- Published on Monday, 09 January 2012 11:15
- Written by Super User
Nearly three-fourths of frac sand comes from the Midwest. It's shipped by rail hundreds of miles to the oil and gas fields of Texas, Pennsylvania and North Dakota, where drillers mix it with water and chemicals, then force it deep underground to fracture shale deposits that hold gas and oil that couldn't be tapped conventionally. Critics say the process can diminish water quality and even cause earthquakes.