SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue (Details)		3 Months Ended		6 Months Ended
	Jul. 12, 2021 $ / shares	Jul. 31, 2021 USD ($) $ / shares	Jul. 31, 2020 USD ($) $ / shares	Jul. 31, 2021 USD ($) contract item MT $ / shares	Jul. 31, 2020 USD ($) $ / shares	Jan. 31, 2021 USD ($)
Revenue from Contract with Customer [Abstract]
Royalty Revenue		$ 27,744,036	$ 7,218,361	$ 37,146,203	$ 9,353,855
Base overriding royalties, first tier portion percentage				90.00%
Base overriding royalties, first tier shipment ceiling (in million tons) | MT				4
Base overriding royalties, second tier portion percentage				85.00%
Base overriding royalties, second tier shipment ceiling (in million tons) | MT				2
Base overriding royalties, third tier portion percentage				25.00%
Base overriding royalties, third tier shipment threshold (in million tons) | MT				6
Base overriding royalties, number of volume thresholds for transaction price | item				4
Base overriding royalties, volume threshold for transaction price | MT				1
Accrued income receivable		12,634,653		$ 12,634,653		$ 249,477
Number of customer contracts | contract				1
Net contract asset						177,251
Net contract liability		896,931		$ 896,931
Contract asset		5,069,251		5,069,251		239,132
Contract liability		$ 5,966,182		$ 5,966,182		$ 61,881
Distributions declared per unit (in dollars per unit) | $ / shares	$ 0.09	$ 0.0900	$ 0.0500	$ 0.9800	$ 0.6100
Base Overriding Royalties
Revenue from Contract with Customer [Abstract]
Royalty Revenue		$ 16,645,464	$ 4,174,785	$ 22,284,617	$ 5,356,796
Bonus Royalties
Revenue from Contract with Customer [Abstract]
Royalty Revenue		10,910,823	$ 3,043,576	14,483,164	3,823,288
Fee Royalties
Revenue from Contract with Customer [Abstract]
Royalty Revenue		$ 187,749		$ 378,422	$ 173,771