SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS (Details)	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2010
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS
Percentage of revenue recognized pursuant to the Robinson royalty agreement	3.00%
Minimum
Geographic distribution of royalty revenue and long-lived assets (royalty interests in mineral properties, net)
Period to compute final true-up sales price payments after concentrate arrives at third-party smelter	1 month
Period for concentrate to arrive at the third-party smelter	4 months
Maximum
Geographic distribution of royalty revenue and long-lived assets (royalty interests in mineral properties, net)
Period to compute final true-up sales price payments after concentrate arrives at third-party smelter	3 months
Period for concentrate to arrive at the third-party smelter	5 months
Chile
Geographic distribution of royalty revenue and long-lived assets (royalty interests in mineral properties, net)
Royalty Revenue (as a percent)	25.00%	21.00%	4.00%
Royalty Interests in Mineral Property, net (as a percent)	35.00%	40.00%	42.00%
Canada
Geographic distribution of royalty revenue and long-lived assets (royalty interests in mineral properties, net)
Royalty Revenue (as a percent)	24.00%	19.00%	4.00%
Royalty Interests in Mineral Property, net (as a percent)	43.00%	36.00%	27.00%
Mexico
Geographic distribution of royalty revenue and long-lived assets (royalty interests in mineral properties, net)
Royalty Revenue (as a percent)	20.00%	18.00%	15.00%
Royalty Interests in Mineral Property, net (as a percent)	9.00%	11.00%	13.00%
United States
Geographic distribution of royalty revenue and long-lived assets (royalty interests in mineral properties, net)
Royalty Revenue (as a percent)	18.00%	24.00%	40.00%
Royalty Interests in Mineral Property, net (as a percent)	5.00%	3.00%	5.00%
Africa
Geographic distribution of royalty revenue and long-lived assets (royalty interests in mineral properties, net)
Royalty Revenue (as a percent)	4.00%	9.00%	29.00%
Royalty Interests in Mineral Property, net (as a percent)	1.00%	2.00%	2.00%
Australia
Geographic distribution of royalty revenue and long-lived assets (royalty interests in mineral properties, net)
Royalty Revenue (as a percent)	5.00%	5.00%	5.00%
Royalty Interests in Mineral Property, net (as a percent)	3.00%	5.00%	6.00%
Other
Geographic distribution of royalty revenue and long-lived assets (royalty interests in mineral properties, net)
Royalty Revenue (as a percent)	4.00%	4.00%	3.00%
Royalty Interests in Mineral Property, net (as a percent)	4.00%	3.00%	5.00%