Everyone is talking about shale oil and gas, especially those reserves that are being fracked open across the US.

And everyone seems to have accepted the thesis that the massive uptick in production from unconventional sources in recent years will simply continue on a more or less exponential trajectory, and will catapult the US into an energy independent future. But there is also a growing awareness that shale production, especially as concerns natural gas, is expensive, and outside of massive reserves like the overlapping Marcellus and Utica shales, perhaps even too expensive to continue producing.

Much less is said about oil shale however, perhaps because it sounds the same, so who knows? Be that as it may, oil shale is distinctly different from shale oil. It’s extracted differently, with the oil being heated out of the rock (at temperatures of 600 to 900 degrees) after openings have been fractured, and unlike fracked shale, the US is thought to have the largest reserves on the planet.

For the time being, the technology hasn’t quite caught up, but this is not for lack of effort. Indeed, America’s premiere oil giant, ExxonMobil (XOM) , is quietly working away in Colorado’s Uintah basin to make this plentiful resource an economically viable one as well.

Readers will want to get ahead of the game here, and familiarize themselves with this relatively less heralded national resource. PBS’s Rocky Mountain affiliate aired a program on the subject last year, via its award winning “Colorado State of Mind” program, which serves as a decent introduction to oil shale.