In US shale bust, frack-sand miners are the new coal companies

Three years ago, companies selling frack sand to oil producers were booming, opening multi-million dollar mines, buying rivals and selling shares in what was the hottest niche in oilfield services.

But the shale bust in early March has turned the frack sand mining business into the new coal. As US oil prices plunged, sand suppliers have shut mines, dismissed workers and slashed operations as customers stop drilling and fracking new shale oil wells.

"You can drive by plants and see which ones have already been walked away from," said Peter Allen, a director at closely held Black Mountain Sand, which operates mines in Texas and Oklahoma.

"It will remove a substantial amount of supply and will leave the healthy companies in place," he said, adding Black Mountain sits on enough cash to weather the downturn.