A geological anomaly where a coal seam thins out or disappears entirely, replaced by sandstone or shale. These zones were formed millions of years ago when ancient river channels eroded the peat bed before it lithified, filling the channel with sediment. Hitting a want halts production and forces the mining crew to drive through barren rock to find the seam again.
The continuous miner just hit a want, so we're going to be cutting sandstone for the next fifty feet.
Also heard as
- washout
- nip-out
Related terms
Washout
A channel in a coal seam or orebody where the original deposit was eroded and replaced by barren sediment.
Nip-out
A geological anomaly where a coal seam thins rapidly or disappears completely.
Fault
A planar fracture in a rock volume across which there has been significant displacement.
Trouble
A geological disruption such as a fault or washout that interrupts a coal seam or ore body.