When shale oil boomed, so did the silica sand that makes fracking possible. But when shale bust, it took the sand business down with it. Some US Midwest sand operations cut staff and halved outputs and many smaller operations closed entirely, as prices tanked to below $40/t. This picture shows a winter stockpile of sand at Superior Silica Sands, in Barron, Wisconsin, where there was nonstop 24/7 action during the boom, but now stop-start listlessness during the bust.