They drill down to the shale, then go sideways and inject high-pressure water, sand or other material into the rock.

VOA: special.2009.10.23

Instead,you should use sand from rivers or from other areas of land that are not near the sea.

VOA: special.2009.09.14

For example, you can add sand to prevent tiny breaks or lines from forming in the finished product.

VOA: special.2009.09.14