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Sinking large-diameter drill holes, Lake Superior district underground iron mines

Support of ground, iron-ore mines, Lake Superior district

Published Year

• 1940-1949 (2)

Subject

• Iron mines and mining--Lake States (2) *
• Ground control (Mining)--Lake States (1)
• Shaft sinking (1)

Author

• Cash, Frank E. (2)
• Johnson, Ernest W. (1)
• Petersen, Max S. (1)

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