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Note 7 - Sales Transaction with KG Mining (Details Textual) |  |  | 1 Months Ended | 12 Months Ended |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2020 USD ($) shares | Sep. 29, 2020 a | Jun. 30, 2021 USD ($) | Sep. 30, 2020 USD ($) shares | Jun. 30, 2021 USD ($) | Jun. 30, 2020 USD ($) | Dec. 31, 2020 | Oct. 01, 2020 | Jun. 30, 2019 USD ($) | Jun. 30, 2018 USD ($) | Jun. 30, 2017 USD ($) | Jun. 30, 2016 USD ($) | Jun. 30, 2015 USD ($) | Jun. 30, 2014 USD ($)
Proceeds from Sale of Equity Method Investments |  |  |  |  | $ 31,250,000 |  |  |  |  |  |  |  |  |
Equity Method Investment, Realized Gain (Loss) on Disposal, Total |  |  |  |  | 39,692,857 |  |  |  |  |  |  |  |  |
Equity Method Investments |  |  |  |  |  |  |  |  |  |  |  |  |  |
Option Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from Sale of Productive Assets, Total |  |  | 50,000 |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Disposition of Assets, Total |  |  | $ 50,000 |  |  |  |  |  |  |  |  |  |  |
The Joint Venture Company [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Invesment, Interest Sold, Percent | 30.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Ownership Percentage | 30.00% | 30.00% | 30.00% | 30.00% | 30.00% |  | 30.00% |  |  |  |  |  |  |
Equity Method Investment, Realized Gain (Loss) on Disposal, Total | $ 39,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Investments | $ 0 |  | $ 0 | $ 0 | $ 0 | $ 0 |  |  |  |  |  |  |  |
The Joint Venture Company [Member] | KG Mining [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Ownership Percentage by Other Owner | 70.00% |  |  | 70.00% |  |  |  |  |  |  |  |  |  |
CORE Alaska [Member] | The Joint Venture Company [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Invesment, Interest Sold, Percent | 30.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from Sale of Equity Method Investments | $ 32,400,000 |  |  | $ 32,400,000 |  |  |  |  |  |  |  |  |  |
Shares Received From Sale of Equity Method Investments (in shares) | shares | 809,744 |  |  | 809,744 |  |  |  |  |  |  |  |  |  |
Sale of Equity Method Investment, Prepayment of Reimbursement | $ 1,200,000 |  |  | $ 1,200,000 |  |  |  |  |  |  |  |  |  |
Percentage Ownership in Company |  |  |  |  |  |  |  | 30.00% |  |  |  |  |  |
Equity Method Investment, Ownership Percentage | 30.00% |  |  | 30.00% |  |  |  |  |  |  |  |  |  |
CORE Alaska [Member] | Contango Minerals [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage Ownership in Company |  | 100.00% |  |  |  |  |  |  |  |  |  |  |  |
KG Mining [Member] | The Joint Venture Company [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of Equity Method Investment, Prepayment of Reimbursement | $ 1,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage Ownership in Company |  |  |  |  |  |  |  | 70.00% |  |  |  |  |  |
KG Mining [Member] | Royal Alaska LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage Ownership in Company | 100.00% |  |  | 100.00% |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Ownership, Shares (in shares) | shares | 809,744 |  |  | 809,744 |  |  |  |  |  |  |  |  |  |
Royal Alaska LLC [Member] | The Joint Venture Company [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Ownership Percentage | 40.00% |  |  | 40.00% |  |  |  |  |  |  |  |  |  |
Contango Minerals [Member] | Separation Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Mining Claims Acquired, Area (Acre) | a |  | 167,000 |  |  |  |  |  |  |  |  |  |  |  |
Net Smelter Returns Royalty Interest, Percent |  | 1.00% |  |  |  |  |  |  |  |  |  |  |  |
The Joint Venture Company [Member] | Separation Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Smelter Returns Silver Royalty, Percent |  | 28.00% |  |  |  |  |  |  |  |  |  |  |  |
The Joint Venture Company [Member] | Option Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Mining Claims, Option to Acquire, Area (Acre) | a |  | 13,000 |  |  |  |  |  |  |  |  |  |  |  |
The Joint Venture Company [Member] | Alaska State Mining Claims [Member] | Separation Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Smelter Returns Royalty Interest, Percent |  | 1.00% |  |  |  |  |  |  |  |  |  |  |  |
Total Net Smelter Returns Royalty, Percent |  | 3.00% |  |  |  |  |  |  |  |  |  |  |  |

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