Hull–Rust–Mahoning Open Pit Iron Mine - DM&IR Part One

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The worlds largest open pit iron mine in Minnesota's Mesabi Range. When you play 20 questions, you usually make the "animal/vegetable/mineral" distinction, but the Precambrian deposit of iron ore is the result of the action of bacteria in a much more oxygen rich environment than exists today. These little cyanobacteria oxidized iron molecules in shallow oceans, and the precipitate became the iron ore deposits. The iron ore mined today in the Mesabi needs to be concentrated into Taconite pellets before it can be used at the steel mill. Formerly, the native iron ore was sufficiently rich enough to be shipped directly to the mills. 

In the pit, the big loader is actually scooping up overburden for use as construction aggergate.

Taconite Plant