Poor economic data was weighing on UK stocks on Tuesday, with decent gains in the mining sector offset by falls from airlines and pharmaceuticals.The FTSE 100 was trading 0.6% lower at 6,522 by around midday.Nervousness ahead of the start of third-quarter earnings season in the States was also causing investors to tread cautiously, with US stock futures trading firmly lower ahead of the opening bell.German, UK industrial productionEconomic news wasn't helping sentiment in early deals after it was revealed that German industrial production dropped by 4% in August, pulling back after a revised 1.6% increase in July. The consensus estimate was for a lesser decline of 1.5%.The figures followed further weak figures from Germany on Monday which showed that factory orders in August slumped 5.7% after 4.9% growth in July. This was the biggest slump since 2009.Closer to home, UK industrial production was flat in August after a 0.4% expansion in July, though this was in line with estimates.Analysts at Capital Economics said that the industrial recovery in Britain is "still lacking momentum" and the data showed that the economic recovery "remained unbalanced in the third quarter".Rio Tinto jumps after Glencore approach revealedRio Tinto rose strongly after confirming that Glencore had approached the company in July about a "possible combination", though the board had rejected the approach as it "was not in the best interests of [...] shareholders".Rio Tinto was responding to press speculation after Bloomberg earlier said that Glencore was in talks with Rio Tinto's biggest shareholder, Chinalco, to gauge its interest in a potential deal. These discussions had taken place in recent weeks, sources said.Others in the sector were also on the rise, including Antofagasta, Randgold Resources and Centamin. Antofagasta was given a lift by an upgrade to 'neutral' by Nomura.However, leading the downside were airlines Easyjet and IAG after a strong performance the previous session, with the latter especially hit by the news of a person contracting the Ebola virus in Spain.Pharmaceuticals were also under the weather after Morgan Stanley cut its rating on the European healthcare sector to 'underweight'. Astrazeneca, Glaxosmithkline and Shire were all lower.Tesco was continuing to recover after its recent slump after having asked another member of its senior management to step down in the wake of an investigation into accounting practices. The company was also reportedly contacted by private equity buyout company TPG about potentially acquiring Dunnhumby, the data analysis unit that runs its Clubcard loyalty scheme.Oil and gas group Cairn Energy was a high riser on the FTSE 250 after discovering oil at its FAN-1 exploration well offshore Senegal, causing shares to surge. The find "materially upgrades the prospectivity" of the Sangomar Deep Block, the company said.However, telecoms tester Spirent Communications saw shares sink after it warned that revenues and profits in the second half would be lower than previously guided due to lower demand in the US and China.Market MoverstechMARK 2,757.48 -1.27%FTSE 100 6,522.39 -0.63%FTSE 250 15,144.22 -0.87%FTSE 100 - RisersRio Tinto (RIO) 3,139.50p +4.75%Tesco (TSCO) 182.30p +3.14%Anglo American (AAL) 1,377.50p +2.19%Randgold Resources Ltd. (RRS) 4,200.00p +1.13%Standard Chartered (STAN) 1,140.50p +1.02%Admiral Group (ADM) 1,299.00p +0.70%Aberdeen Asset Management (ADN) 395.50p +0.64%Antofagasta (ANTO) 710.00p +0.50%Sports Direct International (SPD) 616.50p +0.41%Coca-Cola HBC AG (CDI) (CCH) 1,331.00p +0.30%FTSE 100 - FallersInternational Consolidated Airlines Group SA (CDI) (IAG) 349.70p -5.82%easyJet (EZJ) 1,400.00p -4.57%Carnival (CCL) 2,400.00p -3.81%Schroders (SDR) 2,287.00p -2.72%InterContinental Hotels Group (IHG) 2,271.00p -2.49%TUI Travel (TT.) 388.20p -2.29%London Stock Exchange Group (LSE) 1,821.00p -1.94%Ashtead Group (AHT) 995.00p -1.78%Petrofac Ltd. (PFC) 965.00p -1.78%Whitbread (WTB) 4,067.00p -1.76%FTSE 250 - RisersCairn Energy (CNE) 194.30p +8.00%Tullett Prebon (TLPR) 265.60p +2.55%Zoopla Property Group (WI) (ZPLA) 219.60p +1.34%Centamin (DI) (CEY) 58.60p +1.30%Lonmin (LMI) 170.00p +1.25%Countrywide (CWD) 471.60p +1.20%Merlin Entertainments (MERL) 348.70p +0.87%Kazakhmys (KAZ) 252.00p +0.72%Ted Baker (TED) 2,013.00p +0.65%Hikma Pharmaceuticals (HIK) 1,770.00p +0.51%FTSE 250 - FallersSpirent Communications (SPT) 79.70p -19.21%Just Retirement Group (JRG) 120.90p -4.28%Thomas Cook Group (TCG) 114.50p -3.78%Hunting (HTG) 846.00p -3.42%Fidessa Group (FDSA) 2,236.00p -3.20%EnQuest (ENQ) 99.85p -2.96%Enterprise Inns (ETI) 118.10p -2.88%Telecity Group (TCY) 713.50p -2.86%Spirax-Sarco Engineering (SPX) 2,759.00p -2.41%Big Yellow Group (BYG) 498.70p -2.41%