Subject
Gold mines and mining
485
Geology
75
Gold mines and mining History
46
Mines and mineral resources
45
Gold mines and mining Environmental aspects
40
Silver mines and mining
30
Gold ores
22
Frontier and pioneer life
20
Hydraulic mining
19
Placer deposits
17
Klondike River Valley (Yukon) Gold discoveries
13
Copper mines and mining
11
Silver mines and mining History
11
Ore deposits
10
Prospecting
10
California Gold discoveries
9
Colorado
9
Gold
9
Treasure troves
9
California Description and travel
8
Colorado History
8
Cripple Creek (Colo.) History
8
Legends
8
Colorado Gold discoveries
7
Water-supply
7
Coal mines and mining
6
Forest management
6
Geology, Economic
6
Mineral industries
6
Placer mining
6
West (U.S.)
6
British Columbia Description and travel
5
Colorado Description and travel
5
Geochemistry
5
Gold Milling
5
Gold industry
5
Mercury Environmental aspects
5
Mercury mines and mining
5
Paleontology
5
Alaska
4
California
4
California History
4
Coal
4
Georgetown (Colo.) History
4
Gold dredging
4
Gold ores Geology
4
Gold panning
4
Kansas
4
Kansas Description and travel
4
Lead mines and mining
4
more ...