I just scored a 40% return on one of my stocks in about three months, and I feel confident in saying that similar opportunities abound within the sector in question. But to catch the next big breakout stock, you first need to boldly go where few Fools seem inclined to venture.

I've been doing my level best to keep a spotlight focused on the metallurgical coal market for quite some time now, and I have to say it can be disappointing to see how unpopular the sector remains with retail investors. Even as a ruthless correction slammed the met coal miners this summer, I observed no increase in bullish sentiment after several stocks retreated by 50% or more over recent months. I am hopeful that the 70% advance in shares of Grande Cache Coal (OTC: GACHF.PK) on Monday will serve as a timely wake-up call for Fools to position themselves to profit from the ongoing tsunami of resilient global demand and resulting consolidation that's washing over this undervalued sector.

How I scored my 40% gain
Covering coal stocks for The Motley Fool, I've enjoyed a front-row seat in witness to the remarkable long-term growth story underlying the global market for metallurgical coal. A sudden case of the jitters regarding China's growth trajectory -- coupled with increasingly realistic economic outlooks in the U.S. and Europe -- contributed to an exodus from bulk commodities that has left some astonishing stock valuations in its wake. In a nutshell, I remained quite skeptical that Peabody Energy's (NYSE: BTU) repeated calls for a long-term global supercycle for coal could so abruptly come into question -- as market dynamics suggested -- and so I became an aggressive buyer of met coal mining stocks into the recent sell-off.

After all, as recently as mid-July, Peabody had extended its glance further ahead with a powerful 10-year forecast calling for 500 million tons of incremental met coal demand! That's a figure to stagger the imagination, and a similarly resilient outlook by the coal market gurus at Joy Global (Nasdaq: JOYG) poured additional conviction onto my contrarian strategy. Within its third-quarter earnings release last week, Peabody reminds us that "infrastructure buildouts related to new five-year plans in China and India are expected to add more than a trillion dollars of investment in the power and rail sectors alone through 2015, continuing to fuel the acceleration of coal demand in Asia." The miner also noted that Chinese steel production has increased another 11% year to date!

Some of the vehicles I selected -- particularly those struggling Appalachian producers, including Patriot Coal and Alpha Natural Resources (NYSE: ANR) -- are bound to require some time before beating their 2011 peaks. But thanks to some concerted dollar-cost averaging, I stand near breakeven today on those longer-term plays. Others, I surmised, would prove more prone to a rapid bounceback, and Monday's announcement that Japanese trading house Marubeni and China met coal importer Winsway Coking Coal teamed up for a $1 billion buyout of Grande Cache Coal immediately converted one of my opportunistic purchases into a major winner. By paying a 70% premium over the pre-announcement share price, these buyers handed me a 40% gain on a stake that I amassed gradually and methodically into weakness.

All the signs were there, even if they had gone overlooked by an indifferent equity market. As a backdrop, we had a string of major transactions targeting Australian coal during 2011, featuring Rio Tinto's (NYSE: RIO) protracted bid for Riversdale Mining, and Peabody's joint bid with ArcelorMittal (NYSE: MT) for Macarthur Coal (ArcelorMittal subsequently left Peabody alone at the altar). Meanwhile, resilient interest in smaller-scale Canadian met coal assets remained starkly evident. In July, Swiss miner Xstrata pounced on Canadian developer First Coal for $153 million. In mid-August, the coal arm of Anglo American consolidated its stake in the Peace River Coal Partnership. And in early October, Xstrata struck again with the $40 million purchase of Cline Mining's (OTC: CLNMF.PK) Lossan property within that same Peace River Coalfield in British Columbia. Although Grande Cache's met coal assets are located within a distinct coalfield in Alberta, the overarching pattern remains clear: Even met coal deposits of relatively modest scale have leapt onto the radar screens of determined consolidators in a very big way. This suggests to me that the recent collapse in met coal share valuations is likely to prove a short-lived anomaly within a still-anticipated global supercycle for the strategic resource.

How you can outperform my 40% gain
Because the noteworthy 70% premium offered for Grande Cache's shares would appear to make competing bids unlikely, the window of opportunity has probably been slammed shut with respect to that one met coal play. But I encourage Fools to carefully scour the sector for some stocks that could yet yield a similar or even greater return over a relatively brief span. By far my favorite remaining prospect within the sector holds a majority interest in a well-studied property within that same Peace River Coalfield in British Columbia that has clearly garnered the attention of some major operators. Because that stock has dipped deep into micro-cap territory, I will refrain from identifying the company by name, but I am confident that Fools will discover the stock in the course of their own due diligence.

My second-favorite met coal play, meanwhile, is Cline Mining. This budding new producer is busily ramping up production at the New Elk coal mine in Colorado, with a view toward reaching 3 million tons by 2013. In fact, Cline's 2012 production target of 2.75 million tons would place it ahead of Grande Cache's anticipated output of 2.2 million tons for its current 2012 fiscal year! What's more, Cline's measured and indicated resource of 388.5 million tons at New Elk easily exceeds Grande Cache's corresponding cache of 300.8 million tons (measured and indicated resource). Although variations in the precise characteristics of coal products can render direct comparisons of the sort rather problematic, I can't help but to discern compelling value in the notion that Cline's stock would need to advance by more than 200% just to reach the per-ton valuation implied in the recent bid for Grande Cache. When you toss in the $40 million in cash Cline just acquired by monetizing its Lossan deposit, the prospect turns sweeter still. Investors in the U.S. will find Cline Mining trading on the Pink Sheets under the symbol CLNMF.PK, and I strongly recommend a closer look.

In closing, I would remind investors that U.S. coals still have an important role to play in satisfying the enormous demand that will continue to emerge from China, India, and key emerging economies over the next decade or more. For those like me who truly adhere to a long-term perspective even amid remarkable near-term volatility, I believe that gains far in excess of 40% will result for investors building stakes in quality U.S. coal miners during this dramatic correction. After gobbling up the Voldemort of coal stocks -- Massey Energy -- Alpha Natural Resources now trades near its worst levels of the 2008 financial crisis. In part because the resulting entity is an absolute behemoth for met coal production, I consider Alpha Natural Resources a reliable double from here for Fools who are prepared to wait patiently for such a gain.