Mining stocks were making small gains on Monday despite some disappointing economic data from top metals consumer China.Anglo American was among the best performers on speculation that the former boss of Xstrata could bid for some its assets.The Chinese government's official manufacturing purchasing managers' index (PMI) for October unexpectedly declined from 51.1 to a five-month low of 50.8, while the non-manufacturing PMI fell from 54 to a nine-month low of 53.8."The world's second-biggest economy [...] once again appears to be showing further signs of a slowdown," said analyst Michael Hewson from CMC Markets UK.Nevertheless, the mining sector in London was seemingly shrugging off any concerns with stocks on average up 0.7% in afternoon trade.Anglo was up 1% after The Sunday Times reported that Mick Davis' X2 Resources had made an offer for Anglo's Chilean copper mines, Brazilian nickel mines and some coal projects. Davis is said to have built up a war chest of nearly $5bn to fund acquisitions to create a mid-tier diversified metals company.However, Cityam has cited a source close to X2 Resources as saying that reports of a potential bid for Anglo's assets are premature.Others in the sector were also making gains, including BHP Billiton, Vedanta Resources, Lonmin, Centamin and African Barrick Gold. Kaz Minerals, the copper miner formerly known as Kazakhmys which completed its restructuring last week, was also up 6%.Even Rio Tinto was putting in a decent performance, up 0.6% despite various press reports that the company could take a $2.5bn write-down on its Oyu Tolgoi mine in Mongolia after project delays and a long-running stand-off with the government.Glencore, however, was bucking the trend, down 0.4% after analysts at Nomura downgraded their rating on the stock to 'reduce', saying that the company is the most exposed among its peer group to the thermal coal market. Top performing sectors so far todayOil Equipment, Services & Distribution 21,445.63 +1.97%Food & Drug Retailers 2,568.93 +1.62%Mining 15,166.77 +0.72%Industrial Metals & Mining 1,361.33 +0.40%Electronic & Electrical Equipment 3,608.39 +0.30%Bottom performing sectors so far todayGas, Water & Multiutilities 6,099.96 -1.63%Electricity 9,823.87 -1.50%Banks 4,423.93 -1.34%Personal Goods 23,276.49 -1.30%Tobacco 40,023.62 -1.18%