Subject
Coal
11
Coal mines and mining
7
Mines and mineral resources
5
Longwall mining
4
Firedamp
3
Mine roof control
3
Mineral industries
3
Acid mine drainage
2
Anthracite coal
2
Coal mine waste
2
Coal mines and mining Environmental aspects
2
Coal mines and mining Safety measures
2
Coalbed methane
2
Ground control (Mining)
2
Longwall mining Safety measures
2
Manganese
2
Mine subsidences
2
Mine ventilation
2
River channels
2
Sediment control
2
Water Pollution
2
Wetlands
2
Abandoned coal mines
1
Abandoned coal mines Environmental aspects
1
Abandoned coal mines Fires and fire prevention
1
Acid mine drainage Environmental aspects
1
Bedford County (Pa.)
1
Bituminous coal
1
Boring
1
Coal Analysis
1
Coal Geology
1
Coal mine accidents
1
Coal mines and mining Dust control
1
Coal preparation
1
Coalbed methane drainage
1
Coalbed methane drainage Testing
1
Coking coal
1
Diamond bits
1
Dredges
1
Elevators
1
Geology
1
Geology Remote sensing
1
Hoisting machinery
1
Huntingdon County (Pa.)
1
Landsat satellites
1
Lead ores
1
Magnetite
1
Methane
1
Microphotography
1
Mine accidents
1
more ...