ore-leaching tank - pad construction
- original in-place reserves
- original interstices
- original map
- original mineral
- original oil in place
- original order
- original position
- original river
- original rock pressure
- original silt
- original solution
- original stope
- original temperature
- original water line
- originate
- origofacies
- Oriskanian stage
- Oriskany formation
- orletz
- ornament