“Mount Frac,” a 50,000 ton pile of frac sand in Winona, Minn., blocks from view most of the Winona County Law Enforcement Center. Frac sand is used in fracking, a drilling technique for extracting oil and natural gas. Minnesota environmentalists are trying to slow the spread of frac sand mining. Their efforts have failed so far, the Minneapolis Star Tribune reports. Even a small bill that would block mining within a mile of any trout stream is being resisted in the state legislature by an industry that says additional regulations would kill jobs and economic growth.