Mining stocks were tracking commodity prices sharply lower on Monday afternoon as a disappointing reading of Chinese economic growth dampened the demand for 'riskier' assets.As such, defensive sectors were at the top of the pile: stocks that are expected to hold up relatively well during tough economic conditions were performing well, such as pharmaceuticals, utilities and food stocks.China's first-quarter gross domestic product (GDP) growth dropped from 7.9% in the prior quarter to 7.7% (consensus forecast: 8.0%), sparking concerns about demand from the world's second-largest economy. The reading still remains above China's 2013 GDP growth target of 7.5%, but will scale back hopes for any material upside surprise to official forecasts."The poor China data follows a week after a batch of poor US economic data, reinforcing the markets' worry that the global recovery could be derailed," said Market Strategist Ishaq Siddiq from ETX Capital.Spot gold prices were trading down 7.74% at $1,367.97 an ounce before the close in London, down nearly $120 on the day, with Citigroup today joining the growing list of brokers to downgrade its price forecasts for the yellow metal. Gold had reached its lowest level since February 2011.Meanwhile, the silver price was down 10.73% at $23.21 an ounce, its worst value since October 2010.Precious metals producer Fresnillo was the standout faller of the day on the FTSE 100 in London, dropped a whopping 15.2% to 1,079p before the close.It was followed closely behind by sector peer Polymetal, down 12.4% at 752.5p, after Citi cut its recommendation for the stock from 'neutral' to 'sell'.Randgold, EVRAZ, Antofagasta, Xstrata, Glencore and ENRC were all registering steep losses today, ranging between 5-10%.Rio Tinto was also lower after an Australian judge rejected the miner's plan to expand a coal mine in the wine-growing region of Hunter Valley. The judge cited "the significant, adverse, biological diversity, noise and dust, and social impacts of the project."On the FTSE 250, Petropavlovsk lost over a quarter of its value after Citi downgraded the shares to 'sell'. Bumi, Centamin, African Barrick Gold and Ferrexpo were also lower.Top performing sectors so far todayPharmaceuticals & Biotechnology 11,074.09 +2.37%Gas, Water & Multiutilities 5,933.13 +1.02%Health Care Equipment & Services 4,258.45 +0.99%Food Producers & Processors 7,525.75 +0.43%Household Goods & Home Construction 10,180.03 +0.20%Bottom performing sectors so far todayIndustrial Metals & Mining 1,799.39 -8.22%Mining 16,392.57 -5.25%Oil Equipment, Services & Distribution 23,079.14 -3.69%Chemicals 8,918.65 -2.58%Industrial Engineering 9,229.65 -2.47%BC