shipments and cost savings. BAE Systems was in the red after the Serious Fraud Office admitted that it has lost certain documents involved in an investigation into the defence firm.FTSE 250: Miners surge, Ladbrokes disappointsSecond-tier mining stocks were tracking their blue-chip counterparts higher after the Chinese data. Hochschild Mining, Kenmare Resources, Polymetal, Kazakhmys and Lonmin all finished with strong gains. Bookmaker Ladbrokes was a heavy faller today after seeing operating profits fall in the first half due to increased costs and tax and the lack of a major football tournament. Meanwhile, investors welcomed an update from leased and tenanted pubs operator Enterprise Inns which said that trading improved in the fourth quarter following a tough year.FTSE 100 - RisersAviva (AV.) 399.00p +7.61%Anglo American (AAL) 1,454.50p +4.27%Antofagasta (ANTO) 876.50p +3.79%Glencore Xstrata (GLEN) 280.40p +3.68%BHP Billiton (BLT) 1,899.00p +2.95%Fresnillo (FRES) 957.00p +2.68%Old Mutual (OML) 203.00p +2.47%ARM Holdings (ARM) 880.00p +2.27%Rio Tinto (RIO) 3,016.50p +2.13%International Consolidated Airlines Group SA (CDI) (IAG) 323.40p +1.95%FTSE 100 - FallersSchroders (SDR) 2,368.00p -5.32%Standard Life (SL.) 377.50p -2.56%BAE Systems (BA.) 439.00p -2.16%Whitbread (WTB) 3,179.00p -1.30%Resolution Ltd. (RSL) 326.30p -1.30%Imperial Tobacco Group (IMT) 2,132.00p -1.16%Admiral Group (ADM) 1,253.00p -0.95%Johnson Matthey (JMAT) 2,786.00p -0.89%Smiths Group (SMIN) 1,296.00p -0.77%Rolls-Royce Holdings (RR.) 1,185.00p -0.75%FTSE 250 - RisersHochschild Mining (HOC) 193.40p +10.20%Kenmare Resources (KMR) 30.25p +6.74%FirstGroup (FGP) 111.90p +6.67%Polymetal International (POLY) 693.00p +6.21%Kazakhmys (KAZ) 261.10p +5.32%Enterprise Inns (ETI) 148.00p +5.19%Lonmin (LMI) 325.60p +3.93%Kentz Corporation Ltd. (KENZ) 449.80p +3.88%AZ Electronic Materials SA (DI) (AZEM) 329.90p +3.74%Evraz (EVR) 95.25p +3.53%FTSE 250 - FallersLadbrokes (LAD) 199.60p -3.90%Alent (ALNT) 341.50p -3.83%Ashtead Group (AHT) 689.00p -2.34%Carillion (CLLN) 292.50p -2.34%Catlin Group Ltd. (CGL) 489.10p -1.71%Ferrexpo (FXPO) 182.20p -1.51%Cobham (COB) 295.60p -1.30%Greene King (GNK) 838.50p -1.18%TR Property Inv Trust (TRY) 212.00p -1.17%Barratt Developments (BDEV) 351.00p -1.02%BC