mine — an excavation made in the earth for the purpose of extracting ores, coal, precious stones, etc.
tons — a unit of weight, equivalent to 2000 pounds (0.907 metric ton) avoirdupois (short ton) in the U.S. and 2240 pounds (1.016 metric tons) avoirdupois (long ton) in Great Britain.
iron — Chemistry. a ductile, malleable, silver-white metallic element, scarcely known in a pure condition, but much used in its crude or impure carbon-containing forms for making tools, implements, machinery, etc. Symbol: Fe; atomic weight: 55.847; atomic number: 26; specific gravity: 7.86 at 20°C. Compare cast iron, pig iron, steel, wrought iron.