Frac sand destined for the oil and gas fields piles up at the EOG Resources Inc. processing plant in Chippewa Falls, Wisc. Largely overlooked in the national debate over fracking is the emerging fight in the U.S. heartland over mining frac sand, which has grains of ideal size, shape, strength and purity. Mining companies say the work provides good jobs in rural areas, but some residents fear the increase in mining could harm human health and the environment. (AP Photo/Steve Karnowski)
Read the article: Frac sand from Minnesota-Wisconsin border bluffs assists natural gas, oil boom in N.D., elsewhere
