If a mining company extracts 1,500,000 tons in a period but only sells 1,200,000 tons,

		total depletion on the mine is based on the 1,200,000 tons.
		depletion expense is recognized on the 1,500,000 tons extracted.
		depletion expense is recognized on the 1,200,000 tons extracted and sold.
		a separate accumulated depletion account is set up to record depletion on the 300,000 tons extracted but not sold