SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue (Details)	3 Months Ended		6 Months Ended
	Jul. 31, 2020 USD ($)	Jul. 31, 2019 USD ($)	Jul. 31, 2020 USD ($) contract item MT	Jul. 31, 2019 USD ($)	Jan. 31, 2020 USD ($)
Revenue from Contract with Customer [Abstract]
Royalty Revenue	$ 7,218,361	$ 14,301,838	$ 9,353,855	$ 19,663,627
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	1,048,727		$ 1,048,727		$ 69,588
Number of customer contracts | contract			1
Net contract asset	1,059,624		$ 1,059,624
Net contract liability					2,511,720
Contract asset	1,964,472		1,964,472		192,059
Contract liability	904,848		904,848		$ 2,703,779
Base Overriding Royalties
Revenue from Contract with Customer [Abstract]
Royalty Revenue	4,174,785	8,326,504	5,356,796	11,394,522
Bonus Royalties
Revenue from Contract with Customer [Abstract]
Royalty Revenue	$ 3,043,576	5,818,223	3,823,288	7,925,180
Fee Royalties
Revenue from Contract with Customer [Abstract]
Royalty Revenue		$ 157,111	$ 173,771	$ 343,925