6. Income Tax (Details 1) (USD $)	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Income Tax Details 1
Federal tax at statutory rate	$ 160,000	$ 562,000	$ 451,000	$ 1,145,000
State taxes, net of federal benefit	5,000	27,000	12,000	55,000
Excess percentage depletion	(89,000)	(163,000)	(296,000)	(371,000)
Other adjustments, net	25,000	77,000	34,000	(6,000)
Income tax expense	$ 101,000	$ 503,000	$ 201,000	$ 823,000
Effective rate expressed as a percentage of income before income tax	21.40%	30.40%	15.20%	24.40%