Shale is having a rock star moment.

Coal is still the real rock star of the sedimentary set, with both Google search results (164 million to a little over 20 million) and New York Times mentions (5,460 to 1,220) dwarfing those of shale over the past year.

Oh, and coal is still the most popular source of energy for electricity in the world.  Ho hum.

But the fossil fuels trapped in shale rock formations have captured  imaginations and economies from New England to the Old West: the Marcellus shale, the Bakken shale, the Barnett shale. Shale is often mentioned with its sister fuel, natural gas. It’s also associated with hydraulic fracturing, an old drilling practice with a new, sci-fi sounding name: fracking. (Why so controversial? You could do worse than watch this video.)

So, we’re hearing a lot about oil shale, shale oil, and oil-bearing shales. Get your shale together and know the difference.

Oil shale is a rock that can be burned for heating or fuel. It’s a lot like coal, but a lot more expensive to drill and process. Although the U.S. has the largest oil shale deposits in the world, we currently don’t extract this fossil fuel at all.

I take that back! We do extract one thing from our shale deposits: Truly awesome fossils.

The oil extracted and processed from oil shale is imaginatively called shale oil. Just for shales and giggles, it can also be called oil-shale oil. Although the U.S. doesn’t use shale oil, other countries (like China, Brazil, and Estonia) rely on it for energy.

Oil-bearing shales, however, are the real rock stars of the moment. Oil-bearing shales are rock (shale) formations with petroleum (oil) or natural gas trapped between layers. The shale is not the fossil fuel in this case. The dense, hard rock has simply created a reservoir deep underground. These reservoirs are often called shale plays.

The Marcellus shale is a shale play stretching from southern New York through Pennsylvania, Ohio, Maryland, West Virginia, and Virginia. It is rich in natural gas. This is the shale play that’s in the news for restoring the economy of the “Rust Belt.” And, uh, flaming water.

The Bakken shale is a shale play in western North Dakota, eastern Montana, and the Canadian province of Saskatchewan. It is rich in both natural gas and petroleum. Thanks to improved drilling technologies, North Dakota is truly “Bakken business”, with one of the most vibrant economies in the nation, and no signs of slowing down.

The Barnett shale is a shale play in northern Texas. Some analysts say it’s the largest natural-gas shale play in the United States, and has created a boom to match the oil boom on Texas’ southern shore.

So, that’s the real shale.

I’ll leave you with one final image I first saw as part of the Bakken cover story in this month’s Harpers. The Daily Mail calls it a “mystery city,” and it’s a haunting, telling complement to the “lights at night” images we’re familiar with.

The bright lights are the big cities of Minneapolis and St. Paul, Minnesota. The glowing regions in northwest are natural gas flares produced by oil wells in the red-hot Bakken.

Actually, do yourself a favor and watch the dazzling time-lapse video stitched together from related footage. You’ll fall in love with the Earth, technology, and science all over again.