A processing machine used in arid regions to extract heavy minerals, typically gold, from loose surface material without using water. The operator feeds dry pay dirt over a vibrating riffle board while a bellows or motorized fan blows air up through the material. The air current blows away the lighter dust and sand, leaving the dense gold particles trapped behind the riffles.
Heard on the job
You have to make sure the dirt is completely baked by the sun before running it through the dry blower.