Mining stocks are in the firing line as markets plummet around the world and commodity prices slide. Among the heaviest fallers in the large-cap index are Xstrata, Anglo American and Rio Tinto. Copper prices fell back after stockpiles monitored by the London Metal Exchange rose again.Precious metals prices also slipped and silver miner Fresnillo, which saw revenues slide in the first half of 2009, is among the fallers.Similarly, industrial metals stocks are unwanted, with iron ore producer Ferrexpo at the bottom of the pile.Bottom performing sectors so far todayChemicals 3,725.23 -5.30%Industrial Metals 4,472.15 -5.25%Mining 14,989.85 -4.98%Automobiles & Parts 2,602.27 -4.22%Personal Goods 8,089.92 -3.99%