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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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