Mining stocks were under the weather on Tuesday as risk appetite was scaled back ahead of policy decisions from central banks later this week.Markets on the whole were on the cautious side today as investors awaited the outcomes of the Federal Reserve and European Central Bank (ECB) meetings this week. The Fed is expected to maintain the current rate of it quantitative easing programme given weaker-than-forecast growth in the first quarter, while the ECB is likely to reduce its key interest rate in an effort to ease the pressure on member nations.Market Analyst Craig Erlam from Alpari said that a rate cut in Europe is already priced into markets. "What this means for Thursday is that if the ECB puts off cutting rates for another month, we could see a strong sell-off in response."As such, investors were choosing to sit on the fence today, refraining from building exposure to relatively 'riskier' sectors such as mining which would likely bear the brunt of the selling if the ECB did disappoint. A number of gloomy updates from platinum miners were also weighing on share prices this afternoon.Anglo American was in the red after saying that its Amplats division has agreed with the Department of Mineral Resources to extend their consultation process by 30 days to allow them more time to reach a conclusion. The discussions are being conducted in order to ensure a safe environment for employees across the platinum industry, the group has previously said. Miners have held a number of strikes relating to pay and conditions in recent months.Meanwhile, platinum miner Lonmin was hit by the news that it had experienced an "incident" at its Number Two furnace and has had to shut it down at a time when its Number One furnace was shut for a planned upgrade. A full repair to Number Two is expected to take 30-40 days.This follows the news a few days ago about a fatality at the Merensky section of Lonmin's K3 shaft last week - this resulted in operations being suspended until an investigation takes place.Westhouse Securities cut its target price for the stock from 255p to 235p today after reducing its production estimates for the full year.The broker added: "With labour pay negotiations about to commence, we anticipate the potential for further disruption and share-price weakness."Polymetal, Randgold Resources, EVRAZ and BHP Billiton was also among the heaviest fallers on the FTSE 100 today.Top performing sectors so far todayTechnology Hardware & Equipment 1,167.53 +1.09%Oil & Gas Producers 7,978.84 +0.79%Software & Computer Services 1,040.20 +0.68%Electronic & Electrical Equipment 3,856.75 +0.51%Real Estate Investment & Services 2,306.20 +0.51%Bottom performing sectors so far todayHealth Care Equipment & Services 4,103.36 -2.91%Mining 16,310.19 -2.29%Industrial Metals & Mining 1,728.96 -2.17%Construction & Materials 3,732.62 -1.76%Fixed Line Telecommunications 3,257.82 -1.09%BC