The company said the closure was necessitated by weak volcanic rock above the ore deposit which allowed water to flow into the mine.

FORBES: The perils of mining

Few doubt that the weak yen is the inevitable result of rock-bottom interest rates, which were necessary to pull the economy out of the dumps and to save Japan's troubled banks.

ECONOMIST: The whine of success

The weak link in pavement is bitumen, the black petroleum product that holds the bits of rock together.

FORBES: Uncle Sam's Wild Ideas for Greener Cars