NEW YORK (TheStreet) -- The 8.2% rise in the Metals & Mining Index has outperformed the S&P 500's 7.2% increase so far in September. Investors could see further upside in the volatile metals and mining sector while the markets have positive momentum.The following 10 metals and mining stocks are expected to gain at least 40% in the upcoming months, according to analysts' median estimates. In particular, analysts are bullish on coal as coal companies are set to ride on the wave of industrialization expected in emerging economies over the next decade, and escalating demand from Europe. "Coal is the only sustainable fuel with the scale to meet the primary energy needs of the world's rising populations and economies," said Peabody Energy ( BTU) CEO Gregory Boyce in a press release. Coal has been the world's fastest-growing fuel over the past decade, outstripping the demand for natural gas and crude oil. The world has trillions of tons of coal reserves, which contribute nearly 60% toward global energy resources. Coal demand is likely to grow by more than 1 billion tons every three years, according to Boyce.