Quarterly report pursuant to Section 13 or 15(d)

Note 6 - Asset Retirement Obligation (Details Textual)

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Note 6 - Asset Retirement Obligation (Details Textual) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
Mar. 17, 2017
Asset Retirement Obligations, Noncurrent, Total $ 827,000   $ 827,000   $ 790,000 $ 700,000
Accretion Expense, Including Asset Retirement Obligations, Total 12,000 $ 12,000 36,000 $ 34,000    
Contributions to Trust Fund, Amount $ 670,000   $ 670,000