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- Minerals 36
- Industries 11
- Gold 10
- Gold mines and mining 6
- Mines and mineral resources 6
- Watersheds 6
- Antiquities 5
- Fossils 5
- Museum exhibits 5
- Oregon--History 5
- University of Oregon 5
- Climate 4
- Economics 4
- Groundwater 4
- Politics and government 4
- Quartz 4
- Staged photography 4
- Agriculture 3
- Building 3
- Dead Sea (Israel and Jordan) 3
