The Lorton Company acquired land containing coal. Lorton will restore the land to a condition suitable for recreational use after it has extracted the coal. Geological surveys estimate that the recoverable reserves will be 4,000,000 tons and that the land will have a value of $1 million after restoration. Relevant cost information follows:
Land ................. $12,000,000
Estimated fair value of retirement obligation . 1,200,000

Required
If Lorton maintains no inventories of coal, what is the depletion expense per ton of coal?