Plymouth Mining Corporation acquired, for $5,000,000, a tract of land containing an extractable natural resource. Geological surveys estimate that the recoverable reserves will be 1,000,000 tons. Plymouth is required by its purchase contract to restore the land at an estimated cost of $750,000. The land is expected to have a value of $1,250,000 after restoration. Plymouth maintains no inventories of extracted materials. What is the amount of depletion per ton?