Durango Herald: Like any good story of buried treasure, X marks the spot. In this story, it’s a couple dozen Xes, taped to the side of an ordinary rock face on a corner of Rio Blanco County Road 5, west of Meeker. The Xes mark the outcrop of the Mahogany formation, which gets thicker as it plunges underground. The rocks are made of kerogen, otherwise known as oil shale. Companies have produced oil from these rocks in the past, but they have never done it in a way that makes sense …