uncrossed - ussingite
- undulose
- undulose extinction
- unequigranular
- uneven
- uneven contact
- uneven grain
- unevenly spaced observations
- unevenness
- unexpected zone
- unexplored
- unexplored acreage
- unexplored area
- unfaceted
- unfacetted
- unfailing spring
- unfilled
- unfished
- unfixed
- unfixed sand
- unfocused device
- unfocused electric log
- unfocused electric logging
- unfolded
- unfolding
- unfoliated
- unfossiliferous
- unfossiliferous rock
- unfree water
- unfused
- ungaite
- ungemachite
- unglaciated
- unglazed porcelain
- ungrounded circuit
- ungrounded loop
- ungrounded loop method
- ungrounded loop survey
- ungulates
- ungursaite
- ungursayit